Development of Nd-Fe-B Sintered Magnets with high magnetizing ability

高充磁能力Nd-Fe-B烧结磁体的开发

• 批准号: 07555208
• 负责人: HOMMA Motofumi
• 金额: $ 7.81万
• 依托单位: Tohoku University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (A)
• 财政年份: 1995
• 资助国家: 日本
• 起止时间: 1995 至 1997
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-07555208/
• 关键词: magnetizing ability; sintered magnet; Nd2Fe14B; inverse domain; magnetic domain; coercivity; remanence; maximum energy products; 焼結磁石; Nd_2Fe_<14>B; 残留磁束密度; 磁化エネルギー; 局所的反磁界; 着磁; 永久磁石; Nd-Fe-B系磁石; 反磁界

Purpose : Nd-Fe-B sintered magnets exhibit high coercivity, remanence and the maximum energy products. However, high applied field over 1.2 MA/m, was needed to obtain good magnetic properties. Then Nd-Fe-B sintered magnets with good magnetizing ability, which show higher magnetic properties with lower magnetizing field, have been strongly demanded in order to make a small multipole magnets. In this study, the effects of the microstructure (alignment of Nd_2Fe_<14>B particles and the amount of non-magnetic phases) and magnetizing temperature on the magnetizing ability were investigated.Experimental Procedures : The compositions of studied alloys were Nd_<15>Fe_<77>B_8 and Nd_<14.4>Fe_<79.6>B_<6.0>. These alloy powders were prepared by the conventional powder metallurgy method or the powder mixing method utilizing hydrogen decrepitation. These fine powders were pressed into the compacts in a magnetic field of 0.98MAm^<-1> at a pressure of 100Pa. Magnetic properties were measured by BH looptracer and vibrating sample magnetometer (VSM). The magnetizing ability were evaluated by the ratio of the magnetic properties with every applied field to those after applying pulsed field of 4.0MAm^<-1>. The microstructures were observed using a optical microscope and a scanning electromicroscopy.Results : The magnetizing ability improved with decreasing the amount of non-magnetic phases and increasing alignment of Nd_2Fe_<14>B particles. The main facter affecting magnetizing ability is the demagnetization field breaking out around the Nd_2Fe_<14>B particles. It is found that magnetizing at high temperature is useful method for increasing magnetizing ability. Because the demagnetization field is closely related to the saturate magnetization of Nd_2Fe_<14>B particles and it decreases with increasing temperature.

用途：Nd-Fe-B烧结磁体具有高矫顽力、剩磁和最大磁能积。然而，需要超过 1.2 MA/m 的高施加磁场才能获得良好的磁性能。因此，为了制造小型多极磁体，强烈需要具有良好磁化能力的Nd-Fe-B烧结磁体，其在较低的磁化场下表现出较高的磁性能。在这项研究中，研究了微观结构（Nd_2Fe_<14>B颗粒的排列和非磁性相的数量）和磁化温度对磁化能力的影响。实验过程：所研究合金的成分为Nd_<15> Fe_<77>B_8和Nd_<14.4>Fe_<79.6>B_<6.0>。这些合金粉末通过常规粉末冶金方法或利用氢爆裂的粉末混合方法制备。将这些细粉末在0.98MAm ^ -1 的磁场和100Pa的压力下压制成坯。磁特性通过 BH 环示踪器和振动样品磁力计 (VSM) 测量。磁化能力通过每次施加磁场时的磁特性与施加4.0MAm^-1的脉冲磁场后的磁特性之比来评价。使用光学显微镜和扫描电子显微镜观察微观结构。结果：随着非磁性相数量的减少和Nd_2Fe_ 14 B颗粒排列的增加，磁化能力提高。影响磁化能力的主要因素是Nd_2Fe_ 14 B颗粒周围爆发的退磁场。研究发现，高温磁化是提高磁化能力的有效方法。因为退磁场与Nd_2Fe_ 14 B颗粒的饱和磁化强度密切相关，并且随着温度的升高而减小。

项目成果

Y.G.Hong: "MAGNETIC PROPERTIES OF Nd-Fe-B SINTERED MAGNETS PREPARED BY POWDER MIXING METHOD UTILIZING HYDROGEN DECREPITATED POWDER" Proc.the 3th Int.Symp.on Phys.of Magnetic Materials. 3. 665-669 (1995)

Y.G.Hong：“利用氢爆裂粉末混合方法制备的 Nd-Fe-B 烧结磁体的磁性能”Proc.the 3th Int.Symp.on Phys.of Magnetic Materials。

Y.G.Hong: "MAGNETIC PROPERTIES OF Nd-Fe-B SINTERED MAGNETS PREPARED BY POWDER MIXING METHOD UTILIZING HYDROGEN DECREPITATED POWDERS" Proc.the 3th Int.Symp.on Phys.of Magnetic Materials. 3. 665-669 (1995)

Y.G.hong：“利用氢爆粉混合方法制备的 Nd-Fe-B 烧结磁体的磁性能”Proc.the 3th Int.Symp.on Phys.of Magnetic Materials。

Y.G.Hong: "MAGNETIC PROPERTIES OF Nd-Fe-B SINTERED MAGNETS PREPARED BY POWDER MIXING MRTHOD UTILIZING HYDROGEN DECREPITATED POWDERS" Proc.the 3th Int.Symp.on Phys. of Magnetic Materials.3. 665-669 (1995)

Y.G.hong：“利用氢爆裂粉末通过粉末混合方法制备的 Nd-Fe-B 烧结磁体的磁性能”Proc.the 3th Int.Symp.on Phys.