Effect of adding Y_2O_3 on structural and mechanical properties of Al_2O_3-ZrO_2 ceramics

摘要

The effects of adding 1-8 wt% Y_2O_3 on phase formation and fracture toughness of Al_2O_3-xZrO_2-Y_2O_3(AZY) ceramics were studied. Phase formations of the samples were characterized by the X-ray diffraction (XRD) technique. It was found that the major phase was rhombohedral-AUOi, while the minor phase consisted of the monoclmic-ZrO_2, tetragonal-ZrO_2 and monoclinic-Y_2O_3. It was found that Y_2O_3 contents did not clearly influence grain shape of AZY ceramics. The results obtained from the microhardness test could be used to evaluate the fracture toughness. It was found that the smaller grains had high fracture toughness. The maximum fracture toughness of 4.827 MPam~(1/2) was obtained from 4 wt% Y_2O_3. Refinement of lattice parameters using Rietveld analysis revealed the quantitative phases of AZY ceramics. This shows that under adding Y_2O_3 conditions the proportion of tetragonal-ZrO_2 phase plays an important role for the mechanical properties of AZY ceramics.