Mechanical and degradation behavior of Mg-1%Sn-x%HAp composite for biomedical application

Abstract

Metal implants are preferred for orthopedics due to their strength and durability. A biodegradable metal with a density similar to bone, magnesium (Mg) is being considered for medical implants. This study examines the mechanical and corrosive properties of Mg-1%Sn-x%HAp composites with weight percentages of 0, 2, 5, and 7. Mechanical alloying is used to fabricate the composites. Adding hydroxyapatite (HAp) improves corrosion resistance and biocompatibility characteristics. SEM, XRD, and electrochemical tests were used for characterization. The results showed that adding HAp improved composite mechanical properties and corrosion resistance. SEM and EDS confirmed that Sn and HAp were uniformly distributed in Mg. Additionally, the XRD found α-Mg, Mg₂Sn, and CaSn₃ phases are present in the composite. Density, hardness, compressive and polarization test were performed to analyze the mechanical and chemical properties of the composite pallets. The Mg-1%Sn-2%HAp composites have a density of 1.744 g/cm³, close to human cortical bone. Hydroxyapatite (HAp) increased Vickers hardness by 26% in the Mg-1%Sn-7%HAp composite compared to the alloy. The Mg-1%Sn-7%HAp composite has 121.14 MPa ultimate compressive strength due to greater HAp content. This enhancement increased brittleness and decreased compressive strain. Electrochemical corrosion studies showed that the Mg-1%Sn-2%HAp composite had the lowest corrosion rate (0.28568 mm/year) and current density (12.502 µA/cm²). Due to a protective apatite layer and Sn-based oxides, the composite exhibits good corrosion resistance. The Mg-1%Sn-2%HAp composite showed good mechanical properties and corrosion resistance as a biodegradable orthopedic implant material.