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Study on Key Techniques for Producing High Performance NdFeB Sintered Permanent Magnets 被引量:2
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作者 张深根 李红卫 +3 位作者 赵进松 于敦波 徐静 张耀 《Journal of Rare Earths》 SCIE EI CAS CSCD 2002年第6期587-591,共5页
High energy products (BH) max of 365 and 310 kJ·m -3 with intrinsic coercivity iH c of 1640 kA·m -1 of NdFeB sintered magnets were produced. Some new techniques were applied, such as thin NdF... High energy products (BH) max of 365 and 310 kJ·m -3 with intrinsic coercivity iH c of 1640 kA·m -1 of NdFeB sintered magnets were produced. Some new techniques were applied, such as thin NdFeB ingot technique, narrow particle distribution on jet mill, low oxygen content control and high aligned magnetic field press. It is necessary to produce thin NdFeB ingot with fine flake crystal, narrow particle distribution, the average size of NdFeB powders less than 4.0 μm, uniform microstructure, high oriented Nd 2Fe 14B small grains, and finally high performance NdFeB sintered magnets were prepared. 展开更多
关键词 rare earths ndfeb sintered magnets high performance
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Preparation Technology and Performances of Zn-Cr Coating on Sintered NdFeB Permanent Magnet 被引量:14
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作者 于升学 陈玲 《Journal of Rare Earths》 SCIE EI CAS CSCD 2006年第2期223-226,共4页
Zn-Cr coating was prepared on the surface of sintered NdFeB permanent magnet samples and preparation parameters were established. The anticorrosive property of Zn-Cr coating on NdFeB was studied by whole-immersion tes... Zn-Cr coating was prepared on the surface of sintered NdFeB permanent magnet samples and preparation parameters were established. The anticorrosive property of Zn-Cr coating on NdFeB was studied by whole-immersion test in NaCl solution and compared with that of zinc plating and nickel plating on NdFeB. Open-circuit potential and self-corrosion current of NdFeB samples with and without Zn-Cr coating were measured. The micro-morphology and composition of Zn-Cr coming were analyzed through SEM, XPS, EDS and XRD. The effect of Zn-Cr coating on magnetic property of NdFeB magnet was also investigated. It is exposed that Zn-Cr coating is anodic type coating for NdFeB magnet, and provided substrate electrochemical protection, barrier protection and passivation protection. The anticorrosion property of NdFeB magnet is obviously enhanced by Zn-Cr coating while the magnet property of NdFeB magnet changed little. 展开更多
关键词 sintered ndfeb permanent magnet Zn-Cr coating magnet property anticorrosion property rare earths
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Multilayer ceramic coating for impeding corrosion of sintered NdFeB magnets 被引量:12
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作者 A.Ali A.Ahmad K.M.Deen 《Journal of Rare Earths》 SCIE EI CAS CSCD 2009年第6期1003-1007,共5页
Sintered NdFeB magnets have complex microstructure that makes them susceptible to corrosion in active environments.The current paper evaluated the anticorrosion characteristics of multilayer titanium nitride ceramic c... Sintered NdFeB magnets have complex microstructure that makes them susceptible to corrosion in active environments.The current paper evaluated the anticorrosion characteristics of multilayer titanium nitride ceramic coating applied through cathodic arc physical vapour deposition(CAPVD) for protection of sintered NdFeB permanent magnets.The performance of ceramic coating was compared to the electrodeposited nickel coating having a copper interlayer.Electrochemical impedance spectroscopy(EIS) and cyclic polar... 展开更多
关键词 sintered ndfeb magnets multilayer ceramic coating permeable defects rare earths
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Influence of Solidiflcation Rate on Microstructures of Cast Strips and Corresponding Sintered NdFeB Magnets 被引量:5
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作者 徐静 颜世宏 +3 位作者 于敦波 李宗安 李世鹏 李红卫 《Journal of Rare Earths》 SCIE EI CAS CSCD 2006年第z2期306-309,共4页
The influences of solidification rate on the microstructures of cast strips and corresponding sintered NdFeB magnets were investigated. The experimental results show that the volume fraction and size of columnar grain... The influences of solidification rate on the microstructures of cast strips and corresponding sintered NdFeB magnets were investigated. The experimental results show that the volume fraction and size of columnar grains vary with the wheel speed V, and the fraction is highest to more than 90% with 3.5μm in average width at V = 2m·s-1. The reasons for the improved magnetic performance were discussed based on the micromagnetic theory and microstructure analyses of the strips and sintered magnets. The magnetic properties of sintered NdFeB magnets made from the (Nd,Dy)13.0(Fe,Ga, Al)80.5B6.5 cast strip which was obtained at V = 2 m·s-1 are as follows: Br = 1.15 T( 11.25 kG), iHc = 2799 kA·m-1 (35.2 kOe) and (BH)max = 242 kJ·m-3(30.35 MGOe). 展开更多
