The atmospheric corrosion of copper by hydrogen sulphide in underground conditions

The atmospheric corrosion of copper by hydrogen sulphide has been followed during field tests using different sulphide concentrations, for 77 days, and during exposure to a well-defined synthetic atmosphere in a test chamber. The main components formed at the surface of the samples are copper oxides and sulphide. We show that exposure tests performed for short times in synthetic atmospheres cannot be extrapolated to long time exposure in real conditions, since three successive phases of film growth are observed. The mechanism of film growth is discussed, assuming that cationic diffusion through the cuprous oxides and sulphide is the rate-determining step.     

Runoff of copper and zinc caused by atmospheric corrosion

Runoff and total corrosion loss for copper and zinc were investigated at seven sites in Switzerland. The exposure sites were chosen near the stations of the National Air Pollution Monitoring Network (NABEL), where climatic and air pollution data are measured. Runoff and corrosion rates were investigated after 0.5, 1, 2 and 4 years of exposure. Runoff rates differ from corrosion rates depending on the material, the exposure time and the sampling site.     

The influence of copper upon the atmospheric corrosion of iron

The atmospheric corrosion of pure iron and the binary alloy Fe-0.5Cu has been analyzed by a simultaneous measurement of the anodic current density of the metal dissolution and the cathodic current density of the O₂ reduction reaction during several wet/dry cycles using a magnetic and a gas volumetric technique, respectively. The results show three typical stages of the atmospheric corrosion: stage 1 (wetting of a dry surface): rapid corrosion with rust reduction as cathodic process; stage 2 (wet surface): slow corrosion with O₂ reduction as cathodic process; and stage 3 (drying out of the surface): very rapid corrosion with O₂ reduction as the cathodic process during critical wetting of the surface. The effect of copper is restricted to stage 3, where the corrosion rate is much smaller for the Fe-0.5Cu alloy than for pure iron. Two models are discussed to explain these results.     

On the atmospheric corrosion of thin copper films

Sputtered and electrodeposited copper specimens were exposed to the laboratory atmosphere for 18 months, after which the corrosion products were analysed by electrochemical methods and reflectance spectra. The formation of corrosion products takes place in three stages: initially cuprous oxide is formed, followed by the growth of cuprous sulphide, and finally cuprous oxide is converted to cuprous sulphide. The presence of water is essential for these corrosion reactions to occur.     

Outdoor atmospheric corrosion of copper in Saudi Arabia

Abstract

Copper specimens have been exposed to the action of marine, marine industrial, urban and rural atmospheres of Saudi Arabia. Environmental factors such as average temperature, average relative humidity and deposition rates of atmospheric pollutants (i.e. Cl^- and SO₂) was investigated. By applying the standard ISO 9223, the aggressiveness of the atmospheres corresponding to the different test stations has been determined. Calculations of corrosion rates were made via loss of weight after one, two and three years of exposure and characterisation of the corrosion products formed on samples have been analysed using X-ray diffraction. Three main sequences have been identified on outdoor copper, representing different reaction routes in chloride dominated environments. Many kinds of patina were found on copper specimens such as cuprite (Cu₂ O), atacamite (Cu₂ Cl(OH)₃), paratacamite (Cu₂ (OH)₃Cl), copper amine nitrite hydroxide, gerhardite, copper hydroxide nitrate and copper amine nitrate.     

The corrosion inhibition of copper by benzimidazole

The chemical nature of the complexes formed between copper and benzimidazole in solution has been determined with the aid of Auger electron spectroscopy. Measurements of the adsorption isotherm of benzimidazole on copper reveal that such adsorption is of the Langmuir type. Some correlation is seen to exist between the corrosion inhibition tendency of benzimidazole on copper and the composition of the surface films formed.     

Comparative investigation on copper atmospheric corrosion by electrochemical impedance and electrical resistance sensors

Electrochemical impedance (EIS) and thin electrical resistance (ER) sensors were invented for atmospheric corrosion measurement of copper (Cu) during cyclic wetting–drying/high–low temperature tests and field exposure tests. Three-month field exposure results showed that average corrosion rate of Cu measured by ER sensor was well in accordance with that by weight loss method. During cyclic wetting–drying test, EIS was proven to reflect sensitively time of wetting and drying on the surface of sensor. Although corrosion rate obtained from EIS had a similar tendency to that obtained from ER sensors, the former was more dependent on environmental humidity than the latter. When relative humidity was low than 60%, corrosion rate of Cu measured by EIS was much lower than that by weight loss method, mainly attributing to the fact that impedance sensor failed to detect corrosion current of interlaced Cu electrodes due to the breakdown of conductive passage composed of absorbed thin liquid film under low humidity condition. Promisingly, ER sensor was proven to be more suitable for atmospheric corrosion monitoring than electrochemical techniques because it could sensitively monitor thickness loss of Cu foil according to the Ohmic law, no matter how dry or wet the sensor surface is.     

