The influence of thermal treatment on structure and properties of plasma sprayed oxide and carbide coatings.

This paper presents the results of the investigations of oxide (Cr2O3, Al2O3, ZrO2) and carbide (Cr3C2, W2C) coatings as applied onto the steel substrate by the plasma spraying method and subsequently remelted. Diverse methods of remelting were used in the experiments - the single and repeated treatments with the continuous microplasma arc, the impulsive remelting technique and TIG method. The coatings were examined both prior to, and after the thermal treatment with the use of light an scanning microscopy, X-ray structural analysis, and the measurements of surface roughness. A reduction of surface roughness, an increase in intensities of diffraction lines and a densification of ceramic and bond layers as a result of reduction of porosity and voids, were observed.