Study On Forming Mechanism Of The Fe-Al₂O₃-FeAl₂O₄ Composite Coating By Reractive Plasma Spraying

In this paper, composite powders of Al/Fe2O3 were prepared successfully by spray granulation using industrial aluminum and iron oxide powder. The metal-ceramic composite coating was prepared by plasma spraying using the composite powder. The microstructure and phase morphology of the composite coating were observed and analyzed. Combine with quenching method and thermodynamic analysis and analysis the data to research the formation mechanism of the reaction.Using the industrial aluminum and iron oxide powder was mixed according to a certain percentage. The powder will be uniformly mixed by dry mixing, wet mixing and other methods. Add the binder to improve the strength of combination. Finally, the composite powder was prepared by spray granulation. After selected appropriate composite powders to get the rounded shapes and well-regularity can be used by plasma spraying.The preparation of the composite powder feed into the plasma flame stream. Powder was heated and be occurred SHS reaction. The resultant was deposited on the surfaces of the base with plasma gas to stack with each other to form a composite coating. The mainly organization of the composite coating is FeAl2O4, Fe and Al2O3 was dispersedly embedded in the coating.The organizations of the composite powder coating at different Flight distance were obtained by the composite powders quenching test. The composition of coating was analyzed by XRD. Organizational change and reactions of the composite powder were obtained in the heating process by DTA and TGA. The change of temperature and speed of the composite powder was observed by Spray-Watch2i during the flight. Through the data obtained above analysis and combining thermodynamic analysis, the composite powder consists of three phases in the flame reaction. Each stage of the reaction will release a lot of heat, but the strength of the reaction was gradually reduced and stabilized. Figure out the chemical reaction at each stage and determine the reaction mechanism. The formation of metal-ceramic composite coating was known clearly.