ИСТИНА

One of the most important development directions of modern medical materials science is the creation of inorganic materials for artificial bone implants. The regenerative medicine development requires the creation of resorbable materials based on calcium phosphates in which the Ca/P ratio is smaller than in the main inorganic component of the bone – hydroxyapatite (HA, Ca/P = 1.67). Creation of such materials requires the development in methods for synthesis of calcium phosphates with Ca/P ratio = 1.5; 1.0; 0.5. The composite materials containing phase of calcium polyphosphate (Ca/P = 0.5) have the highest solubility. The purpose of the present work is to obtain ceramic materials containing calcium polyphosphate, calcium pyrophosphate and calcium orthophosphate phases. We assume that depending on the components ratio, various bioresorbable phases are formed via following reactions during the heat treatment. 3Ca10(PO4)6(OH)2 + 2(NH4)2HPO4 = 10Ca3(PO4)2 + 4NH3 + 6H2O Ca10(PO4)6(OH)2 + 4(NH4)2HPO4 = 5Ca2P2O7 + 8NH3 + 7H2O Ca10(PO4)6(OH)2 + 14(NH4)2HPO4 = 10Ca(PO3)2 + 28NH3 + 22H2O The ceramic materials were obtained from highly concentrated hydroxyapatite suspensions in an environment of sucrose and diammonium phosphate aqueous solutions. Cordshaped samples were formed via 2 mm diameter plastic injectors. The ability to form homogeneous paste layers and stable multi-layer constructions was studied. The most reassuring results were given by suspensions with HA/sucrose solution ratio of 0.8 g/ml and sucrose aqueous solution concentration of 0.5M. After molding the samples were sintered in the range of temperatures from 900 °C to 1100 °C depending on the target phase. Phase composition of the sintered samples is presented below. The properties of ceramic materials obtained were also studied with thermal analysis (TA), mass spectrometry (MS) and scanning electron microscopy (SEM).