Effect of surface etching on the magnetic properties and grain-boundary Dy-diffusion in DyH<inf>2</inf>-dip-coated sintered Nd-Fe-B magnets

Ju Young Kong, Tae Hoon Kim, Seong Rae Lee, Hyo Jun Kim, Min Woo Lee, Tae Suk Jang

Research output: Contribution to journalArticle

7 Citations (Scopus)


We investigated the effects of surface etching on the magnetic and microstructural properties of DyH<inf>2</inf>-dip-coated, sintered Nd-Fe-B magnets. When the magnets were dip-coated with DyH<inf>2</inf> solution after their surfaces had been optimally etched in 1 wt% HNO<inf>3</inf> for 50 s, the Dy diffusion depth (~450 μm) improved compared with the values for unetched and DyH<inf>2</inf>-dip-coated etched magnets (~350 μm). In addition, the core-shell microstructure of the dip-coated magnet was well developed by the optimal etching process. As a result, the coercivity of the dip-coated magnet increased by 4.6%. The optimal surface state of the Nd-Fe-B sintered magnet showed minimal surface damage after it was homogeneously etched along the grain boundaries. In contrast, overetched magnets showed kinks on the demagnetization curves because of surface damage. The relationship between the change in the etched magnet surface and the magnetic properties of dip-coated magnets was examined.

Original languageEnglish
Pages (from-to)600-606
Number of pages7
JournalMetals and Materials International
Issue number3
Publication statusPublished - 2015 May 1



  • diffusion
  • grain boundary
  • magnetic materials
  • magnetic properties
  • sintering

ASJC Scopus subject areas

  • Condensed Matter Physics
  • Metals and Alloys
  • Mechanics of Materials
  • Materials Chemistry

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