Study On Forming Mechanism Of The Fe-al₂o₃-feal₂o₄ Composite Coating By Reactive Plasma Spraying

Composite powders of Al/Fe2O3 were synthesized by spray granulation method using inexpensive aluminium powder and iron oxide powder. And the metal and ceramic composite coating was synthesized by plasma spraying using the composite powders of Al/Fe2O3. The microstructure of the composite coating was checked and its component was analyzed. The products of the reaction by composite powders were tested. Combined with thermodynamic analysis, the forming mechanism of the composite coating was studied.After mixing the aluminium powder and iron oxide powder, the composite powders were synthesized by spray granulation method using the aluminium powder and iron oxide powder. By selecting appropriate ones, the composite powders with high intensity, rounded shapes, well-regularity and excellent liquidity, can be used for plasma spraying to synthesize the composite coating. The better processing parameter was obtained by orthogonal experiment to improve the process of the composite powder synthesize.By plasma spraying technology, the metal and ceramic composite coating was synthesized using the composite powders. During the process, the composite powders would take reaction at the same time. That would release high energy to let the powders become liquid. The molten powders impacted to the substrate and spread out to form the composite coating. The composite coating was mainly constituted by FeAl2O4, Fe and Al2O3 was dispersedly embedded in the coating.In the process of synthesizing composite coating, there were three periods: the incubation period, the reaction period and condensation period. By the composite powders quenching test, the reaction products were studied. The reaction of the composite powders in balance condition was studied by thermodynamics analysis. And combining with the products by actual reaction, the forming mechanism of the composite coating can be studied.