How Many Salt Spray Tests Are There?
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The salt spray tester simulates salt spray environment to assess the corrosion resistance of products or metal materials.
The salt spray test is divided into two kinds, one is the natural environment exposure test, and the other is the artificial accelerated simulated salt spray test.
There are 4 kinds of salt spray tests:
(1) NSS test
The neutral salt spray test (NSS test) is one of the earliest accelerated corrosion test methods with the widest application field. It uses 5% sodium chloride salt aqueous solution, the pH value of the solution is adjusted in the neutral range (6-7) as the spray solution. The test temperature is 35℃, and the sedimentation rate of the salt spray is required to be between 1～2ml/80cm².h.
(2) ASS test
The acetic acid salt spray test (ASS test) is developed on the basis of the neutral salt spray test. It is to add some glacial acetic acid to 5% sodium chloride solution to make the pH value of the solution drop to about 3, the solution becomes acidic, and the salt mist formed finally turns from neutral salt mist to acid. Its corrosion rate is about 3 times faster than the NSS test.
(3) CASS test
Copper salt accelerated acetic acid salt spray test (CASS test) is a kind of rapid salt spray corrosion test recently developed abroad. The test temperature is 50℃, and a small amount of copper salt—copper chloride is added to the salt solution to strongly induce corrosion. Its corrosion rate is approximately 8 times faster than the NSS test.
(4) Alternating salt spray test
The alternating salt spray test is a comprehensive salt spray test, which is actually a neutral salt spray test plus a constant damp heat test. It is mainly used for cavity-type complete products. Through the penetration of the wet environment, the salt spray corrosion is not only generated on the surface of the product, but also inside the product. It is to alternately switch the product under two environmental conditions of salt spray and damp heat, and finally check whether the electrical and mechanical properties of the whole product have changed.
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