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Introduction The formability and strength of steel make it suitable and economic for most uses. Rust is the worst feature. Paint does not protect it for long: scratches and even pores in the paint allow access of water and rust forms, weakening the steel and spreading brown stains.

The ability of zinc to inhibit the rusting of steel depends on a natural phenomenon — the electrical reaction between dissimilar metals, first noted by an Italian scientist named Luigi Galvani. A French chemist discovered in 1740 that zinc could protect steel from the effects of rust. However, it would be almost 100 years before the practical problems of coating steel with zinc would be solved. In 1887 Stanislaus Sorel, a French engineer, secured a patent for hot dip galvanizing. It is basically on this method that today's techniques have been developed. Recognizing Galvani's earlier discovery, Sorel called his process Galvanization.

Treatment for ‘Triazine’. Coatings applied by the anti‐corrosion specialists Lithgow Saekaphen Ltd, are performing a vital function for FBC Ltd, in the production of the weedkiller ‘Triazine’.

Legislation and consumer demand are two of the main driving froces behind the decision by vehicle manufacturers to look to their suppliers to carry out research and development work in the complex area of corrosion. With fluid carrying systems, like the brake lines, now expected to last the “life of the car” and with emissions from fuel lines needing to be contained to minimum levels, how are suppliers responding? Bundy, a world‐leader in automotive fluid carrying systems, is at the forefront of identifying solutions in this field. Claims that the results of the company's work are innovative solutions which meet environmental standards and higher quality systems which ultimately offer greater value for money to motorists. Looks in detail at some of the issues now facing the industry.

A method is presented by means of which the lift coefficient of an arbitrary aerofoil in a two‐dimensional cascade is obtained explicitly in terms of a number of cascade functions, whose values depend only on the cascade geometry. The method is based on Schlichting's theory, whereby the profile is substituted by a continuous row of singularities arranged along the blade chord, and it consists in a simplification of the usual procedure of satisfying the boundary conditions. The simplified method greatly reduces the amount of work involved, and an analysis of a number of representative aerofoils indicated a good agreement with the values obtained by the more exact procedure. The values of the special cascade functions required for the application of the method are tabulated over a wide range of stagger angles and pitch/chord ratios.

This paper aims to investigate the structural, corrosion and the study of tribocorrosion features of the AA7075 aluminum alloy with and without the application of electroless Ni-P/Ni-B duplex coating with a thickness of approximately 40 microns.

Surface characterization of the samples was made by structural surveys (light optic microscope, scanning electron microscopic examinations and X-ray diffraction analyses), hardness measurements, corrosion and tribocorrosion tests.

Results of the experiments showed that upper Ni-B coating deposited on the surface of first Ni-P layer by duplex treatment caused remarkable increment in the hardness, corrosion resistance and tribocorrosion performance as compared to the AA7075 aluminum alloy.

This study can be a practical reference and offers insight into the effects of duplex treating on the increase of hardness, corrosion and tribocorrosion performance.

This work aims to investigate the wear behavior of manganese phosphate coating on plasma nitrided AISI 5140 steel.

Prior to manganese phosphate coating, plasma nitriding of substrates was performed at gas mixture of 50 percent H₂ and 50 percent N₂, for the different treatment parameters. The structural, mechanical and tribological properties of the substrates were determined using hardness test, optical microscope, scanning electron microscopy , X‐ray diffraction and pin‐on‐disk tribotester. The wear behavior of untreated, nitrided and duplex treated substrates was evaluated under dry sliding conditions.

The results indicated that the duplex treatment improved the wear behavior. It was also observed that manganese phosphating of the nitrided substrates at low temperature (450°C‐2h‐N) resulted in a decrease of the wear rate and yielded a reduction in the friction coefficient by forming a transfer film at the counter face.

This study can be a practical reference and offers insight into the effects of duplex treating on the increase of wear resistance.

This paper aims to investigate the effects of deposition time on the structure and anti-corrosion properties of a micro-arc oxidation (MAO)/Al coating on AZ31B Mg alloy.

The study describes the fabrication of the coating via a combined process of MAO with multi-arc ion plating. The structure, composition and corrosion resistance of the coatings were evaluated using scanning electron microscopy, energy dispersive spectroscopy, X-ray diffraction and electrochemical methods.

The Al-layer is tightly deposited with a good mechanical interlock along the rough interface due to the Al diffusion. However, the Al layer reduces the anti-corrosion of MAO-coated Mg alloy because of structural defects such as droplets and cavities, which act as channels for corrosive media infiltration towards the substrate. Fortunately, the Al layer improves the substrate corrosion resistance owing to its passive behaviour, and the corrosion resistance can be enhanced with increasing deposition time. All results indicate that a buffer layer fabricated through the duplex process improves the interfacial compatibility between the hard coating and soft Mg alloys.

An MAO/Al duplex coating was fabricated via a combined process of MAO and physical vapour deposition. MAO/Al duplex coatings exhibit obviously passive behaviours on AZ31 Mg alloy. The structure and corrosion resistance of MAO/Al coatings were investigated.

The surface coating of drill bits improves the tool life considerably and enhances the end product quality. The improved coating is desirable for long service operations. One of the methods to achieve this is to develop an interface layer between the coat and the tool base such that the transition of shear properties occurs across the interface layer. The application of duplex treatment (plasma pre‐nitriding before PVD TiN coating) to the tool surface becomes fruitful in this regard. In the present study, the wear properties of the duplex treated and untreated M7 HSS twist drill bits are examined. The wear tests are conducted on a dry base, and the feed rate and rotational speed are kept constant during the drilling tests. SEM and EDS are conducted to analyze the wear properties and metallurgical changes on the tool surface after the tests. It is found that the build up edge forms on the untreated tool surface, which in turn results in adhesion and abrasive wear. In the case of duplex treated drill bit, thinning of TiN coat is observed, but the coat is neither partially nor totally pealed off from the tool surface in the wear land.

This paper aims to increase protection behavior of epoxy coating on aluminum alloys with plasma electrolitic oxidation (PEO) process as pretreatment and to investigate the corrosion properties of duplex coating system on aluminum alloy.

The study used micro structure study, electrochemical impedance spectroscopy (EIS) investigation, water uptake investigation and pull-off test.

This study was done to investigate the effect of urea as an additive, which alters the current density and time of process parameters in the protective performance of epoxy coating on the aluminum substrate. The protective behavior of double-layer coatings was examined using EIS in 3.5 per cent NaCl solution. In addition, the adhesion strength of double-layer coatings was evaluated using pull-off test, and the results demonstrated that the adhesion strength of sample with higher content of urea and current density is about two times that of sample without PEO preparation.

The protective properties and adhesion strength of epoxy coating can be increased with PEO pretreatment.