Influence of the corrosion products of copper on its atmospheric corrosion kinetics in tropical climate

In the present paper, the identification of the corrosion product phases formed on copper under different atmospheres of Cuban tropical climate is reported. Cuprite (Cu₂O), paratacamite (Cu₂Cl(OH)₃), posnjakite (Cu₄SO₄(OH)₆ · 2H₂O) and brochantite (Cu₄SO₄(OH)₆) were the main phases identified by X-ray diffraction (XRD) analysis and Fourier transform infrared spectroscopy (FTIR).Copper corrosion products are known to have a protective effect against corrosion. However, a different behaviour was obtained under sheltered coastal conditions. This can be due to the corrosion products morphology and degree of crystallisation, rather than their phase composition. A higher time of wetness and the accumulation of pollutants not washed away from the metal surface can also play an important role.     

The atmospheric corrosion of copper at two sites in Portugal: a comparative study

This paper presents a comparative study on the atmospheric corrosion of copper, at two sites, in Portugal, with exposures started in two different seasons (summer and winter). Particular attention is devoted to the initial stages of the corrosion process.The levels of pollutants, namely of SO₂ and chlorides, in both atmospheres, have been measured, over the periods from August 1999 to July 2000 and from November 2000 until July 2001. Climatic data for both sites and both periods has been collected and analysed.Kinetics of the corrosion process (weight losses) have shown to be described by: Δm=kt^0.6 and Δm=kt^0.4, with k equal to 3.4 (g m⁻² month^−0.6) and 17 (g m⁻² month^−0.4), for the one year exposures, started in summer, at the urban and maritime atmospheres, respectively. Exposures started in winter, at the urban atmosphere, have lead to kinetics described by Δm=kt^0.7 with k=5.0 (g m⁻² month^−0.7).The chemical composition and the morphology of the copper patinas, corresponding to exposures of 2 and 12 months, at the two sites, are compared as well as the morphology of the corroded surfaces.     

Inhibition of copper corrosion by silane coatings

OFHC copper specimens were pre-filmed in hydro-alcoholic solutions of various silanic agents (3-mercapto-propyl-trimethoxy-silane, PropS-SH; bis-triethoxy-silyl-ethane, BTSE; n-octadecyl-trimethoxy-silane, OctadecS; phenyl-trimethoxy-silane, PhS) to evaluate the influence of the silane molecule structure towards copper corrosion protection. Linear polarization resistance, potentiodynamic polarization curves, and electrochemical impedance spectroscopy tests were performed in 0.6 M NaCl.The thiolate bond caused a good anchoring of the silane molecule on the copper surface, which determined a noticeable hindrance to the anodic reaction of copper oxidation. Since this bond was found to be stronger than that of the oxane bond, the PropS-SH coating was more corrosion resistant and more persistent than the other tested silane coatings.The optimum pre-treatment solution pH was 4, although PropS-SH coating presented some imperfections. At this pH the coating was thicker than that at pH 10, when the silanized layer completely covered the copper surface. Nevertheless, the defects of this layer were so small that they could be plugged, for a prolonged time, by the copper corrosion products.     

The inhibition of copper corrosion by azole compounds in humid environments

The ability of azole compounds, benzotriazole (BTA), 2-undecylimidazole (UDI) and poly-N-vinylimidazole (PVI-1) to inhibit copper corrosion in humid environments is studied using Fourier transform infrared reflection-absorption spectroscopy (FT-IR RAS). The corrosion product of bare Cu is shown to be Cu₂O even when moisture is present. The appearance and intensity of its characteristic vibration frequency can be used to monitor corrosion. It is found that dissolution of the Cu substrate, caused by local anodic and cathodic sites set up on the surface, accelerates the degradation process of BTA, UDI and PVI-1. The degradation of UDI on Cu apparently follows the same mechanism in both dry and wet environments while the degradation of PVI-1 on Cu does not. The BTA film is a better corrosion inhibitor than UDI or PVI-1 in this environment although some corrosion is observed. It is concluded that the inhibition ability of an inhibitor compound depends on the stability of the compound in the environment.     

Corrosion of copper and silver plates by volcanic gases

Corrosion products that had been formed on copper and silver plates exposed in Miyake Island, where suffered a volcanic eruption in 2000, were analyzed by X-ray techniques to get better understanding of copper and silver corrosion in harsh environment. The exposure experiment was carried out from September 2004 to April 2005. Many kinds of patina were found on copper such as cuprite (Cu₂O), posnjakite (Cu₄SO₄(OH)₆ · H₂O), brochantite (Cu₄SO₄(OH)₆), antlerite (Cu₃SO₄(OH)₄), and geerite (Cu₈S₅). For silver, silver chloride (AgCl) and silver sulfide (Ag₂S) were formed. Although the volcanic activity had greatly subsided, the atmospheric corrosion of copper and silver plates exposed on Miyake Island was mainly affected by volcanic gases, wet-dry cycles in the environment, and sea-salt aerosols.     

