ИСТИНА

Resorbable biomaterials are one of the neediest technologies for modern humanity. It would save the normal life even in case of severe injury. However, resorption level of modern materials for bone grafting (hydroxyapatite (HA) and tricalcium phosphate (TCP)) is reported, in some cases, to be not enough, this is why the search for more soluble compounds compared to HA and TCP looks very perspective. A possible way to give resorption properties is the partial substitution of Ca2+-ions in Ca3(PO4)2 by alkali cations, like Na+ or/and K+. However, this material has new phase relationships as well as new sintering behavior. Due to the necessity to know thermal behavior of the materials in the sintering process, in this work, an isothermal section for phase diagram of Ca3(PO4)2 - CaKPO4 - CaNaPO4 ternary system was studied. As it was shown earlier, single-phase CaK0.6Na0.4PO4 cannot be sintered to full-dense ceramics by conventional sintering regardless time-temperature schedule. Two-step sintering technique, beneficial in the case of HA-ceramics, was unsuccessful in all cases of calcium-alkali phosphate compositions. Field-assisted sintering techniques like, e.g. Spark Plasma Sintering (SPS), can overcome this problem due to significant impact on grain boundary diffusion. In connection with this fact, grains grow much slower retaining sintering process in a pore control regime. In this work, CaK0.6Na0.4PO4 scaffolds were printed by DLP-method, and spark-plasma sintering experiments were carried out to obtain sintered materials with complex shapes. Acknowledgements. The research of sintering processes in calcium phosphate materials were funded by RFBR according to the research project #18-33-00974. Phase relations survey in ternary system were supported by RSF, grant #14-19-00752.