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A barrier type of finish coat on zinc‐rich primers can effectively prevent corrosion on mild steel structures in marine environments. Chlorinated rubber is well known for its impermeability of water vapours and corrosive ions. Micaceous iron oxide (MIO) and titanium dioxide (Ti0₂) are the best barrier pigments available in the world. The chlorinated rubber based top coatings have been prepared by incorporating these two pigments separately and applied over three types of zinc‐rich primers (ZRP) (butyl titanate ZRP, cashew nut shell liquid ZRP and epoxy polyamide ZRP). The electro chemical aspects of protection afforded by these coating systems have been evaluated on mild steel substrate in 3 percent NaCI solution by potential‐time, polarisation and impedance techniques. This study revealed an interesting correlation between the polarisation and impedance observations. The inorganic ZRP with top coated systems behave differently to organic ZRP with top coated systems. The MIO pigmented finish coat affords equally higher duration of protection of steel substrate from corrosive saline environment, even though the PVC value is considerably lower than the TiO₂ pigmented top coat systems.

Use of aluminium is coming into vogue in the canning industry. However, the very much higher cost of aluminium than tin plate inhibits the scope for substitution of tin plate by aluminium. It is therefore of interest to examine whether steel coated with aluminium by any of the known methods is suitable for manufacture of containers for canned products. Aluminium‐coated steel can be considered only if the coating has a more negative potential than the base metal. In a study of the behaviour of sprayed aluminium coatings on mild steel in sodium chloride solutions at different pHs, Ross has pointed out that sprayed aluminium (99.5%) is more negative than steel in neutral and alkaline solutions. In this paper, the potential relationships between steel, steel sprayed with aluminium, and aluminised steel in some organic acids commonly present in food stuffs are discussed.

GERMANY Preparing metal surfaces with liquid jets A comparative newcomer among the many conventional methods of surface treatment and finishing is the technique of using liquid jets. A method designed to permit multi‐purpose surface treatment in a single series of operations has been developed in Switzerland and is described in Technisclie Zeitschrift für praktische Metalbearbeitung (No. 5, 1964) by O. Burnand, Lausanne.

It is shown that complete derusting of structural steel is not necessary if rust converter which can convert adherent rust into a protective coating is used. The performance of the rust converter developed by the authors is described in this paper.

Metallic finishing of materials, unlike non‐metallic finishing, comprises various popular surface modification processes, e.g. electroplating, conversion coating, anodizing, metal spraying, hot dip coating and also diffusion coatings. Diffusion coatings on metallic substrates are well known for their better abrasion resistance and adhesion to the substrate. Resistance to corrosion may also be incorporated on these surfaces by the addition of appropriate dopant elements like Cr, Ni and Al. However, these diffusion alloy‐layers are more sought after for functional properties than their aesthetic look. It appears that the concept of functional metal finishing is gaining ground for its longer service‐life and better performance. Discusses some of these aspects of diffusion alloy coatings on mild steel substrate and analyses their comparative merits and demerits. In this connection, three distinctly different types of barrier layers, namely, hard diffusion alloy layer, e.g. chromiding, Ni‐Cr diffusion coatings and soft‐diffusion layer, e.g. Pb‐Cd, Zn‐Sn barriers and those in between, e.g. hot dip zinc‐alloy coated barrier layers, have been highlighted for their corrosion resistance properties.

Mine rope‐wire profile is prone to stress concentration zones by virtue of its manufacturing style and reveals a metastable surface. Metastability, being a non‐equilibrium state, tends to revert back to stability. Such a process of reversion may generate a number of non‐equilibrium states on the surface, which in contact with the mining‐environment foster the growth of a stable and adherent passive‐film.

The purpose of this paper is to investigate the heat resistance properties of silicone‐acrylic hybrid system on cold rolled mild steel panel.

The presence of Si−C bonds in hydroxyl functional solid phenyl‐methyl silicone should be able to improve heat resistance properties of silicone‐acrylic polyol coating. Different weight ratios of silicone resin and acrylic polyol resins were blended in order to obtain the composition for optimum thermal properties. Thermal stability of silicone based protective coatings has been investigated by means of potential time measurement (PTM) and electrochemical impedance spectroscopy (EIS) techniques.

The blending of silicone intermediate resin with acrylic polyol resins. The coating consisting of 30 per cent silicone resin and 70 per cent acrylic resin showed significant improvement of heat resistivity compared to pure acrylic polyol resins on cold roll mild steel panels. This study demonstrates an interesting correlation between PTM and EIS studies.

Findings may be useful in the development of heat resistant paints.

The blending method provides a simple and practical solution to improve the heat resistance properties of acrylic polyol resins.

Durability and functionality of the coating, critically depend on the strength and adhesion properties of the materials. This may be a useful source of information for the development of organic‐inorganic coatings.

The aim of this paper is to study the corrosion protection behavior of water‐borne inorganic zinc‐rich coatings based on potassium silicate/nanosilica developed with various zinc and micaceous iron oxide (MIO) contents during cathodic protection stage.

The formulated coatings were applied on carbon steel panels and were subjected to electrochemical impedance spectroscopy (EIS) and free corrosion potential measurements for characterization of corrosion protection behavior. Also atomic force microscopy (AFM) and optical microscopy were used to investigate the surface topography of coatings.

All of the coatings preserved the cathodic protection ability throughout 75 days of exposure to 3.5% NaCl solution. Supporting results of electrochemical tests and microscopic observations revealed that replacement of zinc by MIO particles reduced both the rate of reactivity and the duration of cathodic protection of inorganic zinc‐rich coatings. It was observed that the coatings demonstrated a reactivation step after a dry‐wet cycle implying that cyclic immersion can change the overall duration of cathodic protection stage.

The paper describes formulation and investigation of corrosion protection behavior of an environmentally friendly zero‐VOC coating as well as providing an insight into EIS of zinc‐rich coatings.

To develop a method for the preparation of micaceous zinc ferrite (MZF), anticorrosive pigment having desirable chemical and physical properties.

MZF pigment was prepared after firing the oxidised solid molten salts without washing. The MZF pigment obtained was characterised using X‐ray diffraction analysis, crystal size analysis, scanning electron microscope and energy dispersive X‐ray analysis. The pigment obtained was also evaluated chemically with respect to moisture content, content of water‐soluble salts, hydrogen ion concentration (pH) and weight loss; and physically with respect to particle shape, colour, specific gravity and oil absorption. Commercially available micaceous iron oxide and zinc ferrite pigments were also characterised in comparison.

A spinel, MZF pigment was prepared using relevant oxidised solid molten salts. The preparation produced a lamellar structure with a basic nature giving not only barrier protection but also chemical passivation of the substrate.

The anticorrosive properties of the pigments obtained could be evaluated using more conventional methods such as salt‐spray test.

The pigment prepared could be used as a highly efficient pigment for anticorrosion coating for steel.

The method for the preparation of MZF pigment was novel. The pigment obtained could be used in various resin systems to produce anticorrosive paints for steel protection.

Paint has long been used for the protection of iron and steel against corrosion.