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The influence of surface adsorption of benzotriazole (BTAH) and of chloride ions (Cl-) on the kinetics of copper electrodeposition/dissolution in copper sulfate solutions and on copper deposit char ...

Ingress of chloride into alpha-Al2O3(0001) and Al(111) was calculated by first-principles theory calculations by considering Cl insertion into Al or O vacancies within alpha-Al2O3(0001) or into vac ...

The corrosion inhibition of self-assembled octadecylphosphonic acid (ODPA) layers on non-oxidized and pre-oxidized copper and Langmuir-Blodgett deposited ODPA layers on pre-oxidized copper was investigated under a simulated indoor atmospheric corrosion environment containing 80% RH and 100 ppb formic acid. The corrosion process was monitored in-situ with infrared absorption/reflection spectroscopy, and the corrosion products were further characterised by grazing incidence X-ray diffraction. Nano-FTIR microscopy was used to reveal the nature, size, and distribution of the corrosion products on the nanoscale. The combination of pre-formed cuprite and ODPA layers, both with only some nanometres thickness, provided an excellent protection under this environment. Data availability The raw/processed data required to reproduce these findings cannot be shared at this time as the data also forms part of an ongoing study.

Insertion and migration of chlorine atoms (Cl) in α-Al2O3 were studied by density functional theory calculations focusing on the influence of oxide thickness and doping by Mg, Cu and Si. Work function, electronic band gap, and insertion energy were calculated to explore thermodynamics of Cl migration. Partial density of state (PDOS) calculations revealed the role of dopants in the electronic character of metal–O and Al–Cl bonds. Work function data showed the effect of Cl insertion into the oxide film on the corrosion resistance. Cl can locate at an O vacancy ( V O ) with a large exothermic insertion energy, independent of oxide thickness, but can only locate at superficial Al vacancy ( V A l ) exothermically. The energy barrier for Cl migration via neighboring V O increases with oxide thickness, and is 2 ∼2.5 eV for thicker oxides. Cl insertion causes a work function reduction exceeding 2 eV, implying a decreased corrosion resistance. The inhibition of Cl migration by Si-doping can be explained by a more intense hybridization peak of Si–O over Al–O in the PDOS profile, while the reduction of energy barrier by Mg–/Cu-doping probably is due to the deviation of metal-s state from the Fermi energy, thus facilitating Cl movement within the oxide.

Hexane selenol (CH3(CH2)(5)SeH) was adsorbed from gas phase in ultra-high vacuum on polycrystalline Cu and studied with synchrotron radiation based photoelectron spectroscopy (PES) and Near edge X- ...

The initial steps of Cu2O sulphidation to Cu2S have been studied using plane-wave density functional theory at the PBE-D3+U level of sophistication. Surface adsorption and dissociation of H2S and H2O, as well as the replacement reaction of lattice oxygen with sulphur, have been investigated for the most stable (111) and (100) surface facets under oxygen-lean conditions. We find that the (100) surface is more susceptible to sulphidation than the (111) surface, promoting both H2S adsorption, dissociation and the continued oxygen–sulphur replacement. The results presented in this proceeding bridge previous results from high-vacuum experiments on ideal surface to more realistic corrosion conditions and set the grounds for future mechanistic studies. Potential implications on the long-term final disposal of spent nuclear fuel are discussed.This paper is part of a supplement on the 6th International Workshop on Long-Term Prediction of Corrosion Damage in Nuclear Waste Systems.

Accelerated NVDA (VDA 233-102) tests were performed on bare Zn and Al sheets, Galfan coating (Zn–5 wt-% Al) and Galvalume coating (Zn–55 wt-% Al) on steel. ZnO, Zn(OH)2 and Zn5(OH)8Cl2·H2O were the main corrosion products identified on both bare Zn sheet and Galfan. AlOOH and Al(OH)3 were preferentially formed on bare Al sheet and Galvalume. In addition, Zn–Al–containing corrosion products, Zn6Al2(OH)16CO3·4H2O and/or Zn2Al(OH)6Cl·2H2O were identified on both Galfan and Galvalume. Corrosion products of Zn6Al2(OH)16CO3·4H2O with a platelet morphology were preferentially formed in the zinc-rich interdendritic regions of the Galvalume surface. Galfan revealed a similar corrosion behaviour as bare Zn sheet, whereas Galvalume exhibited similar behaviour as bare Al sheet. Deposition of chlorides highly influenced the corrosion of both Galvalume and Al rather than Galfan and Zn due to the rapid local damage of the compact native thin film of Al2O3.

