Experimental Investigations of Mechanical Characteristics and Tribological Mechanisms of Nanometric Zirconia Dental Ceramics

This study was focused on the experimental investigations about mechanical characteristics and tribological mechanisms of nanometric zirconia dental ceramics. A universal mechanical testing machine was used to test the threepoint flexural strength and the fracture toughness. A microhardness tester was used to test the Vickers hardness of the test specimens. An MRH-3 digital-display high-speed ring-on-block tribometer was used for frictional wear experiments. A PGI800 coarseness profiling instrument was used to test the width and the length of the grinding defects on specimen surfaces. An S-3500N SEM was employed in the microscopic observation of the surface morphology after the abrasion. Results indicates that the flexural strength of the test specimens 890MPa, the fracture toughness 6Mpa.m 1/2 , the Vickers hardness 1240MPa, the linear contraction 21%, and the apparent porosity 0.32%. Moreover, the frictional factor and the wear rate of nanometric ZrO2 ceramics decreased significantly under identical working and frictional conditions compared with ZrO2. The wear mechanism of nanometric ZrO2 ceramics was micromachining and plastic deformation while the wearing mechanism of ZrO2 ceramics was brittle fracture and abrasive wear.