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What factors will affect the progress of the salt spray corrosion test chamber?

2023/06/07

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Corrosion is the damage or deterioration of materials or their properties under the action of the environment. Most corrosion occurs in the atmosphere, which contains corrosive components and corrosive factors, such as oxygen, humidity, temperature changes, and pollutants.
 
Salt spray corrosion is one of the most common and destructive atmospheric corrosion. Salt spray refers to the atmosphere of chloride, and its main corrosion component is sodium chloride. Salt spray corrosion on the surface of metal materials is caused by the electrochemical reaction between chloride ions penetrating the oxide layer and protective layer of the metal surface and the internal metal.
salt spray chamber
The salt spray corrosion test chamber is used to test the reliability of the tested samples through salt spray corrosion. Salt spray refers to a diffusion system composed of tiny salt-containing droplets in the atmosphere. It is one of the three-proof series for artificial environments. However, the salt spray corrosion test chamber also has some influencing factors during the experiment, mainly in the following points.
 
1. Test temperature and humidity
 
Temperature and relative humidity will affect the corrosion of salt spray. The critical relative humidity of metal corrosion is about 70%; when the relative humidity reaches or exceeds the critical humidity, the salt is easy to deliquesce and produce an electrolyte with good conductivity. When the relative humidity decreases, the solution The concentration will increase, and the corrosion rate will decrease accordingly, until the crystalline salt precipitates.
 
2. Salt solution concentration
 
The base material, coating type and salt solution concentration have a great influence on the corrosion rate. When the concentration is less than 5%, the corrosion rate of steel, nickel and brass increases with the increase of concentration; when the concentration is greater than 5%, The corrosion rate of these metals decreases with increasing concentration.
 
3. The pH value of the solution
 
The pH value of the salt solution has a great influence on the efficiency of salt spray corrosion. The lower the concentration of hydrogen ions, the stronger the acidity and the stronger the corrosion; due to environmental factors, the pH value of the solution will change. Therefore, the salt spray test standards at home and abroad stipulate the pH range of the salt solution, and under stable test conditions, the pH value of the solution that improves the reproducibility of the salt spray test results is proposed.
 
4. The angle of view of placing the sample
 
The viewing angle of placing the sample has a significant impact on the results of the salt spray test, and the settlement direction of the salt spray corrosion test chamber is close to the vertical direction. When the sample is placed horizontally, its expansion area is the largest, and the amount of salt spray on the surface of the sample is large, so the corrosion is very serious.

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