Change search
Refine search result
12 1 - 50 of 57
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Rows per page
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sort
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
Select
The maximal number of hits you can export is 250. When you want to export more records please use the Create feeds function.
  • 1. A. Hosseini, V.
    et al.
    Karlsson, L.
    Örnek, Cem
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science. Swerea KIMAB AB.
    Reccagni, P.
    Wessman, S.
    Engelberg, D.
    Microstructure and functionality of a uniquely graded super duplex stainless steel designed by a novel arc heat treatment method2018In: Materials Characterization, ISSN 1044-5803, E-ISSN 1873-4189, Vol. 139, p. 390-400Article in journal (Refereed)
    Abstract [en]

    A novel arc heat treatment technique was applied to design a uniquely graded super duplex stainless steel (SDSS), by subjecting a single sample to a steady state temperature gradient for 10 h. A new experimental approach was used to map precipitation in microstructure, covering aging temperatures of up to 1430 °C. The microstructure was characterized and functionality was evaluated via hardness mapping. Nitrogen depletion adjacent to the fusion boundary depressed the upper temperature limit for austenite formation and influenced the phase balance above 980 °C. Austenite/ferrite boundaries deviating from Kurdjumov–Sachs orientation relationship (OR) were preferred locations for precipitation of σ at 630–1000 °C, χ at 560–1000 °C, Cr2N at 600–900 °C and R between 550 °C and 700 °C. Precipitate morphology changed with decreasing temperature; from blocky to coral-shaped for σ, from discrete blocky to elongated particles for χ, and from polygonal to disc-shaped for R. Thermodynamic calculations of phase equilibria largely agreed with observations above 750 °C when considering nitrogen loss. Formation of intermetallic phases and 475 °C-embrittlement resulted in increased hardness. A schematic diagram, correlating information about phase contents, morphologies and hardness, as a function of exposure temperature, is introduced for evaluation of functionality of microstructures.

  • 2.
    Alekseeva, L. A.
    et al.
    Natl Acad Sci Ukraine, B Verkin Inst Low Temp Phys & Engn, 47 Nauky Ave, UA-61103 Kharkov, Ukraine..
    Dobryden, Illia
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science.
    Determination of the low-temperature self-diffusion coefficient in solid p-H-2 from creep experiments2018In: Low temperature physics (Woodbury, N.Y., Print), ISSN 1063-777X, E-ISSN 1090-6517, Vol. 44, no 9, p. 946-951Article in journal (Refereed)
    Abstract [en]

    Dependencies of the relative elongation epsilon under the constantly applied stress at T = 1.8 K on the endurance time t of polycrystalline parahydrogen (p-H-2, similar to 0.2% of o-H-2) of high purity (99.9999 mol.%), with varying deuterium content, were measured. The region of linear dependence between the measured creep rates (epsilon) over dot of samples and the applied stress s was revealed. The conclusion that the low-temperature creep of the studied p-H-2 possesses a vacancy-type diffusion character was made on the basis of linear dependence (epsilon) over dot similar to s. Determination of the low-temperature self-diffusion coefficient of vacancies D in solid p-H-2, which characterizes the rate of low-temperature mass transfer, was performed. The cases of migration of vacancies in the crystal bulk, along boundaries separating individual crystallites, as well as between dislocations existing in crystals, are considered. A significant decrease in the (epsilon) over dot and D values with an increase in the isotope concentration in the samples was observed, while maintaining the linear relationship between (epsilon) over dot and s for the studied p-H-2. Published by AIP Publishing.

  • 3. Angiolini, L.
    et al.
    Valetti, S.
    Cohen, B.
    Feiler, Adam
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science. Nanologica AB, Södertälje, Sweden.
    Douhal, A.
    Fluorescence imaging of antibiotic clofazimine encapsulated within mesoporous silica particle carriers: Relevance to drug delivery and the effect on its release kinetics2018In: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 20, no 17, p. 11899-11911Article in journal (Refereed)
    Abstract [en]

    We report on the encapsulation of the antibiotic clofazimine (CLZ) within the pores of mesoporous silica particles having hydrophilic (CBET value of 137) and more hydrophobic (CBET value of 94 after calcination at 600 °C) surfaces. We studied the effect of pH on the released amount of CLZ in aqueous solutions and observed a maximum at pH 4.1 in correlation with the solubility of the drug. Less release of the drug was observed from the more hydrophobic particles which was attributed to a difference in the affinity of the drug to the carrier particles. Fluorescence lifetime imaging microscopy, emission spectra, and fluorescence lifetimes of single drug loaded particles provided detailed understanding and new knowledge of the physical form of the encapsulated drug and the distribution within the particles. The distribution of CLZ within the particles was independent of the surface chemistry of the particles. The confirmation of CLZ molecules as monomers or aggregates was revealed by controlled removal of the drug with solvent. Additionally, the observed optical "halo effect" in the fluorescent images was interpreted in terms of specific quenching of high concentration of molecules. The emission lifetime experiments suggest stronger interaction of CLZ with the more hydrophobic particles, which is relevant to its release. The results reported in this work demonstrate that tuning the hydrophilicity/hydrophobicity of mesoporous silica particles can be used as a tool to control the release without impacting their loading ability.

  • 4.
    Badal Tejedor, Maria
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science. RISE Research Intitutes of Sweden.
    Pazesh, Samaneh
    Nordgren, Niklas
    Schuleit, Michael
    Rutland, Mark W.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science. RISE Research Intitutes of Sweden.
    Alderborn, Göran
    Millqvist-Fureby, Anna
    Milling induced amorphisation andrecrystallization of α-lactose monohydrate2018In: International Journal of Pharmaceutics, ISSN 0378-5173, E-ISSN 1873-3476, Vol. 537, no 1-2, p. 140-147Article in journal (Refereed)
    Abstract [en]

    Preprocessing of pharmaceutical powders is a common procedure to condition the materials for a better manufacturing performance. However, such operations may induce undesired material properties modifications when conditioning particle size through milling, for example. Modification of both surface and bulk material structure will change the material properties, thus affecting the processability of the powder. Hence it is essential to control the material transformations that occur during milling. Topographical and mechanical changes in surface properties can be a preliminary indication of further material transformations. Therefore a surface evaluation of the alpha-lactose monohydrate after short and prolonged milling times has been performed. Unprocessed alpha-lactose monohydrate and spray dried lactose were evaluated in parallel to the milled samples as reference examples of the crystalline and amorphous lactose structure. Morphological differences between un-processed a-lactose, 1 h and 20 h milled lactose and spray dried lactose were detected from SEM and AFM images. Additionally, AFM was used to simultaneously characterize particle surface amorphicity by measuring energy dissipation. Extensive surface amorphicity was detected after 1 h of milling while prolonged milling times showed only a moderate particle surface amorphisation. Bulk material characterization performed with DSC indicated a partial amorphicity for the 1 h milled lactose and a fully amorphous thermal profile for the 20 h milled lactose. The temperature profiles however, were shifted somewhat in the comparison to the amorphous reference, particularly after extended milling, suggesting a different amorphous state compared to the spraydried material. Water loss during milling was measured with TGA, showing lower water content for the lactose amorphized through milling compared to spray dried amorphous lactose. The combined results suggest a surface-bulk propagation of the amorphicity during milling in combination with a different amorphous structural conformation to that of the amorphous spray dried lactose. The hardened surface may be due to either surface crystallization of lactose or to formation of a low-water glass transition.

  • 5.
    Chang, Tingru
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science.
    Atmospheric corrosion of copper and copper-based alloys in architecture: from native surface oxides to fully developed patinas2018Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Copper and copper-based alloys are commonly used in both ancient and modern architecture. This requires an in-depth fundamental and applied understanding on their atmospheric corrosion behavior at different climatic, environmental and pollutant levels and how these parameters influence e.g. corrosion initiation, patina characteristics, aesthetic appearances, corrosion rates, and runoff rates. This doctoral thesis elucidates the role of native surface oxides on the corrosion performance, corrosion initiation, formation and evolution of corrosion products from hours to months, years and even centuries, to diffuse dispersion of metals from Cu metal/Cu alloy surfaces focusing on the roles of alloying elements, microstructure, and deposition of chlorides. In-depth investigations have been performed at both laboratory and field conditions on commercial Cu metal and copper-based alloys of a golden alloy (Cu5Zn5Al1Sn) and Sn-bronzes (Cu4Sn, Cu6Sn). Patina characteristics and relations to the presence of microstructural inclusions have in addition been investigated for historic patinas of Cu metal roofing of different age and origin, highlighted with data for a 400 years old Cu patina exposed at urban conditions.

    A multi-analytical approach comprising microscopic, spectroscopic and electrochemical methods was employed for in-depth investigations of surface characteristics and bulk properties. Electron backscattered diffraction (EBSD) was utilized to characterize the microstructure. Auger electron spectroscopy (scanning-AES), X-ray photoelectron spectroscopy (XPS), glow discharge optical emission spectroscopy (GDOES) were employed for surface chemical compositional analysis, and atomic absorption spectroscopy (AAS) to assess the amount of metal release from the patinas. Cathodic reduction (CR) and electrochemical impedance spectroscopy (EIS) were used to assess the amount and corrosion resistance of corrosion products formed at laboratory conditions. Confocal Raman micro-spectroscopy (CRM), infrared reflection absorption spectroscopy (IRAS) and grazing incidence X-ray diffraction (GIXRD) were used to identify the phases of corrosion products. Colorimetry was used to assess surface appearances.

    Cu5Zn5Al1Sn and Cu4Sn/Cu6Sn exhibit favorable bulk properties with respect to corrosion in terms of smaller grain size compared with Cu metal and show non-significant surface compositional variations. The presence of multi-component native oxides predominantly composed of Cu2O enriched with Sn-oxides on Cu4Sn/Cu6Sn, and with ZnO, SnO2 and Al2O3 on Cu5Zn5Al1Sn, improves the barrier properties of the native surface oxides and the overall corrosion resistance of Cu4Sn/Cu6Sn and Cu5Zn5Al1Sn. The formation of Zn/Al/Sn-containing corrosion products (e.g. Zn5(CO3)2(OH)6 and Zn6Al2(OH)16CO3·4H2O) significantly reduces the corrosion rate of Cu5Zn5Al1Sn in chloride-rich environments. Alloying with Sn reduces the corrosion rate of Sn-bronze at urban environments of low chloride levels but results in enhanced corrosion rates at chloride-rich marine conditions.

    A clear dual-layer structure patina was observed for centuries-old naturally patinated copper metal with an origin from the roof of Queen Anne's Summer Palace in Prague, the Czech Republic. The patina comprises an inner sub-layer of Cu2O and an outer sub-layer of Cu4SO4(OH)6/Cu3SO4(OH)4. Abundant relatively noble inclusions (mainly rosiaite (PbSb2O6)) were observed and incorporated in both the copper matrix and the patina. The largest inclusions of higher nobility than the surrounding material create significant micro-galvanic effects that result in a fragmentized patina and large thickness ratios between the Cu4SO4(OH)6/Cu3SO4(OH)4 and the Cu2O sub-layer, investigated via a statistical analysis of inclusions and patina characteristics of eight different historic urban copper patinas.