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 g...

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. Berger

Stainless steels have been widely used as architectural and construction materials because of their high degree of corrosion resistance, unique aesthetic quality, and stability in an unpolluted atmosphere. Although stainless steel is highly corrosion resistant, localized corrosion can occur in certain environments, especially in marine atmospheric conditions if the appropriate grade is not used. Exposure of stainless steel to an environment more aggressive than the limiting conditions may be harmful to its aesthetic appearance and ultimately even to its load-bearing capacity. Selecting a suitable stainless steel grade requires knowledge of the actual location of the application and the atmospheric conditions. In terms of materials selection, the austenitic stainless steel grade 316/316L has proved a very popular choice for architectural applications in many locations, but it is not always suitable at demanding sites such as marine environments in the Middle-East. In such cases the use of a higher-performance grade, often in combination with a good surface finish and established cleaning routines, is required to maintain pristine surfaces. The main objective of this paper is to present information about the atmospheric corrosion resistance of a number of stainless steels in the Middle-East at a marine site. The results obtained are analysed and discussed in terms of factors affecting atmospheric corrosion of stainless steel such as the, alloying element level, surface roughness, surface treatment, and microclimate.

The water–cuprite interface plays an important role in dictating surface related properties. This not only applies to the oxide, but also to metallic copper, which is covered by an oxide film under typical operational conditions. In order to extend the currently scarce knowledge of the details of the water-oxide interplay, water interactions and reactions on a common Cu2O(100):Cu surface have been studied using high-resolution photoelectron spectroscopy (PES) as well as Hubbard U and dispersion corrected density functional theory (PBE-D3+U) calculations up to a bilayer water coverage. The PBE-D3+U results are compared with PBE, PBE-D3 and hybrid HSE06-D3 calculation results. Both computational and experimental results support a thermodynamically favored, and H2O coverage independent, surface OH coverage of 0.25–0.5 ML, which is larger than the previously reported value. The computations indicate that the results are consistent also for ambient temperatures under wet/humid and oxygen lean conditions. In addition, both DFT and PES results indicate that the initial (3,0;1,1) surface reconstruction is lifted upon water adsorption to form an unreconstructed (1 × 1) Cu2O(100) structure.

This paper presents an in-depth characterisation study of the patina formed on a copper tile taken from the roof of Queen Anne's Summer Palace in Prague after > 300 years of exposure to the action of the atmosphere. A wide variety of techniques have been used, including metallographic and chemical analysis (electrogravimetry, AAS, XRF) of the copper matrix, and spectroscopic and microscopic investigations (GIXRD, FTIR, TEM/EDS and SEM/EDS) to determine the composition and structure of the patina. The major conclusions of the study are: (a) the base copper contains abundant inclusions mainly of rosiaite (PbSbO); (b) the patina is formed by an inner sublayer of cuprite (CuO) and an outer sublayer of brochantite [CuSO(OH)] and antlerite [CuSO(OH)] and traces of azurite [Cu(CO)(OH)]; and (c) the brochantite/antlerite crystals are randomly doped with Fe and C.

This work is a further step to develop a finite element model to simulate localized corrosion of aluminum alloys driven by micro-galvanic effects. The focus herein is to explore the effect of density (porosity and tortuosity) of Al(OH)3 precipitates generated both on the electrode surface and in the liquid phase. Two coupled processes are identified and discussed, both influencing the local pH: the Al3+ dissolution from the electrode surface, and the steric hindrance effects on mass transport of species between the bulk solution and the anolyte next to the corroding surface. With the densest precipitate investigated, Al3+ dissolution is more effectively blocked and the mass transport largely hindered of Al3+ ions leaving the electrode surface. With increasing porosity of the precipitate, Al3+ dissolution is enhanced, also the mass transport of species in the electrolyte. The most severe localized acidification inside the occluded volume occurs when the density, namely ascribed by porosity, of precipitate is at an intermediate level with ec = 0.01. In qualitative agreement with experimental observations, this work highlights the importance of corrosion product density on the progress of localized corrosion.

Presents a comprehensive look at atmospheric corrosion, combining expertise in corrosion science and atmospheric chemistry Is an invaluable resource for corrosion scientists, corrosion engineers, a ...

