Investigating the Bio-tribological Aspects of Novel Squeeze Rheo Casted Magnesium Alloy Composites for Orthopedic Implant Applications

The present research work assessed the influence of zinc and tin alloying elements on the wear behavior of hydroxyapatite-reinforced magnesium-based composites such as Mg/HA, Mg-Zn/HA and Mg-Sn/HA. These composites were made through the new ultrasonic-assisted squeezing rheo casting method. The SEM analysis reveals the even distribution of HA and formation of MgZn as well as Mg2Sn secondary phases. The microhardness and compression test results showed that the mechanical properties of Mg-Sn/HA composites were better. Wear tests were performed under a simulated body fluid environment with a constant load of 45 N, sliding velocity of 2 m/s and sliding distance of 1000 m. Wear test results revealed that the Mg-Sn/HA sample had a lower wear rate and COF than the other samples. The predominant form of wear was abrasion but there was also evidence of fatigue cracks, oxidation, adhesion and delamination. The improvement in mechanical properties and wear resistance shown by Mg-Sn/HA composites has been attributed to grain size reduction as well as proper dispersion of secondary phases and formation of protective tribolayers between the sliding surfaces. Thus, the 1% Sn alloyed Mg/HA composite can be adopted as a wear-resistant implant in biomedical applications.