Laboratory soil corrosion test of steel grounding materials

The most commonly used grounding materials in China are galvanized steel, copper and copper clad steel. The effect of grounding material corrosion on the reliability of electronic equipment is of growing importance as the growing of power capacity. For better understanding the factors influencing the protective effects against corrosion by zinc and copper coatings, two experiments have been performed and reported in this paper. The polarization curve test is first conducted to obtain the uniform corrosion rates. It can be found that copper clad steel coating has the best corrosion resistance, while carbon steel has the worst. Then, DC accelerated electrolysation test is introduced to compare the corrosion behavior of galvanized steel and copper clad steel under the condition of defective coatings. The result shows that whether the coatings of galvanized steel are damaged or not, corrosion arises mainly on zinc coatings. The breakage forms make little difference on corrosion of steel substrate, due to the sacrificial protection of zinc coatings. When breakage area of copper clad steel coating is small, corrosion exists mainly on copper coatings. As the breakage area of copper coatings increases, corrosion will turn to arise mainly in the steel substrate. In the case that the coatings are damaged, copper clad steel coating has a greater corrosion rate than that of galvanized steel coating.