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The purpose of this paper is to study the stress corrosion cracking (SCC) behaviour of anodized 1050 Al‐alloy in marine environments at different concentrations of sulphate ions.

The SCC experiments were performed by measuring the time to failure in 3.5% NaCl solution, or in the presence of three different concentrations of sulphate ions under conditions of applied anodic current. For the interpretation of the results, changes in potential during SCC tests and optical microscope micrographs of stress corrosion tested specimens at various periods of time, were obtained.

The influence of seawater composition on the SCC behaviour of the anodized 1050 Al‐alloy depends on the concentration of sulphate ions, the oxide thickness and the stress level. At the higher stress levels and low concentrations of sulphate ions, increased times to failure were observed. These results were attributed to the inhibitory action of sulphate ions. At a low stress level and higher concentration of sulphate ions, the increased times of exposure and the more intensive corrosive environment led to partial destruction of the anodic coatings and a decrease in the time to failure. Better protective properties were observed at an oxide thickness of 10 μm. The thicker oxides did not protect so well because they were more brittle, cracking under strain and allowing corrosive species to reach the metal surface.

The hypothesised mechanism of the effect of seawater composition on the SCC behaviour of anodized Al‐alloys depended on the concentration of sulphate ions and the stress level remains yet to be confirmed.

The selection of suitable anodic coatings for the protection of aluminium alloys against stress corrosion cracking depends on the composition of the marine environment.

The paper provides information regarding the influence of sulphate ions on the anticorrosive properties of electrolytically prepared anodic coatings on aluminium alloys.

Besides with a large amount of Na⁺ and Cl⁻ ions in seawater, the presence of Mg⁺² and SO₄⁻² ions builds more complex corrosion mechanism. This paper aims to investigate the corrosion of embedded reinforcement in concrete with the environment of both Cl⁻ and SO₄⁻² anions associated Mg⁺² cation.

The concrete specimens were prepared by using ordinary Portland cement (OPC), and OPC blended with metakaolin (MK) for water to cementitious material ratio (w/cm) 0.48 and 0.51. The concrete mixes were contaminated with the addition of MgCl₂ alone and combined MgCl₂ and MgSO₄ in mix water. Reinforcement corrosion was evaluated by half-cell potential and corrosion current densities (I_corr) at regular intervals. Moreover, the influence of cementitious material type, salt type and w/cm ratio on electrical resistivity of concrete was also investigated. The statistical models were developed for electrical resistivity as a function of calcium to aluminium content ratio, compressive strength, w/cm ratio and age of concrete.

Although the corrosion initiation time increases in the concomitant presence of MgSO₄ and MgCl₂ as internal source compared to MgCl₂, I_corr values are higher in both OPC and MK blended concrete. However, electrical resistivity decreased with addition of MgSO₄. MK blended concrete performed better with increased resistivity, corrosion initiation time and decreased I_corr values.

This study reports statistical distributions for scattered I_corr of rebar in different concrete mixtures. Stepwise regression models were developed for resistivity by considering the interactions among different variables, which would help to estimate the resistivity through basic information.

This paper aims to examine the recipe for and standard methods of dyeing cotton fabric with natural dyes from jackfruit wood extract. The dyeing of the fabric was performed by immersion it without heating for a short time to obtain the best results.

The dyeing experiment using cotton fabric with jackfruit wood extract was conducted by immersion at room temperature. The independent variables studied were the mordant method, type of mordant, mordant concentration, salt concentration and dyeing pH. The dependent variables were colour strength and colour fastness to washing and rubbing. The orthogonal array L16 (45) was used in the study to obtain the optimal values for each parameter of the response variables. The multi-response signal-to-noise (MRSN) method was used to optimise the five response variables with different quality characteristics so that the best parameters could be obtained based on the highest MRSN ratio value.

The best parameters were obtained at an MRSN value of 4.5254 under A3B3C1D2E4 conditions, namely, the dyeing process with post mordant, aluminium nitrate type mordant, mordant concentration of 10 g/L, salt concentration of 15 g/L and dyeing a pH: of 10. Under these conditions, the value of K/S was obtained at 1.893, colour fastness to washing (GS: 4) and (SS: 4–5), dry rubbing (SS: 5) and wet rubbing (SS: 4–5).

Obtaining a standard recipe and method for dyeing cotton cloth with jackfruit wood extract by immersion without heating is expected to lead to the development of natural dyes, and especially their application on an industrial scale. This standard and method can be used as technical guidelines by industry. The use of aluminum nitrate as a mordant will help achieve optimal dyeing results. The use of polyaluminium chloride (PAC) mordant, which has the potential to produce high colour strength, and papaya fruit sap, which has the capacity to increase colour fastness, still need to be developed to improve the results of natural dyes.

The standard recipe and dyeing method will be able to improve the results of the dyeing of cotton fabrics with natural dyes. Short immersion dyeing without heating and the optimal results obtained are the main attractions for their use by the textile/batik industry, as the process is easier and a lower cost. The results of dyeing with dark colours and good colour fastness mean the textile products are of the higher quality demanded by consumers, thereby increasing sales. This will encourage the use of and increase the need for natural dyes by industry, consequently reducing the use of synthetic dyes.

