Microstructure and mechanical properties of the spark plasma sintered TaC/SiC composites

Abstract

► Dense TaC/SiC composites with 5–40 vol.% α-SiC particles were fabricated by spark plasma sintering. ► The densifying process was consisted of two stages. ► Adding SiC enhanced elimination of the closed porosity. ► The 40 vol.% SiC composition had good flexural strength at both room temperature and 1400 °C. TaC/SiC composites with 5–40 vol.% 6H–SiC were fabricated by spark plasma sintering at 1800 °C for 5 min. Effects of SiC concentrations on the densification, microstructure, and mechanical properties of the materials were investigated. The results showed the densification process of the TaC/SiC composites was composed of six sequent stages. SiC addition was effective in eliminating the closed porosities in the final stage to yield fully dense TaC/SiC composites at 20 vol.% SiC concentrations and above. TaC grain sizes decreased with SiC concentration increase. The 40 vol.% SiC composition had the highest flexure strength and fracture toughness up to 703 MPa and 6.8 MPa m 1/2 due to the reinforcement of the SiC agent. The TaC/SiC composites with 20 and 40 vol.% SiC showed good flexural strength at 1400 °C.