This study explores the initial release of zinc and aluminum from non-treated Galvalume and the parallel formation of corrosion products when exposed to synthetic seawater and rainwater of different chloride content. Comparisons were made with long-term field exposures at non-sheltered marine conditions. Observed release rates from short-term conditions agree qualitatively with the long-term findings with a selective release of zinc over aluminum. The release and corrosion processes were intertwined through the formation of corrosion products with properties that influence the long-term release process. Prior to exposure, Al2O3 dominated the entire surface, and was subject to local destruction upon interaction with chloride ions. As a consequence Al2O3 was gradually replaced and covered by zinc-rich corrosion products primarily in interdendritic areas during the first year of marine exposure. This was followed by the gradual formation and integration of aluminum-rich corrosion products, reflected by an increased zinc release rate during the first year, followed by a gradually decreased rate during subsequent years. The importance of Al2O3 was also evident in deaerated synthetic rainwater or seawater, where the formation of Al2O3 was presumably hindered. In synthetic rain water this resulted in a higher ratio between released aluminum and zinc compared with non-deaerated conditions.

Martensitic stainless steel grade AISI 420 intended for cutlery knives and scissor blades has been investigated in an attempt to correlate microstructure and surface finish (polishing procedure) to metal release rates of the main alloy constituents, iron and chromium. Metallographic investigations proved the knife steel and, in particular the scissor steel to have very inhomogeneous microstructures. The knife steel contained bands of ferrite in the martensitic structure while the scissor steel revealed large amounts of tempered martensite and inclusions of manganese sulphides and silicon oxides. Samples of different surface finish were immersed in 3 vol% acetic acid at 40 °C from 1 to 10 days for metal release testing, simulating food contact. The largely inhomogeneous microstructure of the scissor steel results in high and greatly varying metal release rates, despite a fairly high chromium content of the surface oxide. Areas of inclusions seem to act as initiation points for accelerated metal release and the forming of a surface oxide depleted in chromium, but rich in copper. The generation of high surface temperatures during polishing was found beneficial from a metal release perspective as a result of the formation of a surface oxide of improved passivating properties.

Ferritic stainless steel grade AISI 430 with three different surface finishes, glossy, line and abraded has been evaluated regarding changes in metal release rates and corresponding changes in surf ...

Despite numerous studies on atmospheric corrosion of copper and copper based alloys, the corrosion induced release processes of individual alloy constituents suffer from significant knowledge gaps. This investigation comprises metal release rate measurements of copper, zinc and tin from some copper based alloys including brass (20 wt-%Zn) and bronze (6 wt-%Sn), and their pure alloying metals, copper, zinc and tin. Data have been generated during a 2·5 year urban field exposure in Stockholm, Sweden and parallel laboratory investigations in a specially designed rain chamber using artificial rain. Brass shows significantly lower annual release rates of both copper and zinc compared to pure metal sheets of its alloy constituents. Zinc is preferentially released compared to copper. Dezincification of brass occurs both at field and laboratory conditions, a process influenced by rain characteristics. Alloying with tin does not largely reduce the release rate of copper from bronze compared to pure copper....

Release rates of total copper in artificial seawater (without organic matter) from anti-fouling paints of different active copper compounds range from 0.5 to 75 μg cm-2 day-1. Approximately 80% of ...

Corrosion-induced copper runoff has been monitored for copper sheet, naturally patinated copper and pre-patinated copper, with and without surface treatments, in a marine environment during one yea ...

Data on metal release from stainless steel particles can be used in the assessment and quantification of the potential impact of stainless steel on health and the environment. To elaborate a test method suitable for the study of metal release from particles, the experimental parameters particle loading, agitation and separation of particles from the solution were investigated through exposure of 316L powder particles in two artificial biological media. The results suggest that a small particle loading, bi-linear shaking and centrifugation for separation of particles from the solution give the most reproducible results. They also show that metal release rates are strongly influenced by the physico-chemical properties of the test medium and the effective surface area of particles during exposure.

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, Fou ...

The electrochemical behavior and stability of Pt, Ti, TiN, and nano-porous carbon for implantable cardioverter-defibrillator (ICD) electrode application were investigated in a phosphate buffered saline solution. The electrochemical interfacial properties were examined by electrochemical impedance spectroscopy, and the potential and current response during ICD shock pulses were recorded by a digital oscilloscope. Changes in surface composition and structure were investigated using X-ray photoelectron spectroscopy and environmental scanning electron microscopy. When exposed to anodic 700 V shock pulses with duration of 10 ms, only Pt was stable, nano-porous carbon electrode was slightly attacked, whereas Ti and TiN electrodes suffered severe degradation. Upon cathodic shock pulsing, all the materials were stable, but Ti and TiN electrodes with a smooth surface showed evidence of hydrogen adsorption. Porous and rough electrodes produced less gas evolution compared to a smooth surfaces, due to a higher amount of charge transferred through non-Faradaic processes. The reason for this could be higher interfacial capacity due to the large surface area.

