ИСТИНА

The aim of our research activity was to obtain and explore powders and ceramics based on calcium phosphates with a ratio of 0.5≤Ca/P≤1. Five powders were investigated in this range with a ratio of Ca/P=0.5; 0.625; 0.75; 0.875 and 1. Solutions of poly- or/and pyrophosphoric acids were obtained from sodium polyor/ and pyrophosphates by means of the ion exchange. Then, calcium nitrate solution was added to these solutions of the acids. Afterward, ammonia solution was added to solutions containing the following ions: pyrophosphate ion, polyphosphate ion, NO3 - and Ca2+. In all cases pH-value of these solutions were adjusted to 10. This procedure resulted in formation of amorphous precipitates of hydrated calcium phosphates. Finally, dried and disaggregated powders were pressed into pellets, which were fired to obtain ceramics. The powders of calcium phosphates with a ratio of 0.5≤Ca/P≤1, which were obtained by means of the wet precipitation method from solutions of condensed phosphate acids prepared by ion exchange method, had rather uniform composition. Such ceramics consisted of calcium poly- and pyrophosphates are suitable for making bone implants due to high resorption and osteoconductivity.