  • 6.
    Chang, Tingru
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science.
    The role of Sn on the long-term atmospheric corrosion of binary Cu-Sn bronze alloys in architectureManuscript (preprint) (Other academic)
  • 7.
    Chang, Tingru
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science. University of Science and Technology Beijing, China.
    Wallinder, Inger Odnevall
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science.
    Jin, Ying
    Leygraf, Christofer
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science.
    The golden alloy Cu-5Zn-5Al-1Sn: A multi-analytical surface characterization2018In: Corrosion Science, ISSN 0010-938X, E-ISSN 1879-0496, Vol. 131, p. 94-103Article in journal (Refereed)
    Abstract [en]

    The golden alloy Cu-5Zn-5Al-1Sn has found many applications because of its appearance and resistance to tarnishing. The microstructure and multi-component surface oxide of Cu-5Zn-5Al-1Sn have been investigated through a multi-analytical approach. Compared to commercial Cu metal, Cu-5Zn-5Al-1Sn has significantly smaller grains and higher fraction of coherent twin boundaries. The 5-10 nm thick oxide formed after diamond polishing has four identified sub-oxides all contributing to the overall corrosion resistance. Cu2O is mainly located in the outer part, followed by ZnO, SnO2 and Al2O3 closer to the alloy substrate. The latter three possess barrier properties, while Cu2O exhibits a more complex structure.

  • 8.
    Cheng, Jie
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science. Tsinghua University, Beijing, China.
    Pan, J.
    Wang, T.
    Lu, X.
    Micro-galvanic corrosion of Cu/Ru couple in potassium periodate (KIO4) solution2018In: Corrosion Science, ISSN 0010-938X, E-ISSN 1879-0496, Vol. 137, p. 184-193Article in journal (Refereed)
    Abstract [en]

    This paper focuses on the study of micro-galvanic corrosion of the Cu/Ru couple in KIO4 solution. Practical nobility across the Cu/Ru interface was evaluated by Volta potential mapping, and the morphological changes were monitored by in-situ atomic force microscopy measurements during exposure in a KIO4 solution. Chemical composition of precipitated corrosion product was analyzed by Confocal Raman spectroscopy immediately after the exposure. The results show that Cu is the anode of the Cu/Ru couple, and accelerated dissolution of Cu preferentially occurs near the Cu/Ru interface. However, subsequent formation of insoluble Cu(IO3)2·nH2O leads to precipitation, which impedes further Cu corrosion.

  • 9.
    Di Bucchianico, Sebastiano
    et al.
    Karolinska Inst, Inst Environm Med, Stockholm, Sweden..
    Gliga, Anda R.
    Karolinska Inst, Inst Environm Med, Stockholm, Sweden..
    Åkerlund, Emma
    Karolinska Inst, Inst Environm Med, Stockholm, Sweden..
    Skoglund, Sara
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science. KTH Royal Inst Technol, Dept Chem Surface & Corros Sci, Stockholm, Sweden..
    Odnevall Wallinder, Inger
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science.
    Fadeel, Bengt
    Karolinska Inst, Inst Environm Med, Stockholm, Sweden..
    Karlsson, Hanna L.
    Karolinska Inst, Inst Environm Med, Stockholm, Sweden..
    Calcium-dependent cyto- and genotoxicity of nickel metal and nickel oxide nanoparticles in human lung cells2018In: Particle and Fibre Toxicology, ISSN 1743-8977, E-ISSN 1743-8977, Vol. 15, article id 32Article in journal (Refereed)
    Abstract [en]

    Background: Genotoxicity is an important toxicological endpoint due to the link to diseases such as cancer. Therefore, an increased understanding regarding genotoxicity and underlying mechanisms is needed for assessing the risk with exposure to nanoparticles (NPs). The aim of this study was to perform an in-depth investigation regarding the genotoxicity of well-characterized Ni and NiO NPs in human bronchial epithelial BEAS-2B cells and to discern possible mechanisms. Comparisons were made with NiCl2 in order to elucidate effects of ionic Ni. Methods: BEAS-2B cells were exposed to Ni and NiO NPs, as well as NiCl2, and uptake and cellular dose were investigated by transmission electron microscopy (TEM) and inductively coupled plasma mass spectrometry (ICP-MS). The NPs were characterized in terms of surface composition (X-ray photoelectron spectroscopy), agglomeration (photon cross correlation spectroscopy) and nickel release in cell medium (ICP-MS). Cell death (necrosis/apoptosis) was investigated by Annexin VFITC/PI staining and genotoxicity by cytokinesis-block micronucleus (cytome) assay (OECD 487), chromosomal aberration (OECD 473) and comet assay. The involvement of intracellular reactive oxygen species (ROS) and calcium was explored using the fluorescent probes, DCFH-DA and Fluo-4. Results: NPs were efficiently taken up by the BEAS-2B cells. In contrast, no or minor uptake was observed for ionic Ni from NiCl2. Despite differences in uptake, all exposures (NiO, Ni NPs and NiCl2) caused chromosomal damage. Furthermore, NiO NPs were most potent in causing DNA strand breaks and generating intracellular ROS. An increase in intracellular calcium was observed and modulation of intracellular calcium by using inhibitors and chelators clearly prevented the chromosomal damage. Chelation of iron also protected against induced damage, particularly for NiO and NiCl2. Conclusions: This study has revealed chromosomal damage by Ni and NiO NPs as well as Ni ionic species and provides novel evidence for a calcium-dependent mechanism of cyto- and genotoxicity.

  • 10. Ekvall, Mikael T.
    et al.
    Hedberg, Jonas
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science.
    Wallinder, Inger Odnevall
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science.
    Hansson, Lars-Anders
    Cedervall, Tommy
    Long-term effects of tungsten carbide (WC) nanoparticles in pelagic and benthic aquatic ecosystems2018In: Nanotoxicology, ISSN 1743-5390, E-ISSN 1743-5404, Vol. 12, no 1, p. 79-89Article in journal (Refereed)
    Abstract [en]

    As the production and usage of nanomaterials are increasing so are the concerns related to the release of the material into nature. Tungsten carbide (WC) is widely used for its hard metal properties, although its use, in for instance tyre studs, may result in nano-sized particles ending up in nature. Here, we evaluate the potential long-term exposure effects of WC nanoparticles on a pelagic (Daphnia magna) and a benthic (Asellus aquaticus) organism. No long-term effects were observed in the benthic system with respect to population dynamics or ecosystem services. However, long-term exposure of D. magna resulted in increased time to first reproduction and, if the particles were resuspended, strong effects on survival and reproductive output. Hence, the considerable differences in acute vs. long-term exposure studies revealed here emphasize the need for more long-term studies if we are to understand the effects of nanoparticles in natural systems.

  • 11.
    Ghamgosar, Pedram
    et al.
    Lulea Univ Technol, Div Mat Sci, Dept Engn Sci & Math, S-97187 Lulea, Sweden..
    Rigoni, Federica
    Lulea Univ Technol, Div Mat Sci, Dept Engn Sci & Math, S-97187 Lulea, Sweden..
    You, Shujie
    Lulea Univ Technol, Div Mat Sci, Dept Engn Sci & Math, S-97187 Lulea, Sweden..
    Dobryden, Illia
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science.
    Kohan, Mojtaba Gilzad
    Lulea Univ Technol, Div Mat Sci, Dept Engn Sci & Math, S-97187 Lulea, Sweden..
    Pellegrino, Anna Lucia
    Univ Catania, Dipartimento Sci Chim, INSTM UdR Catania, Viale A Doria 6, I-95125 Catania, Italy..
    Concina, Isabella
    Lulea Univ Technol, Div Mat Sci, Dept Engn Sci & Math, S-97187 Lulea, Sweden..
    Almqvist, Nils
    Lulea Univ Technol, Div Mat Sci, Dept Engn Sci & Math, S-97187 Lulea, Sweden..
    Malandrino, Graziella
    Univ Catania, Dipartimento Sci Chim, INSTM UdR Catania, Viale A Doria 6, I-95125 Catania, Italy..
    Vomiero, Alberto
    Lulea Univ Technol, Div Mat Sci, Dept Engn Sci & Math, S-97187 Lulea, Sweden..
    ZnO-Cu2O core-shell nanowires as stable and fast response photodetectors2018In: Nano Energy, ISSN 2211-2855, E-ISSN 2211-3282, Vol. 51, p. 308-316Article in journal (Refereed)
    Abstract [en]

    In this work, we present all-oxide p-n junction core-shell nanowires (NWs) as fast and stable self-powered photodetectors. Hydrothermally grown n-type ZnO NWs were conformal covered by different thicknesses (up to 420 nm) of p-type copper oxide layers through metalorganic chemical vapor deposition (MOCVD). The ZnO NWs exhibit a single crystalline Wurtzite structure, preferentially grown along the [002] direction, and energy gap E-g = 3.24 eV. Depending on the deposition temperature, the copper oxide shell exhibits either a crystalline cubic structure of pure Cu2O phase (MOCVD at 250 degrees C) or a cubic structure of Cu2O with the presence of CuO phase impurities (MOCVD at 300 degrees C), with energy gap of 2.48 eV. The electrical measurements indicate the formation of a p-n junction after the deposition of the copper oxide layer. The core-shell photodetectors present a photo-responsivity at 0 V bias voltage up to 7.7 mu A/W and time response <= 0.09 s, the fastest ever reported for oxide photodetectors in the visible range, and among the fastest including photodetectors with response limited to the UV region. The bare ZnO NWs have slow photoresponsivity, without recovery after the end of photo-stimulation. The fast time response for the core-shell structures is due to the presence of the p-n junctions, which enables fast exciton separation and charge extraction. Additionally, the suitable electronic structure of the ZnO-Cu2O heterojunction enables self-powering of the device at 0 V bias voltage. These results represent a significant advancement in the development of low-cost, high efficiency and self-powered photodetectors, highlighting the need of fine tuning the morphology, composition and electronic properties of p-n junctions to maximize device performances.

  • 12. Hagman, H.
    et al.
    Lundberg, Mats
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science.
    Boström, D.
    Alloy Selection for a Cofired Circulating Fluidized Bed Boiler Vortex Finder Application at 880 °c in a Complex Mixed Mode Corrosion Environment2017In: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 31, no 11, p. 12857-12866Article in journal (Refereed)
    Abstract [en]

    X-ray diffraction and scanning electron microscopy (SEM) were used on a corroded industrial-scale circulating fluidized bed (CFB) boiler vortex finder (VF) 253MA alloy plate material to identify the dominating corrosion products and to enable a qualified selection of candidate alloys for the long-term, full-scale exposure study. Alloys 253MA, 310S, 800H/HT, Alloy DS, and Alloy 600 were chosen, and the alloy plates were exposed to the CFB boiler combustion atmosphere having an average temperature of approximately 880 °C, consisting of a moist globally oxidizing gas, burning hydrocarbons, CO2, CO, SO2, HCl, NH3, N2, alkali species, and erosive particles. The exposure times used in this study were 1750, 8000, 12000, and 16000 operating hours. After exposure, the alloy samples were cut, and cross-sections were dry-polished and analyzed with an SEM-backscatter electron detector (BSD) setup to quantify material loss and penetration depth of the corrosion attack. This work suggests two novel concepts: heavily affected depth (HAD) enabling quantitative evaluation of heavily degraded alloys and remaining serviceable metal thickness (RSMT) enabling the use of long-term corrosion data from one alloy to make rough service life estimations of other alloys exposed for significantly shorter periods. The findings of this work show that there is no simple correlation between the heavily affected depth of the alloy and the nickel, chromium, or iron content. Instead, there seem to be two successful alloy composition principles that work well for this application. Furthermore, the work shows that major improvements can be made in terms of both technical life-span and the cost-effectiveness of the VF application if the most appropriate alloy is selected. In this study, a replacement of the frequently used Alloy 253MA with Alloy 310S doubled the lifespan of full-scale VFs, reducing the average VF maintenance cost to half.

