The Amazing CASS Test
One day in the lab,equals to one year?
When it comes to salt spray test, which is an environmental test that primarily utilizes salt spray test equipment to create an artificially simulated salt spray environment to assess the corrosion resistance performance of products.
Salt spray test classification
There are four main methods of salt spray test: Neutral Salt Spray (NSS), Acetic Salt Spray (AASS), and Copper Accelerated Acetic Salt Spray (CASS)and Alternating Salt Spray Test.
1.The NSS test is the earliest and most widely used accelerated corrosion test method. It uses a 5% sodium chloride saltwater solution with a pH value adjusted to the neutral range (6-7) as the spraying solution. The test temperature is usually set at 35°C, and the salt spray settlement rate is required to be between 1-2ml/(80cm2.h).
Scope of application: metals and alloys, metal coatings, conversion coatings, anodized films, organic coatings on metal substrates.
2.The ASS test is developed based on the NSS test. It involves adding some glacial acetic acid to the 5% sodium chloride solution, lowering the pH value to around 3, and transforming the solution into an acidic state. The resulting salt spray is acidic, and the corrosion rate is approximately three times faster than that of the NSS test.
Scope of application: copper + nickel + chromium or nickel + chromium decorative coating, aluminum anodized film and organic coating.
3.The alternating salt spray test combines various test conditions, including the salt spray test, humidity test, and others. It aims to simulate more realistic and challenging corrosion conditions.
Scope of application: metals and alloys, metal coatings, conversion coatings, anodized films, organic coatings on metal substrates.
4.The CASS test is a relatively new and fast salt spray corrosion test method developed abroad. It is conducted at a temperature of 50°C, and a small amount of copper salt, such as copper chloride, is added to the salt solution. The addition of copper salts significantly accelerates corrosion, resulting in a corrosion rate approximately eight times faster than the NSS test.
Scope of application: copper + nickel + chromium or nickel + chromium decorative coating, aluminum anodized film and organic coating.
The below table, according to GB/T10125-2021 “Artificial Atmosphere Corrosion Test – Salt Spray Test” and related materials, presents a comparison of the four salt spray tests
How long is the salt spray test converted to natural environment time?
Generally speaking, compared with the natural environment in the artificial simulated salt spray environment test, the salt concentration of chloride in the salt spray environment can be several or dozens of times that of the salt spray content in the general natural environment, which greatly increases the corrosion rate and affects the corrosion rate. Products undergo salt spray testing, and the time to obtain results is also greatly shortened. For example, if a product sample is tested in a natural exposure environment, it may take a year for it to corrode, but if tested under artificially simulated salt spray environment conditions, similar results can be obtained in just 24 hours. According to the existing standard conversion (theoretical value) in the industry, the conversion relationship between the 24-hour salt spray test and the natural environment is as follows:
Neutral salt Spray test 24h ⇌ Natural environment 1 year
Acetate salt Spray test 24h ⇌ Natural environment 3 years
Copper salt Accelerated acetate salt spray test 24h⇌ natural environment 8 years
CASS Test Report
Solaracks conducted a CASS test in accordance with the standards of ISO9227:2002 to assess the salt spray corrosion resistance and wear resistance of the anodized film. After 16 hours, the results indicated that the film thickness level was AA10, which exceeds level 9. Additionally, the wear resistance coefficient was greater than 300.Rest assured, our products have successfully passed the rigorous CASS test, showing their remarkable corrosion-resistant properties.
Solaracks is a reputable supplier of solar mounting systems, with more than 12 years of expertise in solar industry, which is known for offering comprehensive one-stop services to EPC partners. Our products are specifically designed to excel in challenging environmental conditions, assuring customers of exceptional performance.
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