Tungsten carbide: A versatile additive to get trace alkaline-earth oxide impurities out of ZrB2 based ceramics

In this work, trace amounts of alkaline-earth oxide impurities (MxOy), M = Mg, Ca and Al, are identified from different graded ZrB2 based ceramics. The reactions in MxOy-WC systems at high temperature are therefore investigated via X-ray diffraction and element analysis, which have been further supported by thermodynamic calculations. Since MxOy with low melting point deteriorates the high temperature performance of ceramics, the effective role of WC on strong ZrB2-SiC-WC ceramics is re-considered: apart from the contribution on removing of ZrO2, WC serves as a versatile additive with capacity to remove different oxide impurities from the ceramic body. (C) 2018 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.