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He, Y. (2019). Corrosion protection and nanomechanical properties of waterborne acrylate-based coating with and without nanocellulose on carbon steel. (Doctoral dissertation). KTH Royal Institute of Technology
Open this publication in new window or tab >>Corrosion protection and nanomechanical properties of waterborne acrylate-based coating with and without nanocellulose on carbon steel
2019 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Corrosion protection is commonly achieved by applying a thin polymer coating on metal surfaces. In this doctoral thesis, a waterborne hydroxyacrylate-melamine copolymer coating was used for this purpose. The first step was to find the optimal curing conditions. To this end the effect of curing time at 180 °C on the conversion of the cross-linking reaction, surface topography, nanomechanical and nanowear properties were investigated using atomic force microscopy, AFM. The results demonstrated that optimal performance required 10 min curing at 180 °C. This resulted in 80% conversion of the cross-linking reaction, as well as good barrier performance with polarization resistance of the order of 109Ω·cm2during 35 days in 0.1 M NaCl solution as determined by Electrochemical Impedance Spectroscopy (EIS). It also resulted in minor surface roughness and high surface elastic modulus in the order of GPa. 

 

This waterborne coating and its nanocomposite containing 0.5 wt.% cellulose nanocrystals (CNC) were systematically studied, focusing on their corrosion protection performance and the effect of environment and localized wear on the properties of the top surface. The results show that both coatings have high polarization resistance, Rp. For the matrix coating the polarization resistance displays a slightly decreasing trend with time, as expected for a barrier coating. In contrast, the CNC nanocomposite coating exhibits an unusual and unexpected increase in polarization resistance with time. The difference in the time dependence of Rp can be attributed to the reinforcement effect of CNC, which form strong hydrogen bonding interactions with the matrix coating. Further, the appearance of a second time constant in the corresponding EIS spectra implies formation of a more protective second layer at the metal-coating interface. The presence of this compact layer also contributes to the corrosion protection offered by the CNC nanocomposite coating. In addition, both coatings show only limited water-uptake during long term exposure to 0.1 M NaCl. The water up-take is too small to measurably change the coating capacitance, as studied by EIS. However, AFM studies of surface nanomechanical properties show that for the CNC nanocomposite some water penetration occurs, which irreversibly renders the surface softer.

 

Inspired by the CNC nanocomposite coating and its favorable corrosion protective properties, 0.5 wt.% cellulose nanofibrils, CNF, nanocomposite coatings were also studied using the same methodologies. The results revealed that the CNF nanocomposite coating cannot provide efficient corrosion protection performance even over a period of 24 h. The measured polarization resistance decreases rapidly over time, and consistently water uptake is readily observed by analyzing coating capacitance using EIS technique. The substantial difference in corrosion protective properties of the CNC nanocomposite and the CNF nanocomposite are explained mainly from the perspective of microstructure, matrix-CNC or matrix-CNF interactions by using scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). The results show the presence of defects on the surface and in the bulk and absence of strong hydrogen bonding interactions between matrix and CNF. These are two reasons for why the CNC nanocomposite performs well in terms of corrosion protection, whereas the CNF nanocomposite does not. 

 

In real applications good barrier coatings may also fail due to external forces such as erosion by wind and water, impact of solid particles or sliding motions against other objects, which may destroy the coating integrity. This motivated further studies of the matrix and the CNC nanocomposite, by focusing on their nanomechanical and nano-wear properties using local measurements by means of AFM. The effect of applied normal load, ranging from 50 – 400 nN, scanning speed, ranging from 1 – 20 µm/s, operating environment including air and water, as well as exposure to corrosive 0.1 M NaCl solution, were systematically studied and discussed.

Abstract [sv]

Korrosionsskydd uppnås vanligtvis genom att applicering av en tunn polymerbeläggning på metallytan. I denna doktorsavhandling studerades först en vattenburen hydroxyakrylat-melamin-sampolymerbeläggning för att hitta de optimala härdningsförhållandena. Effekten av härdningsbetingelserna, t ex längd på härdningstiden vid 180 °C, på omvandling av tvärbindningsreaktion, yttopografi och nanomekaniska egenskaper och nanodegrarderingsegenskaper undersöktes med användning av AFM. Resultaten visar att det optimala härdningsförhållandet är vid 180 ° C under 10 min, vilket kan ge 80% omvandlingen av tvärbindningsreaktionen, liksom goda barriärprestanda med en polarisationsresistens i storleksordningen 109Ω·cm2under lång tids exponering under 35 dagar för 0,1 M NaCl-lösning utvärderat med elektrokemisk impedansspektroskopi (EIS). Mindre ytråhet och hög ytelastisk modul i storleksordningen GPa uppnås också för prover under optimalt härdningsförhållande.

