Oxidation models of the growth of corrosion products on the intermetallic coatings strengthened by a fine dispersive Al2O3

In this paper, the cyclic oxidation test of intermetallic coatings with iron and nickel aluminium is presented. The oxidation behavior of coatings strengthened by a fine dispersive Al2O3 was investigated in aggressive gases for exposure times of up to 500 h. The surfaces of the composite coatings after the corrosion test in air were analyzed by light and scanning microscopy observation. An analysis of the corrosion products' phase composition was conducted by an X-ray diffraction method. The results obtained from the presented investigations enable the elaboration of the two models of the growth of corrosion products on the intermetallic coatings strengthened by a fine dispersive Al2O3, first, on the coating with FeAl phase and second on the coating with NiAl intermetallic phase. The results show that the composite, thermally sprayed coatings have very good high-temperature corrosion resistance.