The Structure and Properties of Calcium Phosphate Ceramics Produced from Monetite and Biogenic Hydroxyapatite

It is shown that porous calcium phosphate ceramics can be produced from monetite and biogenic hydroxyapatite, the starting materials being in the ratios 25 : 75, 50 : 50, and 75 : 25 wt.%. It is established that phase transitions and solid-phase reactions take place during sintering to form polyphosphate ceramics consisting of hydroxyapatite (Ca5(PO4)3(OH)), β-pyrophosphate (β-Ca2P2O7), and β-tricalcium phosphate (β-Ca3(PO4)2), in which β-Ca2P2O7 and Ca5(PO4)3(OH) phases are predominant, depending on starting composition. When the biogenic hydroxyapatite content changes from 25 to 75 wt.%, the grain size decreases and the pore size increases. The ceramics have 40 to 42% porosity with predominant open porosity for all compositions. The ceramics show 32–55 MPa strength, which increases with the amount of biogenic hydroxyapatite in starting composition.