关键词 sintered ndfeb magnets solidification rate cast strip microstructure rare earths
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High Energy and High Coercivity Sintered NdFeB Magnets by Low Oxygen Process 被引量:5
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作者 Kaihong DING, Guozheng LIU, Zhejun LI, Jieming YAN, Yingjie TAO and Bing WU (Baotou Research Institute of Rare Earth, Baotou 014010, China) 《Journal of Materials Science & Technology》 SCIE EI CAS CSCD 2000年第2期127-128,共2页
Using ball milling and single direction pressing, we can produce high performance NdFeB sintered magnets. The oxygen content of sintered magnets can be controlled under 1500xl0^-6 and the magnetic performance can be i... Using ball milling and single direction pressing, we can produce high performance NdFeB sintered magnets. The oxygen content of sintered magnets can be controlled under 1500xl0^-6 and the magnetic performance can be improved by using low oxygen processing. The high preformance NdFeB sintered magnets with Br=(1.4 ± 0.2)T, iHc>796 kA/m and (BH)max=(390± 16) kJ/m^3, have been batch produced. 展开更多
关键词 ndfeb CO High Energy and High Coercivity sintered ndfeb magnets by Low Oxygen Process
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Effect of grain boundary diffusion of terbium on mode of mechanical fracture of sintered NdFeB magnets
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作者 Zexin Lu Tinghui Wang +6 位作者 Jianjun Jiang Bizhang Zheng Lijing Yang Xingqi He Anli Lin Shengzhi Dong Zhenlun Song 《Journal of Rare Earths》 SCIE EI CAS CSCD 2024年第4期696-704,共9页
Grain boundary diffusion process(GBDP)is a widely used method of increasing the coercivity of sintered NdFeB magnets.In this study,the effects of the GBDP on the bending strength and microhardness of sintered NdFeB ma... Grain boundary diffusion process(GBDP)is a widely used method of increasing the coercivity of sintered NdFeB magnets.In this study,the effects of the GBDP on the bending strength and microhardness of sintered NdFeB magnets and the fracture mode were investigated.Results show that the bending strength of magnets is reduced by pickling and heat treatment and greatly recove rs after heavy rare earth element(Tb)grain boundary diffusion.The pickling and the heat treatment cause a slight decrease in microhardness.Compared with the recovery of the bending strength,the hardness decreases after the GBDP.The fracture mode of bended magnets changes from intergranular to transgranular.This study helps in further improving the mechanical and magnetic properties of sintered NdFeB magnets. 展开更多
关键词 sintered ndfeb magnets Grain boundary diffusionprocess Bending strength Heavy rare earth element COERCIVITY
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Corrosion Resistance of Sintered NdFeB Permanent Magnet With Ni-P/TiO_2 Composite Film 被引量:19
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作者 SONG Lai-zhou YANG Zhi-yong 《Journal of Iron and Steel Research International》 SCIE EI CAS CSCD 2009年第3期89-94,共6页
The Ni-P/TiO2 composite film on sintered NdFeB permanent magnet was investigated by X-ray diffraction (XRD),environmental scanning electron microscopy (ESEM),and energy dispersive X-ray spectrometer (EDX). The c... The Ni-P/TiO2 composite film on sintered NdFeB permanent magnet was investigated by X-ray diffraction (XRD),environmental scanning electron microscopy (ESEM),and energy dispersive X-ray spectrometer (EDX). The corrosion resistance of Ni-P/TiO2 film coated on NdFeB magnet,in 0.5 mol/L NaCl solution,was studied by potentiodynamic polarization,salt spray test and electrochemical impedance spectroscopy (EIS) techniques. The self-corrosion current density (icorr) and the polarization resistance (Rp) of Ni-P/TiO2 film are 0.22 μA/cm2 (about 14% of that of Ni-P coating),and 120 kΩ·cm2 (about 2 times of that of Ni-P coating),respectively. The anti-salt spray time of Ni-P/TiO2 film is about 2.5 times of that of the Ni-P coating. The results indicate that Ni-P/TiO2 film has a better corrosion resistance than Ni-P coating,and the composite film increases the corrosion resistance of NdFeB magnet markedly. 展开更多
关键词 sintered ndfeb permanent magnet Ni-P/TiO2 composite film sodium chloride solution corrosion resistance
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Microstructure improvement related coercivity enhancement for sintered NdFeB magnets after optimized additional heat treatment 被引量:5
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作者 Qing Zhou Wei Li +5 位作者 Yuan Hong Lizhong Zhao Xichun Zhong Hongya Yu Lili Huang Zhongwu Liu 《Journal of Rare Earths》 SCIE EI CAS CSCD 2018年第4期379-384,共6页
