Optimisation of two-step sintering parameters to produce bioactive and dense Zirconia-Hydroxyapatite composite ceramics

3Y-TZP along with Hydroxyapatite (HAp) are common bioceramics used in bone tissue engineering scaffolds to yield better patient outcomes and faster healing times. However, significant differences in thermal expansion of these ceramics result in challenges to co-sintering these materials without losing functionality and strength. In this work, a two-step sintering (TSS) process was utilised to co-sinter composites using (1-x)3Y-TZP and xHAp where x varies between 20 and 80 wt%. A peak temperature of 1300 degrees C, a plateau temperature of 1175 degrees C, a holding time of 600 min and heating rate of 10 degrees C/min were the optimum TSS conditions for all compositions. The TSS process produced specimens with grain sizes between 0.5 and 1.2 mu m and a compression strength be-tween 88 and 176 MPa. The similarity in compression strength of these zirconia-hydroxyapatite composites with natural bone and the retention of HAp make them suitable for bone tissue engineering applications in load bearing areas.