Effect of WC addition on the mechanical properties and oxidation resistance of ZrB2/SiC-based UHTCMCs

Abstract

The sintering behavior, mechanical properties, and oxidation resistance of carbon fiber reinforced ZrB₂/SiC/WC composites were investigated. Sintering was carried out between 1800 and 2000°C via hot pressing at 40 MPa. WC was completely consumed in the process, and the resulting microstructure was characterized by the formation of Zr_1−xW_xC solid solutions and WB at the ZrB₂ border grains. The sample sintered at 1800°C was characterized by high porosity, whereas the sample sintered at 2000°C was fully dense, but fibers were severely degraded. A temperature of 1900°C allowed to obtain 92% relative density while preserving the fibers integrity, which was reflected in the higher mechanical properties. Comparing these results with a reference ZrB₂/SiC composite, the addition of WC did not seem to significantly affect the mechanical properties, but it promoted the formation of a more compact oxide scale during oxidation, resulting in the higher protection of the material at 1650°C in air.