서강대학교

초록/요약

The nanocomposite permanent magnet with high performance has been a fascinating research project for wide usage in modern industry and technology. For increasing the energy product, bottom-up process by wet chemistry method of exchange coupled nanocomposite magnet with well organized alternative assembly of hard/soft magnetic nanoparticles can be a breakthrough compared to conventional top-down process by hot-melting method. In this work, Sm2Fe17N¬3 nanoparticles as hard magnet for exchange coupled nanocomposite were prepared by using the modified hydrothermal method combining traditional chemical synthesis and the annealing-diffusion process. The magnetic properties of Sm2Fe17N3 magnetic nanoparticles prepared by hydrothermal wet chemistry method were more enhanced comparing with that prepared by traditional physical synthesis such as HDDR, hot melting, ball milling, etc[18]. In this study, the nano sized Sm2Fe17 powders were prepared by a wet chemistry method and a subsequent HDDR (Hydrogenation Disproportionation Desorption Recombination) process. The impurities such as CaO in the Sm2Fe17 powders were removed by washing with deionized water several times. After washing, the nitrogenation reaction was carried out to produce Sm2Fe17N3 powders. The size of Sm2Fe17 powders was less than that of it reported in other studies. Then nitrogen can be effectively diffused into Sm2Fe17 due to the thin film layer of it. Although the final product is nano size, it has strong oxidation resistance due to thin shell by Sm2O3. This could result in the homogeneously distributed nano size of Sm2Fe17N3 powders.