沿海变电站66 kV HGIS套管接线板镀银层腐蚀剥落原因分析

Corrosion and Peeling off Behavior of Ag Coating on Bushing Wiring Board for 66 kV HGIS in a Coastal Substation

采用宏观形貌观察、化学成分分析、金相组织观察等方法,结合实际服役地区大气环境分析,对某沿海变电站66kV HGIS设备套管接线板镀银层大面积腐蚀剥落现象进行研究。结果表明:镀银层出现起泡、剥离的位置全部为基体与Cu过渡层之间,而银层与Cu过渡层之间结合良好;起泡及剥离的镀层已发生氧化或者硫化,暴露出来的铝合金基材被氧化。腐蚀介质通过镀层表面划痕或界面孔隙等通道进入镀层与基体界面形成腐蚀是导致接线板镀银层腐蚀脱落的主要原因。

The corrosion and peeling off behavior of Ag coating on bushing wiring board for 66 kV HGIS in a coastal substation were studied by methods such as macroscopic observation, chemical analysis, metallographic observation and scanning electron microscope (SEM) as well as analysis of the local atmospheric parameters at the region where the substation situated. The result indicated that bubbling and peeling-off emerged in between the Cu-layer and the substrate Al-alloy, whereas the adhesion between the intermediate Cu-layer and the Ag-layer was intact entirely. The bubbled or peeled coating had been oxidized or vulcanized, and the exposed substrate was oxidized. The corrosive media entered the interface between Al-alloy substrate/Ag-layer through scratches on surface or interfacial gaps, which are the main factor causing the corrosion failure of the Al-alloy wiring board.