  • 13.
    Hariramabadran Anantha, Krishnan
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science.
    An Experimental Study to Understand the Localized Corrosion and Environment-Assisted Cracking Behavior of AISI 420-Martensitic Stainless Steel2018Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Motivation and aim: Currently steel molds are designed with cooling channels to reduce the solidification time of molten plastic within the mold to improve the productivity. As water is generally used as the cooling medium, corrosion and environment-assisted cracking (EAC) leading towards the dysfunction of mold, can increase the production downtime. This was observed in some cases. Hence the primary aim of this thesis is to study the corrosion and EAC behavior of a martensitic stainless steel (MSS) in Cl containing environment to further the current understanding thereby to optimize the existing alloy/s and to design and develop new steel grades.

    Methods: The MSS had been austenitised at 1020°C, and subsequently quenched in nitrogen gas at fast (3°C/s), and slow quenching rates (0.6°C/s). Then tempering was done at 250°C, and 500°C, respectively, twice for two hours. Microstructure was predicted and characterized using Thermocalc simulation, dilatometry, light optical microscopy, scanning electron microscopy, energy dispersive X-ray spectroscopy, X-ray diffraction, atomic force microscopy (AFM). Localized corrosion behavior was characterized using standard salt spray test, electrochemical experiments, scanning Kelvin probe force microscopy, in-situ AFM. Stress relaxation associated with 250°C, and 500°C tempering was characterized by a new method for both fast (FQ) and slow quenched (SQ) conditions. Based on the %stress relaxation, initial loading levels were altered and the corresponding environment-assisted cracking behavior was investigated at two different loading levels.

    Results: Samples tempered at 250ºC exhibited higher corrosion resistance than samples tempered at 500ºC in both FQ and SQ conditions. FQ samples exhibited higher corrosion resistance with an ability to passivate than SQ samples when tempered at 250ºC. However, when tempered at 500°C, the corrosion resistance was poor for both FQ and SQ samples. These observed differences clearly indicate the strong influence of microstructure on the corrosion behavior of the material. There are preferential active sites in the microstructure, which dictate the sequence of corrosion events. Secondary Cr-rich carbides formed during 500ºC tempering apparently deteriorate the corrosion resistance in spite of their smaller sizes as compared to undissolved Cr-rich carbides.  Stress relaxation increased with increasing tempering temperature. In the FQ condition, 250°C temper exhibited superior EAC resistance than 500°C temper in both loading scenarios, indicating the dominant role of corrosion resistance in delaying the failure. Whereas in SQ condition, 500°C temper exhibited superior EAC resistance than 250°C temper in both loading scenarios, indicating the dominant role of applied stress in delaying the failure. The pitting susceptibility increased with increasing applied stress on both FQ and SQ conditions. The fractographic features suggest that the mechanism of failure was mixed mode involving both active path dissolution and hydrogen embrittlement, which could have been operative during the failure in varying magnitude in respective scenarios. 

    Conclusions: Based on this research work, it can be concluded that, in order to have a longer service life, both the localized corrosion behavior and the residual stresses are to be considered while recommending tempering temperature to mold makers.

  • 14.
    Hariramabadran Anantha, Krishnan
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science.
    Ejnermark, Sebastian
    Medvedeva, Anna
    Sjöström, Johnny
    Pan, Jinshan
    Corrosion Behavior of a Martensitic Stainless Steel AISI 420 Modified From a Mold Size Point of View2016Conference paper (Refereed)
  • 15.
    Hariramabadran Anantha, Krishnan
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science.
    Örnek, Cem
    Ejnermark, Sebastian
    Medvedeva, Anna
    Sjöström, Johnny
    Pan, Jinshan
    Effect of residual stress on environmentally assisted cracking behavior of slow quenched AISI 420martensitic stainless steel tempered at 250°C and 500°CManuscript (preprint) (Other academic)
  • 16.
    Hariramabadran Anantha, Krishnan
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science.
    Örnek, Cem
    Ejnermark, Sebastian
    Thuvander, Anders
    Medvedeva, Anna
    Sjöström, Johnny
    Pan, Jinshan
    Experimental and modelling study of the effects of tempering on the susceptibility to environment-assisted cracking of AISI 420 martensitic stainless steelManuscript (preprint) (Other academic)
  • 17.
    He, Yunjuan
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science.
    Dobryden, Illia
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science.
    Pan, Jinshan
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science.
    Ahniyaz, Anwar
    RISE Res Inst Sweden, Div Biosci & Mat, SE-11486 Stockholm, Sweden..
    Deltin, Tomas
    PTE Coatings AB, Hammarsvagen 4, SE-59432 Gamleby, Sweden..
    Corkery, Robert W.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science.
    Claesson, Per M.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science.
    Nano-scale mechanical and wear properties of a waterborne hydroxyacrylic-melamine anti-corrosion coating2018In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 457, p. 548-558Article in journal (Refereed)
    Abstract [en]

    Corrosion protection is commonly achieved by applying a thin polymer coating on the metal surface. Many studies have been devoted to local events occurring at the metal surface leading to local or general corrosion. In contrast, changes occurring in the organic coating after exposure to corrosive conditions are much less studied. In this article we outline how changes in the coating itself due to curing conditions, environmental and erosion effects can be investigated at the nanometer scale, and discuss how such changes would affect its corrosion protection performance. We focus on a waterborne hydroxyacrylic-melamine coating, showing high corrosion protection performance for carbon steel during long-term (approximate to 35 days) exposure to 0.1 M NaCl solution. The effect of curing time on the conversion of the crosslinking reaction within the coating was evaluated by fourier transform infrared spectroscopy (FTIR); the wetting properties of the cured films were investigated by contact angle measurement, and the corrosion resistance was studied by electrochemical impedance spectroscopy (EIS). In particular, coating nanomechanical and wear properties before and after exposure to 0.1 M NaCl, were evaluated by atomic force microscopy (AFM). Fiber-like surface features were observed after exposure, which are suggested to arise due to diffusion of monomers or low molecular weight polymers to the surface. This may give rise to local weakening of the coating, leading to local corrosion after even longer exposure times. We also find a direct correlation between the stick-slip spacing during shearing and plastic deformation induced in the surface layer, giving rise to topographical ripple structures on the nanometer length scale.

  • 18.
    Hedberg, Yolanda
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science. Institute of Environmental Medicine, Karolinska Institute, Stockholm, Sweden.
    Erfani, Behnaz
    Institute of Environmental Medicine, Karolinska Institute, Stockholm, Sweden.
    Matura, Mihály
    Institute of Environmental Medicine, Karolinska Institute, Stockholm, Sweden ; Unit of Occupational and Environmental Dermatology, Centre for Occupational and Environmental Medicine, Stockholm County Council, Stockholm, Sweden.
    Lidén, Carola
    Institute of Environmental Medicine, Karolinska Institute, Stockholm, Sweden.
    Chromium(III) release from chromium-tanned leather elicits allergic contact dermatitis: a use test study.2018In: Contact Dermatitis, ISSN 0105-1873, E-ISSN 1600-0536, Vol. 78, no 5, p. 307-314Article in journal (Refereed)
    Abstract [en]

    BACKGROUND: Chromium (Cr) is a common skin sensitizer. The use of Cr(VI) in leather is restricted in the EU, but that of Cr(III) is not.

    OBJECTIVES: To assess whether prolonged exposure to Cr-tanned leather with mainly Cr(III) release may elicit allergic contact dermatitis in Cr-allergic individuals.

    METHOD: Ten Cr-allergic subjects and 22 controls were patch tested with serial dilutions of Cr(III) and Cr(VI), and with leather samples. They then conducted a use test with a Cr-tanned and a Cr-free leather bracelet over a period of 3 weeks, for 12 h per day. Cr deposited on the skin from the bracelets was measured in the controls, and the diphenylcarbazide test for Cr(VI) and extraction tests for Cr(III) and Cr(VI) were conducted for the different leathers.

    RESULTS: Four of 10 Cr-allergic subjects developed positive reactions to the Cr-tanned bracelet within 7-21 days, whereas only 1 of 10 had a positive patch test reaction to this leather. Cr released from the Cr-tanned leather was most probably entirely Cr(III), with a quantifiable amount being deposited on the skin.

    CONCLUSIONS: This study strongly suggests that prolonged and repeated exposure to Cr-tanned leather with mainly Cr(III) release is capable of eliciting allergic contact dermatitis in Cr-allergic individuals.

  • 19.
    Hedberg, Yolanda
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science.
    Uter, W.
    Banerjee, P.
    Lind, M. -L
    Skovvang Steengaard, S.
    Teo, Y.
    Lidén, C.
    Non-oxidative hair dye products on the European market: What do they contain?2018In: Contact Dermatitis, ISSN 0105-1873, E-ISSN 1600-0536, Vol. 79, no 5, p. 281-287Article in journal (Refereed)
    Abstract [en]

    Background: Hair dyeing is very common and may cause allergic contact dermatitis. Oxidative (often termed permanent or semi-permanent) hair dye products have constituted the focus of market surveys and toxicological risk assessments, while non-oxidative (semi-permanent, temporary or direct) products have not been assessed. Objectives: To identify the hair dye substances presently used in non-oxidative hair dye products in Europe. Methods: Ingredient label data on eligible products in 5 European countries were collected, and 289 different non-oxidative hair dye products were included in this study. Results: Up to 9 hair dye substances were present in each product. Sixty-eight individual hair dye substances were identified on the 289 product labels, and their occurrence ranged from 0.3% to 34%. There were differences concerning substances used and their number per product between products of different consistency and colour. Conclusions: The hair dye substances in non-oxidative hair dye products are different from those in oxidative hair dye products, and are currently not covered by patch test series. The toxicological and skin-sensitizing profile of the substances in non-oxidative hair dye products, as well as their concentrations, should be further investigated.

