Effects of hydroxyapatite addition on the microstructure and mechanical properties of sintered magnesium matrix composites

This study focused on the microstructure and properties of magnesium alloy (Mg/3Al)-based composites, rein-forced with hydroxyapatite (HA) and produced by powder metallurgy (PM) method. In this investigation, Mg alloys were reinforced on the basis of weight percentage (wt%) of HA to produce Mg3Al alloy as well as Mg3Al/ 3HA, Mg3Al/6HA and Mg3Al/9HAcomposite samples. Measurements were taken based on their properties, including density, hardness, compressive strength, wear rate (WR) and corrosion behaviour. Microstructural studies on the various Mg3Al/HA composites were carried out, using scanning electron microscopy (SEM), en-ergy dispersive X-ray spectroscopy (EDS) and X-ray diffraction (XRD). Wear behaviours of the composites were analysed with aid of Taguchi method. Worn surface analysis was performed, using SEM. From the results ob-tained, better wear resistance property was obtained with the sample Mg3Al/9HA.Evidently, the addition of HA content to the Mg/3Al alloy increased its mechanical strength, due to uniform distribution of HA in the matrix. From signal-to-noise (S/N) ratio analysis, it was observed that the optimum parameters were obtained at HA content of 9 wt%, speed of 2 m/s, displacement of 750 m and applied load of 5 N for minimum WR. Similarly, the optimal parameters for minimal coefficient of friction (COF) were 9 wt%, 1 m/s, 750 m and 5 N. Leveraging from these composite samples, the results obtained stand to advance knowledge on tribology of composite materials, guide the choice and application of the materials, especially where wear and friction are inevitable.