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Lamellar micaceous iron oxide paints are successfully employed to provide longlife corrosion protection for metallic structures when exposed to highly aggressive environments. The aim of this work was to formulate and manufacture lamellar micaceous iron oxide paints, able to be used on the protection of steel structures exposed to water. Several formulation and manufacture variables were taken into account. Many paint films fail when they are saturated with moisture and blistering is a common failure because primers usually are not designed to allow the liquid to dissipate back out through the film. Consequently the film can not resist the formation of projections which result in local adhesion loss. For maximum durability, primers must be properly formulated and manufactured. Film permeability, which depends on paint composition (pigment volume concentration) and micaceous iron oxide dispersion time, seems to be the key characteristic controlling subsequent coating performance. Laboratory results indicated that lamellar micaceous iron oxide is a pigment which provides an anticorrosive action by providing a barrier effect. Film permeability must be compatible so as to attain a satisfactory rusting and blistering resistance.

Micaceous iron oxide coatings are becoming more and more popular in Europe in steel construction, both as an undercoat and as a topcoat. This is mainly due to the protecting platelet structure of the micaceous iron oxide, which protects the resin component from oxidative uv degradation on exposure to the weather. It is also fairly common to combine them with aluminium pigments. This reinforces the scale‐like character of such coating systems and gives a light, metallic appearance. Because of the natural dark colour of micaceous iron oxide, the choice of shades is rather limited. There are nevertheless no problems in matching certain dirty shades as are found, for example, in standardised colour cards.

High strength low alloy steels have attained wide acceptance as structural materials. Research and development have led to different corrosion preventive methods. High strength low alloy (HSLA) of composition C(0.4%), Mn(0.7%), Si(0.25%). Cr(0.8%), Ni(1.7%) was selected for this study. Epoxy iron oxide, epoxy micaceous iron oxide (MIO), zinc‐rich epoxy and zinc ethyl silicate were used for painting the HSLA panels (150mm × 100mm × 3mm). Physical properties such as film thickness, specific gravity, viscosity, drying times of paints were evaluated and salt spray test, AC impedance and metallographic examination were carried out. Performance of zinc ethyl silicate coating over HSLA was found to be the best followed by epoxy micaceous iron oxide system.

Micaceous iron oxide (MIO) paints are employed throughout the world to provide long‐life corrosion protection for structural steelwork.

Micaceous iron oxide pigments have been used successfully for many years in undercoating and finishing paints where a high level of protection is demanded and an impervious coating required.

If a weather‐beaten structural steelwork, protected by a full system of anticorrosive coatings, will show a lifetime of over 20 years without any maintenance during this time, we will speak of a ‘longterm Corrosion Protection.’ These 20 years often seem to be too long, but many case‐histories of structural steelworks over the whole of Europe, such as bridges, tankfarms, cranes etc. will prove it. By the way, the German Railway Administration foresees a major repainting of their objects only every 20 years, the Swiss Federal Railway Administration only after 25–30 years. The most parts of these protective coatings are pigmented with Micaceous Iron Oxide (MIO), a pigment with the highest life expectance.

Micaceous Iron Oxide (MIO) coatings have a well established record for long‐term protection of steelwork against corrosion. Structures protected with MIO paint systems include road and railway bridges, electricity towers, radio masts, gantries, cranes, building frames, gas holders, chemical plant, offshore platforms, storage tanks and pipework.

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.

The need for environmentally acceptable anti‐corrosive pigments to replace those based on lead and chromates in priming paints has stimulated the emergence of phosphate, molybdate and borate types and many others. However there are widespread doubts about the ability of these “non‐toxic” alternatives to provide the same degree of corrosion‐resistance as the lead and chrome pigments. This has encouraged a search for ways and means of boosting the inhibitive action of the newer pigments, for instance by mixing with other ingredients that might promote a synergistic effect. There has been a growing interest in utilising inert “barrier” pigments for this purpose and the development of synthetic iron oxide with a flake‐like crystalline structure is a significant step forward in this context.

This work aims to study the corrosion protection of laboratory‐prepared micaceous zinc ferrite (MZF) pigment in anticorrosive paints for steel.

Acrylic‐modified alkyd coatings, based on MZF pigment, micaceous iron oxide (MIO) and zinc ferrite (ZF) pigments, were prepared at different pigment volume concentrations “PVCs” to the critical pigment volume concentrations “CPVCs” ratio, which denoted hereafter by A. Scanning electron microscope, weight loss measurements, water vapour transmission (WVT) and immersion in 3.5 per cent salt solution as well as physico‐mechanical properties were performed to evaluate the paints anticorrosive performance.

WVT and corrosion protection can be affected by the PVC/CPVC ratio for all systems. At any particular PVC, the barrier property of the pigment was the main factor affecting the WVT and corrosion protection. MZF pigment protected the carbon steel physically through barrier action and chemically by the reaction with the acidic acrylic‐modified alkyd resin to produce soaps which passivate the substrate.

Novel MZF paint could be used with optimum percentage in anticorrosive paints for steel protection especially in humid and coastal regions.