Ceramic Composite Materials in the Ca2P2O7-Ca3(PO4)2 System Based on Powder Mixtures of Natural Calcium Phosphate and Monocalcium Phosphate Monohydrate

Ceramics in the Ca2P2O7-Ca3(PO4)2 system were obtained from powder mixtures containing calcium hydroxyapatite Ca10(PO4)6(OH)2 and monocalcium phosphate monohydrate Ca(H2PO4)2<middle dot> H2O. Fish scale powder was used as a natural source of natural calcium hydroxyapatite Ca10(PO4)6(OH)2. The molar ratios of Ca10(PO4)6(OH)2 /Ca(H2PO4)2<middle dot> H2O in the initial powder mixture equal to 1/4, 3/5 and 2/1, respectively, ensured the formation after firing of ceramics having a desirable phase composition, including calcium pyrophosphate Ca2P2O7 and/or tricalcium phosphate Ca3(PO4)2 . The homogenization of the components was carried out by repeated passing of the powder mixture through a sieve with a mesh size of 200 mu m. Plastic molding of the samples was carried out using ethyl alcohol as a binder. According to XRD data, the phase composition of all samples after the addition of alcohol, molding, and drying included monocalcium phosphate monohydrate Ca(H2PO4)2<middle dot> H2O and calcium hydroxyapatite Ca10(PO4)6(OH)2. Monetite CaHPO4 and brushite CaHPO4<middle dot> 2H2O were also present in the phase composition of the samples. The phase composition of prepared highly porous ceramic samples with relative density 27 - 55% after firing in a temperature range of 900 - 1100 degrees C included beta-tricalcium phosphate beta-Ca3(PO4)2 and/or beta-calcium pyrophosphate beta-Ca2P2O7.