Coatings on ceramic powders by rotary chemical vapor deposition and sintering of the coated powders

Rotary chemical vapor deposition (CVD) is a non-line-of-sight-deposition process with excellent coverage and a versatile technique to modify surfaces of ceramic powders. In this paper, potential applications of rotary CVD for coatings on powders are presented; highly dispersive catalytic nanoparticles can be deposited on support powders, while the conformal thin layers can be coated uniformly on particulates, which are advantageous in powder metallurgy for the preparation of sintered bulk materials. Particularly, this paper focuses on the deposition of silicon carbide (SiC) layers on silica (SiO2) and diamond particles using the rotary CVD technique; the resultant core/shell powders are readily sintered using spark plasma sintering at moderate temperatures and pressures. The CVD-SiC layers formed on powders prevent grain growth and act as protective layers against reactions and phase transformations at the sintering temperatures, resulting in the formation of a discriminating microstructure with enhanced mechanical properties.