Preparation of fibrous, porous hydroxyapatite ceramics from hydroxyapatite whiskers

Hydroxyapatite (HAp) whiskers have been used to prepare fibrous, porous HAp ceramics. The fibrous microstructure was retained in all cases after hot-pressing the HAp whiskers at 800-900°C (1 h, 30 MPa). The fracture path in the fibrous, porous HAp ceramics was partially intergranular, indicating the occurrence of crack deflection, bridging, and pull-out effects. When the whiskers were hot-pressed at 1000-1100°C (1 h, 30 MPa), only large equiaxed grains were present in the HAp ceramics; thus no toughening occurred. When nonstoichiometric HAp whiskers were used to fabricate a porous body, β-TCP precipitated on the whisker surface without destroying the fibrous microstructure. Sintering the HAp whiskers is thus an easy way for in situ fabrication of HAp/β-TCP fibrous, porous materials with a controlled biodegradation rate.