 

Vidare studerades ovan vattenburen beläggning och dess nanokomposit innehållande 0,5 viktprocent cellulosa nanokristaller (CNC) systematiskt med fokus på deras korrosionsskyddsprestanda. Mätningarna utfördes med elektrokemisk impedansspektroskopi (EIS) teknik i 0,1 M NaCl-lösning. Resultaten visar att båda beläggningarna har hög polarisationsbeständighet i storleksordningen 108- 109ohm · cm2. För matrisbeläggningen uppvisar polarisationsmotståndet en svag minskande trend medan CNC-nanokompositbeläggningen uppvisar en ökande trend. Skillnaden i Rp-beteenden kan delvis tillskrivas förstärkningseffekten av CNC där starka vätebindningar bildas mellan CNC och matrisbeläggningen. Dessutom innebär närvaron av en andra tidskonstant i motsvarande EIS-spektra att ett mer skyddande andra skikt bildats, troligen vid gränsytan mellan metallen och beläggningen. Närvaron av detta kompakta skikt bidrar också till de korrosionsskyddande egenskaperna hos CNC-nanokompositbeläggningen. Dessutom uppvisar båda beläggningarna endast begränsat vattenupptag under långvarig exponering, vilka är för obetydliga för att mätbart förändra beläggningskapacitansen, vilket studerades med EIS.

 

Inspirerad av CNC-nanokompositbeläggningen och dess gynnsamma korrosionsskyddande egenskaper studerades också 0,5 vikt-% CNF-nanokompositbeläggningar på samma sätt. Resultaten avslöjar att CNF-nanokompositbeläggningen inte kan ge effektivt korrosionsskydd ens under 24 timmar. Det uppmätta Rp-värdet minskar snabbt över tiden och därigenom ökar vattenupptaget över tiden, vilket studerades med EIS. Den väsentliga skillnaden i korrosionsskyddande egenskaper hos CNC-nanokompositen och CNF-nanokompositen förklarades huvudsakligen från perspektivet av mikrostruktur, matris-CNC eller matris-CNF-interaktioner genom att använda svepelektronmikroskopi (SEM) och Fourier transform infraröd spektroskopi (FTIR). Resultaten visar att närvaron av defekter på ytan och i bulk och frånvaro av starka vätebindningar mellan matris-CNF i den beredda CNF-nanokompositbeläggningen bidrar till de dåliga barriäregenskaperna.

 

I själva verket kan en bra barriärbeläggning också förstöras på grund av yttre krafter som infallande fasta partiklar eller glidande rörelser mot andra föremål, vilket förstör beläggningens integritet. Därför studerades CNC-nanokompositbeläggningen ytterligare med fokus på dess nanomekaniska och nano-nötnings egenskaper med användning av (atomkraftsmikroskopi) AFM-teknik. Effekten av applicerad normal belastning från 50 - 400 nN, skanningshastighet från 1 - 20 um/s, typ av omgivning inklusive luft och vatten, samt exponering för korroderand 0,1 M NaCl-lösning, studerades och diskuterades systematiskt.

Place, publisher, year, edition, pages
KTH Royal Institute of Technology, 2019. p. 53
Series
TRITA-CBH-FOU ; 2019:62
Keywords
Hydroxyacrylate-melamine copolymer, cellulose nanocrystals (CNC), cellulose nanofibrils (CNF); Electrochemical impedance spectroscopy (EIS), atomic force microscopy (AFM); corrosion protection performance, water uptake, nanomechanical and nano-wear properties, coating, nanocomposite., Hydroxyakrylat-melamin-sampolymer, cellulosananokristaller (CNC), cellulosananofibriller (CNF); Elektrokemisk impedansspektroskopi (EIS), atomkraftsmikroskopi (AFM); korrosionsskyddsprestanda, vattenupptag, nanomekaniska egenskaper och nano-slitage, coating, nanokomposit.
National Category
Natural Sciences
Research subject
Chemistry
Identifiers
urn:nbn:se:kth:diva-262709 (URN)978-91-7873-349-1 (ISBN)
Public defence
2019-11-22, M3, Brinellvägen 64, Lecture Hall M3, KTH campus, Stockholm, Sweden., Stockholm, 10:00 (English)
Opponent
Supervisors
Note

