HEAT TREATMENT OF COBALT-BASE ALLOY SURGICAL IMPLANTS WITH HYDROXYAPATITE-BIOGLASS FOR SURFACE BIOACTIVATION

ASTM F-75 Cobalt-base alloy castings are widely used for manufacturing orthopedic implants. The alloy needs both homogenization and solutionizing heat treatment after casting, as well as bioactivation of the surface to increase the ability of tissue bonding. In this study, ASTM F-75 Cobalt-base substrate was heat treated at 1220°C for 1 hour in contact with Hydroxyapatite-Bioglass powder in order to solutionize and homogenize the microstructure and promote surface bioactivation. In order to bioactivity evaluation, heat treated specimens were immersed in Simulated Body Fluid (SBF). Surface of specimens before and after the immersion was analyzed by Scanning Electron Microscopy (SEM), Energy Dispersive Spectroscopy (EDX) and X-Ray Diffraction (XRD). Results showed an appropriate microstructure with bioactive layer on the surface of specimens after heat treatment. In vitro evaluation results and formation of bone-like apatite layer on specimens indicated that heat treated samples were potentially suitable for medical orthopedic applications under highly loaded conditions.