注射成形制备NdFeB粘结磁体

为了制备出高性价比的粘结NdFeB注射磁体，本文系统的研究了粘结剂、添加剂的含罱以及磁粉装载量对注射磁体的加工性能、磁性能等的影响规律，并从微观上揭示了其机理。本文采用低成本的陶广：快淬钕铁硼磁粉和国产尼龙6粘结剂制备出了磁性能Br为0．5158T、Heb为321kA／m、Hcj为730kA／m和（BH）max为40kl／m^3的注射磁体，其性能与日本Mate公司的RNI-50产品性能相当，而价格却低得多.     

粘结稀土永磁体的开发

本文简要叙述钢铁研究总院近年来对稀土永磁体的研制和开发工作。除了已经可以稳定大量生产和供应３５Ｈ牌号的烧结ＮｄＦｅＢ磁体外，在真空快淬工艺、ＨＤＤＲ工艺以及粘结磁体方面也进行了大量的研制工作。现在可以稳定生产供应高磁性能的磁粉和粘结磁体。此外，还简要报道了新一代稀土磁体ＳｍＦｅＮ合金的研制状况。     

超重力强化金属铋提取废旧钕铁硼中稀土元素

钕铁硼是应用最广泛的永磁材料,每年会产生大量达到使用年限的废旧钕铁硼。这些废料中含有20%～30%稀土元素,是宝贵的二次资源。文中以金属铋为提取剂,通过火法熔炼回收废旧钕铁硼中的稀土元素,并利用高温超重力技术将过量的铋分离,用于循环使用。考察了熔炼过程中铋废质量比对稀土提取效率的影响,以及超重力离心过程中温度和重力系数对铋的回收率的影响。结果表明,在铋废质量比大于1∶1时,铋相与铁相分层效果较好,废旧钕铁硼中的稀土元素几乎全部进入铋相中;在较优分离条件：T=500℃、G=1 000下,稀土回收率达99.8%,铋的回收率达72.7%。该工艺的成功开发为废旧钕铁硼中稀土元素回收利用开辟了一条新途径。     

Magnetic Microstructures of 2:17 Type Sm(Co,Fe,Cu,Zr)z Magnets Detected by Magnetic Force Microscopy

The magnetic microstructures of 2:17 type Sm(Co,Fe,Cu,Zr)z magnets were detected by magnetic force microscopy.Comparing the microstructures of the specimens coated with and without Ta thin film before and after heat-treatment, it is found that: (a) as a protection layer, Ta coating layer about 20 nm thick can effectively restrain Sm volatilization under high temperature;(b) the stress built in the 2:17 type Sm-Co magnets during specimen preparation only affects some local parts of the domain structures;(c) the magnetic microstructures vary largely for specimens heat-treated at high temperature without Ta film coating due to Sm volatilization.In addition, by comparing with high coercivity Fe-Pt point tips, it is found that the Co-Cr thin-film tips are not suitable for detecting the magnetic microstructures of strong permanent magnets.     

Sm2(Fe,M)17Nx稀土永磁材料的研究进展

综述了Sm2(Fe，M)17Nx永磁材料的最新研究进展，介绍了Sm2(Fe，M)17Nx磁粉及磁体的制备技术，说明用其他元素替换Sm或Fe对材料性能的影响，以及粉末颗粒具有最佳的尺寸和形貌的重要性。并指出放电等离子烧结技术(SPS)有望成为制备Sm2(Fe，M)17Nx致密磁体的一个有效方法。     

Magnetic Microstructures of 2：17 Type Sm（Co,Fe,Cu,Zr）z Magnets Detected by Magnetic Force Microscopy

The magnetic microstructures of 2：17 type Sm （Co, Fe, Cu, Zr）z magnets were detected by magnetic force microscopy. Comparing the microstructures of the specimens eoated with and without Ta thin film before and after heat-treatment, it is found that： （a） as a protection layer, Ta coating layer about 20 nm thick can effectively restrain Sm volatilization under high temperature; （b） the stress built in the 2.17 type Sm-Co magnets during specimen preparation only affects some local parts of the domain structures; （c） the magnetic microstructures vary largely for specimens heat-treated at high temperature without Ta film coating due to Sm volatilization. In addition, by comparing with high coercivity Fe-Pt point tips, it is found that the Co-Cr thin-film tips are not suitable for detecting the magnetic microstructures of strong permanent magnets.     