The micro structure, especially the Nd-rich phase and the grain boundary, in sintered NdFeB magnets plays an important role in magnetic reversal and coercivity mechanism. To better understand the effects of the micros... The micro structure, especially the Nd-rich phase and the grain boundary, in sintered NdFeB magnets plays an important role in magnetic reversal and coercivity mechanism. To better understand the effects of the microstructure on the coercivity, we investigated the microstructure and properties improvements of a commercial sintered NdFeB magnet after optimized additional heat treatment. The coercivity is enhanced from 1399 to 1560 kA/m. This enhancement has been explained in terms of the evolution of the grain boundary structure, and the formation of continuous thin layers of Nd-rich phase is important for high coercivity. The micromagnetic simulation together with the numerical analysis based on the nucleation model suggest that the reversed magnetic domains nucleate mainly at the interface of multijunctions of Nd_2 Fe_(14)B grains with high stray fields during the demagnetization process. Both improved anisotropy fields at grain boundaries and reduced stray fields at multi-junction Nd-rich phases contribute to the coercivity enhancement. This work has importance in understanding the crucial micro structure parameters and enhancing the obtainable properties for sintered NdFeB magnets. 展开更多
关键词 sintered ndfeb magnets Microstructure Coercivity Micromagnetic simulation Heat treatment Rare earths
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Densification and anticorrosion performances of vacuum evaporated aluminium coatings on NdFeB magnets 被引量:5
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作者 Jun Huang Qing Liu +7 位作者 Zhenyu Yang Guangqing Xu Pengjie Zhang Jun Lv Wei Sun Bingshan Li Dongmei Wang Yucheng Wu 《Journal of Rare Earths》 SCIE EI CAS CSCD 2021年第10期1238-1245,I0003,共9页
Al coated NdFeB magnets obtained by vacuum evaporation technique were densified by high energy ball milling method.The surface morphology,metal composition and micro structure of the coatings were characterized by sca... Al coated NdFeB magnets obtained by vacuum evaporation technique were densified by high energy ball milling method.The surface morphology,metal composition and micro structure of the coatings were characterized by scanning electron microscopy,X-ray diffraction and X-ray photoelectron spectroscopy,respectively.The anticorrosive properties were investigated by potentiodynamic polarization curves and neutral salt spray test.The pores in the Al coatings of columnar crystals(Al) induced by the evaporation technique,were apparently filled in the following ball milling process,leading to the densification of Al coatings and the evident improvement of the anticorrosive performances.When treated with ball milling for 30 min,the sample achieves the best anticorrosive performances with the self-corrosion potential of-0.87 V,self-corrosion current density of 1.65 μA/cm^(2) and the neutral salt spray(NSS) time of 144 h(red rust).The improvement of the anticorro sive performances of vacuum evaporated Al coating mainly lies in the densification effect of the coating,which depends on different loading conditions of ball milling process. 展开更多
关键词 sintered ndfeb magnet Al coating Anticorrosive performances Vacuum evaporation DENSIFICATION Rare earths
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Rare earth passivation and corrosion resistance of zinc coated NdFeB magnets 被引量:3
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作者 Jing Chen Hongyi Yang +8 位作者 Guangqing Xu Pengjie Zhang Jun Lv Wei Sun Bingshan Lidi Jun Huang Dongmei Wang Xia Shu Yucheng Wu 《Journal of Rare Earths》 SCIE EI CAS CSCD 2022年第2期302-308,I0005,共8页
Rare earth passivation was conducted on Zn coated NdFeB magnets by chemical reaction to enhance the corrosion resistance performance.Morphologies,micro structures and compositions of different passivated coatings were... Rare earth passivation was conducted on Zn coated NdFeB magnets by chemical reaction to enhance the corrosion resistance performance.Morphologies,micro structures and compositions of different passivated coatings were studied by X-ray diffraction,field emission scanning electron microscopy,and X-ray photoelectron spectroscopy,respectively.The corrosion behavior was evaluated by electrochemical measurement and neutral salt spray test.The results show that the rare earth passivation can enhance the corrosion resistance of Zn coated NdFeB magnets.When the concentration of cerium nitrate is 5 g/L,the passivated specimens can achieve the longest NSS time of 360 h,which is 144 h longer than that of the pristine Zn/NdFeB magnets.The passivation layer on the Zn coating surface contributes to the enhancement of the magnets’corrosion resistance. 展开更多
关键词 sintered ndfeb magnets Rare earth passivation Zn coating ELECTROPLATING Corrosion resistance
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