Development of a biomaterial based on HAP/TiOy nanocomposite with different stoichiometry

Abstract

At present, composite materials based on bioactive hydroxyappatite (HAP) are intensively developed. To achieve better mechanical properties, different additives are used, for example, titanium, zirconium, etc. In the present study, a dispersionhardened composite material based on nanocrystalline HAP and nanocrystalline titanium monoxide (TiO y , y = 0.92, 1.23) is prepared by low temperature annealing in vacuum. As an additive, titanium monoxide with different mass ratios and stoichiometries (10 or 20 mass % of substoichiometric TiO 0.92 or superstoichiometric TiO 1.23 ) is used. For the preparation of nanocrystalline powders and mixing of initial components, a planetary ball mill was used. According to scanning electron microscopy (SEM) data, using of the ball milling for mechanical mixing of nanopartilces allows one to prepare denser material with a particle shape, which facilitates cold pressing and sintering. It has been established that introducing of the TiO y additive leads to a reduction of the starting temperature of the composite material hardening by 200 to 250°С. The phase composition and properties of the end product (microhardness, density) depend on the stoichiometry and on the amount of additives. For the content of 20 mass % of substoichiometric TiO 0.92 phases Ti 4.5 O 5 and Ti 6 O 11 are found by means of XRD studies. The phase Ti 4.5 O 5 is an ordered phase and is more stable as compared to other phases of Ti-O system., while the phase Ti 6 O 11 has easy slip crystallographic planes. Presence of such two phases positively influences on mechanical properties of the composite. According to SEM, BET and microhardness data, the composites prepared are nanodispersed ones and show an increased density and microhardness as compared to HAP without additives. Ключевые слова: гидроксиапатит, монооксид титана, размол, отжиг, микротвердость.