Fretting-corrosion between 316L SS and PMMA: Influence of ionic strength, protein and electrochemical conditions on material wear. Application to orthopaedic implants

In biomedical field, fretting-corrosion between 316L SS femoral stem and bone cement is one of the significant causes of the hip prosthesis loosening. This article investigates wear by fretting-corrosion at the contact between 316L and PMMA. The influences of the ionic strength (NaCl solutions from 10 −3 to 1 mol L −1 ), a model protein (albumin) and electrochemical conditions on contact behaviour are studied. At OCP (open circuit potential) conditions, the chlorides concentration, i.e. the ionic strength, increases the 316L wear; and albumin, concentration of 1 g L −1 , does not play a significant role in total 316L wear. At cathodic applied potential E = −400 mV(SCE), a threshold concentration of 10 −1 mol L −1 (NaCl solution), C th , indicates two behaviours: a protective effect below C th , and an additional anodic dissolution above C th . One might suggest that, beyond C th , the passive layer is not efficient for protecting against the corrosion. At this potential, albumin reduces wear due to corrosion and amplifies mechanical wear induced by corrosion. Albumin seems to act as an anodic inhibitor. To determine the mechanisms of synergism, a “more cathodic” potential is applied, E = −800 mV(SCE), during fretting-corrosion experiments. Consequently, the corrosive wear can be neglected and the mechanical wear can be only measured.