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  • 1.
    Chen, Zhuo Yuan
    et al.
    KTH, Superseded Departments, Materials Science and Engineering.
    Zakipour, S.
    Persson, D.
    Leygraf, Christofer
    KTH, Superseded Departments, Materials Science and Engineering.
    The Effect of Sodium Chloride Particles on the Atmospheric Corrosion of Pure Copper2004In: Corrosion, ISSN 0010-9312, E-ISSN 1938-159X, Vol. 60, no 5, 479-491 p.Article in journal (Refereed)
    Abstract [en]

    The atmospheric corrosion of copper has been investigated after deposition of sodium chloride (NaCl) particles and 10 days of subsequent exposure to clean, humidified air below, near, and above the point of deliquescence of NaCl (at around 75% relative humidity (RH), Microgravimetry, Fourier transform infrared (FTIR) microspectroscopy, scanning electron microscopy with x-ray microanalysis, and scanning Kelvin probe were used to identify corrosion processes and products. The NaCl deposition resulted in the evenly distributed NaCl particle clusters with a diameter of approximately 100 μm. The clusters consisted of individual NaCl particles of <10 μm. The mass gain increased linearly with the amount of NaCl particles added in the range of this study (up to 4 μg/cm2). Even at very low RH (55%), which lies far below the point of deliquescence (75%), copper with NaCl particles added suffered from significant corrosion attack and the mass gain of copper with 4 μg/cm2 NaCl added was about 7 μg/cm2 after 10 days of exposure. At 55% RH, the NaCl particles did not dissolve. However, significant chloride-induced corrosion effects were observed after 10 days, both in the original particle cluster and in a 20-μm-wide outer zone into which chloride ions had dffused radially. At 75% RH, the NaCl particles dissolved and chloride ions diffused to cover the whole surface. Chloride-accelerated corrosion effects resulted in the formation of cuprite (Cu2O) and copper carbonate, mainly in the area of the original particle cluster. The corrosion effects accelerated further at 95% PH, resulting in the formation of Cu2O over the whole surface and copper carbonate in a concentric zone outside the original particle cluster. The distribution of the corrosion products was related to the localization of the anodic and cathodic reactions during the corrosion process.

  • 2.
    Chen, Zhuo Yuan
    et al.
    wedish Corrosion Institute, Sweden.
    Zakipur, S.
    Persson, D.
    Leygraf, Christofer
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Corrosion Science (closed 20081231).
    The Combined Effects of Gaseous pollutants and Sodium Chloride Particles on the Atmospheric Corrosion of Pure Copper2005In: Corrosion, ISSN 0010-9312, E-ISSN 1938-159X, Vol. 61, no 11, 1022-1034 p.Article in journal (Refereed)
    Abstract [en]

    The atmospheric corrosion of pure copper has been investigated after the deposition of sodium chloride (NaCI) particles and exposure to humid air containing gaseous pollutants. Microgravimetry, Fourier transform infrared (FTIR) micro-spectroscopy, and scanning electron microscopy with x-ray microanalysis were used for the investigation of corrosion processes and products. The effect of NaCl particles on the mass gain was much higher than that of gaseous pollutants. With deposition of NaCl particles on the copper surfaces, the corrosion rate increased significantly, with severe corrosion attack mainly localized to the NaCl particle clusters. A similar corrosion rate was found, however, after exposure to pure humid air and to humid air containing gaseous pollutants, sulfur dioxide (SO2), ozone (O-3), nitrogen dioxide (NO2), and SO2 + NO2. The corrosion rate was not dependent on the concentration of the pollutants. However, this was not the case for the combination of SO2 and O-3, leading to a significantly higher corrosion rate at higher concentrations. Exposure of copper samples with NaCl particles deposited resulted in unevenly distributed corrosion product clusters, with a distribution of corrosion products that could be associated with the locations of the particle clusters. Around the particle clusters, the corrosion resulted in areas with different amounts of corrosion products. After 10 days of exposure to humid air containing 100 ppb SO2 and 100 ppb NO2 + SO2, cuprite (Cu2O), paratacamite (Cu-2[OH](3)Cl), carbonate (CO32-), and sulfate (SO42-) were observed mainly in the area of the original particle cluster, with some sutfate and copper hydroxysulfate also in the areas outside. After 10 days of exposure to humid air containing 100 ppb O-3 + SO2, cuprite (Cu2O), hydroxychloride (maybe paratacamite, Cu-2[OH](3)Cl), carbonate (CO32-), and sutfate (SO42-) were observed in the area of the original particle cluster. A circular zone containing brochantite (Cu-4[OH](6)SO4) was formed around and outside of the original particle cluster, and the formation of this phase was promoted by the presence of NaCl particles on the surface. The location of anodic and cathodic reactions during the corrosion process leads to the distribution of different corrosion products on the surface.

