Porous hydroxyapatite scaffolds containing calcium phosphate glass-ceramics processed using a freeze/gel-casting technique

A freeze/gel-casting technique has been applied to produce porous ceramic composite scaffolds with tailored pore structures and improved compressive strength for tissue engineering applications. Tertiary-butyl alcohol (TBA)-based hydroxyapatite/calcium phosphate glass-ceramic suspensions with 5–15 vol.% solid loading were used in this study. Following sintering at 1050–1250 °C, the composite scaffolds were characterized in terms of microstructure, and physical and mechanical properties. The resulting scaffolds consisted of unidirectional pore channels (macro-sized) aligned in the solidification direction of the TBA solvent used in the freeze casting step and a few inter/intra-granular pores with small diameter (micron sized) remained in the wall structures of the pore channels by gel casting. With the addition of glass-ceramics (≤10 wt%), a liquid phase was formed mainly by the melting of calcium phosphate glasses at a given sintering temperature. The wall structures became more densified (less porous) aided by liquid phase sintering, possibly lending enhanced compressive strength.