The preparation and mechanical properties of the unidirectional carbon fiber reinforced zirconia composite

Unidirectional carbon fiber reinforced calcium stabilized zirconia composites (uni-Cf/ZrO2) were prepared by slurry infiltration and hot-pressing method. The room temperature mechanical properties were investigated and the fracture features of composites were observed. A flexural strength of 588.0 MPa and fracture toughness of 15.4 MPa·m1/2 parallel to the fiber direction for the composite hot-pressed at 1500 °C was attributed to the fiber pull-out. With increasing hot-pressing temperature from 1500 °C to 1650 °C, the relative density was augmented, but the mechanical properties of composites degraded gradually. Especially at 1650 °C, the flexural strength and fracture toughness decreased significantly to 173.2 MPa and 5.0 MPa·m1/2, respectively. Thermodynamic calculation and XRD, TEM investigations showed that carbon fibers reacted with ZrO2 to form ZrC phase at 1650 °C, and then formed chemical bonding and led to a strong interface between fiber and matrix, which resulted in the decrease of mechanical properties of the composite hot-pressed at higher temperatures. Moreover, the mechanical properties of carbon fibers degraded by the above reaction had also an adverse effect on the mechanical properties of the composite.