Salt Spray Testing (One)

Salt Spray Testing (One)

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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. Many products will shorten their service life after corrosion. Products from hand tools to bridges must be properly designed and coated to deal with this phenomenon.


Corrosion is the destruction or deterioration of materials or their properties under the action of the environment. Most corrosion occurs in the atmospheric environment, which contains corrosion components and corrosion factors such as oxygen, humidity, temperature change and pollutants. Salt spray corrosion is one of the most common and destructive atmospheric corrosion. The corrosion of salt spray on the surface of metal materials is caused by the electrochemical reaction between the contained chloride ions penetrating the oxide layer and protective layer on the metal surface and the internal metal. At the same time, chloride ion contains a certain hydration energy, which is easy to be squeezed out by the pores and cracks adsorbed on the metal surface and replace the oxygen in the oxide layer, turn the insoluble oxide into soluble chloride, and turn the passive surface into an active surface.  

Test Classification


a. Neutral Salt Spray Testing

Neutral salt spray test is one of the earliest and most widely used accelerated corrosion test methods. Under normal circumstances, it uses 5% NaCl solution and the pH value is adjusted to neutral range (6.5 to 7.2) as a spray solution. The test temperature is 35 ℃, and the sedimentation rate of salt spray is required to be 1 ~ 3ml / 80cm2 H, the settlement is generally 1 ~ 2ml / 80cm2 H.

b.Acetate Mist

Acetate spray test 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.

c. Copper Salt Accelerated Acetate Spray

Copper salt accelerated acetate spray test 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.

d.Alternating Salt Spray

Alternating salt spray test 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.

This article mainly introduces the definition of salt spray test and corrosion, as well as the classification of salt spray test. The next article will introduce the standards of salt spray test and the steps of salt spray test. If you are interested in this topic, you can follow us, or you are welcome to contact us if you have any comments.

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