Design of Permanent Magnet Systems Using Finite Element Analysis

Rare earth permanent magnets have a wide range of magnetic properties to meet the requirements of an extensive variety of applications. Sintered Sm₂Co₁₇-type magnets have the best thermal stability with high magnetic performance at temperatures up to 550 °C. Sintered NdFeB magnets have the highest maximum energy product, (BH)_max, but are limited to applications with relatively low operating temperatures. Bonded magnets offer some design flexibility at the expense of magnetic properties. In view of these complexities, it is very important to understand the critical factors when designing the magnetic circuit. Using design examples based on finite element analysis (FEA), we will discuss magnetic materials selection, magnetic circuit design principles and design trade-offs for various applications.     

纳米晶交换耦合稀土粘结永磁体磁性能与制备工艺参数间关系的研究

本文利用熔体快淬工艺将成分为Ｎｄ８．１６Ｄｙ１Ｆｅ８５．２６Ｎｂ１Ｂ４．５８的合金在三种不同淬速（１２．２５、１６．３３、２８．６ｍ／ｓ）下制备成非晶快淬条带,并在热处理后经快速淬火而制得纳米永磁体。利用ＴＥＭ和ＸＲＤ方法,对晶化后的稀土永磁粉进行了微结构分析与表征,初步探讨了淬速及晶化条件（包括晶化温度和时间）对稀土粘结永磁体磁性能的影响规律,获得了较高矫顽力的纳米交换耦合稀土粘结永磁体。     

Magnetic Properties and Intergranular Action in Bonded Hybrid Magnets

Magnetic properties and intergranular action in bonded hybrid magnets,based on NdFeB and strontium ferrite powders were investigated.The long-range magnetostatic interaction and short-range exchange coupling interaction existed simultaneously in bonded hybrid magnets,and neither of them could be neglected.Some magnetic property parameters of hybrid magnets could be approximately obtained by adding the hysteresis loops of two magnets pro rata.     

Effects of grain boundary diffusion of PrCu alloy on microstructure and coercivity of hot deformed(Nd,Ce)-Fe-B magnets

The technology of using high abundance rare earth element Ce in permanent magnets has attracted many concerns.In this work,the magnetic properties and microstructures of hot deformed(Nd_(1-x)Ce_x)_(13.8)Fe_(76.1)Co_4 Ga_(0.5)B_(5.6) magnets and a selective magnet treated with PrCu grain boundary diffusion process(GBDP) were investigated systematically.It is found that Ce is beneficial to improving the plastic deformation ability of NdFeB magnets.The strongest c-axis orientation is achieved in the HD magnets with Ce concentration of x=0.3,resulting in good comprehensive magnetic properties of B_r=13.00 kGs,H_(cj)=10.12 kOe,(BH)_(max)=38.42 MGOe.Based on that,the GBDP was implemented on the magnets with the best orientation using Pr_(68)Cu_(32) ribbons and the magnetic properties of B_r=12.87 kGs,H_(cj)=15.65 kOe,(BH)_(max)=37.48 MGOe were obtained.The results of composition distribution and Curie temperature test of the GBDPed magnets illustrate that Pr diffuses into the(Nd,Ce)_2(Fe,Co)_(14)B grains to substitute Ce,which not only improves the Curie temperature of the grains,but also enhances the magnetic performance of the magnets.Through GBDP,the thermal stability of magnets has also been improved.     

注射成形粘结钕铁硼磁体复合粉研究

磁体的注射成形是一种高效生产的近净成形技术。为了制备出具有较好综合性能的注射成形粘结钕铁硼永磁材料,研究了粘结剂对注射成形磁体的磁性能、加工性能及力学性能的影响;分析了硅烷系列的偶联剂、复合润滑剂和抗氧剂等添加剂对注射成形磁体性能的影响。结果表明,用MQP-B快淬钕铁硼磁粉和尼龙12粘结剂制备出了剩余磁感应强度为0.539 T,磁感矫顽力为345.37 k A/m,内禀矫顽力为681.02 k A/m,最大磁能积为47.37 k J/m3的注射成形钕铁硼磁体。     

Rare Earths and Magnetic Refrigeration

Modern coolingis almost entirely based on a com-pression/expansion refrigeration cycle .It is a high-en-ergy demand industry with annual energy consumptionmeasured in billions kWh.Over the years ,all parts ofa conventional refrigerator ,i .e ., compressors , heatexchangers , refrigerants , and packaging have beenconsiderably i mproved by an extensive research anddevelopment effort ,and partly by government edicts .This was made possible by a continuous dollar influxfromboth federal and industr…     

