Comparison of microstructural and mechanical properties of hydroxyapatite-Al<inf>2</inf>O<inf>3</inf> composites with commercial inert glass (CIG) addition

Hydroxyapatite (HA) is one of the most widely used biomaterials for orthopedic and dental applications. However, HA is a brittle and weak material and this constrains its orthopedic applications. There are several methods for the improvement of mechanical properties of the HA. One of these methods is to strengthen the HA material by a secondary phase (i.e polymer, metal or ceramics), to make a stronger composite material. Alumina (Al₂O₃) is a bioinert material, which has been widely investigated as a reinforcing agent for HA. The aim of this study is to compare the microstructural and mechanical properties of HA-Al₂O₃ composites with the addition of 5 and 10 wt.% of commercial inert glass (CIG). The grain samples were produced according to BS 7253 at 350 MPa. Then, they were sintered at temperatures between 1000-1300°C for 4 hours. The samples were also analyzed by SEM + EDS to determine microstructural properties, phase analysis was done by X-ray diffractometer (XRD), mechanical properties were measured by compression and hardness tests. Results show that HA-Al₂O₃ composites with addition of 5 and 10 wt.% CIG have reached high density values and high mechanical properties, such as compression strength and hardness at 1300°C. The compression strength and hardness of composites has increased with the increasing CIG content

Sintering effects of mullite-doping on mechanical properties of bovine hydroxyapatite

In this study, sintering effects on microstructural behavior of bovine derived hydroxyapatite doped with powder mullite are considered in the temperature range between 1000 °C and 1300 °C. Results show that maximum values of both compressive strength and microhardness are achieved in the samples sintered at 1200 °C for all mullite additions of 5, 7.5, 10 and 12.5 wt%. Moreover, above 1000 °C, decomposition of HA and new phase formations such as whitlockite and gehlenite play a major role in both compressive strength and microhardness properties which increase up to 10 wt% mullite reinforcement. © 2017 Elsevier B.V