Formation of Composite Powders and Ceramics from β-SiC-Cr2O3-C Mixtures.

The phase-formation process in the disperse β-SiC + SiO + CrO + C system treated in vacuum at 1273, 1473, 1673, and 1873 K was studied by X-ray phase analysis, IR spectroscopy, EPR, and other methods. It was found that at treatment temperatures of 1273, 1473, and 1673 K, the major process is carbothermal reduction of CrO and SiO with the formation of chromium carbosilicide and chromium carbide (CrC). At T = 1873 K, on the surface of the SiC particles, metastable chromium silicate forms on the base of SiO and CrO. The reduction of CrSiO by silicon carbide is accompanied by the formation of CrSi, CrSi, and chromium carbosilicide. The phase composition of the products of interaction and their distribution over the volume of the composite powder and ceramic material are determined by the dispersion composition of the starting SiC powder and by the degree of development of reduction processes in local volumes of the disperse and compacted material. [ABSTRACT FROM AUTHOR]