Effect of MgO Content on the Microstructure and Properties of Zirconia-Toughened Alumina (ZTA) Ceramics by Hot Pressure Sintering

The effects of MgO addition on the microstructure and mechanical, frictional, and wear properties of zirconia-toughened alumina (ZTA) ceramics were investigated in this study using hot pressure sintering (HP). The addition of trace amounts of MgO led to the refinement of the ceramic grains and an increase in the ceramic density due to the pinning effect of MgO. X-ray diffraction (XRD) and scanning electron microscopy (SEM) results revealed that an MgAl₂O₄ phase was formed in the ceramics, which also contributed to the refinement of the ceramic grains. Moreover, the addition of MgO promoted the uniformity of the ceramic microstructure. Among the tested composites, the composite with 0.4 wt.% MgO exhibited the most favorable comprehensive properties, including a relative density of 99.61%, hardness of 18.29 GPa, and indentation fracture toughness of 9.15 MPa·m^1/2, thereby offering the highest resistance to adhesive wear.