Know more the salt spray test chamber(2/3)

Introduction of salt spray corrosion chamber:

I.Corrosion is the destruction or deterioration of a material or its properties under the action of the environment. Most of the corrosion occurs in the atmospheric environment, and the atmosphere contains corrosive components and corrosion factors such as oxygen, humidity, temperature changes and pollutants. Salt spray corrosion is a common and most destructive atmospheric corrosion. The salt spray here refers to the atmosphere of chloride, the main corrosive component of which is the chloride salt in the ocean - sodium chloride, which mainly comes from the sea and the saline-alkali areas in the interior. The corrosion of salt spray on the surface of metal material is caused by the electrochemical reaction of chloride ions through the oxide layer and protective layer of the metal surface with the inner metal. at the same time, the chloride ion contains a certain hydration energy, which is easy to be adsorbed on the pores of the metal surface, the cracks crowd out and replace the oxygen in the chloride layer, the insoluble oxide becomes soluble chloride, and the passivated surface becomes active surface. causing extremely bad reactions to the product. 
                                                
II.Salt spray test is a kind of environmental test which mainly uses the artificial simulated salt spray environment conditions created by salt spray test equipment to assess the corrosion resistance of products or metal materials. It is divided into two categories, one is natural environmental exposure test, the other is artificial accelerated simulated salt spray environmental test. Artificial simulation of salt spray environment test is to use a kind of test equipment with a certain volume space, salt spray test box, in its volume space with artificial method, resulting in salt spray environment to assess the quality of salt-tolerant fog corrosion performance of the product. Compared with the natural environment, the salt concentration of chloride in its salt spray environment can be several times or several times of the salt spray content in the general natural environment, which greatly improves the corrosion rate, and carries out salt spray test on the product, and the time to get the result is also greatly shortened. If a product sample is tested in a natural exposed environment, the corrosion of the product may take 1 year, and the similar results can be obtained in the artificial simulated salt spray environment for only 24 hours.
                                                   
Artificial simulated salt spray test also includes neutral salt spray test(NSS), acetate salt spray test(ASS), copper accelerated salt spray test(CASS), alternating salt spray test. 
1. The neutral salt spray test (NSS test) is one of the most widely used accelerated corrosion test methods. it uses a 5% sodium chloride saline solution with the solution ph adjusted in the neutral range (6-7) as a solution for spray. The test temperature is all taken at 35°C, and the settlement rate of salt spray is between 1~2 ml /80 cm2.h.
                         
2.Acetate fog test (ASS) was developed on the basis of NSS. It is to add some glacial acetic acid in 5% sodium chloride solution, so that the PH value of the solution is reduced to about 3, the solution becomes acid, and the final salt spray is also changed from neutral salt spray to acid. It corrodes about three times faster than the NSS test. 

3.The copper accelerated acetate salt spray test (CASS)) is a fast salt spray corrosion test recently developed abroad. the test temperature is 50°c and a small amount of copper salt-cobal chloride is added to the salt solution, which strongly induces corrosion. its corrosion rate is about 8 times that of the nss test. 

4.Alternating salt spray test is a comprehensive test, which is actually neutral salt spray test plus constant humidity and heat test. It is mainly used in the whole products, through the penetration of the tidal environment, salt spray corrosion not only in the product surface, but also in the product. It is to change the product alternately under the conditions of salt spray and damp heat, and finally check the electrical and mechanical properties of the whole machine.