Effect of ZrO2 content on the mechanical properties and microstructure of HAp/ZrO2 nanocomposites

This paper presents the effect of Zirconia (ZrO2 = 0, 5, 10, 15, 20 and 25 wt%) on the mechanical properties and micro structural studies of Hydroxyapatite (Ca-10(PO4)(6)(OH)(2)) (HAp) nano composites. HAp and Zirconia nano composites of 20-40 nm were produced using High Energy Ball milling at 300 rpm for 1 h. X-ray diffraction studies showed that the crystallite and grain size gradually decreased with the increase in ZrO2 content till 20 wt %, after which there was a sudden raise in both parameters. A dominant ZrO2 phase was observed in X-ray diffraction studies of sintered samples. Mechanical properties were found to significantly improve on adding 20 wt% of ZrO2 at 1200 degrees C. However, the addition of 25 wt% of ZrO2 powder decreased the mechanical properties of HAp. The reduction could be due to the increase in grain size and dominant smaller particles of ZrO2. The improved mechanical properties were correlated with the observed micro structural features.