High-performance Al 2 O 3 Composite Ceramics Modified with Short Rod-Shaped ZrO 2 Particles

In this study, short rod-shaped monoclinic ZrO2 particles were synthesized from Zr(NO3)4.5H2O, Y(NO3)3 and KOH in a hydrothermal reaction. The reaction conditions, structure of the synthetic ZrO2 and effects of different concentrations of ZrO2 on the mechanical properties of Al2O3 composite ceramics were investigated. Dense monoclinic rod-shaped ZrO2 particles with rough surfaces were obtained when the hydrothermal reaction temperature was 180oC, the reaction time was 24 h and the KOH concentration was 6 mol/L. Results from energy-dispersive X-ray spectroscopy (EDS) and X-ray diffraction spectroscopy (XRD) confirmed the structure and composition of the reaction product. Composite ceramics were prepared by hot press sintering the synthetic ZrO2 with Al2O3, and optimal values of mechanical properties were obtained for 7.5 wt% zirconia. The ZrO2 strengthened the Al2O3 composite ceramics by mechanisms that included reinforcement by fine grains, enhancement by rod-shaped ZrO2 particles and phase transformation toughening.