In this work, the effects of boehmite addition on the reaction-sintering of hydroxyapatite and alumina composites were investigated. Hydroxyapatite (HAp) presents a very important bioceramics and has been widely applied as bone substitutes because of its excellent bioactive properties. However, the low mechanical properties of this bioceramics have been the main problem of the extensive use of this material. The addition of alumina, resulting from the boehmite transitions, to the hydroxyapatite has been carried out to improve the mechanical properties of sintered HAp. After ball-milling of seven compositions (0, 5, 10, 15, 20, 25 and 30 wt.% of Al₂O₃) for 5h, the reactions and phase transformations between hydroxyapatite and boehmite were studied using thermal techniques (DTA/TG), X-ray diffraction (XRD) and infrared spectroscopy (FT-IR). All samples were heated at different temperatures between 1000 and 1500C for 2h and characterized by apparent density, open porosity measurements, XRD, FT-IR, micro-hardness and SEM analysis. The results showed the formation of different phases after high temperature. All mixture powders showed the formation of a number of alumina transitions through heat treatment. The mechanical properties of hydroxyapatite were enhanced by the addition of boehmite (alumina at high temperature).The mixture of hydroxyapatite and boehmite shows the partial decomposition of hydroxyapatite at high temperature.

Key-words: Hydroxyapatite; Bioceramics, Boehmite; Alumina transitions, composites.