Effect of Dysprosium-Compounds Treatment on Coercivity of Nd-Fe-B Sintered Magnets

Title:Effect of Dysprosium-Compounds Treatment on Coercivity of Nd-Fe-B Sintered Magnets

Volume: 10 Issue: 1

Author(s): Dhani Ram Dhakal, Seok Namkung, Min-Woo Lee and Tae-Suk Jang

Affiliation:

Keywords: Coating, coercivity, Dy-saving, grain boundary diffusion, Nd-Fe-B magnets, rare earth metals.

Abstract: In order to find an effective method to increase the coercivity of Nd-Fe-B magnets using less Dy quantity, an ordinaryprocessed Nd-Fe-B sintered magnet was treated with dysprosium-compound suspension in this work. After the magnets were prepared by a normal sintering process, they were cut into the size of 10x10x5 mm³ pieces and then dipped in 20 % DyF₃ suspension and 20 % DyH_x suspension, for one minute, so that the magnets were coated with the dysprosium compounds. These coated magnets were further subjected to heat treatment. As a consequence, coercivity of the coated magnets was increased over 255 kAm^-1 for Dy-contained one and 243 kAm^-1 for Dy-free one without noticeable reduction in the remanence and the energy product values. This improvement of the coercivity was due to Dy diffusion along grain boundaries from the surface of the coated magnets, thereafter, a partial replacement of Nd in Nd₂Fe₁₄B main grain by Dy had taken place near the grain boundaries, resulting in the increase of anisotropy field in that area.

Cite this article as:

Dhakal Dhani Ram, Namkung Seok, Lee Min-Woo and Jang Tae-Suk, Effect of Dysprosium-Compounds Treatment on Coercivity of Nd-Fe-B Sintered Magnets, Current Nanoscience 2014; 10 (1) . https://dx.doi.org/10.2174/1573413709666131111224235