Rapid fabrication of ultra-smooth Y-TZP bioceramic surfaces by dual-axis wheel polishing: process development and tribological characterization

The existing artificial joint implants using bioceramic materials face problems of difficulty in manufacturing and premature failure due to wear. This paper investigated a rapid preparing process of ultra-smooth surfaces of yttria-stabilized tetragonal zirconia polycrystal bioceramics based on the dual-axis wheel polishing (DAWP) system. Friction and wear tests were conducted to prove that the prepared ultra-smooth surface can effectively reduce wear. The effects of process parameters on polishing performances were investigated. The XRD and SEM analysis and micro-hardness testing were used to characterize the prepared surface in material behaviors. Tribological tests were carried out on a ball-on-plate reciprocating tribometer to comparatively study the tribological behavior and wear mechanism of the prepared ultra-smooth surfaces and the conventional surface at sub-microscale. The used finishing technology can steadily achieve fast preparation of ultra-smooth bioceramic surfaces, and with a high material removal rate (the highest value was 1.14 mg/min). Besides, in contrast to the conventional surface (Ra 129 nm), the prepared ultra-smooth surface (Ra 0.38 nm) achieved a much smaller friction coefficient, and much less wear volume, indicating that the wear resistance of the ultra-smooth surface was significantly improved.