Views: 4 Author: Site Editor Publish Time: 2019-12-19 Origin: Site
The 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.
The salt spray test standard is a clear and specific stipulation of the salt spray test conditions, such as temperature, humidity, sodium chloride solution concentration, and PH value. In addition, it also puts forward technical requirements for the performance of the environmental chamber. The salt spray test standard of the same product should be selected according to the characteristics of the salt spray test, the corrosion rate of the metal, and the sensitivity to the salt spray.
The purpose of salt spray test is to assess the salt spray corrosion resistance quality of products or metal materials, and the result of salt spray test is the best way to judge the quality of product. Whether the judgment results are correct and reasonable is the key to correctly measure the salt spray corrosion resistance quality of products or metals.
The judgment methods of salt spray test results include: rating judgment method, weighing judgment method, corrosion appearance judgment method, and corrosion data statistical analysis method.
1. The Rating Judgment Method
The rating judgment method is to divide the percentage of the corrosion area ratio to the total area into several levels according to a certain method. And it uses a certain level as the basis for passing the determination. It is suitable for the evaluation of flat plate samples.
2. The Weighing Judgment Method
The weighing judgment method is a method of weighing the sample before or after the corrosion test and calculating the weight of the corrosion loss to judge the corrosion resistance of the sample. It is particularly suitable for evaluating the corrosion resistance of a certain metal.
3. The Corrosion Appearance Judgment Method
The corrosion appearance judgment method is a kind of qualitative determination method. It judges the samples by whether the products produce corrosion after salt spray corrosion test. This method is mostly used in general product standards.
4. The Corrosion Data Statistical Analysis Method
The corrosion data statistical analysis method provides a method to design corrosion test, analyze corrosion data and determine the confidence degree of corrosion data. It is mainly used for analysis and statistics of corrosion, rather than specific quality judgment of a specific product.
There are three kinds of salt spray tests: neutral salt spray test (NSS), acetate spray test (AASS) and copper accelerated acetate spray test (CASS), among which neutral salt spray test is widely used. The basic content of the salt spray test is to spray a 5% sodium chloride aqueous solution at 35℃ in an environmental test chamber to simulate the accelerated corrosion method of the seawater environment. The length of its resistance time determines the corrosion resistance.
Compared with the natural environment, the salt concentration of chloride in the artificial simulated salt spray environment can be several times or dozens of times higher than the general natural environment. So it can greatly improve the corrosion rate of the product, and shorten the time to get the result. For this reason, the environmental chamber manufacturers specially designed and manufactured salt spray test chambers to meet the experimental requirements.