Tribocorrosão em aços inoxidáveis ferríticos: uma abordagem metodológica

Abstract

The goal of this work was to develop a methodological approach to characterize the tribocorrosion of ferritic stainless steels. For a matter of comparison, the carbon steel was also studied. A reciprocating motion tribometer was used under constant load and sliding velocity conditions. An electrochemical cell associated with a potentiostat was designed, constructed and incorporated to the tribometer. Thus, in order to evaluate the synergic effect of tribocorrosion, a specific methodology was developed, since the literature lacks methodologies to determine the tribocorrosion synergy in potenciodynamic (potential scanning) tests. Therefore, the methodology consists in perform sliding tribological tests in order to strictly evaluate the mechanical wear, the corrosion resistance, in the absence of mechanical wear, and tribocorrosion tests, which associate both mechanical wear and the corrosion degradation from chemical/electrochemical effects. The validation of the developed methodology consisted of its application in ferritic stainless steels with different chromium content. Among the stainless steels, those with 16 % of chromium showed higher friction coefficient and lower wear rate compared to those with 11 % of chromium content. The carbon steel, on the other hand, showed the lowest friction coefficient and the highest wear rate among all materials. The results in corrosion tests showed that higher is the corrosion resistance when the stainless steel has higher chromium content. It was verified similarities of the wear mechanism between the tribocorrosion and the tribological tests. Such similarities can possibly explain the synergy obtained, which was slightly positive, that is, the tribocorrosion apparently intensified the wear rate in the materials, although in a little significant way.