  • 3.
    Forslund, Mattias
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Leygraf, Christofer
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Lin, Changjian
    Pan, Jinshan
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Radial Spreading of Localized Corrosion-Induced Selective Leaching on alpha-Brass in Dilute NaCl Solution2013In: Corrosion, ISSN 0010-9312, E-ISSN 1938-159X, Vol. 69, no 5, 468-476 p.Article in journal (Refereed)
    Abstract [en]

    The radial spreading of selective leaching on an a-brass alloy, Cu20Zn, in diluted sodium chloride (NaCl) has been followed in situ by light optical microscopy. The corrosion process initiates through localized dissolution of micrometer-sized, Zn-rich areas. These areas initially act as anodes, where the Zn will dissolve as Zn2+. The continued growth is a highly dynamic process, involving dezincification that results in local ennoblement of initial anode areas and changes in the local chemistry of the solution. These changes drive the anodic area outward to form a ring-shaped anode with an increasing diameter. At a sufficiently high local Cl- ion concentration, Cu dissolves as CuCl2-, whereby the radial growth continues. At critical minimum local Cl- ion concentration, the radial growth is terminated.

  • 4.
    Forslund, Mattias
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Pan, Jinshan
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Hosseinpour, Saman
    Zhang, Fan
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Johnson, Magnus
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Claesson, Per
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Leygraf, Christofer
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Corrosion Inhibition of Two Brass Alloys by Octadecanethiol in Humidified Air with Formic Acid2015In: Corrosion, ISSN 0010-9312, E-ISSN 1938-159X, Vol. 71, no 7, 908-917 p.Article in journal (Refereed)
    Abstract [en]

    Self-assembled monolayers of octadecanethiol (ODT) have previously shown to provide excellent corrosion inhibition on copper exposed to humidified air containing formic acid, mimicking indoor atmospheric corrosion. ODT layers are, however, much less efficient corrosion inhibitors for zinc. In this work, we elucidate the possibility of using ODT monolayers to inhibit corrosion of brass. Based on a quantitative analysis of corrosion products, we found that ODT provides equally good corrosion inhibition of single-phase Cu20Zn as of pure copper, retarding the transportation of corrosion stimulators to the brass surface. On double-phase Cu40Zn, however, local galvanic effects led to less efficient corrosion inhibition and more corrosion products than on Cu20Zn.

  • 5.
    Hedberg, Yolanda
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Karlsson, M. -E
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Wei, Z.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Znidarsic, M.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Odnevall Wallinder, Inger
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Hedberg, Jonas
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Interaction of Albumin and Fibrinogen with Stainless Steel: Influence of Sequential Exposure and Protein Aggregation on Metal Release and Corrosion Resistance2017In: Corrosion, ISSN 0010-9312, E-ISSN 1938-159X, Vol. 73, no 12Article in journal (Refereed)
    Abstract [en]

