Abradability and hardness in rare-earth-oxide stabilized hafnia

The dry abradability and diamond pyramid hardness of HfO2 fully-stabilized by variable additions of Er2O3 were determined on sintered polycrystalline specimens of near-theoretical densities. Measurements on fused silica and on a single crystal of Y2O3-stabilized ZrO2 were included for comparison. In general, the hardness was decreased and the abradability was increased by increasing additions of stabilizing oxide. These effects were attributed mainly to the increase in defect concentration of the anion sublattice with increasing amounts of modifier oxide. Solution of HfO2 in Er2O3 (rare-earth-oxide Type C structure) increased hardness and decreased abradability: effects which also seemed to be related to the defect concentration of the anion sublattice. (author)