Novel (Ti, W)C–SiC–WSi2 ceramics fabricated via in situ reaction spark plasma sintering at 1600 °C

Abstract

Novel (Ti, W)C–SiC–WSi2 ceramics were fabricated by in situ reaction spark plasma sintering (SPS) at 1600 °C using (Ti, W)C and Si powders. The effect of Si content on densification behavior, microstructures, and mechanical properties was investigated. The in situ reaction and the formation of carbon vacancies reduced the sintering temperature. The densification mechanism of (Ti, W)C-based ceramics transforms from reaction to grain-boundary sliding and diffusion. The WSi2 and primary SiC generated by in situ reactions are distributed along the grain boundaries and have a specific crystallographic orientation relationship. Intragranular secondary SiC formed because of rapid densification, grain-boundary diffusion, and (Ti, W1−y)C1−x particle migration. This multiscale particle-reinforced microstructure can improve the mechanical properties of (Ti, W)C ceramics, giving the TW10S (4.80 wt% SiC–5.01 wt% WSi2) good sintering performance, a fine-grained microstructure, high hardness (23.3 ± 1.6 GPa), and flexural strength (425 ± 24 MPa). The SiC and WSi2 produced through in situ reactions have exceptional intrinsic oxidation resistance, allowing the ceramics to achieve outstanding oxidation resistance.