Tantalum carbide (TaC) matrix composites were produced by the pressureless sintering at temperatures of 2200οC and 2300 οC. Various combinations of TaC, nano-Gr (nano-graphite) and SiC were used. The amount of nano-Gr was constant at 10 vol%, and the SiC content was 0-20 vol% variable. The amount of SiC had a significant influence on the sinterability and mechanical properties of the TaC. The SiC particles locate on the grain boundaries and inhibit grain growth through the sinter process. The relative density was decreased for both temperatures as a result an increasing of amount SiC. It was decreased from 94.2% to 82.5% at 2200 οC, and from 96.1% to 85.7% at 2300 οC, when the amount of SiC was increased from 0 to 20 vol%. By increasing the amount of SiC to 10 vol%, the hardness was enhanced and reached to 1610 HV and 1760 HV at sintering temperatures of 2200 οC and 2300 οC, respectively. However, above 10 vol%, sinterability and as a result the hardness was reduced.

Keywords: Tantalum carbide, Silicon carbide, Pressureless sintering, Composite.