Effect of WSi2 addition on densification and properties of ZrB2

Abstract

Effect of WSi₂ addition on densification and properties of ZrB₂ has been investigated. Samples of the following composition with controlled addition of WSi₂ were prepared by hot pressing (1) ZrB₂, (2) ZrB₂+2·5%WSi₂, (3) ZrB₂+5%WSi₂ and (4) ZrB₂+10%WSi₂. Hot pressing of monolithic ZrB₂ at 1750°C resulted in achieving a density of only 80·1% ρ_th. Addition of WSi₂ enhanced the densification and resulted in near theoretical density. Microstructural investigations revealed the presence of reaction product containing Si and Zr. An increase in WSi₂ content led to an increase in hardness of the product. A slight increase in fracture toughness was observed with WSi₂ addition. Crack deflection was observed in the microstructure. Oxidation study of the composite samples revealed that the oxidised layer is not adherent and resulted in spallation at the end of the test.