Metal release and formation of surface precipitate at stainless steel grade 316 and Hanks solution interface – Inflammatory response and surface finishing effects

The influence of surface finishing (polishing and passivation) on the release of Cr, Fe, Ni from the stainless steel 316 implant materials to Hanks solution with or without H2O2 (simulating a body inflammatory response) was investigated. The surfaces were characterized by means of SEM EDXS, XPS and Kelvin Probe measurements before and after exposure to the synthetic body fluids. The total metal ions release rates are more than 10 times higher in the presence of H2O2, independently of the surface finishing. In the absence of H2O2, formation of a surface layer consisting mainly of Ca3(PO4)2 was observed, most likely it was responsible for the observed decrease of the release rates.