Corrosion is the damage or deterioration of materials or their properties caused by environmental factors. Most corrosion occurs in the atmospheric environment, which contains corrosive components and factors such as oxygen, humidity, temperature changes, and pollutants.
Salt spray corrosion is a common and destructive atmospheric corrosion. Salt spray refers to the atmosphere containing chlorides, and its main corrosive component is sodium chloride. The corrosion of metal surfaces by salt spray is caused by the electrochemical reaction between chloride ions penetrating the oxide and protective layers on the metal surface and the internal metal. At the same time, chloride ions contain hydration energy and are easily displaced and replaced by oxygen in the chloride layer by pores and cracks adsorbed on the metal surface, turning insoluble oxides into soluble chlorides and transforming passive surfaces into active surfaces, causing adverse reactions to the product.
The salt spray test is divided into natural environment exposure test and artificial simulation environment test. The latter uses a salt spray test chamber to artificially create a salt spray environment in its volume space to assess the quality of the product's salt spray corrosion resistance performance.
Compared with the natural environment, the salt concentration of chloride in its salt spray environment can be several times or tens of times higher than the general natural environment salt spray content, greatly increasing the corrosion rate. The time required to obtain the results of salt spray testing on products is also greatly shortened. If a product sample is tested in a natural exposure environment, it may take up to 1 year for it to corrode, while under artificial simulated salt spray conditions, similar results can be obtained in just 24 hours. However, artificial accelerated simulation experiments are still different from natural environments and cannot be replaced.
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