Electrochemical investigations of aluminium alloys tribocorrosion

Abstract

Electrochemical methods based on corrosion potential and polarization current measurements are widely used in tribocorrosion research. However, most equipment types allow recording of integrated electrochemical parameters of metals during tribocorrosion, but little attention is paid to local processes that occur on friction surfaces. It was proposed to use a capillary probe as a reference electrode, which reduces the effect of cathodic sites on sample tribopotential and allows measurements in low-conductivity solutions. The study was carried out on an example of the widely used AA2024 alloy, and may relate to structural aluminum alloys. It was shown that the difference between tribopotential values of the alloy measured by classic electrochemical technique and capillary probe may be up to 0.6 V in a study in glycerin. It was established that correlation exists between the current of alloy polarization at the corrosion potential in distilled water and the volume of worn material. The empirical relationship found for a ball-on-flat tribometer with reversible sliding provides a possibility to estimate the amount of worn material based on polarization currents. This method may also be promising in studies on the efficiency of corrosion inhibitors on mechanically activated surface of passive metal.