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Effect of HD Process on Microstructure and Hard Magnetic Properties of NdFeAlB Magnet

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Journal of Rare Earths 2002年第3期20卷 193-196页

作者：姜忠良陈秀云陈晓东石大立杨昌平朱静 Sch. of Mater. Sci. and Eng. Tsinghua Univ. Beijing 100084 China

The effect of hydrogen decrepitation (HD) process on the magnetic properties and microstructure of sintered NdFeAlB magnet (HD magnet) was investigated. The results show that the coercivity of HD magnet is higher than that of traditional ball milling (BM) magnet, while the remanence and the maximum energy product of HD magnet are lower. Microstructure analysis shows that some fine un sintered powders are distributed at the grain boundaries of HD magnet. X ray diffraction (XRD) analysis reveals that the degree of easy axis alignment of HD magnet is lower. Some ideas to improve the current HD process were proposed.

关键词： rare earths hydrogen decrepitation NdFeB permanent magnet

Regeneration of waste sintered Nd-Fe-B magnets to fabricate anisotropic bonded magnets

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Journal of Rare Earths 2015年第7期33卷 736-739页

作者：李现涛岳明 ZAKOTNIK Miha 刘卫强张东涛左铁镛 College of Materials Science and Engineering Beijing University of Technology

The waste sintered Nd-Fe-B magnets were regenerated as magnetic powders via manually crushing （MC） or hydrogen decrepitation （HD） to fabricate anisotropic bonded magnets. Effect of size distribution on the magnetic properties of the regenerated magnetic MC and HD powders was investigated. For the MC powders, as the particle size decreased, the remanence （Br） increased first, and then decreased again, while the coercivity （Hci） dropped monotonically. The powders with particle size in the range of 200-450μm possessed the best magnetic properties ofBr of 1.22 T and Hci of 875.6 kAJm. The corresponding bonded magnet exhibited magnetic properties ofBr of 0.838 T, Hci of 940.9 kA/m, and （BH）max of 91.4 kJ/m^3, respectively. On the other hand, the liD powders with particle size range of 200-450 μm bore the best magnetic properties Of Br of 1.24 T and Hci of 860.4 kA/m. Compared with magnetic properties of the waste magnet, the powders retained 93.9% of Br and 70.0% of Hci, respectively. The bonded magnet produced from HD powders possessed Br of 0.9 T, Hci of 841.4 kA/m, and （BH）max of 111.6 kJ/m^3, indicating its good potential in practical applications.

关键词： regeneration Nd-Fe-B magnet scraps hydrogen decrepitation anisotropic bonded magnets rare earths

hydrogen Absorption of Nd-Fe-B Alloys

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Journal of Rare Earths 2004年第5期22卷 668-672页

作者：谭春林白书欣张虹张家春蔡珣 College of Materials Science and Chemical Engineering Zhejiang University Hangzhou 310027 China ( School of Materials Science and Engineering Shanghai Jiaotong University Shanghai 200030 China Department of Materials Engineering and Applied Chemistry National University of Defense Technology Changsha 410073 China School of Materials Science and Engineering Shanghai Jiaotong University Shanghai 200030 China . Department of Materials Engineering and Applied Chemistry National University of Defense Technology Changsha 410073 China

The technical parameters of HD process were studied, including the effects of temperature and neodymium contents on the incubation period of hydrogen absorption, hydrogen concentration and the rate of hydrogen absorbed. The results show that the incubation period is shortened and the rate of hydrogen absorbed is accelerated with rising temperature and surface area. These are attributed to the rising rate of hydrogen diffusion at higher temperature. The change of the incubation period and the rate of hydrogen absorbed have the similar trend resulted from the increasing content of the Nd-rich phase owing to the rising temperature. Moreover, the percent of the Nd-rich phase in the ingot can be calculated according to the total hydrogen weight gain.

关键词： metal materials hydrogen decrepitation neodymium content surface area NdFeB rare earths

HD Processes in the Production of SmCo_5 Permanent Magnets

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Journal of Rare Earths 2007年第S1期25卷 191-193页

作者：刘涛李卫刘兴民李建奎郭朝晖 Division of Functional Materials Central Iron &Steel Research Institute

The application of ‘extreme’ hydrogen-decrepitation (HD) process using high-pressure disproportionation was extended to Sm-Co5-type-alloy. The alloy with nominal composition of Sm36Co64 was treated under 1.0～2.0 MPa H2 pressure for several hours at room temperature for decrepitation. After disproportionation were high hydrogen pressures, the bulk alloys were disproportionated into particles with a size of 200. Investigations by powder X-ray diffractometer (XRD) showed, the after HD sample crystallized in the hexagonal CaCu5-type structure. The temperature dependence of pressure analysis (TPA) curve of the SmCo5 alloy showed that the hydrogen absorption temperature was about 150 ℃. Cylindrical sintered magnets of composition Sm36Co64 were prepared using HD ball milled, isostatic pressing, vacuum sintering and subsequent heat treatment. The demagnetization curves showed that the HD processes could improve the magnetic properties and squareness factor of the SmCo5 sintered magnet.

关键词： hydrogen decrepitation SmCo_5 alloys sintered magnets rare earths

A Systematic Classification and Labelling Approach to Support a Circular Economy Ecosystem for NdFeB-Type Magnet

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材料科学与工程（中英文B版） 2020年第4期10卷 125-133页

作者： Carlo Burkhardt Antje Lehmann Benjamin Podmiljsak Spomenka Kobe Institute for Precious and Technology Metals Pforzheim UniversityPforzheim 75175Germany Department of Nanostructured Materials Institut Jozef-StefanLjubljana 1000Slovenia

Availability of magnetic materials is most crucial for modern Europe,as they are integral to energy conversion across the renewable energy and electric mobility ***,there is still no circular economy to reuse and capture value for these types of *** the prediction that the need for NdFeB Rare Earth(RE)magnets will double in the next 10 years,this problem becomes even more *** the quality of the recollected materials varies significantly,the development of a classification system for recyclate grades of EOL NdFeB magnets in combination with an eco-labelling system for newly produced RE permanent magnets is proposed to clearly identify different magnet types and *** categorises the NdFeB magnets by technical pre-processing requirements,facilitating use of the highly effective HPMS process(hydrogen Processing of Magnetic Scrap)for re-processing extracted materials directly from NdFeB *** proposed measures will have a great impact to overcome existing low recycling rates due to poor collection,high leakages of collected materials into non-suitable channels,and inappropriate interface management between logistics,mechanical pre-processing and metallurgical metals recovery.

关键词： NdFeB permanent magnet magnet recycling HPMS hydrogen decrepitation labelling&grading data matrix code(DMC) reycling factor MaXycle SUSMAGPRO