  • 20.
    Hedberg, Yolanda
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science.
    Uter, Wolfgang
    Univ Erlangen Nurnberg, Dept Med Informat Biometry & Epidemiol, Erlangen, Germany..
    Banerjee, Piu
    Guys Hosp, St Johns Inst Dermatol, London, England.;Lewisham & Greenwich NHS Trust, London, England..
    Lind, Marie-Louise
    Stockholm Cty Council, Ctr Occupat & Environm Med, Stockholm, Sweden..
    Steengaard, Sanne Skovvang
    Univ Hosp Herlev Gentofte, Natl Allergy Res Ctr, Hellerup, Denmark..
    Teo, Ying
    Guys Hosp, St Johns Inst Dermatol, London, England..
    Liden, Carola
    Karolinska Inst, Inst Environm Med, Box 210, SE-17177 Stockholm, Sweden..
    Non-oxidative hair dye products on the European market: What do they contain?2018In: Contact Dermatitis, ISSN 0105-1873, E-ISSN 1600-0536, Vol. 79, no 5, p. 281-287Article in journal (Refereed)
    Abstract [en]

    Background: Hair dyeing is very common and may cause allergic contact dermatitis. Oxidative (often termed permanent or semi-permanent) hair dye products have constituted the focus of market surveys and toxicological risk assessments, while non-oxidative (semi-permanent, temporary or direct) products have not been assessed. Objectives: To identify the hair dye substances presently used in non-oxidative hair dye products in Europe. Methods: Ingredient label data on eligible products in 5 European countries were collected, and 289 different non-oxidative hair dye products were included in this study. Results: Up to 9 hair dye substances were present in each product. Sixty-eight individual hair dye substances were identified on the 289 product labels, and their occurrence ranged from 0.3% to 34%. There were differences concerning substances used and their number per product between products of different consistency and colour. Conclusions: The hair dye substances in non-oxidative hair dye products are different from those in oxidative hair dye products, and are currently not covered by patch test series. The toxicological and skin-sensitizing profile of the substances in non-oxidative hair dye products, as well as their concentrations, should be further investigated.

  • 21.
    Herting, Gunilla
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science.
    Karlsson, Maria-Elisa
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science.
    Odnevall Wallinder, Inger
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science.
    A novel method to assess mass loss of aluminium in concrete2018In: Materials and corrosion - Werkstoffe und Korrosion, ISSN 0947-5117, E-ISSN 1521-4176Article in journal (Refereed)
    Abstract [en]

    A novel pickling procedure for aluminium is elaborated for successful removal of corrosion products on aluminium embedded and exposed in concrete, allowing subsequent mass loss evaluation. The current recommended standard procedures for mass loss evaluation of aluminium are not sufficiently effective, either leaving significant amounts of concrete and corrosion products on the aluminium surfaces after pickling, or containing hazardous chemicals. Removal of both concrete and corrosion products from the aluminium surfaces require a stepwise combination of an aqueous glycine solution, nitric acid at elevated temperature and careful manual removal of adherent concrete.

  • 22. Hosseinpour, S.
    et al.
    Leygraf, Christopher
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science.
    Gretic, Z. H.
    Mioc, E. K.
    Curkovic, H. O.
    Bochmann, S.
    Bachmann, J.
    Waegner, V.
    Virtanen, S.
    Peukert, W.
    Self-assembled monolayers as corrosion inhibitors; indoor, marine and biologically relevant exposure2017In: EUROCORR 2017 - The Annual Congress of the European Federation of Corrosion, 20th International Corrosion Congress and Process Safety Congress 2017, Asociace koroznich inzenyru z.s.- AKI - Czech Association of Corrosion Engineers , 2017Conference paper (Refereed)
  • 23. Jin, Ying
    et al.
    Lai, Zhaogui
    Bi, Peng
    Yan, Songtao
    Wen, Lei
    Wang, Yongchao
    Pan, Jinshan
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science.
    Leygraf, Christofer
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science.
    Combining lithography and capillary techniques for local electrochemical property measurements2018In: Electrochemistry communications, ISSN 1388-2481, E-ISSN 1873-1902, Vol. 87, p. 53-57Article in journal (Refereed)
    Abstract [en]

    The relationships between composition, microstructure and electrochemical properties are of fundamental importance in understanding the corrosion of multiphase materials and thus in aiding in the design of new materials. A local electrochemical test system which combines a capillary device with a photolithographic mask has been developed to investigate the local electrochemical properties of a predefined micron-sized area with greater reliability and versatility than existing approaches. Independent electrochemical measurements were conducted on the different phases of a 2205 duplex stainless steel in NaCl solution, demonstrating the feasibility of the developed test system.

  • 24.
    Kaestner, Bernd
    et al.
    PTB, Abbestr 2-12, D-10587 Berlin, Germany..
    Johnson, C. Magnus
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science.
    Hermann, Peter
    PTB, Abbestr 2-12, D-10587 Berlin, Germany.;Deutschland GmbH & Co KG, West Pharmaceut Serv, Stolberger Str 21-41, D-52249 Eschweiler, Germany..
    Kruskopf, Mattias
    PTB, Bundesallee 100, D-38116 Braunschweig, Germany.;NIST, 100 Bur Dr, Gaithersburg, MD 20899 USA..
    Pierz, Klaus
    PTB, Bundesallee 100, D-38116 Braunschweig, Germany..
    Hoehl, Arne
    PTB, Abbestr 2-12, D-10587 Berlin, Germany..
    Hornemann, Andrea
    PTB, Abbestr 2-12, D-10587 Berlin, Germany..
    Ulrich, Georg
    PTB, Abbestr 2-12, D-10587 Berlin, Germany..
    Fehmel, Jakob
    PTB, Abbestr 2-12, D-10587 Berlin, Germany..
    Patoka, Piotr
    Free Univ Berlin, Inst Chem & Biochem, Phys Chem, Takustr 3, D-14195 Berlin, Germany..
    Ruehl, Eckart
    Free Univ Berlin, Inst Chem & Biochem, Phys Chem, Takustr 3, D-14195 Berlin, Germany..
    Ulm, Gerhard
    PTB, Abbestr 2-12, D-10587 Berlin, Germany..
    Infrared Nanospectroscopy of Phospholipid and Surfactin Monolayer Domains2018In: ACS OMEGA, ISSN 2470-1343, Vol. 3, no 4, p. 4141-4147Article in journal (Refereed)
    Abstract [en]

    A main challenge in understanding the structure of a cell membrane and its interactions with drugs is the ability to chemically study the different molecular species on the nanoscale. We have achieved this for a model system consisting of mixed monolayers (MLs) of the biologically relevant phospholipid 1,2-distearoyl-sn-glycero-phosphatidylcholine and the antibiotic surfactin. By employing nano-infrared (IR) microscopy and spectroscopy in combination with atomic force microscopy imaging, it was possible to identify and chemically detect domain formation of the two constituents as well as to obtain IR spectra of these species with a spatial resolution on the nanoscale. A novel method to enhance the near-field imaging contrast of organic MLs by plasmon interferometry is proposed and demonstrated. In this technique, the organic layer is deposited on gold and ML graphene substrates, the latter of which supports propagating surface plasmons. Plasmon reflections arising from changes in the dielectric environment provided by the organic layer lead to an additional contrast mechanism. Using this approach, the interfacial region between surfactin and the phospholipid has been mapped and a transition region is identified.

  • 25. Kawada, S.
    et al.
    Watanabe, Seiya
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science.
    Tadokoro, C.
    Sasaki, S.
    Effects of Alkyl Chain Length of Sulfate and Phosphate Anion-Based Ionic Liquids on Tribochemical Reactions2018In: Tribology letters, ISSN 1023-8883, E-ISSN 1573-2711, Vol. 66, no 1, article id 8Article in journal (Refereed)
    Abstract [en]

    Ionic liquids are expected to become increasingly popular lubricants as they feature a number of attractive properties. This investigation focused on sulfate and phosphate anion-based ionic liquids and the improvement in lubricating performance with the addition of these anions. However, the detailed lubricating mechanism and effect of alkyl chain length on tribochemical reactions are unclear. This study investigates tribochemical reaction processes using a quadrupole mass spectrometer (Q-MS) and X-ray photoelectron spectroscopy. Seven types of ionic liquids: 1-ethyl-3-methylimidazolium hydrogensulfate ([EMIM][HSO4]), 1-ethyl-3-methylimidazolium methylsulfate ([EMIM][MSU]), 1-ethyl-3-methylimidazolium ethylsulfate ([EMIM][ESU]), 1-ethyl-3-methylimidazolium n-octylsulfate ([EMIM][OSU]), 1-ethyl-3-methylimidazolium dimethyl phosphate ([EMIM][DMP]), 1-ethyl-3-methylimidazolium diethyl phosphate ([EMIM][DEP]), and 1-ethyl-3-methylimidazolium dibutyl phosphate ([EMIM][DBP]), were selected as lubricants. The friction coefficient of sulfate anion-based ionic liquids increased as their alkyl chain lengthened. However, wear scar diameter in this case showed the opposite tendency. The friction coefficient and wear scar diameter of phosphate anion-based ionic liquids increased with an increase in the alkyl chain length. Q-MS results indicated that the main outgassing components during sliding were the cation components, whereas the anion remained on the sliding surface and formed a tribofilm. The ionic liquids with short alkyl chains reacted with the sliding surface easily and led to very low friction. However, corrosive wear occurred in the case of the sulfate anion. On the other hand, anions with long alkyl chains underwent gradual tribochemical reactions because that led the mitigation of contact with nascent surface. The phosphate-based ionic liquids with long alkyl chains were unable to cause the lubricating effect due to low reactivity.

  • 26. Kawada, S.
    et al.
    Watanabe, Seiya
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science.
    Tadokoro, C.
    Tsuboi, R.
    Sasaki, S.
    Lubricating mechanism of cyano-based ionic liquids on nascent steel surface2018In: Tribology International, ISSN 0301-679X, E-ISSN 1879-2464, Vol. 119, p. 474-480Article in journal (Refereed)
    Abstract [en]

    This study investigates the lubricating mechanism of cyano-based ionic liquids on steel surfaces using Q-MS, ToF-SIMS, and TGA. [EMIM][DCN], [EMIM][TCC], [EMIM][TCB], [BMPL][DCN], [BMPL][TCC], and [BMPL][TCB] were selected as lubricants. [EMIM][TCB] exhibited the highest friction coefficient. The others exhibited very low friction coefficients of less than 0.08. Q-MS analysis indicated that the cation components were detected in outgassing during sliding tests. However, anion components were not detected. ToF-SIMS results showed that the anions remained on the worn surfaces which would lead low friction coefficients. To achieve low friction coefficient, the tribo-decomposition of the ionic liquids and adsorption of anion were required. TGA indicated thermal stability was an index for tribo-decomposition on the nascent steel surface.

