Improvements to the sintering of yttria-stabilized zirconia by the addition of Ni

We have studied the effect of nickel oxide (NiO) on the sintering of yttria-stabilized zirconia (YSZ) at temperatures from 1100 to 1400 °C. Differences in the densification behaviour were observed between the direct use of NiO powders and Ni metal as precursor. Our results show that with the addition of Ni into YSZ, sintering was completed at 1300 °C instead of 1400 °C, a 100 °C reduction. The addition of Ni also increased the shrinkage rate at 1200 °C from -0.29×10 ^-6 s ^-1 to -0.46×10 ^-6 s ^-1. Young's modulus of the samples heat treated at 1200 °C measured by microindentation also increased from 26 GPa for YSZ to 65 or 191 GPa for YSZ plus NiO or Ni, respectively. Addition of NiO or Ni also stabilised the cubic phase and promoted grain growth in YSZ during sintering.