A Study of the Peculiarities of Molding and Structure Formation of Compacted Multicomponent Silicide Composites

Abstract

Technology for the preparation of carbide and multicomponent powders from scrap of hard alloys and tungsten anhydride for further use in the formation of eutectic coatings have been developed in the laboratory. The temperature–time parameters of a process for obtaining powders with the required chemical composition are determined. It is established that compositions with a controlled melting point in the range of 1000–1200°C can be obtained when boron and silicon additives are introduced into these powders in the quantitative ratios corresponding to eutectic compositions. Dross mixtures based on Ni–Si–B and Ni–Cr–Si–B composite powders with reinforcing additives from industrial and laboratory-synthesized refractory silicides and carbides are prepared. Eutectic coatings whose solid component has a microhardness of 18–26 GPa and plastic matrix has a microhardness of 11–15 GPa are prepared by melting dross mixtures on the substrates made of steel and molybdenum. The comparison of structural characteristics and properties of coatings shows that the high-speed melting allows one to obtain the required thickness of the protective layer and to prevent excessive embrittlement of the substrate due to the formation of boride phases. It is found that the addition of molybdenum disilicide in a concentration of up to 50 wt % increases the homogeneity of the coating without reducing its hardness. The coatings are characterized by high corrosion resistance at temperatures around 1000°C.