PREPARATION AND CHARACTERIZATION OF THE COMPOSITES IN THE CAO-P2O5-SIO2-B2O3 SYSTEM BY THE SOL-GEL PROCESS

Six composites in the CaO-P2O5-SiO2 system with and without B2O3, consisting of Ca/P ratios: 1.50, 1.67 and 2.00, were prepared by a sol-gel process. When the gel. powders were heated at 900 degrees C or higher, Ca-3(PO4)(2) and CaSiO3 were formed from the samples without B2O3, while boron containing apatite and hydroxyapatite were formed from those with B2O3. When the compressed powders were fired at 1100 degrees C for 1 h, the relative density (bulk density/true density) was as low as about 65% in the samples without B2O3, but attained 98% in the samples with B2O3 The bending strength of the latter sample with B2O3 was 82 MPa.