Salt spray test is an environmental test that mainly uses the artificial simulated salt spray environmental conditions created by salt spray test equipment to evaluate 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 simulated salt spray environment test is to use a test equipment with a certain volume space - salt spray test chamber to create a salt spray environment by artificial method in its volume space to evaluate the salt spray corrosion resistance and quality of products. Compared with the natural environment, the salt concentration of chloride in the salt spray environment can be several times or dozens of times of the salt spray content in the general natural environment, which greatly improves the corrosion speed. The time to obtain the results of salt spray test on products is also greatly shortened.
Salt spray test classification
(1) Neutral salt spray test (NSS test)
It is the earliest and most widely used accelerated corrosion test method. It uses 5% NaCl solution, and the pH of the solution is in neutral range (6~7) as a spray solution. The test temperature is 35 ℃, and the sedimentation rate of salt spray is required to be between 1 ~ 2ml / 80cm2. H.
(2) Acetate spray test (ASS test)
It is developed on the basis of neutral salt spray test. It is to add some glacial acetic acid to 5% sodium chloride solution to reduce the pH value of the solution to about 3, turn the solution into acid, and finally form a salt mist from neutral salt mist to acid. Its corrosion rate is about 3 times faster than that of NSS test.
(3) Copper salt accelerated acetate spray test (CASS test)
It is a rapid salt spray corrosion test developed recently 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 about 8 times that of NSS test.
(4) Alternating salt spray test
It is a comprehensive salt spray test, which is actually a neutral salt spray test plus constant damp heat test. It is mainly used for cavity type complete machine products. Through the penetration of humid environment, salt spray corrosion occurs not only on the surface of the product, but also inside the product. It is to alternately convert the product under salt fog and humid and hot environmental conditions, and finally check whether the electrical and mechanical properties of the whole product have changed.
test method
Test item: salt mist test
Reference standards: iec60068-2-11 (GB / t2423.17), ISO 4628.3, ASTM B117, jis-z2371
Common test parameters:
Salt spray can be divided into three categories:
Neutral salt spray test (NSS test) (solution: the pH value is adjusted in the neutral range (6.5 ~ 7.2), and the test temperature is 35 ℃)
Acetate spray test (ASS test) (solution: add some glacial acetic acid and the pH value drops to about 3)
Copper salt accelerated acetate spray test (CASS test) (the test temperature is 50 ℃, and a small amount of copper salt copper chloride is added to the salt solution)
Method standard
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
