Strong ZrB ₂ – SiC – WC Ceramics at 1600°C

Abstract

High temperature flexural strength of ZrB 2 –20 vol% SiC ceramics ( ZS ) up to 1600°C in high purity argon atmosphere was significantly improved by adding 5 vol% WC , but degraded when 5 vol% ZrC was added. ZrB 2 –20 SiC –5 WC ceramic ( ZSW ) has a very high strength (mean ± SD) of 675 ± 33 MPa at 1600°C, and also an elastic and transgranular fracture mode was observed. According to the analysis of the fracture modes and crack origins in ZSW ceramics, the improvement in strength above 1000°C was attributed to the removal of the oxide impurities from grain boundaries.