Effect of MgF2 Addition on the Mechanical Properties of Hydroxyapatite Synthesized via Powder Metallurgy

Hydroxyapatite, a type of bioceramics, is mainly used as an implant for hard tissues due to its similarity to the structure of hard tissues. The aim of this study is to improve the mechanical properties of hydroxyapatite for biological uses. For this purpose the effect of magnesium fluoride (MgF2) addition with different weight percentages (0, 5, 7.5 and 10 wt. %) on the mechanical properties of pure hydroxyapatite sintered at various temperatures (900, 1000 and 1100 °C) for 1 hour was investigated. XRD analysis was performed to study the decomposition of hydroxyapatite and the transformed phases. The density, Vickers microhardness and fracture toughness of the specimens were measured. The SEM analysis was performed to investigate the microstructure of samples. The results showed that the decomposition of hydroxyapatite to tri-calcium phosphate (TCP) decreased with increasing MgF2. Also, an increment in density and mechanical properties of the specimens were observed with increasing the amount of hydroxyapatite. The fracture toughness of sintered pure hydroxyapatite increased from 2.3 to 1.3 MPa.m1/2. The specimen containing 10 wt. % MgF2 sintered at 1100 °C showed the best mechanical properties.