Spark plasma assisted carbothermal reduction-nitridation synthesis of (Ti, W, Mo)(C, N)-(Ni, Co) powders

Abstract Ultrafine (Ti, W, Mo)(C, N)-(Ni, Co) cermet powders were rapidly synthesized from various metal oxides, mainly anatase-TiO 2 , by spark plasma assisted carbothermal reduction-nitridation (SPCRN) at low temperature. The phase evolution of the SPCRN reaction was investigated using X-ray diffraction (XRD) and the microstructure of the product powders was observed using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). NiO, Co 3 O 4 and MoO 3 were converted to Ni, Co and Mo 2 C by CR reaction at temperatures below 900 °C. WO 3 was successively transformed from W 2 C to WC by CR reaction up to 1100 °C. Finally, at up to 1350 °C, (Ti, W, Mo)(C, N) formed into the sequence of TiO 2 , Ti 4 O 7 , Ti 3 O 5 , Ti(O, N), Ti(C, N), (Ti, W)(C, N) and (Ti, W, Mo)(C, N). The crystal structure of (Ti, W, Mo)(C, N)-(Ni, Co) cermet powders was analyzed by the Rietveld method and transmission electron microscopy (TEM). The findings demonstrated that the pure (Ti, W, Mo)(C, N)-(Ni, Co) cermet powders with grain size of below 0.5 µm were synthesized from metal oxides by SPCRN reaction at 1400 °C for 10 min.