Synthesis and sintered properties evaluation of calcium phosphate ceramics

The present paper describes calcination of calcium phosphate ceramics (hydroxyapatite, HA) at 200, 400, 600, 800 and 1000 °C to observe the phase change using X-ray diffraction. HA phase was found to be stable up to 600 °C and later got dissociated into other non-stoichiometric phases like tricalcium phosphate (Ca3(PO4)2 [TCP]), calcium pyrophosphate (Ca2P2O7 [CPP]) and calcium hydrogen phosphate (CaHPO4 [CHP]). TCP was found to be the major phase above 1000 °C. FTIR spectra showed the presence of various PO43− and OH− groups present in the powder. Powders compacted and sintered at 900, 1000, 1100 and 1200 °C showed an increase in density from 2.11 to 2.95 g/cm3 while biaxial flexural strength (BFS) was found to be higher (48.7 MPa) when the samples were sintered at 1100 °C and it decreased with further increase in sintering temperature.