Indoor atmospheric corrosion of copper and steel under heat trap conditions in Cuban tropical climate

Abstract

Corrosion behaviour of copper and steel under heat trap conditions in Cuban tropical climate is reported. Temperature and humidity reach higher values than those reported for traditional outdoor and indoor conditions. Annual calculated time of wetness is in the range corresponding to outdoor or ventilated sheds. This behaviour is not reported for other indoor conditions. Sulphur compounds deposition rate is higher than chloride deposition rate at all corrosion stations. Main corrosion products formed on steel and copper are goethite and brochantite respectively. No significant differences in the statistical influence of exposure time and time of wetness on atmospheric corrosion process of copper and steel under heat trap conditions are determined.     

Long-term atmospheric corrosion of zinc

A great deal of information is available on the short- and mid-term atmospheric corrosion of zinc: corrosion rate data as a function of atmosphere type, corrosion mechanisms, effect of environmental variables, effect of surface orientation, damage functions, etc. However, very little information has been published on the atmospheric corrosion of zinc over long time periods (10-20 years), despite its great usefulness. On the other hand, many studies have analyzed the nature of corrosion products formed on zinc in a wide range of atmospheric environments, using different experimental techniques, but few have focused on the morphology of corrosion product layers. This paper reports the characteristics—mainly composition and morphology—of corrosion products formed on zinc panels after long-term exposure (13-16 years) in various types of atmospheres in Spain: rural, urban, industrial, mild marine and severe marine.     

The atmospheric corrosion of iron as studied by Mössbauer spectroscopy

The composition of the rust on the surface of steel panels was determined after atmospheric exposure times of 2 weeks, 2 months and 6 months. The initial product is γ-FeOOH which converts in time to a mixture of α-FeOOH and γ-Fe₂O₃. Steel exposed for times of the order of 25 years is covered with corrosion product consisting largely of γ-Fe₂O₃. The similarity between the composition of the corrosion products and precipitates formed from FeSO₄ solution under mildly acidic conditions at 90°C suggests that the dominant anion in these atmospheric corrosion experiments is sulfate.     

The kinetics of copper corrosion in nitric acid

The strategy for the permanent disposal of high-level nuclear waste in Canada involves sealing it in a copper-coated steel container and burying it in a deep geologic repository. During the early emplacement period, the container could be exposed to warm humid air, which could result in the condensation of nitric acid, produced by the radiolysis of the humid air, on the copper surface. Previous studies have suggested that both nitrate and oxygen reduction will drive copper corrosion, with the nitrate reduction kinetics being dependent on the concentration of soluble copper(I) produced by the anodic dissolution of copper in the reaction with oxygen. This study focused on determining the kinetics of nitrate and oxygen reduction and elucidating the synergistic relationship between the two processes. This was investigated using corrosion potential and polarization measurements in conjunction with scanning electron microscopy and X-ray photoelectron spectroscopy. Oxygen reduction was shown to be the dominant cathodic reaction with the oxidation of copper(I) to copper(II) by nitrate, promoting the catalytic cycle involving the reaction of copper(II) with copper to reproduce copper(I).     

Effect of direct current electric field on atmospheric corrosion behavior of copper under thin electrolyte layer

A thin layer electrochemical cell was successfully developed to study the atmospheric corrosion behavior of copper film in printed circuit board (PCB-Cu) under thin electrolyte layer (TEL) and direct current electric field (DCEF) by electrochemical impedance and electrochemical noise analysis. The electrochemical measurements and SEM morphologies after corrosion test indicate that DCEF decreases the corrosion of PCB-Cu under TEL. The corrosion rate and probability of pitting corrosion of PCB-Cu under DCEF decrease due to the electric migration of aggressive Cl⁻ ion out of working electrode surface.     

Inhibition behavior for copper corrosion by photoelectrochemical methods

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Hydrogen gas production during corrosion of copper by water

This paper considers the corrosion of copper in water by: (1) short term, open system weight measurements and (2) long term, closed system immersion in distilled water (13,800 h) without O₂ at 21–55 °C. In the latter experiments, the hydrogen gas pressure is measured above the immersed copper and approaches ∼10⁻³ bar at equilibrium. This pressure is mostly due to copper corrosion and greatly exceeds that in ambient air. Accordingly, this measured hydrogen pressure from copper corrosion increases with temperature and has the same dependency as the concentration of OH⁻ in the ion product [OH⁻] [H⁺].