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.

The release of copper, induced by atmospheric corrosion, from naturally patinated copper of varying age (0 and 30 years) has been investigated together with its potential ecotoxic effect. Results were generated in an interdisciplinary research effort in which corrosion science and ecotoxicology aspects were combined. The aim of the investigation was to elucidate the situation when copper-containing rainwater leaves a roof in terms of runoff rate, chemical speciation, bioavailability and ecotoxicity effects. Data have been collected during a three-year field exposure conducted in the urban environment of Stockholm, Sweden. The potential environmental effects have been evaluated using a combination of a copper specific biosensor test with the bacterium Alcaligenes eutrophus and the conventional 72-h growth inhibition test with the green alga Raphidocelis subcapitata. The results show annual runoff rates between 1.0 and 1.5 g/m2 year for naturally patinated copper of varying age. The runoff rate increased slightly with patina age, which mainly is attributed to the enhanced first flush effect observed on thicker patina layers. The total copper concentration in investigated runoff samplings ranged from 0.9 to 9.7 mg/l. Both computer modeling and experimental studies revealed that the majority (60-100%) of released copper was present as the free hydrated cupric ion, Cu(H2O)6(2+), the most bioavailable copper species. However, other copper species in the runoff water, such as, e.g. Cu(OH)+ and Cu2(OH)2(2+), were also bioavailable. The copper-containing runoff water, sampled directly after release from the roof, caused significant reduction in growth rate of the green alga. It should be emphasized that the results describe the runoff situation immediately after release from the copper roof and not the real environmental ecotoxicity. Therefore the data should only be used as an initial assessment of the potential environmental effect of copper runoff from building applications. Future risk assessments should also consider dilution effects of copper, changes in its chemical speciation and bioavailability during environmental entry, and type and sensitivity of the receiving ecosystem.

Electrochemical processes at the electrode–electrolyte (body fluid) interface are of ultimate importance for stimulating/sensing electrode function. A high electrode surface area is desirable for safe stimulation through double-layer charging and discharging. Pt and Pt–Ir alloys have been the most common electrode materials. The use of TiN coating as the surface layer on the electrode has found increasing interest because of its metal-like conductivity, excellent mechanical and chemical properties, and the fact that it can be deposited with a high surface area. In this work, electrochemical impedance spectroscopy (EIS), which is a sensitive and non-destructive technique and widely used for characterization of electrical properties of electrode–electrolyte interfaces, was applied to investigate pure Pt and Ti, and TiN coated electrodes exposed to a phosphate-buffered-saline (PBS) solution. Platinized Pt and Ti were also studied for comparison. The capacitance value of the electrodes in PBS was obtained through quantitative analysis of the EIS spectra. The results reveal that the capacitance of the TiN coated electrodes with a rough surface is several hundreds times higher than that of a smooth Pt surface. Platinization of Ti can also increase the capacitance to the same extent as platina. EIS has been shown to be a powerful technique for characterization of stimulating/sensing electrodes.

Atomic force microscopy (AFM) and infrared reflection absorption spectroscopy (IRAS) were used for in situ investigations of the initial atmospheric corrosion of bronze. In addition ex situ XPS inv ...

This paper summarizes the results from an extensive field exposure program implemented to study possible seasonal dependencies of copper corrosion rates and runoff rates. Two-year exposures in one ...

Low-temperature ion nitriding introduces interstitial nitrogen into the austenitic stainless steel matrix. An enhanced passivity of the nitrided stainless steel was detected by anodic potentiodynam ...

In order to fill some major gaps of knowledge for future risk assessments, an interdisciplinary research effort is going on in order to generate relevant zinc runoff rate data from various commercial zinc-based materials, and to explore the relation between the chemical speciation of zinc in runoff water and its ecotoxicity. This study presents runoff rates, based on 1-year exposures of 15 zinc-based materials, which range from 0.07 to 3.5 g/m2 year. When collected immediately after release from the various zinc-based surfaces, chemical speciation modeling of the runoff water suggests that nearly all zinc (>95%) is present as hydrated Zn2+ ions, the most bioavailable speciation form. Evaluation of zinc runoff for possible environmental effects was performed through growth inhibition test with a green alga, Raphidocelis subcapitata. The results show a high correlation between the amount of zinc in the runoff and the environmental effect, suggesting, again, that all zinc is present as hydrated Zn2+. The insight gained aids in predicting actual ecotoxicity effects during environmental fate of zinc, based on chemical speciation of zinc in the runoff.