  • 27. Kawada, Shouhei
    et al.
    Sato, Keisuke
    Watanabe, Seiya
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science.
    Sasaki, Shinya
    Lubricating property of cyano-based ionic liquids against hard materials2017In: Journal of Mechanical Science and Technology, ISSN 1738-494X, E-ISSN 1976-3824, Vol. 31, no 12, p. 5745-5750Article in journal (Refereed)
    Abstract [en]

    Ionic liquids are expected to be used as a new lubricants and lubricant additives because of their unique properties. However, cyano-based ionic liquids have exhibited poor lubricating property with steel/steel contacts. We evaluated the lubricating properties of cyano-based ionic liquids with steel/hard materials contacts. TiO2, Al2O3, and tetrahedral amorphous carbon (ta-C) DLC were used as hard materials. Six types of ionic liquids, as combination of two types of cations ([EMIM], [BMPL]) and three types of cyanide anions ([DCN], [TCC] and [TCB]), were selected. In sliding tests of steel/TiO2 and steel/Al2O3 lubricated with [EMIM][DCN], [BMPL][DCN], [EMIM][TCC], [BMPL][TCC] exhibited low friction coefficients of less than 0.1. In addition, steel/Al2O3 and steel/ta-C DLC lubricated with [BMPL][TCB] exhibited very low friction coefficients less than 0.05. On the other hand, high friction coefficients were observed at steel/TiO2 and steel/Al2O3 contacts lubricated with [EMIM][TCB] and steel/ta-C DLC contact lubricated with [EMIM] cation group. Peeling of the ta-C DLC was observed when [EMIM] cation group was used. ToF-SIMS analysis indicated that the anion was adsorbed on the worn surfaces in the case of low frictional conditions. However, both ions were hardly observed in the case of high frictional conditions. It is considered that the ionic liquids underwent tribo-decomposition on the worn surfaces at low friction coefficient. To evaluate the degree of tribo-decomposition, Thermogravimetric analysis (TGA) was used. TGA results indicated that [EMIM][TCB], which exhibited high friction coefficient, had the most highest stability among all ionic liquids. Low stability ionic liquids, however, showed a tendency for low friction coefficient. These results suggest that lubricating properties are related to the stability of ionic liquids.

  • 28.
    Kharitonov, Dmitry S.
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science. Belarusian State Technol Univ, Chem Technol & Engn Fac, Dept Chem Electrochem Prod Technol & Mat Elect Eq, Minsk 220006, BELARUS..
    Örnek, Cem
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science. Swerea KIMAB, Dept Corros Energy & Proc Ind, SE-16440 Kista, Sweden..
    Claesson, Per M.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science.
    Sommertune, Jens
    RISE Res Inst Sweden, Chem Mat & Surfaces, SE-11486 Stockholm, Sweden..
    Zharskii, Ivan M.
    Belarusian State Technol Univ, Chem Technol & Engn Fac, Dept Chem Electrochem Prod Technol & Mat Elect Eq, Minsk 220006, BELARUS..
    Kurilo, Irina I.
    Belarusian State Technol Univ, Organ Subst Technol Fac, Dept Phys Colloid & Analyt Chem, Minsk 220006, BELARUS..
    Pan, Jinshan
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science.
    Corrosion Inhibition of Aluminum Alloy AA6063-T5 by Vanadates: Microstructure Characterization and Corrosion Analysis2018In: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 165, no 3, p. C116-C126Article in journal (Refereed)
    Abstract [en]

    Corrosion inhibition of aluminum alloy AA6063-T5 by vanadates (NaVO3) in 0.05 M NaCl solution has been investigated by electrochemical and weight loss measurements, and associated with microstructure and Volta potential data. X-ray diffraction, scanning electron microscopy, and energy dispersive spectroscopy analyses confirmed the presence of micrometer-sized Fe-rich Al4.01MnSi0.74, Al1.69Mg4Zn2.31, and FeAl3 intermetallic phases (IMPs) and nanometer-sized CuAl2, ZnAl2, and Mg2Si precipitates in the microstructure. Scanning Kelvin probe force microscopy measurements showed Volta potential differences of up to 600 mV between the microstructure constituents indicating a high susceptibility to micro-galvanic corrosion, with interphase boundary regions exhibiting the highest propensity to corrosion. Most IMPs had cathodic character whereas some nanometer-sized Mg-rich particles exhibited anodic nature, with large Volta potential gradients within interphase regions of large cathodic particles. Electrochemical potentiodynamic polarization measurements indicated that the vanadates provided mixed corrosion inhibition effects, mitigating both oxygen reduction, occurring on cathodic IMPs, and anodic metal dissolution reaction, occurring on anodic sites, such as Mg2Si and interphase boundary regions. Electrochemical measurements indicated that the sodium metavanadate inhibitor blocks active metal dissolution, giving high inhibition efficiency (>95%) during the initial exposure, whereas long-term weight loss measurements showed that the efficacy decreases after prolonged exposure.

  • 29.
    Koppolu, Rajesh
    et al.
    Abo Akad Univ, Lab Paper Coating & Converting, Ctr Funct Mat, SF-20500 Turku, Finland..
    Abitbol, Tiffany
    RISE Res Inst Sweden, Biosci & Mat Surface Proc & Formulat, S-11428 Stockholm, Sweden..
    Kumar, Vinay
    Abo Akad Univ, Lab Paper Coating & Converting, Ctr Funct Mat, SF-20500 Turku, Finland.;Finland Ltd, VTT Tech Res Ctr, High Performance Fiber Prod, Espoo 02044, Finland..
    Jaiswal, Aayush Kumar
    Abo Akad Univ, Lab Paper Coating & Converting, Ctr Funct Mat, SF-20500 Turku, Finland..
    Swerin, Agne
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science. RISE Res Inst Sweden, Biosci & Mat Surface Proc & Formulat, S-11428 Stockholm, Sweden..
    Toivakka, Martti
    Abo Akad Univ, Lab Paper Coating & Converting, Ctr Funct Mat, SF-20500 Turku, Finland..
    Continuous roll-to-roll coating of cellulose nanocrystals onto paperboard2018In: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, Vol. 25, no 10, p. 6055-6069Article in journal (Refereed)
    Abstract [en]

    There is an increased interest in the use of cellulose nanocrystal (CNC) films and coatings for a range of functional applications in the fields of material science, biomedical engineering, and pharmaceutical sciences. Most of these applications have been demonstrated on films and coatings produced using laboratory-scale batch processes, such as solvent casting, dip coating, or spin coating. For successful coating application of CNC suspensions using a high throughput process, several challenges need to be addressed: relatively high viscosity at low solids content, coating brittleness, and potentially poor adhesion to the substrate. This work aims to address these problems. The impact of plasticizer on suspension rheology, coating adhesion, and barrier properties was quantified, and the effect of different pre-coatings on the wettability and adhesion of CNC coatings to paperboard substrates was explored. CNC suspensions were coated onto pre-coated paperboard in a roll-to-roll process using a custom-built slot die. The addition of sorbitol reduced the brittleness of the CNC coatings, and a thin cationic starch pre-coating improved their adhesion to the paperboard. The final coat weight, dry coating thickness, and coating line speed were varied between 1-11 g/m(2), 900 nm-7 A mu m, and 2.5-10 m/min, respectively. The barrier properties, adhesive strength, coating coverage, and smoothness of the CNC coatings were characterized. SEM images show full coating coverage at coat weights as low as 1.5 g/m(2). With sorbitol as plasticizer and at coat weights above 3.5 g/m(2), heptane vapor and water vapor transmission rates were reduced by as much as 99% and 75% respectively. Compared to other film casting techniques, the process employed in this work deposits a relatively thick coating in significantly less time, and may therefore pave the way toward various functional applications based on CNCs. [GRAPHICS] .

  • 30.
    Kozhuharov, Svilen
    et al.
    Univ Geneva, Dept Inorgan & Analyt Chem, Sci 2, 30 Quai Ernest Ansermet, CH-1205 Geneva, Switzerland..
    Radiom, Milad
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science. Univ Geneva, Dept Inorgan & Analyt Chem, Sci 2, 30 Quai Ernest Ansermet, CH-1205 Geneva, Switzerland..
    Maroni, Plinio
    Univ Geneva, Dept Inorgan & Analyt Chem, Sci 2, 30 Quai Ernest Ansermet, CH-1205 Geneva, Switzerland..
    Borkovec, Michal
    Univ Geneva, Dept Inorgan & Analyt Chem, Sci 2, 30 Quai Ernest Ansermet, CH-1205 Geneva, Switzerland..
    Persistence Length of Poly(vinyl amine): Quantitative Image Analysis versus Single Molecule Force Response2018In: Macromolecules, ISSN 0024-9297, E-ISSN 1520-5835, Vol. 51, no 10, p. 3632-3639Article in journal (Refereed)
    Abstract [en]

    Single molecules of poly(vinyl amine) are analyzed in the adsorbed state by atomic force microscopy (AFM) in two different ways. First, high-resolution images of individual adsorbed polymers were recorded in monovalent electrolyte solutions. The backbone of the imaged polymers was digitized, and the directional correlation function and internal mean-square end-to-end distance were evaluated. These quantities were analyzed with the wormlike chain (WLC) model, and the persistence length was extracted. Second, individual polymer chains were picked up from the surface, and their force extension behavior was recorded in the same electrolyte solutions. These force profiles were also interpreted in terms of the WLC model, whereby the elastic contribution was also considered. Both techniques yield the persistence length of the polymer. From imaging one obtains a persistence length of about 1.6 nm, while the force experiments yield a value around 0.51 nm. We suspect that the force experiments reflect the intrinsic part of the persistence length, while the imaging experiments yield the persistence length including the electrostatic

  • 31.
    Lebedova, Jana
    et al.
    Karolinska Inst, Inst Environm Med, Nobels Vag 13, S-17177 Stockholm, Sweden.;Masaryk Univ, RECETOX, Kamenice 753-5,Pavilon A29, CZ-62500 Brno, Czech Republic..
    Hedberg, Yolanda
    Odnevall Wallinder, Inger
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science.
    Karlsson, Hanna L.
    Karolinska Inst, Inst Environm Med, Nobels Vag 13, S-17177 Stockholm, Sweden..
    Size-dependent genotoxicity of silver, gold and platinum nanoparticles studied using the mini-gel comet assay and micronucleus scoring with flow cytometry2018In: Mutagenesis, ISSN 0267-8357, E-ISSN 1464-3804, Vol. 33, no 1, p. 77-85Article in journal (Refereed)
    Abstract [en]

    Metallic nanoparticles (NPs) are promising nanomaterials used in different technological solutions as well as in consumer products. Silver (Ag), gold (Au) and platinum (Pt) represent three metallic NPs with current or suggested use in different applications. Pt is also used as vehicle exhaust catalyst leading to a possible exposure via inhalation. Despite their use, there is limited data on their genotoxic potential and possible size-dependent effects, particularly for Pt NPs. The aim of this study was to explore size-dependent genotoxicity of these NPs (5 and 50 nm) following exposure of human bronchial epithelial cells. We characterised the NPs and assessed the viability (Alamar blue assay), formation of DNA strand breaks (mini-gel comet assay) and induction of micronucleus (MN) analysed using flow cytometry (in vitro microflow kit). The results confirmed the primary size (5 and 50 nm) but showed agglomeration of all NPs in the serum free medium used. Slight reduced cell viability (tested up to 50 mu g/ml) was observed following exposure to the Ag NPs of both particle sizes as well as to the smallest (5 nm) Au NPs. Similarly, at non-cytotoxic concentrations, both 5 and 50 nm-sized Ag NPs, as well as 5 nm-sized Au NPs, increased DNA strand breaks whereas for Pt NPs only the 50 nm size caused a slight increase in DNA damage. No clear induction of MN was observed in any of the doses tested (up to 20 mu g/ml). Taken together, by using the comet assay our study shows DNA strand breaks induced by Ag NPs, without any obvious differences in size, whereas effects from Au and Pt NPs were size-dependent in the sense that the 5 nm-sized Au NPs and 50 nm-sized Pt NPs particles were active. No clear induction of MN was observed for the NPs.