    Corrosion and metal release mechanisms of the biomedical stainless steel grade Type 316L are at human-relevant biological conditions not fully understood. This study focuses on its corrosion properties and release of iron (Fe), chromium (Cr), manganese (Mn), and nickel (Ni) into simulated physiological solutions at pH 7.4 in the presence of proteins. Parallel studies were performed on stainless steel Type 303 containing a substantial amount of MnS inclusions. Metal release studies were performed in phosphate buffered saline (PBS) for 4 h and 24 h at 37 degrees C with or without different concentrations of bovine serum albumin (BSA), fibrinogen from bovine plasma (Fbn), or mixtures of the same. Studies were in addition performed after 1, 4, 6, and 24 h in solutions that were partially replenished after 5 h in order to investigate whether any Vroman effect (exchange of adsorbed proteins by proteins of higher binding affinity) could influence the extent of released metals in solution. This was performed at physiological concentrations of BSA (40 g/L) and Fbn (2.67 g/L) in PBS, and for reference solutions of PBS, PBS with 40 g/L BSA, and PBS with 2.67 g/L Fbn. Changes in open-circuit potential and linear polarization resistance were investigated for the same conditions. After exposure, the exposed surfaces were rinsed and investigated ex situ by means of x-ray photoelectron spectroscopy and infrared reflection absorption spectroscopy. Metal-protein complexation-induced metal release mechanisms were found to be most pronounced for Type 316L and the release of Fe, Cr, and Ni. Fibrinogen adsorbed differently onto Type 303 (thicker conformation of adsorbed proteins) as compared with Type 316L and occasionally induced corrosion events for Type 303. Mn was mostly released from inclusions present in the Type 303 alloy, most probably via non-electrochemical mechanisms. A Vroman effect was observed for both grades. A significant extent of precipitation of metal-rich protein aggregates influenced the metal release measurements in solution and resulted in an underestimation of the total amount of released metals from the stainless steel grades.

  • 6.
    Kivisäkk, Ulf
    Sankvik Materials Technology.
    Significance of activation of test specimens for the determination of iso-corrosion curves of stainless steels2005In: Corrosion, ISSN 0010-9312, E-ISSN 1938-159X, Vol. 61, no 6, 602-608 p.Article in journal (Refereed)
    Abstract [en]

    The general corrosion resistance of a corrosion-resistant material, for instance, in an acid L's often illustrated in iso-corrosion curves; these curves can be used as a basis for material selection. Therefore, it is important that the information given in one diagram can be compared with diagrams from other sources. Information about the activation of the test specimens is not always given, which makes comparison difficult. Activation is often used to investigate whether the material has the ability to repassivate. In this paper two different forms of activation were used. either with a zinc rod or in boiling hydrochloric acid (HCl). For three superduplex stainless steels, UNS S32750, UNS S32760, and UNS S32520, with similar chemistry except for their copper and tungsten content, the influence of the activation method was studied using general corrosion rate tests in HCL The results were also compared with earlier results in sulfuric acid (H2SO4). No major influence of the alloying with copper and tungsten was found in the range where the materials are resistant, i.e., when they have low corrosion rates. However, in the reducing environments-HCl and H2SO4 at low concentrations-the activation of the test specimens narrowed this range. In contrast, in H2SO4 at high concentrations, which is a more oxidizing acid, it was indicated that activation did not appear to influence the corrosion rates. An activation procedure with boiling HCl seems to give higher corrosion rates than for specimens activated with zinc. However, the influence on the range seems to be minor and not as profound as without activation. Despite the fact that activation may significantly influence the corrosion rate, not all iso-corrosion diagrams indicate whether the experimental procedure includes activation. As a result, a material can be selected on misleading results.

  • 7.
    Kivisäkk, Ulf
    et al.
    Sandvik Materials Technology.
    Chai, G.
    Sandvik Materials Technology.
    Influence of test method and relaxation on the result from stress corrosion cracking tests of stainless steels in dilute neutral chlorides2003In: Corrosion, ISSN 0010-9312, E-ISSN 1938-159X, Vol. 59, no 9, 828-835 p.Article in journal (Refereed)
    Abstract [en]