Recently there has been anincreased environmental concern in severalcountries in Europe, in particular in Sweden andin the Netherlands regarding the amount of copperand zinc that is released from building materialsinto society. Due to lack of runoff data, thelegislators have so far used corrosion ratesmeasured during the last 20 years to calculatequantities of metal released from buildingsassuming that the quantity of metal corrosionequals the quantity of metal runoff. Withdecreasing levels of environmental pollutantsduring the last decade in Europe, it is importantto determine more recent and hence morerepresentative corrosion and runoff rates to beused in the calculations. For this reason a field exposure program was implemented during 48 weeks in an urbanatmosphere in Sweden determining corrosion andrunoff rates for copper and zinc of differentage. New copper exposed for 48 weeks in the urbanatmosphere shows a corrosion rate of 6.7gm-2y-1 and an almost constant runoff rate of1.3 gm-2y-1 during the period. Therunoff rate is significantly lower than thecorrosion rate and represents only a fraction(≤20%) of the total amount of corroded metalduring this period. Zinc shows a graduallydecreasing corrosion rate with time being 5.0gm-2y-1 after 48 weeks of exposure. Therunoff rate is relatively stable with an averagerate of 3.1 gm-2y-1 during the sameperiod. This value represents ≈60% of the totalamount of corroded zinc. The effect of panel age has been investigatedin parallel field and laboratory studies. Theresults show that naturally aged copper exhibitssomewhat higher average runoff rates (2 gm-2y-1) than new copper, probably due to acombined effect of storage and weatherconditions. No significant difference in runoffrate can be found between new and naturally agedzinc. The field and laboratory investigationsshow that precipitation rate and amount influence the magnitude of the runoff rate forboth copper and zinc.

Wet storage staining is a phenomenon that occurs on both zinc coated and 55% Al–Zn coated steel sheets during shipment or storage in damp conditions. Whereas zinc coated sheets form white corrosion products, 55% Al–Zn coated steel sheets form black corrosion products. The effect of temperature, pH and wet storage on the occurrence of black rust staining of unpassivated Aluzink samples has been investigated in the laboratory in terms of corrosion product formation and composition. A characterization of corrosion products formed has been performed mainly based on scanning electron microscopy with X-ray microanalyses (SEM/EDS) for morphological and quantitative analyses and X-ray diffraction techniques (XRD) for crystalline phase identification. Black rust formation is strongly related to alkaline pH regions and is enhanced by the temperature. All black panels show the presence of Bayerite (Al(OH)3), mainly formed on the aluminum rich dendrite branches and a basic zinc aluminum carbonate (Zn6Al2(OH)16CO3·4H2O) formed in the zinc rich interdendritic alloy regions in contact with air. Blackening of Aluzink surfaces is connected to differences in optical properties of embedded metallic zinc and/or aluminum particles of different shape and size in the corrosion layer.

The corrosion performance of coatings depends on both the substrate and coating properties. In this work, duplex TiN coatings were deposited on AISI 304 stainless steel with arc-ion plating. Before deposition, nitriding of the substrate was done with a N+2 ion energy of 500 eV or 700 eV in the same physical vapor deposition plant. The corrosion performance of the duplex TiN coatings was evaluated in an acidic chloride solution by using electrochemical techniques such as potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). The measurements were also performed on the uncoated substrates for comparison. It was observed that the nitriding pretreatment leads to a high corrosion resistance of the substrate due to the formation of a highly protective passive film on the surface. For the coated system, the electrochemical behavior seemed to be dominated by the TiN coating. However, the formation of a thin oxide film on the surface of the TiN coating was also evident from Mott–Schottky plot measurements that indicate a n-type semiconducting behavior. The high donor density obtained suggests that the oxide film is very thin and probably amorphous. The oxide film formed on the TiN coating may be an important factor influencing the corrosion performance of the coated substrate. A model was proposed for the interaction between the duplex coating and aqueous solution which leads to the formation of a passive oxide film on the surface.

Alloying elements such as chromium, silicon and cerium in stainless steels are important for the oxidation behavior of the material at high temperatures. In this work, the oxide films formed on a stainless steel (253MA) with a small variation in the content of chromium, silicon and cerium, were characterized by electrochemical impedance spectroscopy (EIS), after exposure up to 100 hours in air at 750 and 1100 °C. The EIS spectra suggest a two-layer feature of the oxide films, in agreement with complementary surface analysis. The influence of a small variation in alloying element content on the oxidation behavior was revealed by the difference in the electrical properties of the oxide films. At 750 °C, the influence becomes pronounced after 100 hours of oxidation, and the steel with a lower content of chromium, silicon and cerium exhibits a lower film resistance. At 1100 °C, the oxide film formed on the steel with a lower content of chromium, silicon and cerium starts to degrade earlier than that on the steel with a higher content of chromium, silicon and cerium.

