Bioactive coating on a cobalt base alloy by heat treatment

A method to promote a bioactive surface on the cobalt base alloy ASTM F-75 was tested. A set of cylindrical samples was obtained using the investment casting technique and packed in a mixture composed of 70% β-tricalcium phosphate and 30% bioactive glass and then heat treated for 1 h at 1220 °C. To characterize the in vitro bioactivity, a set of heat treated metallic specimens was immersed in a simulated body fluid with an ionic concentration nearly equal to that of human blood plasma (SBF) for 7, 10 and 21 days and in a more concentrated solution (1.5 SBF). After heat treatment, fine agglomerates homogeneously distributed, containing Ca, P, O and Na were observed on the metallic surface. After immersion of the samples in simulated body fluids, a thicker layer identified as apatite was formed on the samples immersed in SBF for 21 days and on all samples immersed in 1.5 SBF.