Identification of the corrosion products formed on copper in sulfur containing environments

Tarnishing layers grown on copper exposed to air contaminated by traces of sulfur dioxide and/or hydrogen sulfide were detected by a coulometric and characterized by a chemical method. Depending on the nature of the corrosive gas, or on the use of a gas mixture, it was found that sulfate, sulfide, oxides or a mixed oxide-sulfide compound could be formed in these conditions. The same tarnishing products were found, either in hydrogen sulfide or in a sulfur dioxide + hydrogen sulfide mixture, and the same linear growth law of the copper (I) sulfide was also found, within the limits of the duration of the corrosion test, in the two gaseous environments.     

Quantitative determination of corrosion products and adsorbed water on copper in humid air containing SO2 by IR-RAS measurements

The time dependency of the amounts of corrosion products and co-existing adsorbed water on copper in humid air containing SO₂ was estimated from a series of in situ time-resolved IR-RAS spectra on the basis of the relations between the band intensities and the mass changes of the corrosion products, which were determined by simultaneous measurement of IR-RAS and QCM. The amounts of both corrosion products increased slowly at the initial stage and later increased rapidly. Although the relative humidity was kept constant, the amount of adsorbed water increased nearly the same behavior as that of corrosion products in the stage of relatively small amounts of corrosion products and later increased rapidly when the amounts of corrosion products increased. In humid air without SO₂, sulfite gradually decomposed and some of it changed into sulfate.     

Characterisation of reaction layers on copper surfaces formed in aqueous chloride and sulphate ion containing electrolytes

Copper is in a passive state in a potential range of 50 mV_H to about 300 mV_H in contact with an aqueous electrolyte at neutral pH caused by the formation of a thin tarnishing layer consisting of copper(I)-corrosion products. This layer inhibits more the anodic than the cathodic partial reaction of the corrosion process. The steep threshold in the transpassive range leads to the oxidation of copper and the formation of secondarily formed reaction layers. In sulphate containing electrolytes voluminous reaction layers of crystalline non-protective copper(I)-oxide are formed. The manifestation of corrosion is general attack. In chloride containing electrolytes a two-fold reaction layer is formed, copper(I)-chloride underneath copper(I)-oxide. This amorphous copper(I)-oxide is formed via hydrolysis of copper(I)-chloride and inhibits anodic metal dissolution. The only observed manifestation of corrosion is repassivating pitting.     

铅鼓风炉中铜、硫、砷和锑对银分布的影响(英文)

研究铅鼓风炉中杂质对银分布的影响。将含有不同Cu、S、As和Sb含量的铅烧结块在管式炉中于1573K下进行烧结,然后随炉冷却。烧结气氛为还原性的CO+CO2气体(p(CO)/p(CO2)=2.45)。采用SEM-EDS对所得样品进行表征。结果表明:烧结样品中含有5种不互溶的相,即炉渣(CaO,FeO,SiO2)、冰铜(S,Cu,Fe)、硬渣(As,Fe,Cu)、Cu-Sb相和铅块。银在Cu与Sb形成的熔体中的溶解度比在液态铅中的高。S与Cu形成冰铜,As与Cu形成硬渣。S和As能减少Cu-Sb合金的生成量,从而降低铅块中银的损失。     

A method for polyaniline coatings on solid polystyrene surfaces and electroless copper deposition

A new efficient method is presented for electroless copper deposition on solid polystyrene surfaces via polyaniline (PANI) coatings. It was demonstrated that, partial polymerization of aniline by catalytic air oxidation in the presence of dissolved polystyrene (PS) (M_n: 87.000 K) gives viscous solution of PANI-PS mixture in aniline. Direct application of the polymerization mixture with copper catalyst onto polystyrene sheets (5 × 15 cm) resulted in extension of the polymerization by air oxygen to give a smooth PANI-PS composite layer on the host surface. Treatment of the surface with a similar PANI solution without PS gave Emeraldine base film with homogenously dispersed copper. Reduction of the surface copper by diluted hydrazine (5%) yielded zero-valent copper serving as seed points for accumulation of more copper from an electroless plating solution in the following process. Experiments showed that, the method presented offers a simple pathway to produce excellent copper deposits on PS substrate. This method is superior to traditional electroless plating process, since tedious surface etching and expensive palladium activation steps are being avoided. The surface characteristics were examined by X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), adhesion tests and contact angle measurements. The results showed that, the electroless plating process gives a homogeneous and highly robust copper layer with 34.2 μm of thickness within 48 h. Adhesion of the copper layer to the underlining surface was satisfactory as inferred from pull-off measurements (1.6 N/mm²).     

