EFFECT OF ELASTIC STRESSES ON THE CONDUCTIVITY OF PASSIVE FILMS

摘要

The electrochemical impedance and surface stresses were measured under straining conditions. The Mott-Schottky analysis, performed at high frequency, appears to be a very useful method to study the effects of an elastic stress on the capacitance values. The results obtained in sodium chloride media indicate that the semi-conducting properties of passive films formed on a type 316 L stainless steel in a tensile elastic stress field reflect a higher donor and acceptor concentration than those formed in a stress-free state, suggesting that the passive film conductivity is increased. It is also shown that micro-plasticity leads to a significant increase in the passive films capacitance. The potential barrier at the passive film/electrolyte interface is unchanged, suggesting that the kinetics of charge transfer remain constant.