Reliability Salt Spray Test Explanation

Project Introduction

Salt spray test is an environmental test that mainly uses artificial simulated salt spray environment 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 the natural environment 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 create a salt spray environment in its volume space by artificial methods to evaluate the salt spray corrosion resistance quality of the product. Compared with the natural environment, the salt concentration of chloride in its salt spray environment can be several times or dozens of times that of the general natural environment salt spray content, which greatly increases the corrosion rate and greatly shortens the time to obtain the results of the salt spray test on the product.

Classification of Salt Spray Test

(1) Neutral Salt Spray Test (NSS Test)

It is the earliest and most widely used accelerated corrosion test method. It uses a 5% sodium chloride salt solution with a pH value adjusted to a neutral range (6-7) as the spray solution. The test temperature is 35℃, and the salt spray sedimentation rate is required to be between 1 and 2ml/80cm2.h.

(2) Acetic acid salt spray test (AS S 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, so that the solution becomes acidic, and the salt spray formed finally changes from neutral salt spray to acidic. Its corrosion rate is about 3 times faster than that of NSS test.

(3) Copper salt accelerated acetic acid salt spray test (CASS test)

It is a fast 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 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 a constant humidity test. It is mainly used for cavity-type complete products. Through the penetration of the humid environment, salt spray corrosion occurs not only on the surface of the product, but also inside the product. It alternately switches the product under salt spray and humid heat conditions, and finally assesses whether the electrical and mechanical properties of the complete product have changed.

Test method

Test item: Salt mist test

Reference standard: 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: pH value is adjusted in the neutral range (6.5-7.2), the test temperature is 35°C)

Acetate spray test (AS S test) (solution: add some glacial acetic acid, the pH value drops to about 3)

Copper salt accelerated acetate spray test (CASS test) (test temperature is 50°C, a small amount of copper salt-copper chloride is added to the salt solution)

Test time: 16H (minimum)

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