Effect of sintering temperature on mechanical and tribological properties of hydroxyapatite measured by nanoindentation and nanoscratch experiments

The aim of this paper is to investigate the mechanical and tribological properties of a commercial hydroxyapatite (HA) by nanoindentation and nanoscratch experiments. The nanoindentation and nanoscratch tests were performed on the HA samples prepared at different sintering temperatures in the range of 1000-1400 °C. Atomic force microscopy (AFM) images were taken from the specimen surface before and after the indentation and scratch tests for analyzing its deformation. The values of Young׳s modulus, hardness and scratch resistance of the HA samples were measured. The effect of sintering temperature on the mechanical and tribological properties of HA samples was also studied. The results indicated that nanoindentation and nanoscratch experiments are acceptable methods for measuring the mechanical and tribologocal properties of HA. The Young׳s modulus of the HA specimens initially enhanced with increasing the sintering temperature, but decreased after the sintering temperature of 1200 °C. Similar trends were observed for hardness and scratch resistance of HA, but their decreasing behavior started at about 1300 °C.