Influence of Reduction Process on the Microstructure and Composition of Plasma Sprayed Al₂O₃-3TiO₂/CuO Composite Coating

Undesirable changes in the coating composition can be reduced if plasma spraying is performed in a special chamber with a regulated atmosphere, the process being extremely costly, though. Another method allowing changes in the structure of coatings is thermal treatment. Numerous works present and discuss the results of the research into the influence of carburizing, nitriding, and laser or electron beam treatment on the properties of plasma sprayed coatings. This work concerned composite coatings obtained by plasma spraying of the blend of Al₂O₃-3TiO₂ and CuO powders, which were then reduced at an atmosphere of dissociated ammonia. Their chemical composition and morphology were determined by means of the EDS microprobe and the Joel 5400 scanning microscope respectively. It has been reported that the process of reduction contributes to the homogeneity of the coating, and that the modified structure contains Al₂O₃ and Cu. Abstract only; no full-text paper available.