Protocol for corrosion testing and for mechanical testing

Protocol for corrosion testing

A study has been carried out to map the relevant testing methods for corrosion resistance of magnetic material/components. The neutral salt fog test (NSS) (DS/EN ISO 9227:2006), the water vapour test (DS/EN ISO 6270-2:2005) and the electrochemical test (ASTM G59 - 97(2009)) are the most simple and effective ways of testing the corrosion resistance of uncoated and coated permanent magnets. The Figure shows three stages of corrosion of a coating ring Nd-magnet from salt spray testing (0 h, 240 h and 500 h).

Protocol for mechanical testing

Magnetic materials, such as e.g. NdFeB, are currently not considered a structural material and no dedicated mechanical testing standards apply. Relevant testing can be performed in a tensile testing machine according to ASTM D638 (plastic) or DS/EN ISO 6892-1 (metals).

An often used mechanical characterization method is the "pull-off test", which may be carried out according to the "Magnet Distribution and Fabrication Association" procedure description MDFA-101-95.

Based on the observed increased industrial use and potential use of magnetic materials, we expect within 2-5 years to see new procedures reg. standardized testing to evolve owing to the increased focus on the lifetime of magnetic components/systems.

Contact: Nikolaj Zangenberg, nzg@teknologisk.dk, +45 7220 2494