Study on corrosion characteristics of grounding materials in high corrosion area

Abstract

Due to the differences in the causes of corrosion, the soil corrosion characteristics in coastal mountains and coastal areas may be quite different. As a result, there are differences in the corrosion causes, corrosion status and service life of the grounding grids of the transmission line towers built in coastal areas. Based on the difference in apparent resistivity of the soil under the transmission line towers in a coastal area with high corrosion, this paper selects 12 soil samples for physical and chemical analysis. The analysis results show that there are two typical soils of acid and weak alkaline in the transmission line erection area, which are highly corrosive but with different corrosion mechanisms. Then the soil liquids of two typical soils were extracted, and the polarization curve test of carbon steel and galvanized steel, which are commonly used in the grounding grid of poles and towers, was carried out for 7 consecutive days, and the corrosion laws of carbon steel and galvanized steel were obtained. The results show that the corrosiveness of acidic soil is much greater than that of weakly alkaline soil. The corrosion rates of carbon steel and galvanized steel in acidic soil are 3.7 times and 5.2 times that of weakly alkaline soil, respectively. In addition, using the extracted soil liquid, a 30-day accelerated corrosion experiment was performed on carbon steel and galvanized steel, and an empirical formula for the change of corrosion weight with time was obtained. Combined with the surface morphology characteristics and corrosion rate after corrosion, this paper analyzed corrosion mechanism of two grounding materials. The research results of this paper provide a reference for the selection and application of grounding materials.