Guangdong ALI Testing Equipment Co,.Ltd

With the rapid development of national industry, technology and economy, the application range of industrial products is more and more wide. In order to ensure the quality and life of the product, many industrial products need to be verified by salt spray corrosion tests, especially automotive products. In recent years, the demand for salt spray testing has been increasing, and many practitioners are confused about how to conduct salt spray testing, how to improve the efficiency of the test and how to choose the standard of salt spray testing. Therefore, this paper systematically introduces what is salt spray test; Types of salt spray tests; Especially, the application of salt spray corrosion test in automobile industry is introduced.
Introduction
Due to the presence of salt spray in the natural environment, salt spray corrosion is one of the most common and destructive atmospheric corrosion. The chloride ions in the salt spray will penetrate the oxide layer and protective layer on the surface of the metal material, and have an electrochemical reaction with the internal metal, thereby destroying the surface of the metal material and its properties, and then further affect and damage the product through the pores and cracks on the metal surface.If you need more models about our test equipment, please reference our chamber-testing（.）com 

Salt spray test is a laboratory simulation of atmospheric salt spray in the environment, which has the characteristics of standardization and acceleration. Compared with the natural environment, the salt concentration of chloride in the salt spray test equipment is usually several times or even dozens of times the salt spray content in the natural environment. Therefore, the corrosion rate is greatly improved, and the corrosion state of salt spray exposed to natural environment for 1 year can be completed in 24 hours under artificial simulated salt spray test environmental conditions, and accurate results can be obtained

Types of salt spray tests
Neutral salt spray test
Neutral salt spray test (NSS test) is the earliest and most widely used accelerated corrosion test method. It uses 5% sodium chloride brine solution, the solution PH adjusted to the neutral range (6.5-7.2) as a spray solution. The test temperature is 35℃, and the salt spray sedimentation rate is required to be 1~2mL/80cm/h.
Acetate spray test
The acetate spray test (ASS test) was developed on the basis of the neutral salt spray test. Is to add some glacial acetic acid to 5% sodium chloride solution, so that the pH value of the solution is reduced to about 3, the solution becomes acidic, and finally the salt spray formed by the neutral salt spray becomes acidic. The corrosion rate is about 3 times faster than the NSS test.
Copper salt accelerated acetate salt spray test
Copper accelerated acetate spray test (CASS test) is a recently developed rapid salt spray corrosion test. The test temperature is 50℃. Adding a small amount of copper salt - copper chloride in salt solution can strongly induce corrosion. The corrosion rate is about 8 times that of NSS test.
Alternating salt spray test
Alternating salt spray test is a comprehensive salt spray test, that is, salt spray, dry, wet and hot (soaking, wet and condensation, etc.) test conditions are combined and cycled to simulate the actual application environment of the product. Through the penetration of the tidal environment, the salt spray corrosion not only occurs on the surface of the product, but also occurs inside the product.
 
Test method item Neutral salt spray（NSS） Acetate spray（ASS） Copper salt accelerated acetate salt spray（CASS）
temperature 35C+/-2C 35C+/-2C 50C+/-2C
Average settlement 15ML/H+/-0.5ML/H 15ML/H+/-0.5ML/H 15ML/H+/-0.5ML/H
Sodium chloride concentration 50g/L+/-5g/L 50g/L+/-5g/L 50g/L+/-5g/L
PH 6.5 to 7.2 3.1 to 3.3 3.1 to 3.3
Standard method for circulating salt spray for automotive materials
The automotive industry is one of the first industries to use cyclic salt spray test as a means of evaluating product reliability. Basically, major automobile manufacturers have their own cyclic salt spray test standards,