Structure evolution and properties of biogenic hydroxyapatite-based biocomposite

Two-step sintering has been used to investigate the structure evolution and properties of the biogenic HA/glass composite containing 50 wt.% Na2O-B2O3-SiO2-based glass. The borosilicate glass facilitated the sintering process due to the viscous glass flow and stabilized the HA phase against thermal decomposition. It has been established that the structure significantly changes, becoming more homogeneous and fine-porous, in going from the charge to two-step sintered biogenic HA/glass composite in comparison with the normal sintering. The composite samples underwent significant deformation and macropore formation (0.05–2 mm) after normal sintering at 1000°C. After two-step sintering pore minimization down to 50–100 μm occurred. The volume changes achieved 10 %. It was found that general porosity reached 15.5 %, open porosity – 74 %, compression strength – 219 MPa and composite solubility – 0.175 % mass loss after two-day soaking in physiological solution.