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HDDR 반응시 수소화 반응이 Nd-Fe-B계 분말의 미세조직과 자기적 특성에 미치는 영향
이상협,유지훈,김양도,Lee, S.H.,Yu, J.H.,Kim, Y.D. 한국분말야금학회 2011 한국분말재료학회지 (KPMI) Vol.18 No.5
The HDDR(hydrogenation-disproportionation-desorption-recombination) process can be used as an effective way of converting no coercivity Nd-Fe-B material, with a coarse $Nd_2Fe_{14}B$ grain structure to a highly coercive one with a fine grain. Careful control of the HDDR process can lead to an anisotropic $Nd_2Fe_{14}B$ without any post aligning process. In this study, the effect of hydrogen gas input at various temperature in range of $200{\sim}500^{\circ}C$ of hydrogenation stage (named Modified-solid HDDR, MS-HDDR) on the magnetic properties has been investigated. The powder from the modified-solid HDDR process exhibits Br of 11.7 kG and iHc of 10.7 kOe, which are superior to those of the powder prepared using the normal HDDR process.
모합금의 균질화처리가 HDDR 처리된 Nd-Fe-Ga-Nb-B 합금의 자기적 특성에 미치는 영향
유지훈,이상협,김동환,이동원,김병기,최문희,김양도,Yu, J.H.,Lee, S.H.,Kim, D.H.,Lee, D.W.,Kim, B.K.,Choi, M.H.,Kim, Y.D. 한국분말야금학회 2009 한국분말재료학회지 (KPMI) Vol.16 No.4
HDDR treated anisotropic Nd-Fe-B powders have been widely used, due to their excellent magnetic properties, especially for sheet motors and sunroof motors of hybrid and electric vehicles. Final microstructure and coercivity of such Nd-Fe-B powders depend on the state of starting mother alloys, so additional homogenization treatment is required for improving magnetic properties of them. In this study, a homogenization treatment was performed at $900\sim1140^{\circ}C$ in order to control the grain size and Nd-rich phase distribution, and at the same time to improve coercivity of the HDDR treated magnetic powders. FE-SEM was used for observing grain size of the HDDR treated powder and EPMA was employed to observe distribution of Nd-rich phase. Magnetic properties were analyzed with a vibrating sample magnetometer.