Novel machinable calcium phosphate/CaTiO3 composites

Hydroxylapatite/CaTiO3 and tricalcium phosphate/CaTiO3 composites were prepared by pressureless air sintering and characterized in terms of phase stability, microstructure and pole drilling for their suitability for machining. In hydroxylapatite/CaTiO3 composites, Ti incorporation into the apatite structure caused lattice shrinkage and eventual decomposition of the hydroxylapatite associated with the formation of α-tricalcium phosphate during sintering at 1100 °C. Later, α-tricalcium phosphate disappeared at 1300 °C, possibly reacting with CaTiO3 at the expense of both phases. On the other hand, tricalcium phosphate/CaTiO3 composites were thermally stable up to 1100 °C insuring a weak interface between the components, which is one of the requirements for machinability in ceramic composites. Drilling tests also verified their suitability for machining.