Hydroxyapatite (HA)-TZP (2.5 mol% Y2O3) containing 2, 5, 7.5 and 10 wt% TZP were prepared using calcium nitrate, diammonium hydrogen orthophosphate, zirconium oxychloride and yttrium nitrate. The composite powder was prepared by a reverse strike precipitation method at a pH of 10.5. The precipitates after aging and washing were calcined at 850 degrees C to yield fine crystallites of HA and TZP. TEM study of the calcined powder revealed that while HA particles had both spherical and cuboidal morphology ( approximately 50-100 nm) the TZP particles were only of spherical nature ( approximately 50 nm). X-ray analysis showed that the calcined powder of all the four composition had only HA and t-ZrO2. Uniaxially compacted samples were sintered in air in the temperature range 1,150-1,250 degrees C. High sintered density (>95% of theoretical) was obtained for composites containing 2 and 5 wt% TZP, while it was 92% for 7.5 wt% and 90% for 10 wt% TZP compositions. X-ray analysis of sintered samples shows that with 2 wt% TZP, the retained phases were only HA and t-ZrO2. However, for 5, 7.5 and 10 wt% TZP addition both TCP and CaZrO3 were also observed along with HA and t-ZrO2. Bending strength was measured by three point bending as well by diametral compression test. While in three point bending, the highest strength was 72 MPa, it was 35.5 MPa for diametral compression. The strength shows a decreasing trend at higher ZrO2 content. SEM pictures show near uniform distribution of ZrO2 in HA matrix. The reduction in sintered density at higher ZrO2 content could be related to difference in the sintering behaviour of HA and ZrO2.

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Hydroxyapatite (HA)–YTZP (2, 5, 7.5, and 10 wt% ZrO2) composite powders prepared from inorganic precursors were characterized by FTIR, DSC/TG, XRD, and TEM. The calcined powders had HA and t/c‐ZrO2, which undergo structural changes between 650°C and 1050°C. TEM of calcined powder showed larger HA particles (100 nm) and smaller ZrO2 particles (≤50 nm). HA and HA–2 wt% ZrO2‐sintered samples had 98% density and it was (90–95%) for HA–5, 7.5, and 10 wt% ZrO2. The bending strength of HA–2wt% ZrO2 composites was 72 MPa. The grain sizes of HA showed a refinement with ZrO2 addition.

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Hydroxyapatite (HA)-YTZP (2, 5, 7.5, and 10 wt% ZrO 2 ) composite powders prepared from inorganic precursors were characterized by FTIR, DSC/TG, XRD, and TEM. The calcined powders had HA and t/c-ZrO 2 , which undergo structural changes between 6501C and 10501C. TEM of calcined powder showed larger HA particles (100 nm) and smaller ZrO 2 particles (r50 nm). HA and HA-2 wt% ZrO 2 -sintered samples had 98% density and it was (90-95%) for HA-5, 7.5, and 10 wt% ZrO 2 . The bending strength of HA-2wt% ZrO 2 composites was 72 MPa. The grain sizes of HA showed a refinement with ZrO 2 addition.