Novel machinable calcium phosphate glass-ceramics for biomedical use

SiO2-free calcium phosphate glass-ceramics with easy machinability were prepared by heat-treatment of a 60CaO-3OP(2)O(5)-3TiO(2)-7Na(2)O (in mol%) glass. The glass-ceramics containing beta-Ca2P2O7 and beta-Ca-3(PO4)(2) crystals were found to show good machinability, as confirmed by a drilling test using a conventional carbide tool. SEM observation of the glass-ceramic showed that beta-Ca2P2O7 crystals having a layered morphology are interlocking one another; plate-like crystals of several tens nanometers in thickness are piled up. The easy machinability of the glass-ceramics was suggested to result from the cleavage of beta-Ca2P2O7 crystals precipitated in the glass. The glass-ceramics formed bonelike apatite crystals on the surface in simulated body fluid. The glass-ceramics were also found to be strongly joined with a new B-type titanium alloy, Ti-29Nb-13Ta-4.6Zr, by heating in air.