This work describes in situ infrared reflection absorption spectroscopy (IRAS) studies of the initial interaction of platinum and palladium to humidified air into which SO 2 has been introduced. The formation of surface species could be followed in situ from 9 min to 20 h of exposure. Supported by X-ray photoelectron spectroscopy and glancing incidence X-ray diffraction analysis after exposure, the IRAS bands from surface species formed in the aqueous adlayer on both metals has been assigned to sulfuric acid, H 2 SO 4 , with no evidence of chemical reaction with the metal. When changing from humid to dry exposure conditions, the aqueous adlayer with sulfuric acid transforms into one or more phases of hydrated crystalline sulfuric acid, H 2 SO 4 .nH 2 O. On platinum there is observed an initially fast formation rate of sulfuric acid followed by a slower formation rate with prolonged exposure. The initial formation rate on palladium, however, is much slower than on platinum. After about 7 h of exposure, a sudden but well-reproduced increase occurs, whereafter the formation rate levels off.

Oxide films formed on three stainless steels(UNS S30403; S44600; S30815) in air at 800°C werecharacterized by electrochemical-impedance spectroscopy(EIS). The film evolution vs. oxidation time wasinvestigated from 1 to 1000 hr. A three-electrodeelectrochemical cell and 0.1 MNa2SO4 solution were employed forEIS measurements. The spectra were interpreted in termsof a two-layer model of the films, where the capacitance and resistance obtained can berelated to the thickness (or roughness) anddefectiveness of the films. The results reveal that theoxide on S30403 grows and becomes defective, the oxideon S44600 thickens rapidly and retains its protectiveability for a relatively long time, and the oxide onS30815 remains thin and resistive. The two-layer modelis supported by surface characterization with SEM/EDS and in-depth profile of the oxide filmsobtained through glow discharge optical emissionspectroscopy (GDOES).

The influence of nitrogen dioxide, NO{sub 2}, and ozone, O{sub 3}, on sulfur dioxide-, SO{sub 2}-, induced atmospheric corrosion of nickel has been investigated through combined laboratory and field exposures. Both types of exposures result in corrosion products with nickel(II) sulfate as the main constituent. NO{sub 2} accelerates SO{sub 2}-induced corrosion significantly more than O{sub 3} and the results suggest that a mixture of SO{sub 2} and NO{sub 2} in proper concentrations can simulate the atmospheric corrosion behavior of nickel in a broad range of environments.

A new experimental setup for in situ studies of the metal/atmosphere interface has been developed based on simultaneous infrared reflection absorption spectroscopy (IRAS) and quartz crystal microbalance (QCM) measurements of a metal surface. It consists of an in situ chamber in which the metal can be exposed to a well-controlled atmosphere. Four external devices are connected to the in situ chamber; a Fourier transform infrared spectrometer with external optical compartments, a QCM sensor probe with a frequency counter, a corrosive air generator, and a corrosive air analyzing system. In order to demonstrate the capability of the IRAS/QCM setup, copper was exposed to purified air at 80% relative humidity and 25 C. Under these exposure conditions, the interface between copper and air consists of cuprous oxide and water physisorbed on the oxide. The kinetics of the cuprous oxide formation could be followed in situ with both techniques. The combined IRAS/QCM results show excellent agreement with previous combined IRAS and cathodic reduction measurements and with optical calculations of the IRAS response. Under these conditions, the detection limit in terms of an equivalent Cu{sub 2}O film thickness is 10 {angstrom} for IRAS in situ analysis and 2 {angstrom} for QCM in situ analysis,more » respectively.« less

In order to investigate episodic changes in atmospheric corrosivity with a high time resolution, a new sensor system for in situ field studies have been developed. Atmospheric corrosivity probes, based on the quartz crystal microbalance technique, are used together with probes for temperature and relative humidity and analyzers for H{sub 2}S, SO{sub 2}, NO{sub 2}, and O{sub 3}. To demonstrate the capability of the sensor system, an indoor field characterization has been conducted in an electrical control room within a pulp and paper factory. The characterization included simultaneous exposures of gold, silver, and copper together with gas analysis during normal operation and simulated malfunctions of the air filtration system. The precision of in situ mass response measurements has a standard deviation of only {+-} 1 ng/cm{sup 2}, corresponding to a mass sensitivity of less than one equivalent monolayer of corrosion products, e.g., Cu{sub 2}O. The mass sensitivity enabled differences in mass increase rates of copper, silver, and gold to be detected within hours after exposure start in normal operating conditions and on silver within minutes after simulated malfunctions of the air filtration system.

