EFFECT OF ALUMINUM IN THERMAL-OXIDATION OF FE-CR-AL CONVERSION COATING FOR CATALYSIS

The use of coatings having special properties for photothermal conversion or catalysis is often complicated by problems of high temperature stability. This study deals with the effect of aluminium, as an additional element in ferritic stainless steel, on the behaviour of Fe-Cr-Al conversion coatings during their thermal oxidation in air up to 1000-degrees-C. X-ray diffraction and infrared spectrometry show that the main component of the coating is a chromium, aluminium substituted magnetite and that the presence of aluminium slows down the oxidation rate of the coating-substrate system mainly owing to the formation of mixed iron oxides containing aluminium and of alumina.