Pressureless Sintering of TaC-HfC-VC Composite

Abstract

  Tantalum carbide (TaC) matrix composite was produced by the pressureless sintering at temperatures of 2200 ºC for 1 & 2 hours and 2300 ºC for 1 hr. Various combinations of TaC, HfC and VC were used. The amount of VC was constant as 2 vol%, and the HfC content was 0-15 vol% variable. Vanadium carbide particles diffused in the structure of TaC and formed solid solution in both temperatures, but the amount of HfC had a different influence on the sinterability and mechanical properties of the TaC. The HfC particles located on the grain boundaries and inhibited from grain growth through the sintering at temperature 2200 ºC. The relative density was decreased from 94.2% to 85% for 1 hr, and from 94.8% to 88% for 2 hrs, when the amount of HfC was increased from 0 to 15 vol%. By increasing the temperature to 2300 ºC, solid solution of TaC-HfC-VC was formed. The relative density increased from 96.1% to 98.2% when the amount of HfC was increased to 10 vol%.