Can Ndfeb magnet plating of nickel withstand salt spray test for 72 hours?
Publish Time: 2024-09-05 Origin: Site
Salt spray corrosion is a common and most destructive atmospheric corrosion, the salt spray here refers to the atmosphere containing chloride (mainly sodium chloride), it mainly comes from the ocean and inland saline areas.
Chloride ion through the metal surface oxide layer and protective layer and internal metal electrochemical cause metal corrosion, at the same time, chloride ion contains certain hydration energy, easy to be adsorbed in the surface of the metal pores, cracks and replace the oxide layer, the insoluble oxide into soluble chloride, the passivation surface into lively surface, cause very bad adverse reactions to the product.
Salt spray test is a kind of environmental test that mainly uses the environmental conditions of salt spray created by salt spray test equipment to assess the corrosion resistance of products or metal materials. It is divided into two kinds of neutral salt spray and acid salt spray.
The difference lies in the different standards and test methods, also known as "NSS" and "CASS" test. The neutral salt spray test of sintering Ndfeb adopts continuous spray test according to the national standard. The test conditions are: 35℃± 2℃, 5% ± 1% NaCl solution (mass fraction), the pH of the collected salt spray settling solution is between 6.5 and 7.2, the sample placement Angle affects the test results, and the tilt angle of the sample surface placed in the salt spray box is 45 °± 5°.
The salt spray test has 24H, 48H, 72H, etc., and will also meet the different salt spray duration according to the actual demand of the product. In the process of the experiment, the coating is darkened and blackened, and it is qualified, and the phenomenon of yellow rust, foaming, crack, falling off and powder is unqualified.
Plating protection method is the most important method to improve the corrosion resistance of NdFeB magnet, and it is also the most effective method for practical application. The corrosion protection layer coated outside the magnet is mainly metal coating represented by Ni, Zn, Al and epoxy resin.
Considering cost, corrosion resistance and mass production, NdFeB magnet is nickel, which is desirable.
However, some customers will ask when choosing a magnet for nickel plating to pass the 48-hour salt spray test. I need a salt spray resistance test for longer, like 72 hours. Can nickel plating be achieved?
To be honest, nickel is difficult. Some customers have high requirements for salt spray resistance and acid and alkali resistance, such as 72 hours resistance. At this time you can choose Parin coating, more secure.
Some people still have questions, why not recommend the use of epoxy?
Salt spray resistance for 72 hours, nickel plating and epoxy are not guaranteed, so they are not recommended.
How long is the salt spray test time equivalent to the field use? According to the data display:
Neutral salt spray test for 24h ⇌ natural environment for 1 year
Acetate salt spray test for 24h ⇌ natural environment for 3 years
Copper salt accelerated acetate spray test for 24h ⇌ natural environment for 8 years
If you have any questions about salt spray test, you are welcome to contact us.