接地网防护涂层材料的电化学腐蚀特性

Electrochemical corrosion characteristics of protective coat for ground grid

接地网是变电站重要的安全防护设备,腐蚀是其服役中的最主要限制因素.为研究Q235接地网材料沉积NiP、DLC涂层之后的抗腐蚀性能,采用化学镀及阳极离子源物理沉积的方法在Q235基体上沉积2种涂层.采用扫描电镜以及拉曼光谱分析沉积涂层之后,分别在3.5%的NaCl溶液中测定3种材料极化曲线以及电化学阻抗谱,电化学试验之后样品采用扫描电镜对比3种材料试验后表面情况.极化曲线测试以及阻抗谱拟合分析均表明,2种涂层相对于Q235具有更小的自腐蚀电流密度,更高的电阻.同时电化学腐蚀后形貌表明Q235表面完全为腐蚀产物覆盖说明表面被完全破坏,而2种涂层的表面只是部分区域产生腐蚀坑.

The grounding grids are important safety protection equipment in substations and corrosion is the main limited factor for its service. The DLC and NiP coating have been deposited on the 0235 substrate by electroless plating and anode layer plasma source respectively to investigate the corrosion resistance of the coated samples. The measurement of the polarization curves and AC impedance spectra have been conducted in 3.5 Gwt sodium chloride solution to study the corrosion behavior of 0235, NiP and DLC coatings after the SEM and Raman spectra analysis of the two coatings. Also, the surface morphology after the electrochemical experiment has been studied by SEM. The results of the polarization curves and AC impedance spectra suggest that these two coatings revealed smaller self-corrosion current density and higher electric resistance. The analysis of the surface morphology revealed that the uncoated Q235 sample has been completely covered by the corrosion product which indicate that the sur- face has been totally corroded in the electrochemical experiment; while only some eroding pits have been found in part of the surfaces of the coated specimens.