Reaction Sintering of Biocompatible Al₂O₃-hBN Ceramics

Biocompatible Al₂O₃-hBN ceramic was sintered from AlN and B₂O₃ precursors by reaction hot pressing at 1750 °C and 30 MPa for 8 min. The ceramic was compared to nonreactive (NR) one sintered from Al₂O₃ and BN under the same sintering conditions. The NR ceramic possesses 9% porosity as opposed to only 2% porosity for the reaction sintered Al₂O₃-hBN. The reaction sintered ceramic has crack resistance in the region of 5.0 ± 0.1 MPa·m^1/2, which is approximately 20% higher than previously reported pure Al₂O₃ or Al₂O₃-hBN sintered without reaction support. The higher amount of hBN in the developed Al₂O₃-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 Al₂O₃-hBN composite opens a new area of creation and formation of load-bearing Al₂O₃-hBN ceramic bioimplants.