Sintering and microstructural effects on mechanical properties of zirconium carbide-tungsten cermets

Zirconium carbide-tungsten cermets were prepared by in situ reaction sintering a mixture of zirconia and tungsten carbide. Tungsten is a refractory metal with a melting point of 3422⁰C; however, its mechanical strength decreases significantly with increasing temperature. One approach to improve the elevated temperature strength is to add ceramic particulates to the matrix. Zirconia and tungsten carbide were compacted and then reacted and sintered in a single step by heating to 2050⁰C. The resulting stoichiometric zirconium carbide-tungsten cermet had a relative density greater than 96%. Cermets with two different grain sizes were produced by altering the final sintering temperature. Sintering at 2050⁰C resulted in features measuring \u3c1 \u3eµm and a strength of 530 MPa, comparted to sintering at 2100⁰C which r4esulted in features measuring \u3e2 µm and a strength measuring 450 MPa. Cermets with different ZrC:W ratios were also evaluated. composites containing 35, 50 and 65 vol% ZrC were prepared and tested for hardness, with values ranging from 9 GPa to 13 GPa for materials containing 35 vol% and 65 vol% ArC, respectively. The cermets were also prepared by hot pressing. The hot pressed samples were used as a comparison of properties and microstructure. The effects of the composition and microstructure on the mechanical properties were evaluated --Abstract, page iv