  • 32. Lee, Jookyeong
    et al.
    Choi, Eun Jung
    Varga, Imre
    Claesson, Per M.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science.
    Yun, Sang-Ho
    Song, Changsik
    Terpyridine-functionalized stimuli-responsive microgels and their assembly through metal-ligand interactions2018In: Polymer Chemistry, ISSN 1759-9954, E-ISSN 1759-9962, Vol. 9, no 8, p. 1032-1039Article in journal (Refereed)
    Abstract [en]

    We developed a terpyridine-functionalized microgel (tpy-mG) for its supramolecular assembly. Tpy-mG was synthesized by amidation between 3-(4-([2,2':6',2 ''-terpyridin]-4'-yl)phenoxy) propan-1-amine and carboxylates of a thermo-responsive p(NIPAM-co-MAA) microgel (A-mG), which was synthesized by emulsion polymerization. After decorating terpyridine, its effects on the hydrodynamic radius, volume phase transition temperature (VPTT), and the colloidal stability of the microgel were investigated. Tpy-mG can be assembled reversibly with several metal ions (Ni2+, Fe2+, Co2+, or Zn2+), and interestingly the assembled tpy-mG-M2+ showed different rheological properties depending on the metal ion type; the weakly bound ions (Co2+, Zn2+) indicated fast dynamics for "inter-particular" exchange, resulting in much higher storage (G') and loss (G '') moduli. Photocatalysts such as Ru dyes can be easily introduced into tpy-mG via metal-ligand interactions, and the photooxidation of benzylamine was tested. The free Ru dye showed almost the same conversions at 25 and 50 degrees C, whereas the assembled Ru-tpy-mG-Mg2+ displayed reduced conversion at 50 degrees C (>VPTT). This is suggested to be due to the collapsed or "locked" structure around the photocatalytic center (Ru). Tpy-mG can be utilized as a good platform for developing responsive functional materials via reversible metal-ligand complexation.

  • 33.
    MacKenzie, Jordan
    et al.
    KTH, School of Engineering Sciences (SCI), Mechanics. KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW.
    Söderberg, Daniel
    KTH, School of Engineering Sciences (SCI), Mechanics. KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Swerin, Agne
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science. RISE Research Institutes of Sweden.
    Lundell, Fredrik
    KTH, School of Engineering Sciences (SCI), Mechanics. KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Turbulent stress measurements of fibre suspensions in a straight pipe2018In: Physics of fluids, ISSN 1070-6631, E-ISSN 1089-7666, Vol. 30, no 2, article id 025104Article in journal (Refereed)
    Abstract [en]

    The focus of the present work is an experimental study of the behaviour of semi-dilute, opaque fibre suspensions in fully developed cylindrical pipe flows. Measurements of the normal and turbulent shear stress components and the mean flow were acquired using phase-contrast magnetic resonance velocimetry. Two fibre types, namely, pulp fibre and nylon fibre, were considered in this work and are known to differ in elastic modulus. In total, three different mass concentrations and seven Reynolds numbers were tested to investigate the effects of fibre interactions during the transition from the plug flow to fully turbulent flow. It was found that in fully turbulent flows of nylon fibres, the normal, < u(z)u(z)>(+), and shear, < u(z)u(z)>(+) (note that <.> is the temporal average, u is the fluctuating velocity, z is the axial or streamwise component, and r is the radial direction), turbulent stresses increased with Reynolds number regardless of the crowding number (a concentration measure). For pulp fibre, the turbulent stresses increased with Reynolds number when a fibre plug was present in the flow and were spatially similar in magnitude when no fibre plug was present. Pressure spectra revealed that the stiff, nylon fibre reduced the energy in the inertial-subrange with an increasing Reynolds and crowding number, whereas the less stiff pulp fibre effectively cuts the energy cascade prematurely when the network was fully dispersed.

  • 34. Niga, P.
    et al.
    Hansson-Mille, P. M.
    Swerin, Agne
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science. RISE – Research Institute of Sweden.
    Claesson, Per M.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science. RISE – Research Institute of Sweden.
    Schoelkopf, J.
    Gane, P. A. C.
    Bergendal, Erik
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science.
    Tummino, A.
    Campbell, R. A.
    Johnson, C. Magnus
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science.
    Interactions between model cell membranes and the neuroactive drug propofol2018In: Journal of Colloid and Interface Science, ISSN 0021-9797, E-ISSN 1095-7103, Vol. 526, p. 230-243Article in journal (Refereed)
    Abstract [en]

    Vibrational sum frequency spectroscopy (VSFS) complemented by surface pressure isotherm and neutron reflectometry (NR) experiments were employed to investigate the interactions between propofol, a small amphiphilic molecule that currently is the most common general anaesthetic drug, and phospholipid monolayers. A series of biologically relevant saturated phospholipids of varying chain length from C18 to C14 were spread on either pure water or propofol (2,6-bis(1-methylethyl)phenol) solution in a Langmuir trough, and the change in the molecular structure of the film, induced by the interaction with propofol, was studied with respect to the surface pressure. The results from the surface pressure isotherm experiments revealed that propofol, as long as it remains at the interface, enhances the fluidity of the phospholipid monolayer. The VSF spectra demonstrate that for each phospholipid the amount of propofol in the monolayer region decreases with increasing surface pressure. Such squeeze out is in contrast to the enhanced interactions that can be exhibited by more complex amphiphilic molecules such as peptides. At surface pressures of 22–25 mN m−1, which are relevant for biological cell membranes, most of the propofol has been expelled from the monolayer, especially in the case of the C16 and C18 phospholipids that adopt a liquid condensed phase packing of its alkyl tails. At lower surface pressures of 5 mN m−1, the effect of propofol on the structure of the alkyl tails is enhanced when the phospholipids are present in a liquid expanded phase. Specifically, for the C16 phospholipid, NR data reveal that propofol is located exclusively in the head group region, which is rationalized in the context of previous studies. The results imply a non-homogeneous distribution of propofol in the plane of real cell membranes, which is an inference that requires urgent testing and may help to explain why such low concentration of the drug are required to induce general anaesthesia.

  • 35.
    Nyström, Lina
    et al.
    Uppsala Univ, Dept Pharm, Uppsala, Sweden..
    Nordström, Randi
    Uppsala Univ, Dept Pharm, Uppsala, Sweden..
    Bramhill, Jane
    Univ Manchester, Manchester, Lancs, England..
    Saunders, Brian
    Univ Manchester, Manchester, Lancs, England..
    Alvarez-Asencio, Ruben
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science. IMDEA Nanosci, Inst Adv Studies, Madrid, Spain..
    Rutland, Mark W.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science. SP Tech Res Inst Sweden, SP Chem Mat & Surfaces, Stockholm, Sweden.
    Malmsten, Martin
    Uppsala Univ, Dept Pharm, Uppsala, Sweden.;Univ Copenhagen, Dept Pharm, Copenhagen, Denmark..
    Peptide-loaded microgels as carriers of antimicrobial peptides2018In: Abstract of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 255Article in journal (Other academic)
  • 36.
    Nyström, Lina
    et al.
    Uppsala Univ, Dept Pharm, Uppsala, Sweden..
    Nordström, Randi
    Uppsala Univ, Dept Pharm, Uppsala, Sweden..
    Strömstedt, Adam
    Uppsala Univ, Dept Med Chem, Uppsala, Sweden..
    Saunders, Brian
    Univ Manchester, Manchester, Lancs, England..
    Alvarez-Asencio, Ruben
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science.
    Rutland, Mark W.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science.
    Malmsten, Martin
    Uppsala Univ, Dept Pharm, Uppsala, Sweden..
    Peptide-loaded microgels as antimicrobial surface coatings2018In: Abstract of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 255Article in journal (Other academic)
  • 37. Peng, T.
    et al.
    Yan, Q.
    Li, Gen
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science.
    Zhang, X.
    The Influence of Cu/Fe Ratio on the Tribological Behavior of Brake Friction Materials2018In: Tribology letters, ISSN 1023-8883, E-ISSN 1573-2711, Vol. 66, no 1, article id 18Article in journal (Refereed)
    Abstract [en]

    Copper and iron are the major ingredients in friction materials, among which Fe often been served as friction reinforcement in the past. But in our recent study, the coefficients of friction (COF) decreased with increasing iron content in composites. In order to study the influence of Cu/Fe ratio on the tribological behavior of the composite under simulative braking conditions, a subscale testing apparatus with the pad-on-disk configuration under various initial braking speeds (IBS) was applied. The changes in mean COFs, wear rates, morphologies and chemical constitutions of friction surface for different composites were investigated. Results showed that the composite containing more Fe content always showed lower mean COF and wear rate, which different from the previous studies. This is because, under severe braking conditions, the tribological behavior of composite mainly depends on the evolution of tribo-oxide film on the surface, not just on the substrate themselves. Higher Fe content accelerated the formation of tribo-oxide film and in turn inhibited the destruction of tribo-oxide film on the surface, which leading to lower mean COF and wear rate, as well as a higher critical IBS for the transition of mean COF and wear rate. This work also provides a way to characterize the fracture strength of tribo-film by carried out a peeling test.

  • 38.
    Petronico, Aaron
    et al.
    Univ Illinois, Dept Chem, Urbana, IL 61801 USA..
    Moneypenny, Timothy P., II
    Univ Illinois, Dept Chem, Urbana, IL 61801 USA.;Univ Illinois, Beckman Inst Adv Sci & Technol, Urbana, IL 61801 USA..
    Nicolau, Bruno G.
    Univ Illinois, Dept Chem, Urbana, IL 61801 USA..
    Moore, Jeffrey S.
    Univ Illinois, Dept Chem, Urbana, IL 61801 USA.;Univ Illinois, Beckman Inst Adv Sci & Technol, Urbana, IL 61801 USA..
    Nuzzo, Ralph G.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science. Univ Illinois, Dept Chem, Urbana, IL 61801 USA.
    Gewirth, Andrew A.
    Univ Illinois, Dept Chem, Urbana, IL 61801 USA..
    Solid-Liquid Lithium Electrolyte Nanocomposites Derived from Porous Molecular Cages2018In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 140, no 24, p. 7504-7509Article in journal (Refereed)
    Abstract [en]

    We demonstrate that solid-liquid nanocomposites derived from porous organic cages are effective lithium ion electrolytes at room temperature. A solid-liquid electrolyte nanocomposite (SLEN) fabricated from a LiTFSI/DME electrolyte system and a porous organic cage exhibits ionic conductivity on the order of 1 x 10(-3) S cm(-1). With an experimentally measured activation barrier of 0.16 eV, this composite is characterized as a superionic conductor. Furthermore, the SLEN displays excellent oxidative stability up to 4.7 V vs Li/Li+. This simple three-component system enables the rational design of electrolytes from tunable discrete molecular architectures.

