When the hardware industry mentioned the product passivation polishing, it is inevitable to say "salt fog test". What is the salt spray test? What are you doing? How important is the salt spray test to the product? Concealed Shower System,Recessed Shower System,Concealed Rain Shower System,Stainless Steel Thermostatic Rain Shower kaiping aida sanitary ware technology co.,ltd , https://www.aidafaucet.com
Basic knowledge and importance of product salt spray testing
When the hardware industry mentioned the product passivation polishing, it is inevitable to say "salt fog test". What is the salt spray test? What are you doing? How important is the salt spray test to the product?
I will explain the salt spray test to everyone now.
The salt spray test is an environmental test that uses 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 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. . Compared with the natural environment, the salt concentration of the chloride in the salt spray environment can be several times or several times higher than the salt spray content of the general natural environment, so that the corrosion rate is greatly improved, and the product is subjected to a salt spray test to obtain a result. The time is also greatly shortened. If a product sample is tested in a natural exposure environment, it may take 1 year to corrode, and in a simulated simulated salt spray environment, as long as 24 hours, similar results can be obtained.
After reading some of the above literature, everyone has a general understanding of the salt spray test! Then let me talk about the mechanism and factors of corrosion.
Corrosion is the destruction or deterioration of a material or its properties caused by the environment. Most of the corrosion occurs in the atmosphere, which contains corrosive components and corrosive factors such as oxygen, humidity, temperature changes, and pollutants. Salt spray corrosion is a common and most destructive atmospheric corrosion. The corrosion of the surface of the metal material by the salt spray is caused by the electrochemical reaction between the oxide layer containing the chloride ions penetrating the metal surface and the protective layer and the internal metal. At the same time, chloride ions contain a certain hydration energy, which is easily adsorbed on the pores of the metal surface, and the cracks are displaced and replace the oxygen in the chlorinated layer, turning the insoluble oxide into a soluble chloride, making the passivated surface active. surface. Causes a bad reaction to the product.
There are several types of salt spray tests:
The artificial simulated salt spray test includes a neutral salt spray test, an acetate spray test, a copper salt accelerated acetate spray test, and an alternating salt spray test.
So which test do we choose for our products? It depends on the requirements of your customers, the general requirements of customers, we can choose the neutral salt spray test, strict requirements, we choose the acetate spray test.
Now our company also has internationally popular copper salt to accelerate the acetate spray test.
Then let me talk about a few standard parameters of the neutral salt spray test:
In general, it uses a 5% aqueous solution of sodium chloride salt, and the pH of the solution is adjusted to a neutral range (6.5 to 7.2) 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 3 ml / 80 cm 2 · h, and the sedimentation amount is generally between 1 and 2 ml / 80 cm 2 · h.
Basic requirements for the acetate spray test:
It was developed on the basis of the 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 spray finally formed is also changed from neutral salt spray to acid. Its corrosion rate is about 3 times faster than the NSS test.
Copper salt accelerated acetate spray test requirements:
This test is a rapid salt spray corrosion test developed recently in foreign countries. The test temperature is 50 °C, 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 the NSS test.
Alternating salt spray experiment
It is a comprehensive salt spray test, which is actually a neutral salt spray test plus a constant damp heat test. It is mainly used for cavity-type machine products. Through the penetration of the tidal environment, salt spray corrosion is generated not only on the surface of the product but also inside the product. It converts the product alternately under the two conditions of salt spray and hot and humid, and finally checks whether the electrical and mechanical properties of the whole product are changed.
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