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Magnetic Properties of Nd-Fe-B Sintered Magnet Powders Recovered by Yb Metal Vapor Sorption
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作者 Horikawa T Itoh M +1 位作者 Suzuki Shunji Machida K 《Journal of Rare Earths》 SCIE EI CAS CSCD 2004年第1期152-156,共5页
Fine ground powders of Nd-Fe-B sintered magnet bulks (particle size=46~125 μm in diameter) were coated and alloyed with Yb metal by sorbing them. A significant recovery of the decreased magnetic properties of the gr... Fine ground powders of Nd-Fe-B sintered magnet bulks (particle size=46~125 μm in diameter) were coated and alloyed with Yb metal by sorbing them. A significant recovery of the decreased magnetic properties of the ground powders (remanence B r=~0.95 T, coercivity H cj =~227 kA·m -1 and maximum energy product (BH) max=~48 8 kJ·m -3) was observed in accordance with increasing temperature up to 800 ℃. The sorbing temperature and time for Yb metal vapor were optimized and after heating at 800 ℃ for 90 min and annealing subsequently at 610 ℃ for 60 min, the B r, H cj and (BH) max values were increased to be 0.98 T, 712 kA·m -1 and 173 kJ·m -3, respectively. From the microstructural characterizations of resulting samples by using X-ray diffraction (XRD), scanning electron microscopy (SEM), and electron probe X-ray microanalyzer (EPMA), it is found that the sorbed Yb metal uniformly covers the surface and diffuses to the Nd-rich grain boundary of fine ground powders of Nd-Fe-B sintered magnet bulks forming a (Nd,Yb)Fe 2 phase. 展开更多
关键词 metal materials Nd 2Fe 14B sintered magnets metal vapor sorption magnetic properties recovery rare earths
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Particle size dependent sinterability and magnetic properties of recycled HDDR Nd-Fe-B powders consolidated with spark plasma sintering 被引量:6
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作者 Awais Ikram Farhan Mehmood +6 位作者 Richard Stuart Sheridan Muhammad Awais Allan Walton Anas Eldosouky Saso Sturm Spomenka Kobe Kristina Zuzek Rozman 《Journal of Rare Earths》 SCIE EI CAS CSCD 2020年第1期90-99,共10页
The dependence of the magnetic properties on the particle size of recycled HDDR Nd-Fe-B powders was investigated,with the aim to assess the reprocessing potential of the end-of-life scrap magnets via spark plasma sint... The dependence of the magnetic properties on the particle size of recycled HDDR Nd-Fe-B powders was investigated,with the aim to assess the reprocessing potential of the end-of-life scrap magnets via spark plasma sintering(SPS).The as received recycled HDDR powder has coercivity(Hci)=830 kA/m and particles in the range from 30 to 700 μm(average 220 μm).After burr milling,the average particle size is reduced to 120 μm and subsequently the Hci of fine(milled) powder was 595 kA/m.Spark plasma sintering was exploited to consolidate the nanograined HDDR powders and limit the abnormal grain coarsening.The optimal SPS-ing of coarse HDDR powder at 750℃for 1 min produces fully dense magnets with Hci=950±100 kA/m which further increases to 1200 kA/m via thermal treatment at 750℃for 15 min.The burr milled fine HDDR powder under similar SPS conditions and after thermal treatment results in Hci=940 kA/m.The fine powder is further sieved down from 630 to less than 50 μm mesh size,to evaluate the possible reduction in Hci in relation to the particle size.The gain in oxygen content doubles for <50 μm sized particles as compared with coarser fractions(>200 μm).The XRD analysis for fractionated powder indicates an increase in Nd2O3 phase peaks in the finer(<100 μm)fractions.Similarly,the Hci reduces from 820 kA/m in the coarse particles(>200 μm) to 460 kA/m in the fine sized particles(<100μm).SPS was done on each HDDR powder fraction under the optimal conditions to measure the variation in Hci and density.The Hci of SPS-ed coarse fraction(>200 μm) is higher than 930 kA/m and it falls abruptly to just 70 kA/m for the fine sized particles(<100 μm).The thermal treatment further improves the Hci to>1000 kA/m only up to 100 μm sized fractions with>90% sintered density.The full densification(>99%) is observed only in the coarse fractions.The loss of coercivity and lack of sinterability in the fine sized particles(<100 μm) are attributed to a very high oxygen content.This implies that during recycling,if good magnetic properties are to be maintained or even increase the HDDR powder particles can be sized down only up to≥100 μm. 展开更多
关键词 Reprocessing end-of life scrap Rare earth permanent magnets HDDR nd2fe14b Recycling Spark plasma sintering
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回火对高矫顽力烧结Nd-Fe-B磁体微结构及磁性能的影响
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作者 赵导文 唐杰 +2 位作者 邓盛贤 杨梨容 刘畅 《磁性材料及器件》 CAS CSCD 2022年第3期38-41,共4页
烧结Nd-Fe-B磁体的磁性能及微观组织结构与其制备工艺尤其是烧结回火工艺密切相关。为此,制备了超高矫顽力的Nd-Fe-B烧结磁体,分析了回火工艺对其微观结构及磁性能的影响。结果表明,烧结Nd-Fe-B磁体的主相晶粒尺寸及形状主要由烧结工艺... 烧结Nd-Fe-B磁体的磁性能及微观组织结构与其制备工艺尤其是烧结回火工艺密切相关。为此,制备了超高矫顽力的Nd-Fe-B烧结磁体,分析了回火工艺对其微观结构及磁性能的影响。结果表明,烧结Nd-Fe-B磁体的主相晶粒尺寸及形状主要由烧结工艺决定,高低温两级回火工艺会改善磁体晶界富Nd相分布,使其更均匀和连续分布在主相晶粒周围,有助于提高磁体的矫顽力。对于IVU16真空波荡器用高矫顽力烧结Nd-Fe-B磁体,经高低温两级回火后磁体Hcj提高了9.3%。 展开更多
关键词 Nd-Fe-B烧结磁体 回火 Nd_(2)Fe_(14)B相 富Nd相 微结构 磁性能
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烧结Nd—Fe—B永磁体的矫顽力Hcj及提高途径的探讨
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作者 万永 《金属材料研究》 2012年第3期27-31,共5页
根据烧结Nd—Fe—B永磁体的内禀初始磁化曲线和退磁曲线的特征,分析了其矫顽力的形成机制,给出了Hcj的表达式,进而讨论了影响Hcj的各种因素。最后,提出了提高Hcj的主要途径。
关键词 烧结Nd—Fe—B永磁体 初始磁化曲线 矫顽力Hcj 取向度 2:14:1主相晶粒
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