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The corrosion behaviour of copper in dilute HCl solution of pH 1.8‐2, in the absence and presence of different additives of Na₂S, was studied by open circuit potential measurement, scanning electron microscopy and polarisation techniques. A complete covering of the surface with the strongly chemisorbed HS⁻ is achieved at ≥10 ppm Na₂S concentration. The addition of different concentrations of ethylene diamine (EDA) to HCl of pH 1.8‐2 promoted the dissolution rate, due to an increase in autocatalytic dissolution at the Cu metal surface. However, the synergistic inhibition effect between EDA and Na₂S, resulting from the adsorption of HS⁻ on the Cu metal, facilitated the adsorption of EDA.

The paper aims to examine the enrichment of Cu, and the type of attack occurring during the dissolution of Al‐3.84%Cu alloy in 0.5 M NaCl.

The approach is to use scanning electron microscopy (SEM) and energy dispersive X‐ray spectroscopy (EDX) and solution analyses using atomic absorption spectrophotometry.

Examination of the surface after five days of immersion showed that Cu clusters had concentrated around the edges of the specimens and two types of localized corrosion were evident, pitting corrosion and the intergranular attack, which were concentrated mainly around the Cu clusters and in the regions where a higher concentration of Cu was evident. After 80 days of immersion, the higher concentration of Cu was distributed over nearly the entire surface and its concentration differed from one site to another.

The analysis results of the study confirmed the mechanism of simultaneous dissolution.

The pitting corrosion of copper in chloride solution has been studied using potentiostatic polarisation and surface analysis techniques. X‐ray photoelectron spectroscopy (XPS) results enabled conclusions to be drawn about the nature of the film formed in different chloride concentrations. In dilute chloride solutions (C≤10⁻³ M), XPS proved the existence of Cu₂O film on the copper surface. It was found that, depending on the chloride content, pitting of copper was evident only after the formation of a protective film of Cu₂O. A current‐time trend plot showed the onset of fluctuations, which were dependent on the NaCl content. On the other hand, introduction of O₂ into the solution during prepolarisation time period increased the current value of the fluctuations at the same concentration of NaCl in comparison with the freely aerated solution. These results, together with the surface analysis, confirm the role of chloride ion on the mechanism of pitting attack on copper metal.

The paper aims to study the dissolution of Al, Al‐3.84%Cu, Al‐5.22%Cu and Al‐11%Cu alloys in different concentrations of NaCl (10‐5‐10‐1 M).

The approach is to use open circuit potential (OCP) and potentiostatic polarization measurements.

Results obtained showed that, as the Cu content was increased in the Al‐Cu alloys, a steady state potential was rapidly reached. Addition of different concentrations of CuCl₂ to 0.5 M NaCl demonstrated that by increasing the concentration of CuCl₂ up to 2 ppm a greater increase in the OCP towards more anodic value occurred from the moment of immersion. Further increases in the concentration of CuCl₂, up to 600 ppm, exhibited the same behavior.

The results of the study reveal that cathodic current was controlled by the oxygen in solution, while the anodic current increased with increased Cu content in the alloy.

Copper and its alloys are widely used in industries because of their good resistance to corrosion and are often used in cooling water systems. Brass has been widely used for shipboard condensers, power plant condensers and petrochemical heat exchangers. Brass is susceptible to the corrosion process known as dezincification by means of which brass looses its valuable physical and mechanical properties leading to failure of structure. The aim of this investigation was to control the dezincification of brass in 3 per cent NaCl solution using benzotriazole (BTA) derivatives.

BTA derivatives namely 1‐hydroxymethylbenzotriazole (HBTA) and N,N‐dibenzotriazol‐l‐ylmethylamine(ABTA) were synthesised and their inhibition behaviour on brass in 3 per cent NaCl solution was investigated by the weight‐loss method, potentiodynamic polarisation, electrochemical impedance and solution analysis techniques. The morphology of the brass after corrosion in the presence and absence of the BTA derivatives was examined using scanning electron microscopy (SEM).