    Recently, as a part in the European Carbon and Steel Community (ECSC) project "SCC of newer SS grades" (NEWSCC), a u-bend test program in neutral dilute chlorides was performed. Earlier presented data of stress corrosion resistance on stainless steel (SS) in the same environment have been based mostly on constant load testing. The results from these two test programs differed, even though they were performed at the same environmental conditions and in the same equipment. The ranking of alloys inside the two material groups of austenitic and duplex SS was not changed. But, the ranking between the groups was changed. In the constant strain test program with u-bends, the austenitic SS received better results compared to the duplex SS, compared to the previously performed constant load test program. Another result was that AISI 304L (UNS S30403) steel experienced cracking first at a temperature as high as 125degreesC in 1% chloride solution. Experiences from service have given a maximum service temperature between 40degreesC and 60degreesC. Mechanical testing including relaxation tests at actual testing temperature was done to evaluate the differences. The austenitic SS experienced up to 30% relaxation but the higher alloyed duplex steels only similar to10%. The differences in relaxation behavior must be considered during evaluation of u-bend test programs. The degree of high relaxation of AISI 304L also might explain the improvement for u-bend specimens compared to constant load test data and service experience. The difference in relaxation behavior is also important when a test method shall be chosen for simulating practical experience. For example, constant strain samples such as u-bends are the most representative for conditions where a strain causes the load (for instance, in nonstress-relieved bent heat exchanger tubing). However, the huge difference in relaxation for different SS in a u-bend will not give representative results for a constant load application (for instance, stress-relieved heat exchanger tubing or pressure vessels).

  • 8.
    LeBozec, N.
    et al.
    Institut de la Corrosion, Brest.
    Jönsson, Martin
    Swedish Corrosion Institute, Stockholm.
    Thierry, Domnique
    Swedish Corrosion Institute, Stockholm.
    Atmospheric Corrosion of Magnesium Alloys: Influence of Temperature, Relative Humidity, and Chloride Deposition2004In: Corrosion, ISSN 0010-9312, E-ISSN 1938-159X, Vol. 60, no 4, 356-362 p.Article in journal (Refereed)
    Abstract [en]

    Laboratory tests have been performed to determine how climatic parameters, e.g., relative humidity, temperature, and the amount of sodium chloride (NaCl), influence the corrosion rate of magnesium alloys AZ91D (UNS M11916) and AM50 (UNS M10500). The effect of the surface state also has been investigated. The exposures were performed at 75%, 85016, and 95% relative humidity (RH) and at 25degreesC and 35degreesC. The amount of NaCl ranged from 14 mug cm(-2) to 240 mug cm(-2). The corrosion rate of both materials increased as a function of temperature, RH, and amount of NaCl. A strong influence of the surface state, i.e., as-cast or polished, was observed mainly due to the combined effect of an active surface layer and the roughness of as-cast surfaces.

  • 9.
    Leygraf, Christofer
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Corrosion Science.
    Hedberg, J.
    Qiu, P.
    Gil, H.
    Henriquez, J.
    Johnson, Claes Magnus
    2007 W.R. Whitney Award Lecture: Molecular in situ studies of atmospheric corrosion2007In: Corrosion, ISSN 0010-9312, E-ISSN 1938-159X, Vol. 63, no 8, 715-721 p.Article in journal (Refereed)
    Abstract [en]

    Atmospheric corrosion involves chemical, electrochemical, and physical processes in three phases (solid, liquid, and gas) and two interfaces (solid/liquid and liquid/gas). Because of inherent experimental and conceptual difficulties, scientific efforts to characterize this highly complex interfacial regime came relatively late into the field. With the access and development of surface and interface-sensitive analytical techniques, it has lately become possible to perform molecular in situ analyses of the interfaces involved in atmospheric corrosion. This Whitney Award paper presents some highlights from our fundamental research in atmospheric corrosion, including results from the most recent efforts in our research group to provide a molecular picture of the interfacial regime that governs atmospheric corrosion. Using copper or zinc as substrates, and formic acid (HCOOH), acetic acid (CH3COOH), acetaldehyde (CH3CHO) or propionic acid (C2H5COOH) as corrosion stimulators in the humidity-containing atmosphere, results will be presented with particular emphasis on probing the metal oxide/water interface (by infrared reflection absorption spectroscopy combined with the quartz crystal microbalance and sum frequency generation) and the water/gas interface (by sum/frequency generation), respectively. Theoretical calculations are also presented, which aid in interpreting the in situ spectroscopy data. The multi-analytical effort provides evidence of the importance of the solid/ liquid interface over the liquid/gas interface. In all, the results can be interpreted to follow the conceptual framework of GILDES, a general model for atmospheric corrosion. Taking copper as an example, identified surface species and reaction pathways include proton- and carboxylate-induced dissolution of the cuprous ion, followed either by formation and precipitation of cuprous oxide or by oxidation of cuprous to cupric ions and subsequent formation and precipitation of copper carboxylate.