QC 2019-10-18

Available from: 2019-10-18 Created: 2019-10-18 Last updated: 2019-10-22Bibliographically approved
Claesson, P. M., Dobryden, I., He, Y. & Li, G. (2019). Surface Nanomechanics of Coatings and Hydrogels. In: IOP Conference Series: Materials Science and Engineering. Paper presented at 18th International Conference Baltic Polymer Symposium 2018, BPS 2018, 12 September 2018 through 14 September 2018. Institute of Physics Publishing (1)
Open this publication in new window or tab >>Surface Nanomechanics of Coatings and Hydrogels
2019 (English)In: IOP Conference Series: Materials Science and Engineering, Institute of Physics Publishing , 2019, no 1Conference paper, Published paper (Refereed)
Abstract [en]

Due to the increasing use of nanostructured materials and thin coatings as barrier materials, it has become of high importance to measure and understand material properties on the nm to 100 nm length scales. In this article we demonstrate and discuss how atomic force microscopy techniques can be used to this end. It is demonstrated that the classical analysis based on the assumption of a purely elastic material response is a fair approximation for relatively stiff coatings (elastic modulus order of GPa), whereas viscous responses must be considered for soft materials (apparent modulus order of MPa) such as hydrogels.

Place, publisher, year, edition, pages
Institute of Physics Publishing, 2019
National Category
Textile, Rubber and Polymeric Materials
Identifiers
urn:nbn:se:kth:diva-255930 (URN)10.1088/1757-899X/500/1/012025 (DOI)2-s2.0-85064865835 (Scopus ID)
Conference
18th International Conference Baltic Polymer Symposium 2018, BPS 2018, 12 September 2018 through 14 September 2018
Note

QC 20190816

Available from: 2019-08-16 Created: 2019-08-16 Last updated: 2019-08-16Bibliographically approved
He, Y., Dobryden, I., Pan, J., Ahniyaz, A., Deltin, T., Corkery, R. W. & Claesson, P. M. (2018). Nano-scale mechanical and wear properties of a waterborne hydroxyacrylic-melamine anti-corrosion coating. Applied Surface Science, 457, 548-558
Open this publication in new window or tab >>Nano-scale mechanical and wear properties of a waterborne hydroxyacrylic-melamine anti-corrosion coating
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2018 (English)In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 457, p. 548-558Article in journal (Refereed) Published
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.

Place, publisher, year, edition, pages
Elsevier, 2018
Keywords
Waterborne anti-corrosive coating, Electrochemical impedance spectroscopy, Nanomechanical property, Nanowear, Fast fourier transform analysis
National Category
Other Chemistry Topics
Identifiers
urn:nbn:se:kth:diva-235097 (URN)10.1016/j.apsusc.2018.06.284 (DOI)000441872300065 ()2-s2.0-85049824578 (Scopus ID)
Funder
Swedish Research Council, 2015-05080
Note

QC 20180917

Available from: 2018-09-17 Created: 2018-09-17 Last updated: 2019-10-18Bibliographically approved
He, Y., Fan, L., Afzal, M., Singh, M., Zhang, W., Zhao, Y., . . . Zhu, B. (2016). Cobalt oxides coated commercial Ba0.5Sr0.5Co0.8Fe0.2O3-delta as high performance cathode for low-temperature SOFCs. Electrochimica Acta, 191, 223-229
Open this publication in new window or tab >>Cobalt oxides coated commercial Ba0.5Sr0.5Co0.8Fe0.2O3-delta as high performance cathode for low-temperature SOFCs
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2016 (English)In: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 191, p. 223-229Article in journal (Refereed) Published
Abstract [en]

In order to improve the catalytic activity of commercial Ba0.5Sr0.5Co0.8Fe0.2O3-delta (BSCF) for low-temperature solid oxide fuel cells (LTSOFC) (300-600 degrees C), CoOx has been used to modify the commercial BSCF through a solution coating approach. Phase and morphology of samples were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) and energy-dispersive spectrometry (EDS), respectively. BSCF with 10 wt% CoOx exhibited an improved conductivity of 44 S/cm, and achieved a peak power density of 463 mW/cm(2) at 550 degrees C for LTSOFC, which is a 100% enhancement than that with the BSCF cathode. The cathode oxygen reduction reaction (ORR) promoted by CoOx and enhanced device performance mechanism have been proposed. This work provides a new way for the exploitation of high effective cathode materials for LTSOFCs.