高硫铝土矿反浮选除硫加工成合格产品实验研究

介绍了用浮选的方法降低铝土矿中硫的含量。以碳酸钠为pH调整剂,六偏磷酸钠为抑制剂,硫化钠和硫酸铜为活化剂．丁基黄药和戊基黄药为捕收剂,对高硫铝土矿进行开路和闭路反浮选除硫实验研究。取得了硫含量为0．27％,产率为97．46％的低硫铝土矿精矿;同时获得硫含量为27．44％,硫回收率为72．60％的高硫尾矿的实验指标。     

Triazolothiadiazine derivatives as corrosion inhibitors for copper,mild steel and aluminum surfaces: Electrochemical and quantum investigations

Protection of Metals and Physical Chemistry of Surfaces - The corrosion inhibition activity of triazolothiadiazine derivatives namely...     

Difference in the inhibitive effect of some Schiff base compounds containing oxygen, nitrogen and sulfur donors

2-(2-Hydroxybenzylideneamino)-2-methylpropane-1,3-diol (BAMP), 2-((2-hydroxynaphthalen-1-yl)methyleneamino)-2-methylpropane-1,3-diol (NAMP), 2-((pyridin-2-ylimino)methyl)phenol (PMP) and N-(thiophen-2-ylmethylene)pyridin-2-amine (TMP) were investigated as corrosion inhibitors of mild steel in 2 M HCl solution using weight loss, polarization and electrochemical impedance spectroscopy techniques. All measurements show that all compounds under study exhibit inhibitor properties for mild steel. Although the effect of molecular size on inhibition efficiency is observed from the results obtained between BAMP and NAMP, the introduction of heteroatoms into the structure is seen to be more pronounced eventhough the molecular size is diminished. TMP is seen to show the highest inhibitor efficiency of 97%.     

Microtribological and corrosion behaviors of 1H,1H,2H,2H-perfluorodecanethiol self-assembled films on copper surfaces

Fluoroorganic monolayers adsorped on copper are studied in terms of organization, structure, electrochemical behavior, corrosion and tribological properties. 1H,1H,2H,2H-perfluorodecanethiol thin films are grafted on copper via a self-assembling process. PM-IRRAS and XPS were used to investigate the organization, composition and structural properties of the SAMs. Cyclic voltammetry studies revealed a good oxidation blocking factor and polarization curves showed good anti-corrosion properties for the fluoroorganic film. However, these properties were inferior to those of n-dodecanethiol based SAMs. This was accounted for by the lower packing density and the larger number of defects of the 1H,1H,2H,2H-perfluorodecanethiol SAMs probably due to electrostatic and steric repulsion between fluorine atoms along the carbon chain and a number of CH₂ groups insufficient to permit good organization.Fluorine groups present in the monolayer of the fluoroorganic SAMs led to excellent lubricant properties for the ultrathin film. Surface wear resistance was also improved thanks to SAM grafting. 1H,1H,2H,2H-perfluorodecanethiol SAMs thus appear to be very interesting lubricants for copper as they improve surface mechanical properties by diminishing surface friction and wear.     

Influence of organic matter on orthophosphate corrosion inhibition for copper pipe in soft water

The adverse effects of organic matter on orthophosphate corrosion inhibition for copper pipe in simulated soft water were investigated. Sodium alginate and fulvic acid were selected to simulate extracellular polymeric substance produced by bacteria and natural organic matter in potable water. The results showed that the doses of organic matters, pH values and stagnation times had significantly affected on the function of orthophosphate corrosion inhibition for copper pipe in soft water. More soluble copper release was observed in low levels for sodium alginate (1 mg/l as TOC) and in high concentration for fulvic acid (16 mg/l as TOC). When the concentration of fulvic acid was high, the 2-week aged copper pipe released more soluble copper than the 6 and 12-month aged copper pipe. The soluble copper release increased with the reduction of initial pH value. Effect of stagnation time on soluble copper release from different aged copper pipe in soft water was highly variable. Compared to the system of no organic matters, organic matters markedly decreased the efficiency of orthophosphate corrosion inhibition for copper pipe in soft water.     

Grain boundary segregation and intergranular fracture in Ferrite containing Mo,Si or Al

