Effects of Carbon Fiber Addition Amount on Thermal Shock Resistance and Sintering Performance of MgO-ZrO₂ Ceramics

Carbon fiber enhanced MgO-ZrO₂ ceramics were prepared by pressureless sintering with magnesia nano-powder and ZrO₂ fiber as raw materials and chopped carbon fiber as additive. The effects of carbon fiber addition amount on sintering performance, phase composition, thermal shock resistance and microstructure of the ceramics were investigated. The results show that with increasing carbon fiber addition amount, the relative density and linear shrinkage rate of the ceramics decreased while the apparent porosity increased, indicating that the addition of carbon fiber was bad for the sintering of MgO-ZrO₂ ceramics. The flexural strength first increased and then decreased with increasing carbon fiber addition amount and reached the largest value of 287.15 MPa with 20vol% carbon fiber. The addition of carbon fiber increased the thermal shock resistance of the MgO-ZrO₂ ceramics. When the volume fraction of carbon fiber was 15%, the thermal shock resistance of the ceramics was the best.