  • 39.
    Pilkington, Georgia A.
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science.
    Harris, Kathryn
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.).
    Bergendal, Erik
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science.
    Reddy, Akepati Bhaskar
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.).
    Pålsson, G. K.
    Vorobiev, A.
    Antzutkin, O. N.
    Glavatskih, Sergei
    KTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.), Machine Design (Div.). Ghent University, Belgium.
    Rutland, Mark W.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science. RISE Research Institutes of Sweden.
    Electro-responsivity of ionic liquid boundary layers in a polar solvent revealed by neutron reflectance2018In: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 148, no 19, article id 193806Article in journal (Refereed)
    Abstract [en]

    Using neutron reflectivity, the electro-responsive structuring of the non-halogenated ionic liquid (IL) trihexyl(tetradecyl)phosphonium-bis(mandelato)borate, [P6,6,6,14][BMB], has been studied at a gold electrode surface in a polar solvent. For a 20% w/w IL mixture, contrast matched to the gold surface, distinct Kiessig fringes were observed for all potentials studied, indicative of a boundary layer of different composition to that of the bulk IL-solvent mixture. With applied potential, the amplitudes of the fringes from the gold-boundary layer interface varied systematically. These changes are attributable to the differing ratios of cations and anions in the boundary layer, leading to a greater or diminished contrast with the gold electrode, depending on the individual ion scattering length densities. Such electro-responsive changes were also evident in the reflectivities measured for the pure IL and a less concentrated (5% w/w) IL-solvent mixture at the same applied potentials, but gave rise to less pronounced changes. These measurements, therefore, demonstrate the enhanced sensitivity achieved by contrast matching the bulk solution and that the structure of the IL boundary layers formed in mixtures is strongly influenced by the bulk concentration. Together these results represent an important step in characterising IL boundary layers in IL-solvent mixtures and provide clear evidence of electro-responsive structuring of IL ions in their solutions with applied potential.

  • 40.
    Pradhan, Sulena
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science.
    Hedberg, Jonas
    KTH, School of Engineering Sciences (SCI), Physics.
    Rosenqvist, Jorgen
    Jonsson, Caroline M.
    Wold, Susanna
    Blomberg, Eva
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Odnevall Wallinder, Inger
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Influence of humic acid and dihydroxy benzoic acid on the agglomeration, adsorption, sedimentation and dissolution of copper, manganese, aluminum and silica nanoparticles - A tentative exposure scenario2018In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 13, no 2, article id e0192553Article in journal (Refereed)
    Abstract [en]

    This work focuses on kinetic aspects of stability, mobility, and dissolution of bare Cu, Al and Mn, and SiO2 NPs in synthetic freshwater (FW) with and without the presence of natural organic matter (NOM). This includes elucidation of particle and surface interactions, metal dissolution kinetics, and speciation predictions of released metals in solution. Dihydroxy benzoic acid (DHBA) and humic acid adsorbed rapidly on all metal NPs (< 1 min) via multiple surface coordinations, followed in general by rapid agglomeration and concomitant sedimentation for a large fraction of the particles. In contrast, NOM did not induce agglomeration of the SiO2 NPs during the test duration (21 days). DHBA in concentrations of 0.1 and 1 mM was unable to stabilize the metal NPs for time periods longer than 6 h, whereas humic acid, at certain concentrations (20 mg/L) was more efficient (> 24 h). The presence of NOM increased the amount of released metals into solution, in particular for Al and Cu, whereas the effect for Mn was minor. At least 10% of the particle mass was dissolved within 24 h and remained in solution for the metal NPs in the presence of NOM. Speciation modeling revealed that released Al and Cu predominantly formed complexes with NOM, whereas less complexation was seen for Mn. The results imply that potentially dispersed NPs of Cu, Al and Mn readily dissolve or sediment close to the source in freshwater of low salinity, whereas SiO2 NPs are more stable and therefore more mobile in solution.

  • 41. Shah, F. U.
    et al.
    Holmgren, A.
    Rutland, Mark W.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science. RISE Research Institutes of Sweden, Bioscience and Materials.
    Glavatskih, S.
    Antzutkin, O. N.
    Interfacial Behavior of Orthoborate Ionic Liquids at Inorganic Oxide Surfaces Probed by NMR, IR, and Raman Spectroscopy2018In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 122, no 34, p. 19687-19698Article in journal (Refereed)
    Abstract [en]

    Absorption modes and the reactivity of nonhalogenated ionic liquids (ILs) at inorganic oxide surfaces of γ-Al2O3, MgO, and SiO2 particles were characterized using multinuclear (11B, 31P, and 29Si) solid-state magic-angle-spinning NMR, FTIR, and Raman spectroscopy. ILs are composed of the trihexyl(tetradecyl)phosphonium cation, [P6,6,6,14]+, and bis(mandelato)borate, [BMB]-, or bis(salicylato)borate, [BScB]-, anions. Spectroscopic measurements were performed on room-temperature (298 K) samples and samples exposed to 15 h at 373 K. The single-pulse 11B NMR data of heated [P6,6,6,14][BMB] mixed with the inorganic oxides showed a significant change in the spectra of the anion for all three oxides. In contrast, no such spectral changes were detected for heated [P6,6,6,14][BScB] mixed with the inorganic oxides. 31P MAS NMR data for the IL/metal oxide systems revealed interactions between [P6,6,6,14]+ and the surfaces of oxides. A significant intensity of 31P CP-MAS NMR signals indicated a low mobility of cations in these systems. The existence of strongly adhered surface layers of ILs on SiO2 particles was also confirmed by 1H-29Si CP-MAS NMR spectroscopy. FTIR and Raman spectroscopic data revealed strong interactions between the anions and the inorganic surfaces, and there is a strong correlation with the data obtained from NMR spectroscopy. Although their chemical structures are rather similar, the [BScB]- anion is more stable than the [BMB]- anion at the inorganic oxide surfaces.

  • 42. Skedung, L.
    et al.
    El Rawadi, C.
    Arvidsson, M.
    Farcet, C.
    Luengo, G. S.
    Breton, L.
    Rutland, Mark W.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science. RISE Research Institutes of Sweden, Bioscience and Materials, Stockholm, Sweden.
    Mechanisms of tactile sensory deterioration amongst the elderly2018In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 8, no 1, article id 5303Article in journal (Refereed)
    Abstract [en]

    It is known that roughness-smoothness, hardness-softness, stickiness-slipperiness and warm-cold are predominant perceptual dimensions in macro-, micro- and nano- texture perception. However, it is not clear to what extent active tactile texture discrimination remains intact with age. The general decrease in tactile ability induces physical and emotional dysfunction in elderly, and has increasing significance for an aging population. We report a method to quantify tactile acuity based on blinded active exploration of systematically varying micro-textured surfaces and a same-different paradigm. It reveals that elderly participants show significantly reduced fine texture discrimination ability. The elderly group also displays statistically lower finger friction coefficient, moisture and elasticity, suggesting a link. However, a subpopulation of the elderly retains discrimination ability irrespective of cutaneous condition and this can be related to a higher density of somatosensory receptors on the finger pads. Skin tribology is thus not the primary reason for decline of tactile discrimination with age. The remediation of cutaneous properties through rehydration, however leads to a significantly improved tactile acuity. This indicates unambiguously that neurological tactile loss can be temporarily compensated by restoring the cutaneous contact mechanics. Such mechanical restoration of tactile ability has the potential to increase the quality of life in elderly.

  • 43.
    Skedung, Lisa
    et al.
    RISE Res Inst Sweden, Biosci & Mat, S-11428 Stockholm, Sweden..
    Harris, Kathryn
    RISE Res Inst Sweden, Biosci & Mat, S-11428 Stockholm, Sweden..
    Collier, Elizabeth S.
    RISE Res Inst Sweden, Biosci & Mat, S-11428 Stockholm, Sweden..
    Arvidsson, Martin
    RISE Res Inst Sweden, Biosci & Mat, S-11428 Stockholm, Sweden.;Tobii AB Publ, Box 743, S-18217 Danderyd, Sweden..
    Wackerlin, Aneliia
    Glas Trosch AG, Ind Str 29, CH-4922 Butzberg, Switzerland..
    Haag, Walter
    Glas Trosch AG, Ind Str 29, CH-4922 Butzberg, Switzerland..
    Bieri, Marco
    Glas Trosch AG, Ind Str 29, CH-4922 Butzberg, Switzerland.;Swiss Natl Sci Fdn, Wildhainweg 3, CH-3001 Bern, Switzerland..
    Romanyuk, Andriy
    Glas Trosch AG, Ind Str 29, CH-4922 Butzberg, Switzerland..
    Rutland, Mark W.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science.
    Feeling Smooth: Psychotribological Probing of Molecular Composition2018In: Tribology letters, ISSN 1023-8883, E-ISSN 1573-2711, Vol. 66, no 4, article id 138Article in journal (Refereed)
    Abstract [en]

    The aim of this study was to evaluate whether smooth surfaces varying in surface chemistry could be perceptually distinguished with the sense of touch. A set of ten glass surfaces was prepared which varied systematically in terms of the molecular composition of a thin coating of low topography. The contact angle, contact angle hysteresis, and surface energy were evaluated as objective physical parameters characterizing each coating. Additionally, the interaction forces between a human finger and the different coatings were quantified and compared in terms of tactile friction coefficients. The surfaces were evaluated psychophysically in terms of perceived similarities and were then ranked according to pleasantness. The participants could perceptually distinguish between surfaces varying in surface chemistry and a primary and secondary perceptual dimension were identified as sufficient to distinguish them. The primary dimension correlates with surface free energy, but both tactile friction and surface energy contribute to this dimension depending on whether the coatings are organic or inorganic. The secondary dimension could not be identified explicitly in terms of a physical quantity but is discussed in terms of recent developments in the literature. Coated glass is characterized by high friction coefficient upon interaction with a human finger as well as significant hysteresis in the stroking directions (lower applied load and higher friction in the backward stroke). Despite the complexity of the tribology, pleasantness can be clearly linked to it, where low friction (high contact angle) materials receive a higher ranking.

  • 44.
    Szakalos, Peter
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science.
    Åkermark, T.
    Rost & Ratt, Ugglev 32C, S-13141 Nacka, Sweden..
    Leygraf, Christopher
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science.
    Comments on the paper "Copper in ultrapure water, a scientific issue under debate" by M. Ottosson, M. Boman, P. Berastegui, Y. Andersson, M. Hahlin, M. Korvela, and R. Berger2018In: Corrosion Science, ISSN 0010-938X, E-ISSN 1879-0496, Vol. 142, p. 305-307Article in journal (Refereed)
  • 45.
    Thorén, Per-Anders
    et al.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Nanostructure Physics.
    Borgani, Riccardo
    KTH, School of Engineering Sciences (SCI), Applied Physics, Nanostructure Physics.
    Forchheimer, Daniel
    KTH, School of Engineering Sciences (SCI), Applied Physics, Nanostructure Physics. KTH, Centres, Nordic Institute for Theoretical Physics NORDITA.
    Dobryden, Illia
    Claesson, Per M.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science.
    Kassa, Hailu G.
    Univ Mons, Ctr Innovat & Res Mat & Polymers, Lab Chem Novel Mat, Pl Parc 20, B-7000 Mons, Belgium..
    Leclere, Philippe
    Univ Mons, Ctr Innovat & Res Mat & Polymers, Lab Chem Novel Mat, Pl Parc 20, B-7000 Mons, Belgium..
    Wang, Yifan
    Univ Chicago, James Franck Inst, 929 East 57th St, Chicago, IL 60637 USA..
    Jaeger, Heinrich M. .
    Univ Chicago, James Franck Inst, 929 East 57th St, Chicago, IL 60637 USA..
    Haviland, David B.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Nanostructure Physics.
    Modeling and Measuring Viscoelasticity with Dynamic Atomic Force Microscopy2018In: Physical Review Applied, E-ISSN 2331-7019, Vol. 10, no 2, article id 024017Article in journal (Refereed)
    Abstract [en]

    The interaction between a rapidly oscillating atomic-force-microscope tip and a soft-material surface is described with use of both elastic and viscous forces in a moving-surface model. We present the simplest form of this model, motivating our derivation with the models ability to capture the impact dynamics of the tip and sample with an interaction consisting of two components: interfacial or surface force, and bulk or volumetric force. Analytic solutions to the piecewise linear model identify characteristic time constants, providing a physical explanation for the hysteresis observed in the measured dynamic-force-quadrature curves. Numerical simulation is used to fit the model to experimental data, and excellent agreement is found with a variety of different samples. The model parameters form a dimensionless impact-rheology factor, giving a quantitative physical number to characterize a viscoelastic surface that does not depend on the tip shape or cantilever frequency.

