The Salt Spray Test of Neodymium Magnets

The Neodymium Magnet Test is important for magnet usage because the Neodymium magnet has the disadvantages like being easy to be corroded and oxidized. That is why neodymium magnets all need to be plated. The salt spray test is one of the important tests for the neodymium magnet. The salt spray test of Neodymium Magnets (NdFeB magnets) is an environmental test that mainly uses the artificial simulated salt spray environmental conditions created by the salt spray test equipment to evaluate the corrosion resistance of Neodymium permanent magnet materials. There are mainly three types of neutral salt spray test (NSS), acetic acid salt spray test (ASS), and copper salt acetic acid accelerated salt spray test (CASS).

Types of Salt Spray Tests – Neodymium Magnet Test

Neutral salt spray test

The neodymium magnet test for common magnet applications like magnet fasteners would use the Neutral salt spray test. The neutral salt spray test is to spray saltwater containing (5±0.5)% sodium chloride and a pH value of 6.5-7.2 through a spray device in a specific test box so that the salt spray settles to the test piece to be tested. After a certain period of time, the surface corrosion state was observed. The temperature of the test chamber is required to be (35±2) ℃, the humidity is greater than 95%, the fog reduction volume is 1~2mL/(h·cm2), and the nozzle pressure is 78.5~137.3kPa (0.8~1.4kgf/cm2).

Acetate salt spray testNeodymium Magnet Test

The acetate salt spray test is developed on the basis of the neutral salt spray test. It is to add some glacial acetic acid to the 5% sodium chloride solution so that the pH value of the solution is reduced to about 3, the solution becomes acidic, and the finally formed salt spray also changes from neutral salt spray to acid. Its corrosion rate is about 3 times faster than that of the neutral salt spray test.

Copper salt acetic acid accelerated salt spray test

Copper salt accelerated acetic acid salt spray test is a rapid salt spray corrosion test developed in recent years. The test temperature is 50 °C. A small amount of copper salt – copper chloride is added to the salt solution to strongly induce corrosion. Its corrosion rate is about 8 times that of the neutral salt spray test.

How long is the salt spray test time equivalent to the natural environment time?

Neutral salt spray test 24 hours is about 1 year in a natural environment

Acetic acid salt spray test 24 hours is about 3 years in a natural environment

Copper salt accelerated acetate spray test for 24h is approximately equal to 8 years in a natural environment

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