Densification, Mechanical Properties, and Oxidation Resistance of TaC-TaB2 Ceramics

The densification of tantalum carbide (TaC) was enhanced by adding 10 wt% (11 vol%) TaB2, reaching 98.6% relative density by hot pressing at 2100° or 2200°C using a 30 MPa applied pressure. X-ray diffraction analysis identified two phases, TaC and tantalum diboride (TaB2), with no peak shifts, indicating a solid solubility was not significant at these temperatures. Mechanical properties were measured for TaC-10 wt% (11 vol%) TaB2 hot pressed at 2100°C and compared with monolithic TaC hot pressed at 2300°C. The Young\u27s modulus increased from 472 GPa for monolithic TaC to 543 GPa for TaC with 10 wt% (11 vol%) TaB2 additions. Vickers\u27 hardness increased from 14.1 to 19.4 GPa. Fracture toughness values were comparable, in the range of 3.4-3.5 MPa·m1/2. The average flexure strength was 600 MPa, comparable to the flexure strength of monolithic TaC (686 MPa). Thermal gravimetric analysis indicated that the TaC-10 wt% (11 vol%) TaB2 oxidized at a slightly higher temperature than monolithic TaC. Together, the results indicate that TaB2 is an effective sintering aid for the densification of TaC