Place, publisher, year, edition, pages
Elsevier, 2016
Keywords
Low-temperature solid oxide fuel cells, Perovskite cathode material, Electrical conductivity, High electrical performance, Oxygen reduction kinetics
National Category
Materials Chemistry
Identifiers
urn:nbn:se:kth:diva-184551 (URN)10.1016/j.electacta.2016.01.090 (DOI)000371143200027 ()2-s2.0-84955451175 (Scopus ID)
Funder
Swedish Research Council, 621-2011-4983
Note

QC 20160406

Available from: 2016-04-06 Created: 2016-04-01 Last updated: 2017-11-30Bibliographically approved
Afzal, M., Saleemi, M., Wang, B., Xia, C., Zhang, W., He, Y., . . . Zhu, B. (2016). Fabrication of novel electrolyte-layer free fuel cell with semi-ionic conductor (Ba0.5Sr0.5Co0.8Fe0.2O3-delta- Sm0.2Ce0.8O1.9) and Schottky barrier. Journal of Power Sources, 328, 136-142
Open this publication in new window or tab >>Fabrication of novel electrolyte-layer free fuel cell with semi-ionic conductor (Ba0.5Sr0.5Co0.8Fe0.2O3-delta- Sm0.2Ce0.8O1.9) and Schottky barrier
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2016 (English)In: Journal of Power Sources, ISSN 0378-7753, E-ISSN 1873-2755, Vol. 328, p. 136-142Article in journal (Refereed) Published
Abstract [en]

Perovskite Ba0.5Sr0.5Co0.8Fe0.2O3-delta (BSCF) is synthesized via a chemical co-precipitation technique for a low temperature solid oxide fuel cell (LTSOFC) (300-600 degrees C) and electrolyte-layer free fuel cell (EFFC) in a comprehensive study. The EFFC with a homogeneous mixture of samarium doped ceria (SDC): BSCF (60%:40% by weight) which is rather similar to the cathode (SDC: BSCF in 50%:50% by weight) used for a three layer SOFC demonstrates peak power densities up to 655 mW/cm(2), while a three layer (anode/ electrolyte/cathode) SOFC has reached only 425 mW/cm(2) at 550 degrees C. Chemical phase, crystal structure and morphology of the as-prepared sample are characterized by X-ray diffraction and field emission scanning electron microscopy coupled with energy dispersive spectroscopy. The electrochemical performances of 3-layer SOFC and EFFC are studied by electrochemical impedance spectroscopy (EIS). As-prepared BSCF has exhibited a maximum conductivity above 300 S/cm at 550 degrees C. High performance of the EFFC device corresponds to a balanced combination between ionic and electronic (holes) conduction characteristic. The Schottky barrier prevents the EFFC from the electronic short circuiting problem which also enhances power output. The results provide a new way to produce highly effective cathode materials for LTSOFC and semiconductor designs for EFFC functions using a semiconducting-ionic material.

Place, publisher, year, edition, pages
Elsevier, 2016
Keywords
Co-precipitation, Ba0.5Sr0.5Co0.8Fe0.2O3-delta (BSCF), LTSOFC, Electrolyte-layer free fuel cell (EFFC), Perovskite oxide, Semi-ionic conductor
National Category
Materials Chemistry Inorganic Chemistry Ceramics
Identifiers
urn:nbn:se:kth:diva-193795 (URN)10.1016/j.jpowsour.2016.07.093 (DOI)000383293400015 ()2-s2.0-84984850892 (Scopus ID)
Funder
EU, FP7, Seventh Framework Programme, TRISOFC_03042012Swedish Research Council, 621-2011-4983ÅForsk (Ångpanneföreningen's Foundation for Research and Development)
Note

