Gildes model studies of aqueous chemistry. III. Initial SO2-induced atmospheric corrosion of copper

The GILDES computer model, incorporating Stumm's concept of proton- and ligand-promoted dissolution, has been used to simulate the exposure of copper at room temperature to 210 ppb sulfur dioxide and 80% relative humidity. The agreement is good between the calculations and laboratory exposures performed under these exposure conditions. Surface reactions are relatively more important at lower relative humidities and the dominant corrosion products formed are solid state Cu₂SO₃, CuSO₃ and Cu₂U. Free-radical redox processes are important participants and control the relative distribution of Cu(I)- and Cu(H)-containing corrosion products.     

A study of copper runoff in an urban atmosphere

Initiated by the concern in several countries regarding the release of copper from, e.g., roofs, facings and other outdoor constructions, the present study aims to compare runoff rates with corrosion rates during exposure of copper in an urban atmosphere. The copper runoff rate turns out to be relatively stable during the 2 year period studied, with an average rate per year of around 135 μg Cu cm⁻². This stable runoff rate is associated with the formation and dissolution properties of cuprite (Cu₂O), which is the dominating copper patina phase throughout the 2 year period. The copper corrosion rate, on the other hand, is highly time-dependent. It exhibits an initially high value and decreases with exposure time. As a consequence, the ratio between copper runoff and copper mass loss is very low in the beginning, around 7% after 1 month, and increases with time to reach around 22% after 2 years. With prolonged exposure this ratio eventually reaches 100%, corresponding to a copper patina thickness that does not change any further with time.     

Gildes model studies of aqueous chemistry. II. The corrosion of zinc in gaseous exposure chambers

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.     

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.     

Morphological study of 16-year patinas formed on copper in a wide range of atmospheric exposures

Much information is available on the atmospheric corrosion of copper and patina formation mechanisms in the short, mid and even long term. However, studies of the structure and morphology of patina layers are less abundant and mostly deal with patinas formed in the atmosphere over a small number of years. The present study concentrates on the structure and morphology of corrosion product films formed on copper after long-term atmospheric exposure (13-16 years) in five Spanish atmospheres of different types: rural, urban, industrial and marine (mild and severe). Characterisation has been performed by X-ray diffraction (XRD) and scanning electron microscopy/energy dispersive X-ray spectroscopy (SEM/EDS). Long-term copper corrosion is higher in industrial and marine atmospheres and lower in rural and urban atmospheres. In all cases a decrease in the corrosion rate with exposure time is observed. The formation of antlerite [Cu₃SO₄(OH)₄] is seen in more acidic conditions and in specimen areas subject to a high time of wetness. The presence of nantokite (CuCl), which is not generally mentioned in field studies, has been detected under the cuprite layer very close to the base copper.     

Accelerated corrosion of MoO3-deposited copper

The accelerated oxidation kinetics of MoO₃-deposited copper were studied in the temperature range of 480–700 °C in air. The accelerated oxidation followed the parabolic-rate law, indicating that the process was diffusion-controlled. Oxygen diffusion along liquid channels in the oxide scale was inferred to be the rate-limiting step in the overall mechanism. The rate constant increased from 9.2 × 10⁻⁶ to 3.8 × 10⁻⁵ kg² m⁻⁴ s⁻¹ with increasing the deposit mass from 0.3 to 0.9 kg m⁻² at 700 °C.     

Corrosion behaviour of aluminium in copper containing environment

Corrosion behaviour of pure aluminium galvanically connected to metallic copper or in the presence of Cu²⁺ ions was investigated by electrochemical measurements in Na₂SO₄ and Na₂SO₄ + NaCl test solutions. It has been found that in aerated Cl⁻ ion containing solutions pitting corrosion of aluminium emerged immediately, while in the absence of oxygen this process was less violent. Effect of passivating pre-treatment of aluminium surface on corrosion behaviour Cu-Al bimetallic system is also demonstrated.     

