Sych O. Evolution of structure and properties of composite materials based on calcium phosphates prepared by liquid-phase sintering

The thesis is devoted to investigation of structure evolution and properties of composites based on calcium phosphates of different nature (biogenic hydroxyapatite, synthetic hydroxyapatite, mixture of synthetic calcium phosphates) and glass prepared by liquid-phase sintering, establishment of correlation "structure - properties" and development of new biomaterials. It was established that prevent foaming of liquid phase was possible by facilitating gas transport to the surface due to the formation of interphase boundaries "liquid - solid". It was shown that use of primary refining sintering of mixture of calcium phosphate and glass charge at 1100 ?С during biocomposite preparation completely prevented foaming, volume growth in the system and porosity transformation from open to closed. It was shown that for optimization such contradictory properties of biomaterials as strength and resorption rate besides parameters of porous structure it was necessary to include one more structural parameter - phase composition of phosphate component. That is why in order to increase the resorption rate of the material four phase mixture of synthetic calcium phosphates was used as the phosphate component. The mixture except hydroxyapatite contains tricalcium phosphate, calcium pyrophosphate and tetracalcium phosphate, which solubility is higher than the solubility of hydroxyapatite. It made it possible to decide the optimization problem of creation material with high strength and resorption rate. Obtained materials were successfully experimental tested by cloning efficiency of stromal bone marrow stem cells at the Ukrainian Research Institute of Traumatology and Orthopedics of Ministry of Health Protection of Ukraine and may be recommended as carrier for mesenchymal stromal cells for improve bone repair and replace bone tissue in reconstructive surgery.