Mechanical properties of 3Y-ZrO2/Ni composites prepared by reductive sintering

3Y-ZrO2/Ni composites were fabricated by reductive hot-pressing from 3Y-ZrO2/NiO powder mixtures, which prepared by wet ball-milling. Reduction was carried out in H-2 atmosphere at 700degreesC, and the powder mixtures were continuously hot-press sintered at 1500degreesC and 1600degreesC. X-ray diffraction analysis showed that all NiO transformed to Ni, and the sintered composites consisted of only tetragonal zirconia and metallic Ni. Neither monoclinic zirconia nor other reaction phase was existed. The three-point bending strength of over 1.9 GPa was achieved by dispersing only 1 and 2 vol% of Ni. The fracture toughness of 10 vol% Ni composite was 6.1 MPam(1/2). It was found that the fracture strength increased and then deceased with the Ni addition, while the toughness monotonously increased with increasing Ni addition.