National University of Science and Technology “MISiS”, Moscow, Russia:

V. P. Tarasov, Professor, Head of the Department of Non-Ferrous Metals and Gold
E. S. Gorelikov, Deputy Director of Engineering Center and Industrial Technology
A. V. Kutepov, Chief Engineer of Engineering Center and Industrial Technology
O. V. Khokhlova, Assistant of Department of Non-Ferrous Metals and Gold, e-mail: hohlova.oksana.v@gmail.com

Nowadays permanent magnets of Nd – Fe – В system are widely used in various branches of production. The trend has been toward increase of the world consumption of the magnets in the making of advanced technology gadgets (smartphones, navigators, television sets, and computers). However, this magnet material can not be always applied in the special-purpose devices because of its low corrosion resistance and poor temperature stability. To elongate service life of the magnets it is necessary to deposit a protective coating based on nickel, zinc, copper as well as on the combination of other substances (phosphate, epoxy resin). The given paper is dedicated to the results of implemented comparative research of corrosion resistance of permanent magnets made of magnetically hard material based on Nd – Fe – В alloy both with metallic anticorrosive coat and without it in a magnetized and non-magnetized state. It has been found that the inherent magnetization influence on the corrosion resistance of PM made of Nd – Fe – В MHM both with metallic anticorrosive coat and without it are of an opposite nature. The corrosion resistance of the samples without coating in the magnetized state has increased by 12%. At the same time, the corrosion resistance of Zn- and Ni-coated samples in the magnetized state has decreased by 40–45%. It is determined that the coating-free magnets are better to be stored and transported in the magnetized condition while the magnets protected by metallic anticorrosive coats need to be stored in the non-magnetized condition.

"This article was prepared within the framework of the Agreement No.1/2015 of July 28, 2015 between the “MISiS” and “RPA Magneton” Stock Company, realized with the financial support according to the Resolution of the Government of the Russian Federation No. 218 dated April 09, 2010”."

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