Enhanced Oxidation Resistance of ZrB2‐SiC‐WC Composite Below 1800 °C

Abstract

The effect of 3.6 vol.% WC addition to ZrB2‐20 vol.% SiC (ZSW) on oxidation resistance is studied over a broad range of oxidation temperatures, 1000‐1800 °C. Non‐WC‐containing samples (ZS) show significant surface damage and degradation during oxidation, losing protective B2O3 and SiO2‐based surface layers, exposing a porous ZrO2 layer and base material for further oxidation. ZSW samples preserve their surface protective layers during oxidation up to 1800 °C while the underlying ZrO2 scale remains dense. We report the appearance of convection cells on the surface of ZSW samples during oxidation above 1600 °C. This confirms the presence of boron‐rich phases, suppressing oxygen permeation into material, enhancing oxidation resistance of ZSW samples above. During exposure of the samples to 1800 ºC for 15 min, ZS and ZSW samples gained 11.1 ± 1.5 and 7.8 ± 0.3 mg cm‐2, respectively, due to oxidation. Exposure of the composites for 5 hours at 1600 ºC resulted in weight gains of 10.5 and 7.0 mg cm‐2 for ZS and ZSW samples, respectively. Cross‐sections of oxidized samples at 1800 °C show a tight zirconia layer below a glassy surface in ZSW and complete loss of surface glass in ZS, demonstrating the effectiveness of WC addition.This article is protected by copyright. All rights reserved.