Reaction Sintering of Biocompatible Al 2 O 3 -hBN Ceramics

Biocompatible Al O -hBN ceramic was sintered from AlN and B O precursors by reaction hot pressing at 1750 °C and 30 MPa for 8 min. The ceramic was compared to nonreactive (NR) one sintered from Al O and BN under the same sintering conditions. The NR ceramic possesses 9% porosity as opposed to only 2% porosity for the reaction sintered Al O -hBN. The reaction sintered ceramic has crack resistance in the region of 5.0 ± 0.1 MPa·m , which is approximately 20% higher than previously reported pure Al O or Al O -hBN sintered without reaction support. The higher amount of hBN in the developed Al O -hBN material (27 vol %) facilitates hardness lowering to the region of 6 GPa, which is closer to the bone hardness and makes the ceramic machinable. Reaction sintering of the Al O -hBN composite opens a new area of creation and formation of load-bearing Al O -hBN ceramic bioimplants.