Glass-Ceramic Precursors in B2O3–SiO2–MxOy Systems (M — Ti, Zr, Cr) as a Source for Producing Fine-Dispersed Mixtures of High-Melting Carbides and Borides

A new approach to the homogenization of the reaction mixture is presented consisting in the creation of glass-ceramic precursors in oxide systems containing enough components for the joint synthesis of carbides and borides mixed at the molecular level. By the joint carbothermal reduction of glass-ceramic precursors in vacuum at 1600 °C fine mixtures in B 4 C–SiC–MB 2 systems ( M —Ti, Cr, Zr) without or with an insignificant content of impurities were obtained. Due to the good solubility of titania in the silicate-borate melt the microstructure of the ternary B 4 C–SiC–TiB 2 sample is represented by boron carbide crystals up to 1 μm in size surrounded by nanoparticles of 30 – 40 nm.