| Summary: | The beneficial effects of incorporating small amounts of manganese oxide, MnO2 (0.05, 0.1, 0.3, 0.5 and 1.0 wt%) into biphasic calcium phosphate in promoting sintering and its effect on physical and mechanical properties of the dense sample sintered at 1000-1400 degrees C were investigated. In this work, a wet precipitation method was employed to prepare biphasic calcium phosphate powder. The starting materials of calcium hydroxide and orthophosphoric acid were used in the titration process and the as-synthesised powder was subsequently doped with manganese oxide by wet milling. The X-ray diffraction analysis revealed that the phase present in the as-synthesised powder was predominantly hydroxyapatite. However, upon sintering, all the samples revealed the existence of biphasic calcium phosphate i. e. a mix phase comprising of hydroxyapatite and tricalcium phosphate. The highest relative density of 99.5% was obtained for biphasic calcium phosphate doped with 0.3 wt% MnO2 when sintered at 1400 degrees C. The results also revealed that 0.3 wt% MnO2-doped biphasic calcium phosphate gave a maximum Vickers hardness of 5.14 GPa. On the other hand, 1.0 wt% MnO2-doped biphasic calcium phosphate exhibited highest fracture toughness of 1.32 MPa m(1/2) as compared to 0.88 MPa m(1/2) for undoped biphasic calcium phosphate when sintered at 1200 degrees C.
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