Highly‐stable, nondegradable M₂A‐reinforced YSZ ceramic composites prepared by SPS

Abstract

Magnesia‐rich spinel (M2A)‐reinforced yttria‐stabilized zirconia (YSZ) ceramic composites have been fabricated by SPS using m‐ZrO2, Y2O3, and waste‐derived M2A powders. The results showed that m‐ZrO2 in M2A‐free YSZ0 specimen is partially stabilized upon temperature rising into tetragonal phase whereas YSZ10‐50 composites containing 10‐50 wt% M2A demonstrated variant behavior where their m‐ZrO2 is stabilized into a cubic form. YSZ10‐50 composites SPSed at 1400°C for 30 minutes revealed greater than 99% relative density, 10‐13 GPa Vickers hardness, 3.5‐5 MPa m0.5 fracture toughness and less than 0.5% apparent porosity. Aging hydration test for five hours soaking at 134°C and water vapor pressure of 2 bar, resulted in a conversion of ~2.8% of t‐ZrO2 to m‐ZrO2 for M2A‐free YSZ0 composite but it does not affect the YSZ10‐50 composites. The outcomes indicate that M2A has significantly improved both the densification and stabilization behavior of m‐ZrO2 through facilitating the diffusion of Y3+, Mg2+, and Al3+ ions inside zirconia lattice structure. In this regard, this study opens the door wide for producing fully stabilized c‐ZrO2 ceramics that could be potentially utilized as industrial ceramics for a broad scope of structural applications of high temperature, high‐stress and corrosive environmental conditions.