  • 10. Linder, Jan
    et al.
    Blom, R
    Development of a method for corrosion fatigue life prediction of structurally loaded bearing steels2001In: Corrosion, ISSN 0010-9312, E-ISSN 1938-159X, Vol. 57, no 5, 404-412 p.Article in journal (Refereed)
    Abstract [en]

    In this study a simplified method to predict corrosion fatigue properties for the Cr-alloyed bearing steel 100CrMnMo8 is proposed. With this method corrosion pits are assumed to act as defects, which could initiate fatigue cracks. A linear elastic fracture mechanics (LEFM) model was used to evaluate the critical corrosion pit size when mechanical fatigue crack propagation occurred. The unknown parameters in the prediction model were corrosion pit growth rate and the threshold stress intensity factor (DeltaK(th)) for fatigue crack growth. In this study corrosion pit growth rate was determined for 100CrMnMo8 in a chloride-containing water solution by aid of a statistical method. Corrosion pit growth rate was found to be approximately proportional to the square root of time. The time dependence of corrosion pit growth Zed also to the conclusion that characterization of corrosion fatigue strength must be made with respect to both exposure time in a corrosive environment and the number of cycles to a runout level. DeltaK(th) fatigue crack growth was estimated from interrupted rotating bending fatigue tests in the corrosive environment in question. Since only the corrosion pit growth rate and DeltaK(th), are needed as input in the proposed corrosion fatigue prediction model, much effort can be saved since this can reduce the amount of fatigue testing. Corrosion pit growth rate can be determined on unloaded test coupons In the desired environment. Hence, for materials selection, exposure tests followed by a corrosion pit size analysis can indicate the corrosion fatigue performance in a given environment.

  • 11. Mameng, Sukanya Hagg
    et al.
    Pettersson, Rachel
    Leygraf, Christopher
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Effect of Stainless Steel Composition on Atmospheric Corrosion Resistance at a Marine Site in Dubai2017In: Corrosion, ISSN 0010-9312, E-ISSN 1938-159X, Vol. 73, no 7, 880-891 p.Article in journal (Refereed)
    Abstract [en]

    The influence of the composition of stainless steels on atmospheric corrosion resistance in a marine environment in Dubai was investigated after 2 y and 4 y of exposure. Different stainless steel grades with different surface finishes were included in the investigation: three ferritic stainless steels, five austenitic stainless steels, and four duplex stainless steels. The alloying elements chromium (Cr) and molybdenum (Mo) both had a beneficial influence on the corrosion resistance. The pitting resistance equivalent number (PREN =%Cr + 3.3%Mo + 16%N) and the (%Cr + 3.3%Mo) content in the surface film correlated well to the atmospheric corrosion resistance. An increased Cr content both in the bulk material and in the passive film improved the atmospheric corrosion resistance and the additional presence of Mo was effective in preventing red rust and also reduced the depth of pits. The depth of the pitting attack and the degree of aesthetic degradation were both influenced by alloying level, surface finish, and exposure conditions (open and sheltered). In the severe marine environment in Dubai, it is necessary to use Mo-bearing high-Cr stainless steel for adequate atmospheric corrosion resistance. The most resistant stainless steel grades were the high alloyed grades which ranked in the order UNS S31254 similar to UNS S3750 < UNS S34565 < UNS S32654. The duplex stainless steel grade S32205 may be considered for construction and architectural materials in Dubai but is likely to require more maintenance.

