Influence of oxides addition on the reaction of Fe2O3-Al composite powders in plasma flame

The production of FeAl2O4 matrix composite coatings based on Fe2O3-Al-MexOy systems by reactive plasma spraying was achieved. The influence of oxides addition (Al2O3, Cr2O3, Fe3O4 and SiO2) on the reaction of Fe2O3-Al composite powders in plasma flame was investigated. The results showed that chemical reactions occurred in Fe2O3-Al-MexOy composite powders during plasma spraying. The reaction products were different from that of the equilibrium reaction condition. The as-fabricated composite coatings were mainly composed of FeAl2O4, α-Fe and Al2O3. Introduction of the oxide additives affected the reaction process of Fe2O3-Al system. Oxides addition reduced the reaction heat release of Fe2O3-Al system and improved the initial reaction temperature. The main phase FeAl2O4 in the five composite coatings was actually mixed hercynite containing different proportion of Fe and Al elements. The normal hercynite contained more Al and the inverse hercynite contained more Fe. The addition of the additives was beneficial to improve the content of the normal hercynite.