稀土永磁材料研究新进展

综述了稀土永磁材料研究的新进展，重点介绍了具有磁交换耦合作用的新型纳米复合永磁体。通过列举一些典型永磁体合金和其磁性能，讨论了不同合金成分、制备工艺以及添加微量元素对磁性材料微观结构和磁性能的影响。同时说明了在纳米复合永磁材料中硬磁相与软磁相间的磁交换耦合作用机理，以及交换耦合作用对纳米复合永磁材料磁性能的影响。     

Effect of Particle Size and Distribution of Rapidly Quenching NdFeBMagnetic Powder on Magnetic Properties of PolymerBonded NdFeBPermanent Magnet

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NdFeB稀土永磁材料研究进展

本文综述了NdFeB稀土永磁材料的研究进展,主要包括结构、矫顽力机制、添加元素、磁性能、腐蚀行为及其防护等方面,并就国内NdFeB产业的发展进行了讨论。     

液相扩散对钕铁硼磁体性能和组织结构的影响

用双合金工艺在Nd13.05Dy0.23Fe80.12B6.5铸片主合金中分别添加质量分数为3％～20％的富稀土铸锭辅合金Nd38.2Cc11.8Fe44.88Al4.12B,研究在钕铁硼永磁体中用Ce部分地取代Nd时对永磁体的磁性能的变化规律.实验结果表明,在一定的烧结及热处理工艺条件下,辅合金加入量介于8％ ～ 12％(质量分数)时,磁体的内禀矫顽力和磁能积相对较高,对剩磁的影响不大.显微成分分析表明,采用双合金法,使组织中细小的颗粒状富稀土相增多,形成了更多的对矫顽力有贡献的富稀土相,并且富稀土相分布于晶界上.     

稀土永磁体的新应用

介绍了稀土永磁体在电机、减振器、磁选机、研磨、生产传输线等方面的最新应用趋势。     

晶界扩散中Tb对烧结NdFeB磁体微观组织和磁性能的影响

通过晶界扩散技术提升烧结钕铁硼(NdFeB)磁体矫顽力的方法已获得广泛应用,为了研究重稀土磁粉对磁体综合磁性能的影响,本文采用喷涂扩散的方法将重稀土Tb含量为6.0%(质量分数)的磁粉作为复合扩散源的一部分进行晶界扩散并制备了高性能烧结NdFeB磁体。结果表明,当主扩散源占比为60%(质量分数)时,Nd₄₀Tb₆₀对应扩散磁体的矫顽力最高达到21.52 kOe,矫顽力增幅明显。经过微观组织结构和XRD表征分析,重稀土元素Tb沿晶界相扩散进入磁体内部的同时发生了晶格取代反应,可在晶粒表层生成磁晶各向异性场更强的(Nd,Dy/Tb)₂Fe₁₄B硬磁相,显著增强了磁体矫顽力。当主扩散源占比为20%、40%和80%(质量分数)时,Nd₈₀Tb₂₀,Nd₆₀Tb₄₀和Nd₂₀Tb₈₀对应扩散磁体的矫顽力增幅较小,其中Nd₈₀Tb₂₀扩散...     

赣州钕铁硼磁性材料的产业现状与发展趋势

论述了我国钕铁硼磁性材料的发展历程,总结了赣州近年来钕铁硼磁体产业的生产和发展情况,同时指出赣州是中国南方离子型稀土矿供应基地,但不是钕铁硼生产的基地;近年来,赣州已形成一条从稀土开采-合金冶炼-钕铁硼磁体生产完整的产业链,钕铁硼磁体相关企业正在逐年增加,企业自身的竞争力也在逐年增强。     

Hydrogen Embrittlement Processes and AL／AL2O3 Hydrogen Resistance Coatings of NdFeB Magnets

After analyzing the phenomena and processes of hydrogen embrittlement of NdFeB permanent magnets, RF magnetron sputtering was used to fabricate A1 thin films and then oxidized to form the Al/Al2O3 composite films on the magnets as the hydrogen resistance coatings. SEM and EDS were used to examine the morphology and composition respectively. Hy-drogen resistance performance was tested by exposing the magnets in 10 MPa hydrogen gas at room temperature. The results show that the magnets with 8μm Al/Al2O3 coatings can withstand hydrogen of 10 MPa for 65 min without being embrittledinto powd er. The samples with and without hydrogen resistance coatings have almost the same magnetic properties.