Tribocorrosion of stainless steel in sulfuric acid: Identification of corrosion-wear components and effect of contact area

Electrochemical and friction measurements during unidirectional sliding tests are used to monitor and to evaluate the tribocorrosion behavior of a passivating material. Tribocorrosion is the interplay between chemical, electrochemical, and mechanical processes leading to a degradation of materials immersed in a corrosive environment. The tribocorrosion of AISI 316 stainless steel immersed in a diluted sulfuric acid solution at 25 degrees C was investigated. A modification of the surface characteristics and material loss result from the combined periodic mechanical removal of the surface film during sliding, and the subsequent (electro)chemical re-growth of that surface film in-between two successive sliding contact events. This phenomenon is addressed in this paper as a latency time effect, and its influence on the wear volume and the coefficient of friction is reported. Furthermore, the effect of galvanic coupling between areas without and covered with surface films, on the open-circuit potential is analyzed in terms of Hertzian contact area. Finally a new approach of the concept of synergism in tribocorrosion is presented and validated for AISI 316 immersed in 0.5 M H2SO4 under sliding against zirconia. (C) 2010 Elsevier B.V. All rights reserved.