ALUMINUM PROTECTIVE COATINGS PRODUCED ON TERNARY FE-CR-NI ALLOYS

Protective coatings can defend a material from degradation when it is exposed to severely aggressive environments such as those encountered in the chemical, petroleum and aerospace sectors. Chromium-, aluminium- and silicon-based coatings produced with these elements alone or in combination have been used for quite some time to increase resistance both to hot corrosion and high temperature oxidation, owing to the fact that most structural materials with adequate mechanical properties do not stand up well in difficult environmental conditions If, however, they possess both these positive characteristics their cost is prohibitive. The coating ofNi-based superalloys by diffusing aluminium has been exhaustively studied, but this is not the case where austenitic stainless steels are concerned. The purpose of the work reported here was to characterize the microstructure and microchemistry of aluminium diffusion coatings produced on stainless steels by means of preparation of synthetic alloys.