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In the present work, the authors carried out siliconizing, chromizing, aluminizing and chrome‐aluminizing of mild steel in a pack cementation process with a view to evaluate the optimum experimental conditions to obtain satisfactory coatings which possess high resistance to oxidation. It is visualised to adopt some of the experimental conditions in later experiments where diffusion coating treatments are carried out using pastes containing the various diffusion elements. Some of the findings of the authors in siliconizing, chromizing, aluminizing and chrome‐aluminizing of mild steel in pack process are reported. It was observed that there is excess grain growth during siliconizing by the pack process and the coatings are porous and lack good oxidation resistance compared to coatings in the gas phase carried out by other workers. Chromized, aluminized and chrome‐aluminized samples are superior to 18/8 stainless steel and even Inconel in their oxidation resistance. Chromizing followed by aluminizing makes the coating layer less brittle as observed by the micro hardness measurements across the layer and hence chrome‐aluminizing will improve the spoiling resistance of the coatings.

Aluminium diffusion treated steel by pack process using ferroaluminium was studied for its heat exchanger tube applications properties. The laboratory and inplant corrosion studies reveal that the diffusion treated low carbon steel is extremely resistant to hot corrosion due to sulphurous gases encountered in heat exchanger tubes of sulphuric acid plants at the operating temperatures. The diffusion treated tubes have shown adequate physical properties for heat exchanger tube bundle fabrication.

Maintenance coatings have several functions but certainly one of their most important is to combat corrosion. Corrosion protection is important in both maintenance and industrial coatings and this is stressed in an article in Chemical Marketing Reporter (June 6 (1983) p. 5, 20). According to this article, which quotes results from a marketing research firm, Margolis Marketing and Research, corrosion resistance will provide the objectives for an important segment of the coatings industry in highway construction and in the automotive industry. The use of salt on highways to melt snow and ice is increasing and this causes billions of dollars of damage to iron and steel each year. U.S. roads are covered with over 10 million tons per year of salt. In the industrial area galvanised steel has become an important component of items subject to rust such as the automobile.