전기방사법을 이용한 일차원 Fe-Nd-B 자석의 합성 및 특성

Abstract

A novel method for the synthesis of neodymium-iron-boron (Nd-Fe-B) fibers was demonstrated by adopting four continuous processes: electrospinning, heat treatment, modified in situ reduction-diffusion, and washing process. The one-dimensional (1-D)-structured Nd-Fe-B fibers have significant potential due to their novel structure with a high aspect ratio and dimensions; in contrast, in the case of the conventional methods to fabricate the Nd-Fe-B fibers, control of the 1-D shape is difficult. The structural and thermodynamic studies revealed that as-spun precursor fibers were transformed into FeNdO3, Fe2O3, and NdBO3 phases by non-isothermal heat treatment, and the oxide mixture fibers were reduced to the single Nd-Fe-B phase by the in situ reduction-diffusion process. These Nd2Fe14B submicroscale fibers had the average diameter of 811 nm, which is about 2/3 diameter of as-spun fibers (1222 nm). The Nd2Fe14B magnet fibers exhibited 3.091 kOe coercivity. The values of saturation magnetization (Ms) and remanence (Mr) of fibers were 85 and 36 emu/g, respectively, and the squareness (Mr/Ms) of these fibers was 42 %. This is first attempt to synthesis 1-D Nd-Fe-B fibers successfully. This work provides a simple way to prepare 1-D hard magnetic Nd-Fe-B fibers with shape anisotropy attributed to a high aspect ratio. Overall, the results of this study could be useful in the preparation of a fibrous structure of Nd-Fe-B.