论文部分内容阅读
利用模拟闭塞区溶液研究了18—8不锈钢在Cl~-溶液中蚀孔、缝隙或应力腐蚀裂缝内的加速腐蚀效应。发现一个临界pH值,pH≌1.3([Cl~-]≌1.5M),当pH降至低于临界值以下时腐蚀率加速上升。在裂缝或蚀孔的引发阶段,外部电位需要超过临界破裂电位,以引起蚀孔或缝隙内的pH下降和Cl~-浓集。但当闭塞区pH下降到临界值以下后,腐蚀的加速过程和裂缝(或蚀孔)的扩展则由缝内H+Cl~-酸性电池的作用所控制。并将导致裂尖区氢脆。
The effect of accelerated corrosion on 18-8 stainless steel in the corrosion of pores, cracks or stress corrosion cracking in Cl ~ - solution was studied by using simulated occlusion zone solution. A critical pH of 1.3 was found ([Cl ~ -] ≌1.5M) and the corrosion rate increased rapidly as the pH dropped below the critical value. During the initiation phase of cracks or pits, the external potential needs to exceed the critical rupture potential to cause a drop in pH and Cl ~ - concentration within the pits or gaps. However, when the pH of the occluded zone drops below the critical value, the acceleration of corrosion and the expansion of cracks (or pits) are controlled by the action of the H + Cl ~ -acid cell in the seams. And will lead to hydrogen cracking in the crack area.