Mechanical properties and microstructure of two-dimensional carbon fiber reinforced zirconia composites prepared by hot-pressing

Two-dimensional carbon fiber reinforced zirconia matrix composites have been fabricated by slurry infiltration and hot pressing techniques. The room temperature mechanical properties were investigated and the fracture features of composites were observed. The results showed that with the increase of temperature the relative density of as-prepared Cf/ZrO2 composites increased. But the mechanical properties of composites on fiber configuration firstly increased and then decreased. Higher mechanical properties were obtained for the composite hot-pressed at 1500 °C i.e. the flexural force and fracture energy were 136.0 N and 31.3 kJ· m−2 respectively. SEM observation revealed fiber pull-out in the composite sintered at ≤1500 °C. For the composite sintered at a higher temperature, however, chemical diffusion between fiber and ZrO2 was found by HRTEM, which indicates the formation of strong bonding. Also the reduced nonlinear region and short pullout length of fiber suggest a strong interfacial bonding between the fiber and matrix. The strong interfacial bonding and large thermal residual stress mainly contribute to the degradation of mechanical properties above 1500 °C.