The salt spray test is divided into two categories, one is the natural environmental exposure test, and the other is the artificial accelerated simulated salt spray environment test. The artificial simulated salt spray environment test uses a test equipment with a certain volume space, the salt spray test chamber, to artificially use the salt spray environment in the volume space to assess the salt spray corrosion resistance quality of the product. .
The artificial simulated salt spray test includes a neutral salt spray test, an acetate salt spray test, a copper salt accelerated acetate spray test, and an alternating salt spray test.
(1) Neutral salt spray test (NSS test) is one of the earliest applications in the field of accelerated corrosion test. It uses a 5% aqueous solution of sodium chloride solution, and the pH of the solution is adjusted to a neutral range (6-7) as a solution for spraying. The test temperature is taken at 35 ° C, and the sedimentation rate of the salt spray is required to be between 1 and 2 ml / 80 cm 2 · h.
(2) The acetate spray test (ASS test) was developed on the basis of a neutral salt spray test. It is to add some glacial acetic acid to the 5% sodium chloride solution, the pH value of the solution is reduced to about 3, the solution becomes acidic, and the salt mist formed finally changes from neutral salt spray to acidity. Its corrosion rate is about 3 times faster than the NSS test.
(3) Copper salt accelerated acetate spray test (CASS test) is a rapid salt spray corrosion test developed recently in foreign countries. The test temperature is 50 ° C. 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 the NSS test.
The specific time is converted to:
Neutral salt spray test 24h ⇌ natural environment 1 year
Acetate spray test 24h ⇌ natural environment 3 years
Copper salt accelerated acetate spray test 24h ⇌ natural environment 8 years