Estimating galvanic corrosion rate of copper/steel couple by using remote earth mixed potential

Abstract

Copper and steel are often electrically connected in industrial devices, which causes galvanic corrosion in environments. To ensure the safety of the devices, it is needed to assess the corrosion rate of galvanic couples. The galvanic current is often used to calculate the galvanic corrosion rate in theory, however, in the actual devices, the copper parts are generally coupled with the steel parts and it is difficult to separate them to measure the galvanic current between them, as well as to determine the galvanic corrosion rates for actual devices. In this paper, the galvanic couple mixed potential distribution and influencing factors including area ratios, polarization characteristics, and medium resistivity are studied by experiments and calculation. The mixed potential becomes stable with a certain distance from the surface of copper/steel couple and acts as remote earth mixed potential. Remote earth mixed potential is positively associated with galvanic corrosion rate. Based on the results of experiments and calculation, a method to estimate the galvanic corrosion rate of steel in copper/steel couple by using the remote earth mixed potential is proposed.