Influence of Fracture Toughness on the Wear Resistance of Yttria‐Doped Zirconium Oxide.

Yttria-doped zirconium oxide was prepared in the fully tetragonal, mixed tetragonal and cubic, and the fully cubic phases by varying the yttria conent. The fracture toughnesses of the materials were 11.6, 8.7, and 2.5 Mpa · m½, respectively. The wear resistance, measured in air at room temperature in slow sliding (1 mm/s speed and 9.8 N load), increases by a factor of 1200 from the brittle to the toughest material; it is proportional to the fourth power of toughness. Wear occurs predominantly by fracture in the brittle (cubic) material; plastic deformation is observed in the tougher zirconium oxide.