针对某电力系统接地金属材料镀锌扁钢在土壤中服役11年后的腐蚀行为,采用金相、扫描电镜、能谱和X射线衍射等技术对其进行了宏观分析、组织分析、腐蚀产物分析和断口分析。结果表明,该镀锌扁钢接地极的腐蚀类型属全面腐蚀,腐蚀产物主要由FeOOH和Fe₃O₄等组成。镀锌扁钢基体中发现一些颗粒状的Al-Si复合型夹杂物,这些夹杂物的存在促进了腐蚀的发生和发展,并在局部区域为侵蚀性离子渗入基体提供了通道。研究结论表明在腐蚀环境作用下,镀锌扁钢发生腐蚀与导电性能失效是影响接地网的散流特性和寿命的主要原因。

The corrosion behavior of galvanized flat steel, which has been used for more than eleven years in the soil environment, is investigated by using optical microscopy, scanning electron microscopy, and X-ray diffraction techniques. It is found that the corrosion type of galvanized flat steel is mainly general corrosion after buried in soil. The corrosion products are composed of FeOOH, Fe₃O₄ and others. The EDS results show that there are some sulfur elements in the corrosion product, and the elements might be caused by the sulfate-reducing bacteria. Also there are some Al-Si composite granular inclusions existing in the substrate of galvanized steel, and the inclusions could promote the corrosion occurrence and development, therefore provide the channel for the corrosive ion to permeate into matrix in the local region. In order to extend the lifespan of grounding electrode in the soil, the galvanized steel is often considered in the design. The zinc in the soil is priority eroded to protect ordinary carbon steel's lifespan. In the absence of current role, the service lifespan of galvanized steel is indeed better. However, due to the role of the ground current, as the ground material, galvanized steel surface electrolytic zinc coating will soon come off; then the corrosion rate of grounding electrode accelerates rapidly. The conclusions also indicate that in the corrosive soil environment, the corrosion and failure of galvanized flat steel could affect the function and lifespan of grid.