对采用阴阳极保护的一些探讨

STUDIES ON THE CATHODE-ANODE PROTECTION

地埋石油管道,通电作阴极保护,效果比不通电的要好。本文从这一事实出发,进行了理论研究,提出了自己的看法。当阴阳极同时埋在地下,两者相距较远,约1公里,外加电压不高,约0.8 V～1.5V时,阴阳极之间很难构成直接回路,因此离子运动主要依靠扩散而不是电迁移。在阴阳极附近,由于扩散速度远小于离子在电极上的反应速度,因此在阴极周围就会形成负离子区,阻止O^(-2)向阴极区趋近形成对负离子的屏蔽状态。从而保护了阴极不被腐蚀。至于阳极,由于不与阴极构成直通回路,因此如果周围没有溶解阳极的介质,阳极表面就会生成一层致密的氧化层而导致钝化,因而减少了损耗并取得了良好的效果。

As the petroleum pipe are burried under earth, the effect of cathode protection with power supply is better then that without it. Based on this fact, theoretical investigation has been carried out and some conclusions are presented. When both anode and cathode are hurried under earth, the distance between them is as far as about 1 kin, applied voltage is not high, about 0.8v-1.5v,it is diffcult to form direct circuit between them, therefore, ion movement mainly depends on diffusion rather than electromigratlon. In the vicinity of cathode and anode, as diffusion rate is far lower than reaction rate on electrode, an anion region is formed around cathode, as a barrier layer against anion, preventing O^(2-) from approaching to cathode, thus cathode is protected from corrosion, As for anode, as there is no direct circuit connected to cathode, a dense oxidized layer would be shaped on the surface of anode and lead to passivation in the absence of any media which can make anode dissolve, thus the anode loss is reduced and good effects can be obtained.