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In recent years VACUUMSCHMELZE's development engineers have succeeded in greatly reducing the corrosion rate of Nd-Fe-B magnets in warm and damp environments by replacing the especially reactive Nd-rich structural components with intermetallic compounds containing Co, which are much better in terms of electrochemistry.

The magnets of the 8xx series concurrently have a remanence about 4 % higher than VACODYM® 6xx.

In addition to the magnetic properties, such as remanence, energy density and coercitivity field strength, the corrosion stability of Nd-Fe-B magnets in particular is decisive for the reliable functioning of magnet systems.

VACODYM 6xx / 8xx
conventional Nd-Fe-B

Corrosion behavior of Nd-Fe-B magnets in climate test (HAST, 130°C, 2,7 bar, 95 % moisture)

In the case of conventional Nd-Fe-B magnets, the Nd-rich structural components gradually react at increased temperatures with water vapour from the surroundings. This leads to the swelling of these structural components and ultimately to the powdery disintegration of these magnets. To date, this type of corrosion could be prevented only by an adequately dense coating or encapsulation of the magnet.

Weight loss in the climate test (HAST, 130 °C, 2,7 bar, 95 % moisture)

After 10 days' ageing in a Highly Accelarated Stress Test (HAST, 130 °C, 95 % moisture) these magnets of the VACODYM 6XX and 8XX range suffer a weight loss up to 1000x lower in comparison to conventional magnets. In many cases, these magnets can now be used completely without coating. Only in the case of direct water contact or if aggressive chemicals are used the use of one of our tried and tested coatings is being advised.

More information is available in the sections

 Publications   or Skills.

Last update: 29.04.2014


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