Roles of molybdenum, silicon or aluminum in ferrite on grain boundary segregation and hence on intergranular fracture have been investigated by using Auger electron spectroscopy (AES) and tensile test. Competitive segregation between sulfur and carbon or nitrogen, which caused the decrease below 700°C of sulfur content at the grain boundaries, was observed in the pure iron. The intergranular brittleness of the pure iron was caused by sulfur at the grain boundaries. When molybdenum was added to the pure iron, the sulfur contents at the grain boundaries were lowered in comparison to those in the pure iron. The molybdenum-bearing alloy showed higher fracture strength than that of the pure iron, and fractured mostly in the transgranular mode. This arises from the intrinsic effect of molybdenum on the grain boundaries as well as the decrease in sulfur content. Tn the 3.37 wt.%Si alloy, silicon and carbon or nitrogen competitively segregated to the grain boundaries, and such a competitive segregation was also observed between sulfur and carbon or nitrogen. The sulfur content at the grain boundaries decreased with increasing silicon content. The fracture modes in the 3.37- and 4.26 wt.%Si alloys were transgranular in the rolling direction, but were mostly intergranular in the transverse direction and in the as-rolled condition. The intergranular characteristic in the fracture behavior may be attributed to the detrimental effect of silicon as well as sulfur on the intergranular cohesion. Carbon and aluminum only were found at the grain boundaries of the aluminum-bearing alloy. This suggests that aluminum is a strong repulser of sulfur or nitrogen at the grain boundaries. Additionally, it was found that aluminum has a detrimental effect on grain boundary strength of ferrite.     

Comparative studies of anticorrosion performance of novel inhibitors based on oleic acid and sulfur/nitrogen containing compounds in UV-curable coatings

A natural resource-based oleic acid was epoxidised to produce epoxidised oleic acid (EOA). The epoxidation reaction was confirmed by different analyses. Then, EOA was reacted with nitrogen- and sulphur-containing compounds such as glycine (GLY) and thioglycolic acid (TGA) to prepare EOA-GLY and EOA-TGA compounds, respectively. The EOA, EOA-GLY, and EOA-TGA compounds were evaluated as corrosion inhibitors (CIs) for mild steel in different coating formulations. Corrosion resistance tests and weight loss measurements of the coated steel panels were carried out, in addition to the physico-chemical and mechanical measurements. It was found that the coating formulations containing the prepared EOA-TGA inhibitor with a concentration (0.04 g/100 g coating) imparted higher protection for steel surface against corrosion and also competed efficiency known commercial CI at the same concentration. Also, the efficiency of the commercial and prepared inhibitors was increased in the following order: EOA-TGA > EOA-GLY > commercial inhibitor > EOA.     

EIS characterisation of anodic films formed on 2024 aluminium alloy, in sulphuric acid containing molybdate or permanganate species

Electrolytes composed of sulphuric acid and corrosion inhibitors (molybdate or permanganate species) were proposed in order to replace chromic acid for the anodising of 2024 aluminium alloy. The electrochemical impedance spectroscopy (EIS) method was used to visualise the correlation between the corrosion performance in NaCl and the morphology of these new anodic layers. From an appropriate equivalent circuit, EIS parameters concerning the porous and barrier layers were detected. Their evolution during corrosion tests was discussed. The results indicate that the morphology and the corrosion resistance of anodic films formed in acid sulphuric with molybdate species remain unchanged. On the contrary, morphological properties of anodic films formed in presence of permanganate species are modified, favouring their corrosion performance. EIS analyses were completed with SEM technique.     

Adsorption studies of water on copper,nickel, and iron using the quartz-crystal microbalance technique: Assessment of BET and FHH models of adsorption

In the atmospheric corrosion of copper, nickel, and iron, the adsorption of water affects the corrosion rates. Knowledge of water adsorption and metal oxyhydroxide formation is important in understanding the atmospheric corrosion process. The purposes of the present research were (1) to measure the adsorption of water on metal surfaces as a function of temperature and relative humidity (RH) and (2) to assess Brunauer-Emmett-Teller (BET) model and Frenkel-Halsey-Hill (FHH) model for water adsorption. In the present research, the quartz-crystal microbalance (QCM) technique was used to measure the mass changes of copper, nickel, and iron at 0 to 100% RH and 7–90°C under nitrogen environments. Less water was adsorbed on copper, nickel, and iron which formed oxides than on gold. BET and FHH models could not fit the data points with single functional relationships. ΔH values were calculated using modified BET method and they decreased with temperature.     

Titanium-supported Ce-, Zr-containing oxide coatings modified by platinum or nickel and copper oxides and their catalytic activity in CO oxidation

A combination of plasma electrolytic oxidation (PEO) and impregnation techniques followed by annealing in air has been used to obtain composites Pt/nZrO₂ + pTiO₂/Ti, Pt/nZrO₂ + pTiO₂ + zCeO_x/Ti, NiO + CuO/nZrO₂ + pTiO₂/Ti, NiO + CuO/nZrO₂ + pTiO₂ + zCeO_x/Ti with different zirconium and titanium contents and ZrO₂/TiO₂ phase ratio. The composites have been investigated by means of XRD, XPS and SEM/XSA methods. According to the XPS data, the platinum content on the coating surface is ~ 0.4 at.%, whereas the XSA measurements have shown that the nickel and copper contents in coatings attain 16 and 8 at.%, respectively, depending on the initial oxide coatings composition. Nickel and copper oxides form either extended islets or solid layers (“crusts”) on the coating surface. Both the composites promoted with platinum and those with the “crust” built from nickel and copper oxides are active in CO oxidation at the temperatures above 200 °C and 300 °C, respectively.     