  • 12.
    Mazinanian, Neda
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Herting, Gunilla
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Odnevall Wallinder, Inger
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Hedberg, Yolanda
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Metal release and corrosion resistance of different stainless steel grades in simulated food contact2016In: Corrosion, ISSN 0010-9312, E-ISSN 1938-159X, Vol. 72, no 6, 775-790 p.Article in journal (Refereed)
    Abstract [en]

    A new technical guideline has been implemented by the Council of Europe (CoE) to ensure the stability and safety of food contact articles of metals and alloys, using 5 g/L citric acid (pH 2.4) and artificial tap water DIN 10531 (pH 7.5) as food simulants. The objectives of this study were: (i) to quantify the extent of metal release from austenitic (grades AISI 201, 204, 304, and 316L), ferritic (grades AISI 430 and EN 1.4003), and lean duplex stainless steel (grade EN 1.4162) in citric acid (5 g/L, pH 2.4) and in artificial tap water (pH 7.5); (ii) to compare the release of metals to the surface oxide composition, the open circuit potential-time dependence, and the corrosion resistance; and (iii) to elucidate the combined effect of high chloride concentrations (0.5 M NaCl) and citric acid at pH 2.2 and 5.5 on the extent of metal release from AISI 304 with and without prior surface passivation by citric acid. Exposures of all stainless steel grades in citric acid and artificial tap water up to 10 d (at 70°C/40°C) resulted in lower metal release levels than the specific release limits stipulated within the CoE protocol. For all grades, metals were released at levels close to the detection limits when exposed to artificial tap water, and higher release levels were observed when exposed to citric acid. Increased surface passivation, which resulted in reduced metal release rates with time, took place in citric acid for all grades and test conditions (e.g., repeated exposure at 100°C). There was no active corrosion in citric acid at pH 2.4. Fe (in citric acid) and Mn (in all solutions, but mostly tap water) were preferentially released, as compared to their bulk alloy content, from all stainless steel grades. Ni was released to the lowest extent. 0.5 M NaCl induced a very low (close to detection limits) metal release from grade AISI 304 at pH 5.5. When combined with citric acid (5 g/L) and at lower pH (2.2), 0.5 M NaCl induced slightly higher metal release compared to citric acid (pH 2.4) alone for coupons that were not pre-passivated. Pre-passivation in 5 g/L citric acid (pH 2.4) at 70°C for 2 h largely reduced this solution dependence. Pre-passivation resulted in an up to 27-fold reduced extent of metal release in solutions containing citric acid and/or NaCl at pH 2.2 to 5.5, and resulted in improved reproducibility among replicate samples.

  • 13.
    Odnevall Wallinder, Inger
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Leygraf, Christofer
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    A Critical Review on Corrosion and Runoff from Zinc and Zinc-Based Alloys in Atmospheric Environments2017In: Corrosion, ISSN 0010-9312, E-ISSN 1938-159X, Vol. 73, no 9, 1060-1077 p.Article, review/survey (Refereed)
    Abstract [en]

    This critical review aims at addressing important issues concerning zinc corrosion and zinc runoff processes of zinc or zinc alloyed with aluminum or magnesium exposed to atmospheric environments. The evolution of the corrosion product (patina) layer is very important for both processes. While corrosion largely is controlled by electrochemical reactions at the metal/patina interface, runoff is predominantly governed by chemical reactions at the patina/atmosphere interface. The gradual evolution of compounds in zinc patina follows one of two main routes: one in more sulfur-dominated and one in more chloride-dominated environments. Because of climatic changes and reduction of sulfur-containing atmospheric species in many parts of the world, the chloride-route is expected to dominate over the sulfur-route. Alloying with aluminum and magnesium results in substantial improvement in corrosion protection, whereby several mechanisms have been proposed. The released amount of zinc is highly dependent on the amount of rainfall, also on sulfur dioxide concentration or deposition, and to only a low extent on chloride deposition. Based on all runoff data, a model is presented which predicts 70% of all observed zinc runoff rates within 40% from their measured value.

  • 14. Sefer, B.
    et al.
    Dobryden, Illia
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science. Lulea University of Technology, Sweden.
    Almqvist, N.
    Pederson, R.
    Antti, M. -L
    Chemical milling of cast Ti-6Al-4V and Ti-6Al-2Sn-4Zr-2Mo alloys in hydrofluoric-nitric acid solutions2017In: Corrosion, ISSN 0010-9312, E-ISSN 1938-159X, Vol. 73, no 4, 394-407 p.Article in journal (Refereed)
    Abstract [en]

