湿态电绝缘对电偶腐蚀行为的影响

Effect of Moistened Electrical Insulation on Galvanic Corrosion Behavior of Dissimilar Metals

采用串联不同阻值电阻和3种不同的湿态绝缘材料进行了模拟异种金属电绝缘连接构件的电偶腐蚀实验,研究了湿态电绝缘状态对船体钢-白铜电偶腐蚀的影响。结果表明:绝缘材料在湿态下可成为电子导电的材料,湿态绝缘材料的电阻既包括离子导电引起的离子电阻Ri,还包括电子导电引起的电子电阻Re。湿态电绝缘下的白铜-船体钢电偶对中船体钢的腐蚀行为主要与湿绝缘材料的Re有关。当Re小于1 kΩ时,串联电阻时的电偶电流可高于直接短接时的电偶电流,船体钢的腐蚀速率可高于直接短接时的;当Re大于1 kΩ时,Re越大,电偶电流越小,船体钢的腐蚀速率越低。湿态绝缘材料Re的形成与绝缘材料的材质有关,选择合适的电绝缘材料是防止白铜-船体钢电偶腐蚀的关键。

The effect of moistened electrical insulation on galvanic corrosion behavior of dissimilar metals was investigated with a simulated galvanic corrosion setup, which consisted of a cell containing 3%NaCI solution with hull steel and cupronickel as electrodes and then by series connecting resistance elements or moistened insulation materials into the circuit. The results showed that through moistening the insulation material can be transformed into electrical conducting material. The resistance of moist- ened insulation material （Rm） may involve ionic resistance （R~） and electrical resistance （Re）, which are produced respectively by ionic conducting and electrical conducting. The corrosion behavior of the hull steel for the couple steel/cupronickel beneath a moistened insulation material may relate to the term Re. When Ro is not higher than 1 k~, the galvanic current of the couple connected with a resistance element of a moistened insulation material may higher than that of the short-circuited couple, and the corrosion rates of hull steel of the couples connected with resistance elements may higher than that the short-cir- cuited couple. When Re is higher than 1 kE~, the galvanic currents of the couples connected with resis- tance elements decreased with the increase of R., whilst the corroslon rate of the hull steel of the couples connected with resistance elements decreased with the increase of Re. The conduction of the moistened insulation material related to the nature of insulation material, the key to prevent galvanic corrosion of couple hull steel/cupronickel is the appropriate selection of insulation material.