ZrO2-Al2O3 LAMINATED CERAMICS AND THEIR TRIBOLOGICAL BEHAVIORS

ZrO2-Al2O3 laminated ceramics of 3 layers were prepared by dry-pressing and pressureless sintering, and their mechanical properties and toughening mechanisms were studied. Furthermore, their tribological behaviors and wear mechanisms under dry friction and water lubrication conditions were also investigated, and compared with those of monolayer ZrO2-Al2O3 ceramics under the same conditions. The results show that the bending strength, fracture toughness and hardness of the laminated ceramics are all better than those of the monolayer ceramics, moreover the friction factor and wear rate of the laminated ceramics are clearly lower than those of the monolayer ceramics. The excellent mechanical properties of the laminated ceramics, especially toughness, result mainly from effects of residual stress in the specially-designed layer, interface structure and phase transformation together. Good tribological properties of the laminated ceramics are supposed due to the high toughness and low shearing stress in the wear surface. The friction and wear of the composites are effectively decreased by water lubrication because of the transformation of the main wear mechanisms from abrasive and adhesive wear under dry friction to tribo-chemical and fatigue wear under water lubrication.