Effect of alumina addition on hydroxyapatite biocomposites fabricated by underwater-shock compaction

Hydroxyapatite [HAp; Ca-10(PO4)(6)(OH)(2)] biocomposites are ceramic materials that exhibit excellent bioactivity, but their inherent low fracture strength and toughness render them unusable for practical applications. Alumina (Al2O3) is added to improve in mechanical properties without diminution of biocompatibility. Powder mixtures of HAp and Al2O3 in various volume ratios (90:10, 80:20, and 70:30) were compacted by underwater shock waves generated by explosives. High explosives of 6900 m s(-1) detonation velocity served as the energy generators. The compacts were sintered at 1473, 1573, and 1673 K in order to investigate the influence of sintering temperature. All compacts were found to be free of defects and to have undergone continuous compositional changes to a tricalcium phosphate and tetracalcium phosphate. K-1c showed maximum value with HAp-30vol.% Al2O3 that have been sintered at 1673 K for 7.2 ks, and the value of 3.0 MPa m(-1/2) is 2.5 times that of HAp monolithic material. The results of optical microscopy, scanning electron microscopy, X-ray diffraction, and other analyses are reported. (C) 2002 Published by Elsevier Science B.V.