    The behavior of cast Ti-6Al-4V and Ti-6Al-2Sn-4Zr-2Mo during chemical milling in hydrofluoric-nitric (HF-HNO3) acid solutions with 1:3 and 1:11 molar ratios was investigated using electrochemical and atomic force microscopy (AFM) techniques. Faster corrosion rate in 1:3 solutions was measured for Ti-6Al-4V than for Ti-6Al-2Sn-4Zr-2Mo, whereas in 1:11 solution Ti-6Al-2Sn-4Zr-2Mo exhibited higher corrosion rate. Scanning Kelvin probe force microscopy measurements revealed difference in the Volta potential between the α-laths and the β-layers in the Widmansttäten microstructure indicating operation of microgalvanic cells between the microconstituents when in contact with HF-HNO3 solution. The AFM topography measurements demonstrated faster corrosion of the α-laths compared to the β-layers, in both alloys. In 1:3 solutions, higher α/β height difference was measured in Ti-6Al-4V, whereas in 1:11 solution, the difference was higher in Ti-6Al-2Sn-4Zr-2Mo. The results revealed that the chemical milling behavior of the two investigated alloys is controlled by the microscopic corrosion behavior of the individual microconstituents.

  • 15. Sefer, Birhan
    et al.
    Dobryden, Illia
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science. Lulea University of Technology, Sweden.
    Almqvist, Nils
    Pederson, Robert
    Antti, Marta-Lena
    Chemical Milling of Cast Ti-6Al-4V and Ti-6Al-2Sn-4Zr-2Mo Alloys in Hydrofluoric-Nitric Acid Solutions2017In: Corrosion, ISSN 0010-9312, E-ISSN 1938-159X, Vol. 73, no 4, 394-407 p.Article in journal (Refereed)
    Abstract [en]

    The behavior of cast Ti-6Al-4V and Ti-6Al-2Sn-4Zr-2Mo during chemical milling in hydrofluoric-nitric (HF-HNO3) acid solutions with 1: 3 and 1: 11 molar ratios was investigated using electrochemical and atomic force microscopy (AFM) techniques. Faster corrosion rate in 1: 3 solutions was measured for Ti-6Al-4V than for Ti-6Al-2Sn-4Zr-2Mo, whereas in 1: 11 solution Ti-6Al-2Sn-4Zr-2Mo exhibited higher corrosion rate. Scanning Kelvin probe force microscopy measurements revealed difference in the Volta potential between the alpha-laths and the beta-layers in the Widmansttaten microstructure indicating operation of microgalvanic cells between the microconstituents when in contact with HF-HNO3 solution. The AFM topography measurements demonstrated faster corrosion of the alpha-laths compared to the beta-layers, in both alloys. In 1: 3 solutions, higher alpha/beta height difference was measured in Ti-6Al-4V, whereas in 1: 11 solution, the difference was higher in Ti-6Al-2Sn-4Zr-2Mo. The results revealed that the chemical milling behavior of the two investigated alloys is controlled by the microscopic corrosion behavior of the individual microconstituents.

  • 16. Wallinder, D.
    et al.
    Odnevall Wallinder, Inger
    KTH, Superseded Departments, Materials Science and Engineering.
    Leygraf, Christofer
    KTH, Superseded Departments, Materials Science and Engineering.
    Influence of surface treatment of type 304L stainless steel on atmospheric corrosion resistance in urban and marine environments2003In: Corrosion, ISSN 0010-9312, E-ISSN 1938-159X, Vol. 59, no 3, 220-227 p.Article in journal (Refereed)
    Abstract [en]

    The influence of surface treatment of Type 304L (UNS S30403) stainless steel on atmospheric corrosion resistance in urban and marine environments was investigated during 2 months and 7 months of exposure. The surface conditions investigated included as-received, pickled, abraded, and bright-annealed samples. The surfaces were investigated before the exposures, and differences in surface composition, polarization resistance, surface roughness, and wettability were observed between the various surface treatments. During the exposures, all samples decreased in weight. Under the present conditions, the as-received samples showed the best performance in the urban environment, whereas the bright-annealed samples showed the best performance in the marine environment. Different effects of surface treatments on atmospheric corrosion resistance in both environments could be explained best by the resulting differences in passive film composition.

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