Solvent Sublimation Behavior in Freeze Drying Method for Lamellar Porous Hydroxyapatite Scaffold

Lamellar porous hydroxyapatite(HA) ceramic scaffolds were fabricated by freeze drying from aqueous HA slurries and sintered at 1 250 ℃ for 3 h.Effects of freezing temperature,drying pressure and drying temperature on the solvent sublimation be-havior were investigated.The average lamellar spacing of porous HA ceramic scaffolds decreases and the sublimation time increases with the decrease of freezing temperature.The sublimation time firstly decreases and then increases with the increase of the drying pressure due to the effect of heat and mass transfer in the drying process of HA scaffolds.The sublimation time decreases with in-creasing drying temperature.The optimum parameters in the freeze drying are drying pressure of 40 Pa and drying temperature of 5 ℃.The sublimation time of porous ceramics could be predicted based on the freezing temperature and drying parameters in the freeze drying.