The use of natural dyes, chemical mordant from aluminum salts, and natural mordant from papaya fruit sap in the dyeing process in the textile/batik industry in Indonesia will produce eco-textile and eco-batik products that are environmentally friendly and of high quality. This in turn will increase consumer interest and sales, meaning that the income and economy of workers in the textile industry/crafts sector will also increase. In addition, the use of natural dyes with the selection of a safe mordant (not containing heavy metals) will reduce the use of synthetic dyes, which pollute and damage the aquatic environment.

This study found a standard recipe and method of dyeing cotton fabric with natural dyes from jackfruit wood extracted by immersion without heating for a short time to obtain the best results. In addition, the discovery was of PAC, a new mordant which is effective in the use of natural dyes can give high colour strength to cotton fabric. In addition to the discovery of a new mordant, PAC, which has the potential to produce high colour strength, papaya fruit sap also has the capacity to increase colour fastness with the use of natural dyes from the flavonoid group.

GERMANY Metals in contact with aqueous solutions. When metals are brought into contact with aqueous solutions at room temperature there is said to be an initial or ‘incubation’ period which may be of extremely short duration, almost a transient. After this period corrosion may increase rapidly to a thousand times its initial value or more, or may decrease even more rapidly. The latter process can be followed only with a cathode ray oscilloscope. The formation of local elements is assumed to be the cause of the processes observed. The effect on corrosion is shown at the instance of aluminium of different degrees of purity. Dissolution speeds are 6 g./sq.m./day for Al 99.998% rising to 190,000 g./sq.m./day for Al 99.2%.— (F. Tödt, Werkstoffe & Korrosion, 1954, 5, (11), 430–433).

The domestic copper boiler presented few problems until the advent of the closable stove. In this article the corrosion problems now met with are described and a tentative explanation is advanced. Alternative materials are also discussed.

This paper aims to report on corrosivity of secondary-stage paper mill effluent and corrosion performance of stainless steels.

For this purpose, immersion test and electrochemical polarization tests were conducted in mill and synthetic effluent to evaluate the uniform and localized corrosion.

Corrosivity of mill effluent has been compared with synthetic and primary-stage effluent of the same mill. It is observed that anions present in them, viz. SO₄−, PO₃4−, NO₂− and NO₃−, impart inhibition, whereas Cl− and chlorophenols enhance the corrosivity of the effluent. The overall effect of various components was reduction in corrosivity of secondary mill effluent.

These observations can be useful for material selection and helpful in corrosion mitigation in paper mill effluent treatment plants.

This paper aims to construct the E-pH diagrams for AISI 316L stainless steel in chloride solutions containing SO₄²⁻ ions and therefore investigate the role of SO₄²⁻ ions on pitting corrosion of stainless steel.

A cyclic potentiodynamic polarisation method was performed to obtain polarisation curves at different pH. From these curves, corrosion, primary passivation, pitting and repassivation potentials were determined and plotted as a function of pH giving the E-pH diagram.

The addition of SO₄²⁻ ions to 10,650 ppm NaCl solution up to 3,000 ppm widened the passivation regime of the E-pH diagram mainly by shifting the pitting corrosion potential to the noble direction. This indicated the inhibiting role of SO₄²⁻ on the nucleation of new pits in the transpassive region. It also stabilised the pitting corrosion potential at the pH ranging from 5 to 11. However, at pH 7, it caused the pit area to increase, implying the catalytic role of SO₄²⁻ on the pit growth. Finally, it did not change the types of ions dissolved in solutions after pitting.

The diagrams can be used as a guideline in industries to determine the passivation regime of the AISI 316L stainless steel in chloride- and sulphate-containing solutions.

This paper reported the E-pH diagrams for the AISI 316L stainless steel in chloride solutions containing SO₄²⁻ ions. The roles of pH and SO₄²⁻ ions on pitting corrosion were innovatively discussed using a point defect model.

The function of lead additives in petrol is described, together with the effects on various engine components of their removal. The corrosive wear mechanisms are described in detail, and the effect of alternative additives in reducing corrosion and wear are covered. A number of field case histories are described, including experiences in Sweden, where lead replacement petrol was introduced in 1992. The article concludes with a series of recommendations designed to minimise possible damage to engines caused by substitution of leaded petrol by LRP.

Concrete is the most basic of building materials and yet, in the hands of the expert, is capable of providing strength, durability and even elegance far in excess of many of its manufactured competitors. The technology is by now well established but the production of concrete of a consistently good quality is by no means simple.

Poly(styrenesulphonic acid)‐doped polyaniline has been synthesised and the influence of this polymeric compound on the inhibition of corrosion of mild steel in 1M HCl has been investigated using weight loss measurements, galvanostatic polarisation studies, electropermeation studies and a.c. impedance measurements. The polymer acts predominantly as an anodic inhibitor. Hydrogen permeation studies and a.c. impedance measurements clearly indicate a very effective performance of the compound as a corrosion inhibitor. The adsorption of the compound on the mild steel surface obeys Temkin's adsorption isotherm.