Effect of magnesium particle size on compressive strength of Mg/Hydroxyapatite porous bio-composite

Magnesium and its alloys have found a wide range of applications in medical industry and manufacturing of absorbable bio-implants because of having a modulus of elasticity similar to bone as well as having biocompatibility and biodegradability characteristics. Moreover, employing magnesium implants with a porous structure can lead to an increase in the rate of bone replacement instead of the initial absorbable implant. On the other hand, by adding hydroxyapatite reinforcing particles to magnesium and its alloy, their mechanical properties and corrosion resistance may be improved. In this paper, the effect of magnesium particle size on compressive strength of Mg/hydroxyapatite porous bio-composites has been studied. The magnesium and composite specimens with non-porous and porous (with a volume porosity of 24% and 58%) structures were produced using powder metallurgy method. For this purpose, two types of magnesium powder with particle sizes of 63 µm and 250 µm, hydroxyapatite particles as reinforcement, and ammonium bicarbonate particles as space holder, were used. The results of the uniaxial compressive tests revealed that the strength of all the pure and composite specimens fabricated by 63 µm powder has improved up to 103%, compared to those of the specimen fabricated by 250 µm powder. In addition, for both amounts of volume porosity, the composites offer a higher compressive strength than that of the pure specimens.