The GILDES model has been used to perform the first theoretical mechanistic study of the atmospheric corrosion of zinc in a controlled environment. Detailed comparisons are made of model results with laboratory data for short-term (0–1000 min) and long-term (0–680 h) exposures of zinc to SO2, NO2 and O3 at high relative humidities. The agreement of theory and experiment is excellent, indicating that the model has captured the principal processes (especially ligand-promoted dissolution) involved in the corrosion of zinc under these conditions.

Whereas addition of beryllium into Ni-based dental alloys can improve their casting properties, its effect on the corrosion behavior may be deleterious. The influence of beryllium addition on the corrosion resistance of Ni-25Cr-10Mo cast dental alloys has been investigated by different electrochemical techniques in artificial saliva and by measuring the rate of dissolution through atomic absorption spectroscopy analysis of the medium. The corrosion attack has also been examined by scanning electron microscopy. The coherent results obtained from the different techniques indicate that a low beryllium content [below 0.6 weight percent (w/o)] has no significant influence when the alloy is exposed to artificial saliva, whereas higher beryllium content results in negative effects on the corrosion resistance of the alloy. Hence, despite high content of chromium and molybdenum, the nickel-based dental alloy is susceptible to localized corrosion attack such as pitting and crevice corrosion when the alloy contains higher levels of beryllium. This is due to the high heterogeneity of the alloys, i.e., the formation of an intermetallic NiBe phase in the eutectic structure which is susceptible to corrosion attack

Sulfur dioxide is considered to be one of the most important stimulators of atmospheric corrosion in outdoor environments and numerous investigations have been made to understand its role. Despite clear evidence of the corrosion accelerating effect of SO{sub 2} there is still a lack in detailed knowledge on a molecular level of how SO{sub 2} interacts with metal surfaces during conditions of atmospheric corrosion. In situ infrared reflection absorption spectroscopy (IRAS) has been used to study the initial interaction of sulfur dioxide with water adlayer covered copper, nickel, and zinc surfaces. Each metal was exposed to 0.21 ppm SO{sub 2} in flowing air at 80% relative humidity and the formation of sulfite was followed from submonolayer thickness to layers of corrosion products of a few manometers thickness. From the positions of sulfite bonds in the experimentally obtained IRAS spectra and from considerations of optically induced band shifts in calculated IRAS spectra, it is suggested that the sulfite ions are coordinated with sulfur or sulfur and oxygen to the copper surface and with oxygen to the nickel and zinc surfaces. A fast initial growth rate was observed for the sulfite layer, which was followed by a slower growth rate after amore » few hours of exposure. A reaction sequence is suggested where bisulfite ions, formed by hydrolysis of sulfur dioxide in the water adlayer, generate surface metal-sulfite complexes at the oxide covered metal surface which subsequently detach from the surface and precipitate as thin layers of corrosion products.« less

Copper samples were exposed for 10 days in synthetic laboratory air at 75% relative humidity. To explore the possible influence of ozone on the atmospheric corrosion rate of copper, various combinations of the gaseous pollutants sulfur dioxide, nitrogen dioxide, and ozone were added. Ozone promotes the oxidation of sulfur dioxide to sulfate more efficiently than nitrogen dioxide does. A synergism between sulfur dioxide and ozone is suggested. This synergism includes both the oxidation of sulfur dioxide by ozone and the capability of ozone to form oxides, hydroxides, or other oxygen-containing reaction products in the presence of smaller amounts of sulfur dioxide. The synergistic effect possibly can explain the unexpectedly high corrosion rates of copper found at rural sites within the UN ECE exposure program. The rural sites are characterized by low sulfur dioxide and nitrogen dioxide concentrations, and by high ozone concentrations.

