Improved Oxidation Resistance of Zirconium Diboride by Tungsten Carbide Additions

The effect of tungsten carbide (WC) additions on the oxidation resistance of zirconium diboride (ZrB 2 ) was studied. Zirconium diboride ceramics, nominally pure and with the addition of 4 mol% WC, were densified by pressureless sintering. During densification, the WC that was added to the ceramic dissolved into the ZrB 2 matrix, forming a solid solution. Oxidation behavior was evaluated using thermal gravimetric analysis up to 1500°C and isothermal furnace oxidation at 1500° and 1600°C. The WC additions reduced both the weight gain and the oxide scale thickness. After oxidation at 1600°C for 3 h, the mass gain decreased from 22 mg/cm 2 for nominally pure ZrB 2 to 8 mg/cm 2 for the WC‐containing ceramic. Analysis showed that the WC additions improved the oxidation resistance of ZrB 2 by promoting densification of the zirconia scale formed during oxidation through liquid‐phase sintering.