  • 46.
    Thorén, Per-Anders
    et al.
    KTH, School of Engineering Sciences (SCI).
    Borgani, Riccardo
    KTH, School of Engineering Sciences (SCI), Applied Physics, Nanostructure Physics.
    Forchheimer, Daniel
    KTH, School of Engineering Sciences (SCI), Applied Physics, Nanostructure Physics.
    Dobryden, Illia
    KTH.
    Claesson, Per M.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science.
    Kassa, Hailu G.
    Leclère, Philippe
    Wang, Yifan
    Jaeger, Heinrich
    Haviland, David B.
    KTH, School of Engineering Sciences (SCI), Applied Physics, Nanostructure Physics.
    On modeling and measuring viscoelasticity with dynamic Atomic Force MicroscopyManuscript (preprint) (Other academic)
  • 47.
    Wallenius, Janne
    et al.
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Engineering. LeadCold Reactors, Valhallavagen 79, S-11428 Stockholm, Sweden.
    Qvist, S.
    LeadCold Reactors, Valhallavagen 79, S-11428 Stockholm, Sweden..
    Mickus, Ignas
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Engineering. LeadCold Reactors, Valhallavagen 79, S-11428 Stockholm, Sweden.
    Bortot, Sara
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Engineering. LeadCold Reactors, Valhallavagen 79, S-11428 Stockholm, Sweden.
    Szakalos, Peter
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science. LeadCold Reactors, Valhallavagen 79, S-11428 Stockholm, Sweden.
    Ejenstam, Lina
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science.
    Design of SEALER, a very small lead-cooled reactor for commercial power production in off-grid applications2018In: Nuclear Engineering and Design, ISSN 0029-5493, E-ISSN 1872-759X, Vol. 338, p. 23-33Article in journal (Refereed)
    Abstract [en]

    In this paper, the conceptual design of a small lead-cooled nuclear reactor intended to replace diesel-power in off-grid applications is presented. In a vessel of dimensions making it transportable by air, the targeted design performance is to produce 3 MW of electrical power for up to 30 years without reloading of fuel. Consequently, the inner vessel can be sealed, delaying malevolent access to the nuclear fuel and improving security. Alumina forming alloys are applied to ensure long term corrosion protection of fuel cladding tubes, steam generator tubes and primary vessel over the operational temperature regime. Moreover, decay heat can be removed in a completely passive manner by natural convection from the core to the primary coolant and by thermal radiation from the primary vessel to the environment. Finally, the source term is such that relocation of population residing beyond 1 km from the reactor will not be required even in the case of a complete core melt.

  • 48. Wang, Yongchao
    et al.
    Yin, Litao
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science. University of Science and Technology Beijing, China.
    Jin, Ying
    Pan, Jinshan
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science.
    Leygraf, Christofer
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science.
    Numerical Simulation of Micro-Galvanic Corrosion in Al Alloys: Steric Hindrance Effect of Corrosion Product2018In: Journal of the Electrochemical Society, ISSN 0013-4651, E-ISSN 1945-7111, Vol. 164, no 14, p. C1035-C1043Article in journal (Refereed)
    Abstract [en]

    An improved finite element model was established to demonstrate the steric hindrance effect of the precipitated corrosion product (Al(OH)(3)) on micro-galvanic corrosion triggered by intermetallic particles (IMPs) in an Al-matrix. In this model, the precipitation/ dissolution of the corrosion product could occur in the whole liquid field as the result of a reversible reaction. Simulation results show that the precipitated insulating Al(OH)(3) on the electrode surface can inhibit further corrosion by reducing the conductivity of the solution and the active electrode surface area. Meanwhile, the steric hindrance effect of the precipitated Al(OH)(3) also slows down the diffusion and migration of species in the solution. Moreover, considering the porous nature of precipitated Al(OH)(3), a porosity parameter epsilon was introduced to describe the degree of compactness of corrosion product, which reaches a certain minimum value epsilon(c) under a specific corrosion situation. Compared to the previous work in which a surface coverage parameter was used to describe the blocking effect of Al(OH)(3) on surface activity, the present model is more realistic in mimicking the micro-galvanic corrosion, and also useful for the simulation of the transition from metastable pit formation to pit propagation.

  • 49.
    Wei, Zheng
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science.
    Edin, Jonathan
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Applied Physical Chemistry.
    Karlsson, Anna Emelie
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science.
    Petrovic, Katarina
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Applied Physical Chemistry.
    Soroka, Inna L.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science.
    Odnevall Wallinder, Inger
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science.
    Hedberg, Yolanda
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science.
    Can gamma irradiation during radiotherapy influence the metal release process for biomedical CoCrMo and 316L alloys?2018In: Journal of Biomedical Materials Research. Part B - Applied biomaterials, ISSN 1552-4973, E-ISSN 1552-4981, Vol. 106, no 7, p. 2673-2680Article in journal (Refereed)
    Abstract [en]

    The extent of metal release from implant materials that are irradiated during radiotherapy may be influenced by irradiation-formed radicals. The influence of gamma irradiation, with a total dose of relevance for radiotherapy (e.g., for cancer treatments) on the extent of metal release from biomedical stainless steel AISI 316L and a cobalt-chromium alloy (CoCrMo) was investigated in physiological relevant solutions (phosphate buffered saline with and without 10 g/L bovine serum albumin) at pH 7.3. Directly after irradiation, the released amounts of metals were significantly higher for irradiated CoCrMo as compared to nonirradiated CoCrMo, resulting in an increased surface passivation (enhanced passive conditions) that hindered further release. A similar effect was observed for 316L showing lower nickel release after 1 h of initially irradiated samples as compared to nonirradiated samples. However, the effect of irradiation (total dose of 16.5 Gy) on metal release and surface oxide composition and thickness was generally small. Most metals were released initially (within seconds) upon immersion from CoCrMo but not from 316L. Albumin induced an increased amount of released metals from AISI 316L but not from CoCrMo. Albumin was not found to aggregate to any greater extent either upon gamma irradiation or in the presence of trace metal ions, as determined using different light scattering techniques. Further studies should elucidate the effect of repeated friction and fractionated low irradiation doses on the short- and long term metal release process of biomedical materials.

  • 50.
    Yin, Litao
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science. University of Science and Technology Beijing.
    FEM Modelling of Micro-galvanic Corrosion in Al Alloys Induced by Intermetallic Particles: Exploration of Chemical and Geometrical Effects2018Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Localized corrosion, such as pitting, crevice corrosion or galvanic corrosion, is a long-standing phenomenon that can greatly limit the life of metallic materials. For decades experimental methods have been used to try to understand the underlying physical, chemical and electrochemical processes that control localized corrosion in order to find effective protection methods against its propagation. The complexity of the phenomenon and its small geometric size have often severely restricted the basic understanding of local corrosion. In recent decades, computational methods have been developed as an alternative to the experimental methods. Compared to experimental methods, modeling and numerical simulation enable complicated systems to be systematically investigated without considering the inherent constraints of experimental methods.

        In the current Doctoral thesis, advanced calculation methodology has been used to study galvanic corrosion of an aluminum alloy with geometric resolution at micrometer level. The computational platform has been a commercial FEM-based software, COMSOL Multiphysics, which was combined with another software, Matlab. The current model system consists of a semi-spherical intermetallic particle, surrounded by a pure aluminum matrix. The aluminum surface is covered by an inert passive film, except for a ring-shaped surface around the particle itself. By assuming that the particle is electrochemically more noble than aluminum, it acts as a cathode and the surrounding aluminum ring as anode. By utilizing the FEM-based software, it has been possible to incorporate important physicochemical reactions, including the electrochemical anode and cathode reactions of the individual phases, mass transport of various chemical compounds formed during ongoing electrochemistry, homogeneous reactions in the electrolyte, as well as deposition of corrosion products consisting of Al(OH)3 along parts of the anodic area.

        What has made this study a significant step forward is that not only chemical changes but also geometrical changes have been taken into consideration in the simulation of ongoing micro-galvanic corrosion. Particularly challenging has been to mathematically master the gradual deposition of compact Al(OH)3 on an aluminum surface which gradually dissolves anodically. In the initial modeling work, the deposition of Al(OH)3 was assumed to occur only on the electrode surface, resulting in a gradual blockage of surface activity. In an even more advanced stage, the modeling has also sought to simulate the effect of a deposited porous film of Al(OH)3, formed through homogeneous reactions in the electrolyte. By taking into account inhibited diffusion and migration of chemical products that the porous film causes, its sterically inhibiting effect has for the first time been quantitatively interpreted. The porous corrosion product can most closely resemble the lid experimentally observed above local corrosion attacks, which leads to an even more diminished surface activity in electrochemical reactions compared with the deposition of only compact corrosion products on the anode surface.

        The kinetic model has resulted in a significantly deeper insight into the mechanism of micro-galvanic corrosion of the investigated system. The simulation has been shown to predict the time-dependent geometric changes of the anodically dissolved aluminum surface as well as the flow and distribution of generated chemical products. Contrary to the widely accepted perception that Al(OH)3 is not stable in the occluded acidified electrolyte environment, the calculations predict a higher local pH in the occluded electrolyte. This means that insoluble Al(OH)3 can be deposited on the electrode surface, the blocking effect of which may lead to a termination of the micro-galvanic corrosion. If the ring width is initially 0.5 μm or less, transport of OH- ions from the cathode surface to the occluded electrolyte environment is limited, leading to a local acidification within the occluded dissolving volume. At a given anodic ring width, an increased radius of the cathodic particle instead leads to an increased anodic dissolution rate by formation of a larger area for the cathode reaction. Variation of the chemical parameters in the electrolyte also shows that the simulated micro-galvanic corrosion rate of aluminum has a minimum at pH = 6. Both more acidic and more alkaline conditions result in an elevated anodic dissolution of aluminum. When pH ≤ 4, the deposition of Al(OH)3  becomes negligible, and the micro-galvanic corrosion will continue uninterrupted, completely in accordance with experimental data.

12 1 - 50 of 57
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf