What is the salt spray test mainly for? Professional third-party testing agency

Date：2022-11-25 16:32:05Views：541

Salt spray test is an environmental test that mainly uses artificial 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 natural environmental exposure test, the other is artificial accelerated simulated salt spray environmental test. The artificial simulated salt spray environment test is to use a kind of test equipment with a certain volume space - salt spray test chamber, and use manual methods in its volume space to create a salt spray environment to assess the quality of salt spray corrosion resistance of products.

Salt spray corrosion will destroy the metal protective layer, making it lose its decorative property and reduce the mechanical strength; Some electronic components and electrical circuits are interrupted due to corrosion, especially in the environment with vibration; When the salt spray falls on the insulator surface, the surface resistance will be reduced; After the insulator absorbs the salt solution, its volume resistance will decrease by four orders of magnitude; The moving parts of mechanical parts or moving parts increase friction due to the generation of corrosives, which may cause the moving parts to be stuck. Chloride ions play a major role in the process of salt spray corrosion damage. It has a strong penetration ability, easy to penetrate the metal oxide layer into the metal interior, and destroy the metal passivity. At the same time, chloride ions have very small hydration energy and are easily adsorbed on the metal surface, replacing the oxygen in the oxide layer protecting the metal and damaging the metal.

The salt spray test can atomize the brine of concentration; Then spray it into a closed constant temperature box, and reflect the corrosion resistance of the tested sample by observing the change of the tested sample after being placed in the box for a period of time. It is an accelerated test method. The salt concentration of chloride in the salt spray environment is several times or dozens of times of the salt spray content in the general natural environment, which greatly increases the corrosion rate and shortens the time for the product to obtain results through the salt spray test.

The artificial simulated salt spray test includes

1) Neutral salt spray test (NSS test), using 5% sodium chloride saline solution, solution PH

Adjust the value to the neutral range (6-7) solution. The test temperature is 35 ℃, and the settling rate of salt spray is 1~2ml/80cm H.

2) The acetate spray test (ASS test) is to add some glacial acetic acid into the 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 after that also changes from neutral salt spray to acidic. Its corrosion rate is about 3 times faster than that of NSS test.

3) The copper salt accelerated acetate spray test (CASS test) is a fast salt spray corrosion test. The test temperature is 50 ℃. A small amount of copper salt copper chloride is added to the salt solution to strongly induce corrosion.

Salt spray test standard and determination of test results

The salt spray test standard specifies the salt spray test conditions, such as temperature, humidity, concentration of sodium chloride solution, PH value, etc. In addition, it also puts forward technical requirements for the performance of the salt spray test chamber. The salt spray test standard for the same product shall be selected according to the characteristics of salt spray test, the corrosion rate of metal and the sensitivity to salt spray.

The function of salt spray test is to assess the salt spray corrosion resistance quality of products or metal materials. The judgment of salt spray test results is the judgment of product quality. Whether the judgment results are correct and reasonable is the key to correctly measure the salt spray corrosion resistance quality of products or metals.

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