Corrosion behavior of copper in extremely harsh marine atmosphere in Nansha Islands,China

The corrosion behavior of pure copper exposed to the atmosphere of Nansha Islands for 21 months was studied by mass loss method, composition analysis, morphology observation and electrochemical measurements. The results showed that the average corrosion rate of copper exposed for one year was approximately 7.85 μm/a, implying that Nansha Islands was classified as a corrosion category of CX. The structure and properties of the corrosion product layer generated on the front and back sides of the exposed sample differed significantly. The inner corrosion product layer (Cu₂O) on the front side was relatively thick and dense, whereas the outer product layer (Cu₂Cl(OH)₃) was extremely thin. However, the outer product layer on the back side was thicker than the inner layer. Electrochemical measurements indicated that the protection afforded by the corrosion product layer on the front side was improved gradually, while that on the back side was deteriorated.     

Corrosion of ultra-fine grained copper fabricated by equal-channel angular pressing

Corrosion of ultra-fine grain (UFG) copper fabricated by equal-channel angular pressing (ECAP) has been investigated in comparison with that in recrystallized coarse grain (CG) copper. Corrosion current was estimated by a Tafel extrapolation method to examine the kinetics of corrosion in a modified Livingstone etchant, which is sensitive to dislocations and grain boundaries. UFG copper exhibited a lower corrosion current in comparison with that in its recrystallized coarse grain (CG) counterpart despite the fact that the dislocation density and total fraction of grain boundaries are much greater in UFG copper than in CG copper. Corrosion damage on the surface of UFG copper is macroscopically rather uniform whereas obvious attack at grain boundaries and selective corrosion of some grain interiors were observed in CG copper.     

水力发电厂电气设备铜材元件的腐蚀原因

中东地区的铜管发生腐蚀泄漏。为了探究铜管泄漏的根本原因,对铜管的腐蚀形貌及腐蚀产物进行分析,同时对当地的空气成分进行检测。结果表明：铜管表面发生全面腐蚀,泄漏位置位于焊缝,泄漏处的腐蚀产物中存在S元素。铜管泄漏的主要原因是下水道腐殖物发酵生成的SO₂和H₂S污染性气体,加速铜管尤其是焊缝位置腐蚀,其焊缝腐蚀产物的脱落协同铜管的表面腐蚀导致铜管焊缝处漏穿。通过隔离腐蚀性气体以及对铜管进行环氧树脂防腐涂层防护,可以降低泄漏率,提高钢管使用寿命。     

Laboratory scale investigation into the corrosion of copper in a sulphur-containing environment

The effect of temperature and gas composition on the corrosion rate and corrosion by-product of copper foil was studied by exposing it to sulphur (S₂), S₂ + hydrochloric acid (HCl) and hydrogen sulphide. The temperature was varied from 80 to 140 °C. Copper foil reacted with S₂ to form CuS, Cu₉S₈ and Cu_1.8S. Corrosion rates ranged from 9.6 μm/h at 110 °C to 0.5 μm/h at 140 °C. The presence of HCl caused pitting and enhanced the corrosion rate above 112 °C. Cu₂S formed when copper was exposed to hydrogen sulphide gas. Sulphide scale that formed was friable and non-adherent.     

Experimental evidence for enhanced copper release from domestic copper plumbing under hydrodynamic control

We present experimental results to analyze copper release from biotic and abiotic pipe surfaces and its relation to flow parameters, from Reynolds Number (Re) 1027–11,618.For abiotic and biotic surfaces, increasing the flow velocity affected the time scale of the copper release but not necessarily the net amount of total copper incorporated into the bulk flow.For biotic conditions the total copper concentration in the bulk flow was an order of magnitude higher than for abiotic surfaces (3.65 mg/L vs. 0.32 mg/L). Similarly, higher flow velocities enhance the presence of larger size copper nanoparticles in the bulk flow.     

A field study on the first flush effect of copper roof runoff

The runoff of four copper roof surfaces with different aspects were monitored in a field study in order to identify the existence of the first flush effect and to determine the influences. It was found that almost 40% of all sampled precipitation events exhibited a moderate first flush effect regarding the distribution of copper mass in the roof runoff. There was a significant impact of the roof aspect on the presence and on the magnitude of the first flush. No correlation was found between the first flush effect and weather parameters, such as rain height, rain intensity, and antecedent dry weather period.     

