Fabrication and characterization of highly porous calcium phosphate (CaP) ceramics by freezing foamed aqueous CaP suspensions

Abstract

Highly porous calcium phosphate (CaP) ceramics were fabricated by freezing foamed aqueous CaP suspensions with various CaP contents (15, 20, and 25 vol %) containing polyvinyl alcohol (PVA) as the binder and emulsifying agent. All the samples fabricated showed uniformly dispersed macropores, which were created by air bubbles introduced in the suspensions. In addition, aligned micropores were formed in the sintered CaP walls as a replica of the preferentially grown ice dendrites during freezing when CaP contents of 15 and 20 vol % were used. The overall porosity decreased from 83 to 73 vol % with increasing initial CaP content from 15 to 25 vol %, whereas the compressive strength and elastic modulus increased significantly from 1.2 +/- 0.2 to 4.7 +/- 0.9 MPa and from 20 +/- 11 to 163 +/- 42 MPa, respectively. The samples showed good biocompatibility, as assessed by the in vitro cell test using a pre-osteoblast cell line. (C)2011 The Ceramic Society of Japan. All rights reserved.