Salt spray test

Salt spray corrosion is a common and most destructive atmospheric corrosion.

Salt spray test is an environmental test that mainly uses artificially simulated salt spray environmental 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 the natural environment exposure test, and the other is the artificial accelerated simulated salt spray environment test. The artificial simulated salt spray environment test is to use a kind of test equipment with a certain volume space-the salt spray test box, in its volume space, artificial methods are used to create a salt spray environment to assess the quality of the salt spray corrosion resistance of the product . Compared with the natural environment, the salt concentration of chloride in the salt spray environment can be several or tens of times the salt spray content of the general natural environment, which greatly increases the corrosion rate. The salt spray test of the product is carried out and the result is obtained The time is also greatly shortened.

The artificial simulated salt spray test includes neutral salt spray test, acetic acid salt spray test, copper salt accelerated acetic acid salt spray test, and alternating salt spray test.

Guideline:

GB/T 2423.17; IEC 60068-2-11; GB/T 10125; ISO 9227; ASTM B 117;

GB.T 2423.18; IEC 60068-2-52; ASTM B 368; MIL-STD-202; EIA-364-26

(1) Neutral salt spray test (NSS test)

It is the earliest and most widely used accelerated corrosion test method. 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) Acetate spray test (ASS test)

It was 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) Copper salt accelerated acetic acid salt spray test (CASS test)

It is a kind of rapid salt spray corrosion test recently developed abroad. The test temperature is 50℃. 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 that of the NSS test.

(4) Alternating salt spray test

It 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.

Test item: Salt mist Test

Reference standard: IEC60068-2-11 (GB/T2423.17), ISO 4628.3, ASTM B117, JIS-Z2371...

Common test parameters:

Salt fog can be divided into three categories:

Neutral salt spray test (NSS test) (solution: PH value is adjusted in the neutral range (6.5～7.2), the test temperature is 35℃)

Acetic acid salt spray test (ASS test) (solution: add some glacial acetic acid, the PH value drops to about 3)

Copper salt accelerated acetic acid salt spray test (CASS test) (test temperature is 50℃, and a small amount of copper salt-copper chloride is added to the salt solution)

Test time: 16H (minimum)