QC 20161024

Available from: 2016-10-24 Created: 2016-10-11 Last updated: 2019-03-06Bibliographically approved
Xia, C., Wang, B., Ma, Y., Cai, Y., Afzal, M., Liu, Y., . . . Zhu, B. (2016). Industrial-grade rare-earth and perovskite oxide for high-performance electrolyte layer-free fuel cell. Journal of Power Sources, 307, 270-279
Open this publication in new window or tab >>Industrial-grade rare-earth and perovskite oxide for high-performance electrolyte layer-free fuel cell
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2016 (English)In: Journal of Power Sources, ISSN 0378-7753, E-ISSN 1873-2755, Vol. 307, p. 270-279Article in journal (Refereed) Published
Abstract [en]

In the present work, we report a composite of industrial-grade material LaCePr-oxide (LCP) and perovskite La0.6Sr0.4Co0.2Fe0.8O3-δ (LSCF) for advanced electrolyte layer-free fuel cells (EFFCs). The microstructure, morphology, and electrical properties of the LCP, LSCF, and LCP-LSCF composite were investigated and characterized by XRD, SEM, EDS, TEM, and EIS. Various ratios of LCP to LSCF in the composite were modulated to achieve balanced ionic and electronic conductivities. Fuel cell with an optimum ratio of 60 wt% LCP to 40 wt% LSCF reached the highest open circuit voltage (OCV) at 1.01 V and a maximum power density of 745 mW cm-2 at 575°C, also displaying a good performance stability. The high performance is attributed to the interfacial mechanisms and electrode catalytic effects. The findings from the present study promote industrial-grade rare-earth oxide as a promising new material for innovative low temperature solid oxide fuel cell (LTSOFC) technology.

Place, publisher, year, edition, pages
Elsevier, 2016
Keywords
Electrolyte layer-free fuel cell, Industrial-grade material, La0.6Sr0.4Co0.2Fe0.8O3-δ (LSCF), LaCePr-oxide (LCP), Mixed conductor composite
National Category
Materials Chemistry Energy Engineering
Identifiers
urn:nbn:se:kth:diva-180912 (URN)10.1016/j.jpowsour.2015.12.086 (DOI)000370884000034 ()2-s2.0-84953923409 (Scopus ID)
Note

QC 20160129. QC 20160407. QC 20191018

Available from: 2016-01-29 Created: 2016-01-25 Last updated: 2019-10-18Bibliographically approved
He, Y., Li, G., Hwang, K.-H. & Claesson, P. M.Nano-scale mechanical and wear properties of a corrosion protective coating reinforced by cellulose nanocrystals: initiation of coating.
Open this publication in new window or tab >>Nano-scale mechanical and wear properties of a corrosion protective coating reinforced by cellulose nanocrystals: initiation of coating
(English)Manuscript (preprint) (Other academic)
Abstract [en]

Organic coatings are commonly used for protection of substrate surfaces like metals and wood. In most cases they fulfil their purpose by acting as a barrier against unwanted substances such as oxygen, water or corrosive ions. However, with time coatings fail due to degradation caused by chemical reactions or wear by wind, water, impact of solid particles or sliding motions against other solid objects. In this work we focus on a nanocomposite coating having a hydroxyacrylate-melamine matrix and being reinforced by a small amount (0.5 wt.%) of cellulose nanocrystals. This nanocomposite is of interest as it has shown favourable corrosion protection properties on carbon steel. Here we investigate the nanomechanical and nanowear properties of the coating in air and in water, and we also explore how these properties are affected by exposure to a corrosive 0.1 M NaCl solution. Our data show that the nanomechanical properties of the coating surface is strongly affected by the environment (air or water), and that exposure to the corrosive solution affects the coating surface well before any deterioration of the corrosion protective properties are found. We suggest that our experimental methodology constitutes a powerful way to investigate and understand the initiation of coating degradation.

Keywords
Nanomechanical properties, nanowear, nanocomposite, coating degradation, scanning probe microscopy, hydroxyacrylate, cellulose nanocrystal
National Category
Physical Chemistry
Research subject
Chemistry
Identifiers
urn:nbn:se:kth:diva-262698 (URN)
Note

QC 20191023

Available from: 2019-10-17 Created: 2019-10-17 Last updated: 2019-10-23Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0003-2151-2913

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