Corrosion tests

The various types of magnets significantly differ in their resistance to corrosion - see picture.

To improve the corrosion resistance especially of FeNdB magnets different finishes are used.
For testing the corrosion resistance there are two basic tests: salt spray (Salt Spray Test - ISO 9227:2006) and vapor pressure test (Pressure Cooker Test, Autoclave Test - IEC68-2-66). Tests are carried out in a closed corrosive chamber at the following conditions:
 

Salt spray test

Temperature: 35 oC (±2 oC)
Concentration: 5%±0.1% NaCl
pH: 6,6 – 7,2
Exposure time: 24 - 72 hours depending on the type of finish (see finish)
Evaluation criterion: Sample with no visible signs of corrosion
 

Test in a pressure steam

Temperature: 125°C (±5°C)
Relative humidity: 100 %
Pressure: 270 kPa (absolute)
Exposure time: 7 days
Evaluation criterion: Loss of sample up to 5 mg/cm².