Synthesis, processing and properties of TaC-TaB2-C ceramics

Multi-phase ceramics in the TaC-TaB2-C system were prepared from TaC and B4C mixtures by reactive pressureless sintering at 1700-1900 degrees C The pressureless densification was promoted by the use of nano-TaC and by the presence of active carbon in the reaction products. The presence of TaB2 inhibited gram growth of TaC and Increased the hardness compared to pure TaC. If a coarse TaC powder was used, the compositions did not densify In contrast, pure nano-TaC was pressureless sintered at 1800 degrees C by the addition of 2 wt.% carbon introduced as carbon black or graphite The introduction of carbon black resulted in fully dense TaC ceramics at temperatures as low as 1500 degrees C. The grain size of nominally pure TaC ceramics was a strong function of carbon stoichiometry. Enhanced grain size in sub-stoichiometric TaC, compared to stoichiometric TaC, was observed Additional work is necessary to optimize processing parameters and evaluate the properties of ceramics in the TaC-TaB2-C system. Published by Elsevier Ltd.