Repassivation rates of surgical implant alloys by rotating‐disk scratching measurements

As the dissolution of metals ions in living tissues is an issue of primary importance in the field of surgical implant alloys, a rotating disk scratch technique has been used to examine this aspect by studying the potentiostatic repassivation behavior of pure titanium of commercial grade 11 and AISI 316L Stainless Steel (SS) samples in aqueous chloride solutions. By evaluating the effects of applied potential, pH and surface treatment on the current decay transients in the millisecond regime the higher tendency to passivate of titanium with respect to the stainless steel has been clearly demonstrated. An analysis conducted to estimate the efficiency of the oxide formation process has led to the conclusion that the majority of the measured transient current goes to the anodic dissolution process on both the materials investigated. Moreover, a repetitive process of film formation/breakdown on the AISI 316L surface related to pitting corrosion has been observed to strongly increase the ion release in the vicinity of the characteristic pitting potentials.