The corrosion of unprotected steel in an inert-gas atmosphere containing water vapour, oxygen, nitrogen and different amounts of sulphur dioxide and carbon dioxide

The atmospheric corrosion of a commercial steel has been studied in a nominal inert gas. This gas exists inside the cargo tanks of some crude-oil tankers. The gas contained 3.0–21%O₂, 0–12%CO₂, 0–300 ppm SO₂; the balance was N₂. Relative humidity was 90% at 295 K (22.0°C). In contrast to the behaviour at moderate concentrations of SO₂ at high concentrations protective films were formed on the surface of the steel. A mechanism for the process is given. Corrosion products were studied using X-ray, i.r. and ESCA techniques. The following phases were identified: FeS, α-FeSO₃·3H₂O, γ-FeSO₂·3H₂O, FeSO₃·2H₂O and FeSO₄·7H₂O. Crystallographic data of the previously unknown phases γ-FeSO₃·3H₂O and FeSO₃·2H₂O are given.     

Surface pretreatment of austenitic stainless steel and copper by chemical, plasma electrolytic or CO2 cryoblasting techniques for sol-gel coating

The surface pretreatments of the austenitic stainless steel and copper surfaces for the sol-gel coating were carried out by chemical, plasma electrolytic or CO₂ cryoblasting techniques. With the austenitic stainless steel the smoothest surfaces were obtained with plasma electrolytic cleaning, after which the measured contact angles of water were clearly decreased revealing improved hydrophilicity. As well with the copper samples the smooth surface and improved hydrophilicity was obtained with the plasma electrolytic cleaning, but oxide layer formed to the copper surface immediately after the treatment. CO₂ cryoblasting provided rough surface with wetting properties close to the original surface both for austenitic stainless steel and copper surfaces. CO₂ cryoblasting provided best appearance for the copper surface because no oxidation happened with that treatment. XPS and SIMS studies showed that with the plasma electrolytic treatment the surface layer of the austenitic stainless steel enriched of chromium and the oxide layer formed on the surface was less than 10 nm thick. With the chemical cleaning and CO₂ cryoblasting, the chromium enrichment to the stainless steel surface was less. However XPS and SIMS studies showed that chemical treatment provided thinner oxide layer to copper surface than plasma electrolytic treatment.     

An ESCA and Mössbauer study of the oxide layer formed on steel in water containing chromate and chloride ions

The formation of oxidic layers on steel in chromate solutions was studied by photo-electron and Mössbauer spectroscopy. To simulate more aggressive realistic systems, some chloride ions were added to the solution. The layers formed under these conditions were found to be thicker by an order of magnitude than those formed in the absence of chloride ions. They probably consist of ferric and chromic oxides of the corundum type (Fe_1?2Cr_x)₂O₃, with the Cr : Fe ratio being depth dependent. The oxide layer is subdivided into small regions behaving superparamagnetically. This heterogeneity of the layer is ascribed to the attack by the chloride ions. The structure of the oxides found differs from the spinel structure reported by other authors who used chloride-free solutions.     

An electrochemical,topographical and analytical study on the behaviour of the metal-metalloid glass (Fe,Cr)80 (P,C, Si)20 in chloride or sulfate containing aqueous solutions

The metal-metalloid glass (Fe, Cr)₈₀ (P, C, Si)₂₀ was investigated in aqueous solutions which contain high quantities of NaCl (3 M). For comparison we use a solution with 1.5 M Na₂SO₄. These solutions reach from the strong acid area (0.5 M H₂SO₄) to the strong alkaline region (1 M NaOH). The corrosive properties of the metal-metalloid glass were determined at 25°C and 5°C. By the use of electrochemical methods it was possible to estimate the long time corrosive properties. Therefore current-potential-curves were determined by the use of a potentiodynamic technique. Starting from this curves it was possible by use of the tafel plot method or the determination of the polarisation resistance to. calculate an annual pull down of the metallic glass. For these electrochemical experiments we used the glass ribbons as electrodes and we measured under rotating conditions. The determined values of the annual pull down vary in a large region. The highest rate (44 mm/a) was calculated for an acid chloride containing solution at a temperature of 50°C. The lowest pull down rate (≈ 0.3 μm/a) is obtained in the alkaline solution at room temperature. In the alkaline area there is no difference between the addition of NaCl or Na₂SO₄. The treated glass fibres were characterised by the use of Scanning Electron Microscopy (SEM) and EDX-Analysis.