The influence of hydroxyapatite and alumina particles on the mechanical properties and corrosion behavior of Mg-Zn hybrid composites for implants

Abstract

Considering the necessity for a biodegradable implant alloy with good biocompatibility and mechanical strength, dual ceramic particles of HAP and Al2 O3 were added to Mg-Zn alloy to produce a new hybrid composite using powder metallurgy. The paper reports the mechanical and corrosion behaviour of Mg-Zn/HAP/Al2 O3 hybrid composites containing variable wt.% HAP and Al2 O3 with 15 wt.% total ceramic content. The powders of Mg, Zn, Al2 O3 and HAP were milled in a high-energy ball mill, and then compacted under 400 MPa and sintered at 300◦ C. Density and compression strength increased with increasing Al2 O3 content. HAP facilitated weight gain in Hanks balanced salt solution due to deposition of an apatite layer which promoted anodic behaviour with higher corrosion resistance. A hybrid composite of Mg alloy with 5 wt.% Al2 O3 and 10 wt.% HAP displayed 153 MPa compressive strength, 1.37 mm/year corrosion resistance and bioactivity with a CA:P ratio of 1:1.55 and appears to be the most promising biodegradable implant material tested.