Comparative study on mechanism of DC and AC current on corrosion of copper–aluminium composites

In this study, corrosion behaviours accelerated by neutral salt spray were thoroughly investigated on copper–aluminium composites with 3 wt% concentration NaCl for 72 h under DC and AC current respectively. The similarities and differences of the corrosion mechanism of the copper–aluminium composite under the two kinds of current were analysed by weight loss analysis, scanning electron microscopy, energy-dispersive X-ray spectroscopy and electrochemical detection methods. It can be concluded that there are two opposing influences of the current on the corrosive effects, including acceleration by the impressed current and inhibition by the heating effect. Of these, the inhibition effect on corrosion is more obvious, as the thermal effect of DC current is greater under the same current value. It is worth noting that the directional migration of ions caused by DC current will affect the degree of corrosion and the composition of the corrosion products on the surfaces of both sides of the samples, which is a unique characteristic not seen with AC current.