Potentiodynamic polarisation studies showed that the BTA derivatives investigated were mixed type inhibitors, inhibiting the corrosion of brass by blocking the active sites of the brass surface. Changes in the impedance parameters (charge transfer resistance and double layer capacitance) were related to the adsorption of BTA derivatives on the brass surface, leading to the formation of a protective film. Solution analysis revealed that the BTA derivatives excellently controlled the corrosion of brass. SEM micrographs showed the formation of compact surface film on the brass surface in the presence of inhibitors, thereby providing better corrosion inhibition.

Contributes to research on corrosion protection for copper and its alloys.

The purpose of this paper is to review the application of digital holography in studies of the corrosion of metallic materials.

Digital holography is used for in situ observation of the dynamic processes at the electrode | electrolyte interface and on the electrode surface during the corrosion dissolution of metallic materials.

Digital holography is an effect method to in situ observe the corrosion processes, and it can provide a direct experimental foundation for studying the corrosion mechanism.

Even though there are several challenges, digital holography will play a significant role in studying corrosion processes.

Tungstate inhibitors are seldom used alone in open recirculating cooling water systems due to their low oxidising ability and high cost. The objective of the present work was to develop efficient synergistic inhibitor combinations comprising sodium silicate and very low concentration of sodium tungstate, keeping in view of their application in industrial cooling water system. It was demonstrated in the present study that all the combinations of the inhibitors exhibited synergistic benefit and higher inhibition efficiencies than did either of the individual inhibitors. It was also established that a 4:1 ratio of sodium silicate to sodium tungstate (total 1,000 ppm) was the best overall combination. The FTIR spectra also suggest that tungstate and silicate ions were incorporated in the passivating metal oxide layer formed on the surface of carbon steel in the inhibitor solutions. The effects of excess and depleted concentrations of the individual inhibitor components on overall inhibition behaviour are also discussed.

Zinc ions, produced by the electrolytic dissolution of zinc metal rods, exhibited excellent inhibition efficiency, especially in combination with the synergistic additions of tungstate and nitrite ions. The optimum ratio of tungstate: nitrite: zinc was found to be 10:10:1 and the combination of tungstate: 100 ppm ‐ nitrite: 100 ppm ‐ zinc: 10 ppm (System A) gave the best results of all the systems studied. This system requires a much smaller concentration of tungstate and nitrite ions, as compared to the concentrations typically used and claimed to offer optimal inhibition efficiency. Long‐term open circuit potential measurements indicated that effective passivation occurred within 3 days of immersion. The passive layer thus formed on the metal surface retained its protective capability for several weeks, even after test coupons were transferred into a depleted inhibitor solution. The possible mechanism of the passivation is discussed.

The purpose of this paper is to evaluate the corrosion of silver due to hydrogen sulphide pollutant in indoor conditions at a microelectronics plant located in Mexicali, Baja California, a semi‐arid zone in the northwest of Mexico.

Silver coupons and silver plated on to copper‐lead frames are exposed in the assembly process building of a microelectronics company during a period of 60 days and also in a sheltered test chamber that simulates indoor conditions with ambient concentrations of atmospheric pollutants, temperature and relative humidity (rH). Other exposures are made in the test chamber to study the corrosion behaviour of silver coupons over a duration of 24 months. The corrosion products were analysed using the Scanning Electron Microscope (SEM) and Energy Dispersive X‐ray Spectroscopy (EDS). Corrosion rates were measured by Quartz Crystal Microbalance (QCM) under laboratory‐controlled conditions.

The presence of silver sulphide corrosion products, dendrites and whiskers is observed on the exposed samples using SEM and EDS analysis.

The paper is designed to establish whether the company, where the exposure is taking place, constituted an indoor environment with outdoor hydrogen sulphide pollutant in sufficient concentration to induce silver corrosion.

The methodology used in this work can be applied to study the indoor corrosion behaviour of other metals, which will be of interest to the microelectronics industry.

Najib Mahfuz is the first Arab‐language author to win the Nobel Prize in literature. Born in 1911 the son of a middle‐class Jamaliyah merchant, he became the most popular novelist in Egypt and the Arab countries.