Development of porous ceramics with well-controlled porosities and pore sizes from apatite fibers and their evaluations.

Porous hydroxyapatite (HAp) ceramics possessing well-controlled porosities and pore sizes were developed by firing apatite-fiber compacts mixed with carbon beads and agar. The total porosities could be controlled in the range from 40 to 85% by varying compaction pressure (20-40 MPa), firing temperature (1000-1300 degrees C) and carbon/HAp ratio (0/10-10/10 (w/w)). Most of the pores were regarded as open pores. The pore sizes were mainly affected by the carbon-bead diameter (5, 20 or 150 microm) and partly by the compaction pressure and the firing temperature. The pore sizes of the porous HAp ceramics derived from the carbon beads of 150 microm in diameter were distributed in the two separate ranges of several micrometers and more than 100 microm.