Phase identifications of a large number of field exposed sheltered zinc panels have revealed the presence of a number of different corrosion products on zinc. A few of these phases, Zn4SO4(OH)6 · nH2O, Zn5(OH)8Cl2 · H2O, NaZn4Cl(OH)6SO4 · 6H2O and Zn4Cl2(OH)4SO4 · 5H2O, seems to exist as final corrosion products. In order to study the formation of these phases, a field exposure program was implemented in atmospheres yielding different end products. A multi-analytical approach was used for detailed studies from the initial stages to fully developed corrosion films. The present study aims at describing the formation of zinc chlorohydroxysulfate (Zn4Cl2(OH)4SO4 · 5H2O) appearing in urban and industrial atmospheres. It involves the consecutive formation of three phases, namely zinc hydroxycarbonate as the initial phase, zinc hydroxysulfate as the intermediate phase and zinc chlorohydroxysulfate as the final phase.

A field exposure program has been implemented in a rural atmosphere with emphasis on short exposure periods and detailed characterization of layers of corrosion products initially formed on zinc by means of a multi-analytical approach. Surface and bulk analytical studies in combination with deposition and climatic measurements have made it possible to identify a reaction path sequence on sheltered and unsheltered zinc panels, which is consistent with all methods used. It involves the formation of two structurally related phases, namely zinc hydroxycarbonate (Zn 5 (CO 3 ) 2 (OH) 6 ) as the initial phase and zinc hydroxysulfate (Zn 4 SO 4 (OH) 6 · 4H 2 O) as the final phase on sheltered panels and (Zn 5 (CO 3 ) 2 (OH) 6 ) as the final phase on unsheltered panels.

Changes in chemical speciation of copper and the capacity of concrete pavement to retain copper in runoff water from external buildings have been investigated at urban field conditions, and in parallel laboratory experiments simulating outdoor scenarios. The research study showed the concrete surface to form a copper rich surface layer ( approximately 50 microm thick) upon exposure, and a high capacity to significantly reduce the bioavailable fraction of released copper (20-95%). The retention capacity of copper varied between 5 and 20% during single runoff events in the laboratory, and between 10 and 40% of the total copper release during single natural runoff events. The capacity to retain and reduce the bioavailable fraction of non-retained copper increased with increasing wetness of the concrete surfaces, increasing pH of the runoff water and decreasing flow rates. Bioassay testing with bacterial and yeast bioreporters showed the bioavailable fraction of non-retained copper to be significantly lower than the total copper concentration in the runoff water, between 22 and 40% for bacteria and between 8 and 31% for yeast. The application of generated data to simulate a fictive outdoor scenario, suggests a significant reduction of bioavailable and total copper to background values during environmental entry as a result of dilution, and the interaction with solid surfaces, organic matter and complexing agents already in the drainage system.

Erratum to : Radiation Induced Corrosion of Copper in Anoxic Aqueous Solution (vol 15, pg C5, 2012)

Zinc runoff rates from 11 zinc-based construction materials with and without surface treatments or coatings are presented and discussed in terms of patina formation, seawater deposition, wetting co ...

A procedure based on infrared reflection absorption spectroscopy integrated with a quartz crystal microbalance has been developed and used for comparison of initial atmospheric corrosion of copper ...

With increasing environmental awareness, the desire to protect human beings and the environment from adverse effects induced by dispersed metals has become an issue of great concern and interest. New policies, such as REACH (Registration, Evaluation, Authorisation and Restriction of Chemicals) within the European Community, have been implemented to reduce hazards posed by the use of chemicals on producers and downstream users. The generation of exposure assessment data and relevant test procedures able to simulate realistic scenarios are essential in such legislative actions. This doctoral study was initiated to fill knowledge gaps related to the metal release process of stainless steels. A wide range of stainless steel grades, fourteen in total, were investigated. They cover a very broad range of applications, and the focus in the thesis was to simulate a few selected exposure scenarios: precipitation, the human body and food intake. Comparisons were made between metal release from stainless steel alloys and the pure metals that constitute each stainless steel in order to explore the differences between alloys and pure metals, and to provide quantitative data on metal release rates of different alloy constituents. Because of similar surface properties between stainless steel and pure chromium, this metal exhibits similar release rates, whereas iron and nickel exhibit significantly lower release rates as alloy components than as pure metals. Detailed studies were also performed to elucidate possible relations between metal release and steel surface properties. Key parameters turned out to be chromium enrichment of the self-passivating surface film, surface roughness, the electrochemically active surface area and the microstructure of the steel substrate. The degree of metal release increased with decreasing chromium content in the surface oxide, increasing surface roughness, and increasing presence of inhomogeneities in the bulk matrix. More detailed studies were initiated to possibly correlate the nucleation of metastable pits and the extent of metal release. Evidence was given that metastable pits exist even when the stainless steel is passive, and may cause extremely short-lived bursts of released metal before the surface film repassivates again.