Effect of annealing and Fe₂O₃ addition on the high temperature tribological behavior of the plasma sprayed yttria-stabilized zirconia coating

The annealing process of plasma-sprayed 3 mol% yttria stabilized zirconia (3-YSZ) coatings with and without Fe₂O₃ addition was investigated to evaluate the high temperature tribological performance. The wear experiments were carried out on a ring-on-plate type reciprocating wear tester at selected temperatures within the range of 25-600 °C. In addition, plasma-sprayed zirconia-based coatings were annealed at 500 °C up to 10 cycles. The results show that annealing treatment decreases the wear rate due to the release of tensile residual stress. The stress relaxation significantly influences the maximum value of monoclinic intensity. The peak shifts to lower temperature and its values are reduced. The stress relaxation improves the tribological properties by reducing the influence of low temperature degradation. The addition of Fe₂O₃ to the 3-YSZ coating leads to a reduction of wear and friction. This decrease is believed to be the stabilization of the tetragonal phase and the increase of microhardness.