Tuning the Properties of Refractory Carbide Nanopowders

Resumo

Two methods for transition metal carbide nanopowder production such as plasma chemical synthesis and high-energy ball milling are considered. The control of the chemical, phase, and dispersed composition of carbides produced from oxide and halogenide raw materials is studied by an electric arc plasma plant with a power of 20 kW. A study of the grinding time effect of micron-sized carbide powders on a Retsch PM-400 mill tool in hard-alloy containers is carried out to obtain nanosized powders, as well as to determine fractional composition and particle shapes. It is shown that powders obtained by plasma chemical synthesis have a grain size of 20–80 nm and are subjected to a spheroidized or equiaxed shape. The process allows one to tune the phase composition and the content of common and free carbon. Polydispersed carbide powders with a specific surface area of 3–25 m²/g and predominately bimodal particle size distribution in a range from less than 0.1 μm to dozens of microns are thus obtained by high-energy ball milling.