Investigating the effect of Nickel oxide on the microstructure and mechanical properties of zirconia Nano composite stabilized by Yttria and prepared by spark plasma sintering

In this research, zirconia matrix composites stabilized by yttria with 7 and 14% by weight of nickel oxide were prepared by spark plasma sintering process. Investigation of phase changes by X-ray diffraction pattern showed the dominant peak of zirconia stabilized by yttria (YSZ) with tetragonal structure along with peaks with very low intensity of monoclinic phase of YSZ. Also, the addition of nickel oxide for composite samples led to the creation of nickel metal phase. The electron microscope images prepared from the polished surface of the samples showed relatively proper distribution of the nickel phase in the ground phase. Examining the physical and mechanical properties of the samples showed that the maximum fracture toughness (14.21 ± 0.19 MPa square meter), relative density (99.81% of theoretical density), bending strength (665 MPa) is related to the composite containing 14% by weight. It was nickel oxide. But regarding the Vickers hardness of the samples, the increase of nickel oxide in the composites led to a decrease in the hardness of the sample due to the formation of metallic nickel phase.