The freezecasting is a novel method with great possible control for preparing porous ceramic materials. The goal of this study is to investigate the effect of initial freezing temperature on the microstructure and mechanical properties of porous hydroxyapatite samples prepared by freeze-casting method. In this study, stable slurries of hydroxyapatite were first prepared and then,poured into the plate in different temperatures (+7, 0, -7, -14, -21 °C) and after solidification with rate of 1 °C/min, the ice crystals were sublimated in freeze dryer and finally sintered in 1350°C. The size and morphology of pores wereevaluated by SEM. The obtained images indicate that an increase in starting freezing temperature leads to the increase in the pore size and the interstructural bridges. The mechanical properties of the samples werealso investigated which reveals that by decreasing the starting freezing temperature both compressive strength and porosity percentage simultaneously increased.

Keywords: freeze casting, initial freeze temperature, pore size, compressive strength

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