Sintering of different hydroxyapatite powders and low-melting sodium borosilicate glass

The paper analyzes the sintering of three types of calcium phosphate powders and S–B–Na glass powder under the same conditions. It is concluded that a liquid phase, represented by the glass melt, shows up when the glass is sintered with biogenic or synthetic hydroxyapatite or a mixture of synthetic phosphates. The substantial pore formation in the sintering process is mainly due to the removal of carbon oxides and water vapors resulting from glass charge decomposition and glass boiling. Parameters of grain and porous microstructures of the ceramics are shown before and after the primary and secondary sintering. The mechanical strength and biosolubility of the ceramic samples are reported as well.