Enhanced thermal shock and oxidation resistance of Si ₂BC ₃N ceramics through MWCNTs incorporation

Abstract

Multi-walled carbon nanotubes (MWCNTs) reinforced Si ₂BC ₃N ceramics were prepared through mechanical alloying (MA) and following spark plasma sintering (SPS). The thermal shock resistance of Si ₂BC ₃N ceramics was evaluated comparatively through ice water quenching test and theoretical prediction. Furthermore, the oxidation resistance of MWCNTs incorporated Si ₂BC ₃N ceramics was evaluated under high temperature. The results show that the calculated parameters such as the critical thermal shock temperature ( R) and the thermal stresses resistance ( R _st), as well as the toughness ( R′′′′) are improved with addition of 1 vol% MWCNTs. In addition, the crack propagation resistance of 1 vol% MWCNTs incorporated Si ₂BC ₃N ceramics is obviously improved through generating more tortuous crack propagation paths attributing to the “crack bridging”, “pull-out”, and “crack deflection” mechanisms of MWCNTs. Therefore, the residual strengths of 1 vol% MWCNTs containing specimens remained the highest after the thermal shock tests. Besides, the present work also reveals that the oxidation resistance is more sensitive to relative density than MWCNTs addition.