Salt Spray Test/Nss/Ass/Cass

1. Salt spray test:
There are three kinds of salt spray test (NSS), acetate salt spray (AASS) and copper salt accelerated acetate spray (CASS) also known as copper chloride acetate spray).
The most widely applied one is the neutral salt spray test. Neutral salt spray test is mainly used for the metal inspection of metal materials and metal coating or non-metal inorganic coating on metal, and also used to test the coating system. In contrast, acetate spray and copper accelerated acetate spray are generally used only for metal plating but not for organic cladding.
The purpose of salt spray test is to assess the corrosion quality of salt spray resistance of products or metal materials, and the judgment of salt spray test results is the main evaluation factor of product quality. Whether the judgment result is correct and reasonable is the key to correctly measure the corrosion performance of salt spray resistance of products or coatings. The results of the test include foaming, rust, reduction of adhesion, the spread of corrosion from scratches, etc.
(1) Neutral salt spray test (NSS test) is the earliest and the most widely applied field. It uses a 5% sodium chloride saline solution, solution PHValue is in neutral range (6 to 7) as spray solution. The test temperature is 35ºC, and the settlement rate of salt spray should be 1~2ml / 80cm & sup 2. h between.(2) Acetate salt spray test (ASS test) is developed on the basis of neutral salt spray test. It is to add some glacial acetic acid in the 5% sodium chloride solution, so that the PH value of the solution is reduced to about 3, the solution becomes acid, and the salt mist formed finally also changes from the neutral salt spray to acid. Its corrosion rate is about three times faster than the NSS test.(3) Copper salt accelerated acetate spray test (CASS test) is a newly developed rapid salt spray corrosion test abroad, the test temperature is 50ºC, the salt solution with a small amount of copper salt-copper chloride, strongly induced corrosion. It corroded about eight times faster than the NSS.(4) alternating salt spray test is a kind of comprehensive salt spray test, it is actually neutral salt spray test plus constant damp heat test. It is mainly used in the cavity type of the whole machine products, through the penetration of the tidal environment, the salt spray corrosion not only on the surface of the product, but also inside the product. It is the product in the salt fog and hot and humid two environmental conditions alternately conversion, and the final assessment of the electrical performance and mechanical performance of the whole product have changed.