Microstructures and mechanical properties of Gd2Zr2O7/ZrO2(3Y) ceramics

Gd2Zr2O7/ZrO2(3Y) composite ceramics were prepared by vacuum sintering using Gd2Zr2O7 and ZrO2(3Y) nanoparticles. The ceramics were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectrometer (EDS), the three-point-bending technique and single-edge-notched-beam tests. The effect of various proportions of ZrO2(3Y) on the phase composition, microstructure, bending strength and fracture toughness of the final Gd2Zr2O7/ZrO2(3Y) composite ceramics was also analyzed. The change from m-ZrO2 to t-ZrO2 phase contents, before and after fracture, was measured using XRD quantitative phase analysis. The results confirm that, with the increasing content of ZrO2(3Y), a phase transition from solid solution to saturated precipitation occurs and the bending strength and fracture toughness of the samples increase gradually. When the content of ZrO2(3Y) reached 95 vol.%, the Gd2Zr2O7/ZrO2(3Y) composite ceramics had a bending strength of 547 MPa and a fracture toughness of 5.5 MPa m1/2, indicating that stress-induced phase transformation toughening was an efficient way to increase the mechanical properties of the Gd2Zr2O7 ceramics.