Superplastic deformation of hydroxyapatite ceramics with B 2O 3 or Na 2O addition fabricated by pulse current pressure sintering

Abstract

High-density and fine-grained transparent hydroxyapatite (Ca 10(PO 4) 6(OH) 2: HAp) ceramics with B 2O 3 and Na 2O addition were fabricated using pressureless sintering and pulse-current pressure sintering between 1000 and 1100 °C; the superplastic deformation of these HAp specimens was evaluated. The relative density of pure HAp compacts pulse-current pressure sintered at 1000 °C for 10 min under a pressure of 50 MPa attained 99.9% and exhibited translucency. The tensile elongation of the pure HAp specimen, which was measured at 1000 °C under a strain rate of 1.48 × 10 −4 s −1, was as high as 364%. The relative density of HAp compacts with 3.0 mol.% B 2O 3 addition pulse-current pressure sintered under the same conditions as those of pure HAp compacts was 98.9%, whereas the grain size was as low as 0.24 μm. The elongation of HAp specimens, measured at a test temperature of 1000 °C under a strain rate of 1.48 × 10 −4 s −1, was as high as 578%.