Crack corrosion of the Great Wall network is mainly due to the existence of cracks in the media caused by electrochemical non-uniformity, so the protection of crevice corrosion, the main reference to the following aspects:
1, rational design, to avoid the gap. For example: welding is better than riveting; butt welding is better than lap welding; welding time must ensure that quality, to avoid welding; screw joint structure can also be low-sulfur rubber gasket, dense packing, joint surface can be coated with protection. In addition, the design should avoid the water area; maintenance, should be diligent in the clean-up, remove dirt and so on.
2, the design can not be avoided when the gap can be cathodic protection. For example, in seawater, the use of sacrificed zinc or magnesium pole. However, to take this approach, we should pay attention to hydrogen embrittlement.
3. As the corrosion inhibitor is more difficult to enter the gap, it can be painted on the joint surface with corrosion inhibitor, for example, the use of steel with PbCrO4 paint for aluminum, the use of paint with added ZnCrO4; Metal sheet, can be impregnated with vapor-phase corrosion inhibitor packaging paper separated.
4, use the appropriate material, for some important parts, you can switch to a strong anti-crevice corrosion materials, such as high-chromium high-molybdenum stainless steel.