ИСТИНА

Powder mixtures of b-tricalcium phosphate b-Сa3(РО4)2 and potassium hydrogen sulfate КНSO4 homogenized under mechanical activation in acetone medium in planetary mill were used for producing of ceramics in K2O-CaO-SO3-P2O5 system. Powder mixtures were prepared at molar ratios of Сa3(РО4)2/КНSO4 established as 7/2, 4/2 and 1/2. The following formal reactions were used for calculation of quantities of starting components to create opportunity of preparation of ceramic composite materials containing calcium sulfate anhydrate CaSO4 and phases of double calcium potassium phosphates such as potassium-substituted tricalcium phosphate KCa10(РО4)7 and potassium rhenanite KCaPO4 (labeling is given in brackets): 7Са3(РО4)2 + 2КНSO4 → СаSO4 + 2KCa10(РО4)7 + SO3 + Н2О («7/2») 4Са3(РО4)2 + 2КНSO4 → СаSO4 + KCa10(РО4)7 + KCaPO4 + SO3 + Н2О («4/2») Са3(РО4)2 + 2КНSO4 → СаSO4 + 2KCaPO4 + SO3 + Н2О («1/2») According to XRD analysis data b-tricalcium phosphate b-Са3(РО4)2 was the main phase in all powder mixtures after treatment in planetary mill in acetone media. Only powder mixture «1/2» has slight quantities of additional phases. K8H9(SO4)7PO4 and K4H5(SO4)3PO4 were found additionally to b-tricalcium phosphate b-Са3(РО4)2 in powder mixture «1/2». Presumably phases of syngenite K2Ca(SO4)2.H2O and/or gorgeyite K2Са5(SO4)6 Н2О presented in powder mixtures in quasi-amorphous form after treatment in planetary mill. Compacted (Pspecific=100MPa) powder pre-ceramic items based on prepared mixtures were fired at temperature range of 700-900oC for producing ceramic samples. It was found that phase composition of ceramic samples considerably depends on composition of starting powder mixtures. According XRD analysis after firing at 800oC phase composition of ceramic samples «7/2» and «4/2» contained potassium calcium phosphate Ca10K(PO4)7, β-calcium pyrophosphate β-Ca2P2O7 and calciolangbeinite K2Ca2(SO4)3. Phase composition of ceramic samples «1/2» contained calciolangbeinite K2Ca2(SO4)3, β-calcium pyrophosphate β-Ca2P2O7 and potassium sulfate K2SO4. Up to our knowledge all phases of prepared ceramic samples are biocompatible. It should be noted that potassium sulfate K2SO4 presented in ceramics «1/2» is water soluble salt. So additional investigations are required for creation of ceramics in the K2O-CaO-SO3-P2O5 system for different uses including biomedical purposes. Acknowledgements: The financial support of RFBR project # 20-03-00550. Key Words: calciolangbeinite; potassium calcium phosphate; potassium sulfate; calcium pyrophosphate; ceramics