Growth mechanism and repassivation kinetic determinations on stainless steel under sliding: Role of the solution pH and dissolved oxygen concentration

The tribo electrochemical behavior of 2205 duplex stainless steel had been studied under acidic and neutral solutions with control of the dissolved dioxygen. The study focused on the oxide film formation using a galvanic technique approach implemented in a tribometer. Higher wear rates were measured in low pH and aerated solution. In low O-2 concentration, a wear reduction was observed for each pH. Analysis of the passivation transients showed the pH influence on the oxide growth mechanism, irrespective of the O-2 level. Temporal analysis of the transients confirmed the faster passivation of the wear track in acidic solution. In a controlled O-2 environment, the nucleation and the oxide growth were slow down, irrespective of pH. The degradation rate was then correlated to the passivation kinetic and the aging of the passive film.