Tribological Characteristics of Al₂O₃ Nanocomposites for Joint Prostheses

In this study the tribological characteristics of a sliding pair of Al₂O₃ nanocomposites against Al₂O₃ were investigated. Al₂O₃ nanocomposites are proposed as a candidate material for the fabrication of prostheses. Nanopowders of Al₂O₃ (AKP 50, 300 nm), Y-TZP; tetragonal zirconia polycrystal stabilized with 8mol % of yttria (TZ-8YS, 100 nm) and TiO₂ (PS-25, 50 nm) were mixed and hot pressed. A ball-on-plate tribometer was used for the wear test. The nanocomposite plate specimen was rubbed against the Al2O3 ball at a frequency of 1 Hz for 1 h, with a load of 49 N. Distilled water and fetal bovine serum solution (FBSS) were used as lubricants. Mechanical properties were estimated using the indentation method. It was found that the specific wear rate of Al2O3 nanocomposites was about 2–6×10⁻⁸ mm³/Nm and the coefficient of friction from 0.3 to 0.5 for FBSS. The nanocomposites containing 15mol% Y-TZP (ATZ150) had the lowest wear rate (1.77×10⁻⁸ mm³/Nm) for FBSS. Worn surfaces were observed using SEM. Furthermore, AFM, XPS were used to study the effect of the serum lubricant on the articulating surface of the Al2O3 nanocomposites, and AlPO4 was found on the wear track of the samples tested in FBSS.