Tribocorrosion in Ferritic Stainless Steels: an Improved Methodological Approach

Abstract

This study aimed to improve a potentiodynamic-based methodological approach for characterising the tribocorrosion of ferritic stainless steel. Synergistic effects in tribocorrosion systems have been widely investigated and debated under potentiostatic conditions. Because potentiostatic tests can ignore essential phenomena that are typically noticeable in potentiodynamic tests (potential scanning), such as variations in the friction coefficient that are motivated by potential scanning, e.g., during active, passive, and transpassive domains, a potentiodynamic-technique-based methodology was enhanced to analyse tribocorrosion in ferritic stainless steels. The proposed method facilitates the analysis of all essential parameters for tribocorrosion phenomena based on a single figure directly associating the average friction coefficient curves from sliding tests and tribocorrosion tests. It consists of performing sliding tribological tests to evaluate mechanical wear accurately, potentiodynamic corrosion tests to determine corrosion resistance in the absence of mechanical wear, and tribocorrosion tests to associate mechanical wear and corrosion degradation caused by chemical/electrochemical effects. Validation of the methodology consisted of its application to an 11% Cr ferritic stainless steel. The results demonstrate that tribocorrosion intensifies the material loss, but only by a minimal amount. The results demonstrate that the average passivation current density in the tribocorrosive tests was significantly higher. Apparently, the corrosion products generated during the tribocorrosion tests acted as solid lubricants inducing a lower friction coefficient in the tribocorrosive tests. Finally, tribocorrosion intensifies the material loss, but only by a minimal amount.

Keywords:
Tribocorrosion; potentiodynamic; ferritic stainless steels; methodological approach; sliding wear