The nature of the copper sulfide film grown on copper in aqueous sulfide and chloride solutions

In this paper, the properties of copper sulfide films formed both anodically and naturally in deaerated/anoxic aqueous sulfide and chloride solutions were investigated using a series of electrochemical and surface analytical techniques. A combination of cyclic voltammetric, corrosion potential (E_corr), and cathodic stripping voltammetric experiments showed that the sulfide film growth kinetics and film morphologies were controlled by the supply of SH⁻ from the bulk solution to the copper surface. There was no passive barrier layer observed on the copper surface under either electrochemical or corrosion conditions. The film morphology was dependent on the type and concentration of anions (SH⁻, Cl⁻) present in the solution. Scanning electron microscopy on both surfaces and focused ion beam-cut cross-sections showed the growth of a thin, but porous, base layer of chalcocite (Cu₂S) after short immersion periods (up to 2 hr) and the continuous growth of a much thicker crystalline outer deposit over longer immersion periods (≥36 hr), suggesting a solution species transport-based film formation process and the formation of an ineffective thin “barrier-type” layer on copper.     

Intergranular environmentally assisted cracking of Alloy 182 weld metal in simulated normal water chemistry of boiling water reactor

Following characterization of grain boundaries in Alloy 182 weld metal, intergranular environmentally assisted cracking (IGEAC) growth behavior of the alloy in simulated normal water chemistry (NWC) of boiling water reactor (BWR) was tested by employing a crack growth rate test. The grain boundary was found consist of about 72% random boundaries, 21% low-angle boundaries and a few coincident boundaries.The correlation between the grain boundary characters and IGEAC was discussed. Based on the IGEAC growth rates obtained in the test and evaluations of the crack tip strain rate, the parameter of the slip-dissolution/oxidation model that embodies the kinetics of oxidation/repassivation in the crack-tip environment of Alloy 182 in BWR-NWC was quantitatively determined.     

Application of GC-MS metabolic profiling to ‘blue-green water’ from microbial influenced corrosion in copper pipes

This paper presents a novel application of fluorescence spectroscopy and gas chromatography-mass spectrometry (GC-MS) to water samples exposed to copper piping which had undergone some degree of microbial influenced corrosion. Using 3D fluorescence spectroscopy we were able to observe the ‘protein-like’ fluorophore associated with presence of bacteria, and cross reference this with derivatized fatty acid metabolites determined via GC-MS analyses of the same sample. This methodology can be used as a simple screening tool to establish the presence or otherwise of microbial processes in waters, and correlation of specific metabolite profiles with different microbes will further enhance the utility of this tool.     

铜在含SO2大气中的腐蚀初期规律和机理

利用原子力显微镜 (AFM)原位考察了铜在SO2 质量分数为 0 .9× 1 0 - 6和 90 %相对湿度条件下 ,大气腐蚀过程中表面形貌及结构变化 ,观察到铜在大气腐蚀中高分辨的形貌变化过程 :铜表面逐渐形成纳米级的蚀点 ,并随着时间延长变大和彼此交迭 ,而后开始更大尺度的新一层次蚀点的发展 ,表现出腐蚀微电池层次发展特征。红外反射吸收光谱 (IRAS)表明 ,碱式硫酸盐是构成腐蚀产物膜的主要组分。石英晶体微天平 (QCM)原位测得的动力学曲线表明 ,铜在该条件下的腐蚀速度呈现出随时间延长而逐渐下降的趋势 ,说明形成的腐蚀产物对进一步腐蚀产生抑制作用。     

A new corrosion inhibitor for copper protection

Methyl 3-((2-mercaptophenyl)imino)butanoate (MMPB) was synthesized as inhibitor compound for copper protection. The molecule was designed with azole, thiol functional groups and carboxylate tail group. The inhibition efficiency was examined in acidic chloride media, by means of various electrochemical and spectroscopy techniques. Electrochemical study results showed that high efficiency of MMPB was mainly related with its capability of complex formation with Cu(I) at the surface. The thiol group also improves the adsorptive interaction with the surface, as the carboxylate groups provide extra intermolecular attraction.