Reinforcement of Hydroxyapatite Bioceramic by Addition of ZrO2 Coated with Al2O3

The mechanical properties of hydroxyapatite (HAp) bioceramic material were improved significantly by adding tetragonal‐zirconia‐polycrystalline (TZP) powder coated with Al2O3. The coating was done by dispersing the TZP powder in a boehmite suspension and adjusting the pH to cause heterocoagulation. The coating effectively reduced the deleterious reaction between the HAp and the TZP that tended to form tricalcium phosphate (TCP) and fully stabilized cubic zirconia. When 15 vol% zirconia and 30 vol% alumina were added to the HAp by the coating method, the strength and the fracture toughness of the composite were 300 MPa and 3 MPa·m1/2, respectively, which are about 3 times higher than those of pure HAp.