Bioactivity and corrosion resistance of hydroxyapatite doped ceramic oxides coated magnesium alloys for biomedical applications

Abstract

Metallic materials such as stainless steel, titanium alloys and Co Cr alloys are widely used for load bearing application due to excellent corrosion resistance and mechanical strength Though they fulfill the requirements of biomaterials they remain in the body after wound healing process resulting in long term endothelial dysfunction With the passage of time these materials release toxic corrosive ions resulting in negative impact on the body Moreover metallic implant has to be removed by a second surgery after the bone has healed. In contrast, biodegradable magnesium alloys are promising materials and recently attracted much attention. It has favourable properties including light weight biocompatibility and are essential to human metabolism Moreover it obviates the need for the second surgery for the implant removal and minimizes the stress shielding effect due to the closer elastic modulus to natural bone Magnesium ions are present in large amount in human body and involved in body metabolisms It degrades too quickly and releases hydrogen gas to the surrounding tissue leading to loss of mechanical integrity of the implant from the bone This results in the failure of the implant. To improve the mechanical integrity and corrosion resistance the interactive surface should be modified to get proper biological response and control the corrosion resistance Physical vapour deposition chemical vapour deposition ion implantation and laser irradiation have been adopted to improve the corrosion resistance and slow down the formation of wear particles Among these techniques sol gel is a versatile technique and offers several advantages such as better control on the chemical composition homogeneous film formation control on film structure reduction in densification temperature of ceramic layer to provide effective coatings with improved properties by varying the parameters like precursor to solvent ratio hydrolyzing agent curing temperature rate of hydrolysis and coating technique newline