Archives of Metallurgy and Materials

Institute of Metallurgy and Materials Science of Polish Academy of Sciences
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MULTISTEP HEAT-TREATMENT EFFECTS ON ELECTROSPUN Nd-Fe-B-O NANOFIBERS

  • EUN JU JEON (KOREA INSTITUTE FOR RARE METALS, KOREA INSTITUTE OF INDUSTRIAL TECHNOLOGY) ;
  • NU SI A. EOM (KOREA INSTITUTE FOR RARE METALS, KOREA INSTITUTE OF INDUSTRIAL TECHNOLOGY) ;
  • JIMIN LEE (FUSION CHEMISTRY ENGINEERING, HANYANG UNIVERSITY) ;
  • BIN LEE (KOREA INSTITUTE FOR RARE METALS, KOREA INSTITUTE OF INDUSTRIAL TECHNOLOGY) ;
  • HYE MI CHO (KOREA INSTITUTE FOR RARE METALS, KOREA INSTITUTE OF INDUSTRIAL TECHNOLOGY) ;
  • JI SUN ON (KOREA INSTITUTE FOR RARE METALS, KOREA INSTITUTE OF INDUSTRIAL TECHNOLOGY) ;
  • YONG-HO CHOA (FUSION CHEMISTRY ENGINEERING, HANYANG UNIVERSITY) ;
  • BUM SUNG KIM (KOREA INSTITUTE FOR RARE METALS, KOREA INSTITUTE OF INDUSTRIAL TECHNOLOGY)
  • Published : 20180000
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Abstract

Neodymium-Iron-Boron (Nd-Fe-B) magnets are considered to have the highest energy density, and their applications include electric motors, generators, hard disc drives, and MRI. It is well known that a fiber structure with a high aspect ratio and the large specific surface area has the potential to overcome the limitations, such as inhomogeneous structures and the difficulty in alignment of easy axis, associated with such magnets obtained by conventional methods. In this work, a suitable heat-treatment procedure based on single-step and multistep treatments to synthesize sound electrospun Nd-Fe-B-O nanofibers of Φ572 nm was investigated. The single-step heat-treated (directly heat-treated at 800℃ for 2 h in air) samples disintegrated along with the residual organic compounds, whereas the multistep heat-treated (sequential three-step heat-treated including three steps;: dehydration (250℃ for 30 min in an inert atmosphere), debinding (650℃ for 30 min in air), and calcination (800℃ for 1 h in air)) fibers maintained sound fibrous morphology without any organic impurities. They could maintain such fibrous morphologies during the dehydration and debinding steps because of the relatively low internal pressures of water vapor and polymer, respectively. In addition, the NdFeO3 alloying phase was dominant in the multistep heat-treated fibers due to the removal of barriers to mass transfer in the interparticles.

Keywords

Acknowledgement

This study has been performed with the support of Korea Institute of Industrial Technology titled "Development of one-dimensional FeNdB exchange coupling magnets manufacturing technology (PUR 17240)"