Carbon content-dependent microstructures, surface characteristics and thermal stability of mechanical alloying derived SiBCN powders

Three types of SiBCN: carbon-lean, -moderate and -rich powders with the same Si/B/N mole ratio were subjected to high-energy ball milling to yield an amorphous structure. The effects of carbon content on microstructures, solid-state amorphization, surface characteristics and thermal stability of the as-milled powders were studied in detail. Results showed that the increases in carbon content can drive solid-state amorphization accompanied by strain-induced, crystallite refinement-induced and/or chemical composition-induced nucleation of nano-SiC from an amorphous body. The specific surface area increases as carbon content increases. The amorphous networks of Si-C, C-B/C-C, C-N, B-N and C-B-N bonds that compose the amorphous nature, but the species and contents of the chemical bonds are carbon content-dependent. Carbon-moderate powders possess satisfying thermal stability while carbon-rich ones perform the worst. Mechanical alloying derived SiBCN powders have outstanding oxidation resistance below 800 °C; however only carbon-moderate powders show desirable anti-oxidation ability at higher temperatures. Thus, mechanical alloying of SiBCN appears a suitable technique for developing amorphous matrix materials for practical applications.