Fabrication of porous ceramics with well-controlled open pores by sintering of fibrous hydroxyapatite particles

Porous hydroxyapatite (Ca-10(PO4)(6)(OH)(2); HAp) ceramics with various porosity values were fabricated by sintering fibrous HAp particles prepared from the aqueous solutions in the Ca(NO3)(2)- (NH4)(2)HPO4-(NH2)(2)CO-HNO3 system by the homogeneous precipitation method using urea. The total porosities, total pore volumes, median pore sizes and specific surface areas of the resulting ceramics were controlled in the range of 16.7 to 55.0%, 0.04 to 0.36 cm(3) . g(-1), 0.28 to 0.78 mu m and 0.29 to 2.90 m(2) . g(-1), respectively, by changing the compaction pressures (20, 30 and 40 MPa) and firing temperatures (1000 degrees C, 1100 degrees C, 1200 degrees C and 1300 degrees C). Most of the pores in the resulting ceramics were regarded as the open pores.