Cermet Plasma Coatings Based on Silicon Carbide

Abstract

The structure, phase composition, and C, O, and N content in two cermet coatings sprayed from powders of the initial composition of 30SiC–NiCr and 30SiC–TiNi are studied. The change in the chemical and phase composition is monitored at the stage of obtaining powders and plasma spraying of the coatings. The powder is obtained by mechanical alloying and subsequent sintering of the compact. With mechanical alloying, the content of oxygen and nitrogen increases. When sintering, the content of silicon carbide is reduced by 10 times, silicides are formed, and the content of light elements at this stage changes insignificantly. After plasma deposition, the phase composition of the coatings does not qualitatively change with respect to the powder to be sprayed, but nonequilibrium crystalline and amorphous phases are formed and the content of carbon and oxygen decreases. The microhardness of coatings of 10 GPa at load on an indenter of 10 g is determined by 50% of the volume fraction of SiC in the initial powder.