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An effective and complete processing route for the recycling of sintered Nd-Fe-B scrap magnets was proposed. Sintered Nd-Fe-B magnets were subjected to the Hydrogen Decrepitation (HD) process at various temperatures in the range of 50–300 °C, at two different pressures, 50 kPa and 200 kPa, followed by vacuum dehydrogenation in …The behavior of hydrogen absorption in the NdFeB Hydrogen Decrepitation process is affected by the shape of the NdFeB alloy, pressure and temperature curves of the reaction process, which makes the reaction process with characteristics of nonlinear, time-varying parameters and coupling. In this study, we proposed a state space modeling method to …Nov 15, 2021 · After the hydrogen decrepitation process, the powders were pulverized by either He-jet milling or N 2-jet milling, obtaining a powder with a particle size of ~0.8 µm for the HDDR processed and He-jet milled sample, ~1.0 µm for the He-jet milled sample, and ~3.0 µm for the N 2-jet milled sample.
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NdFeB ingot exposed to hydrogen atmosphere due to the changes of hydride lattice parameters cracks. The process called HDDR (Hydrogenation - Decrepitation -D...@article{osti_37277, title = {Hydrogen decrepitation of sintered NdFeB magnets}, author = {Stiller, C and Roth, S and Binner, A}, abstractNote = {The kinetics of the hydrogen absorption and desorption behavior of a NdFeB sintered magnet is studied. Hydrogenation at temperatures above 200 C is used to crumble the Nd-enriched phase. …The room temperature hydrogenation causes decrepitation of the material, where the Nd-rich material forms NdH 2.7 and the Nd 2 Fe 14 B matrix grains form an interstitial hydrogen solution. The material expands by ∼5% and because of its brittle nature and differential expansion, undergoes decrepitation [16] .Hydrogen Decrepitation and Recycling of NdFeB-type Sintered Magnets. Miha Zakotnik, E. Devlin, +1 author. A. Williams. Published 2006. Materials Science, Engineering. Journal of Iron and Steel Research International. View via Publisher. Save to Library.Hydrogen Decrepitation and Recycling of NdFeB-type Sintered Magnets. Miha Zakotnik, E. Devlin, +1 author. A. Williams. Published 2006. Materials Science, Engineering. Journal of Iron and Steel Research International. View via Publisher. Save to Library.Various efforts have been made in the past for direct recycling of spent NdFeB magnet using hydrogen decrepitation followed by resintering method (Zakotnik et al., 2009; Herraiz et al., 2016). In ...A Hydrogen Decrepitation Press-Less Process (HD-PLP) recycling method for recycling of anisotropic NdFeB magnets is demonstrated. The method combines hydrogen decrepitation (HD) disintegration of the initial magnet, powder sieving and the Press-Less Process (PLP), where hydride powder is sintered in a graphite mold. Fully dense, sintered NdFeB-type magnets have been subjected to the hydrogen decrepitation (HD) process. The resultant powder has been subsequently …Jul 8, 2020 · The application of hydrogen decrepitation (HD) as a process for recycling Nd-Fe-B sintered magnets was reported in [ 6 ], in which the essential role of hydrogen in the recycling process was demonstrated. The obtained magnetic properties of the recycled magnet were ( BH) max = 290 kJ/m 3 (±5 kJ/m 3 ), Br = 1240 mT (±50 mT) and jHc = 830 kA/m ... High performance NdFeB permanent magnets are widely manufactured using the conventional powder metallurgy route involving distinct steps: alloy synthesis by strip casting, pulverization by hydrogen decrepitation and jet milling, shaping by compaction and sintering followed by annealing [32]. Every step of this manufacturing process has …Novel hydrogen decrepitation behaviors of (La, Ce)-Fe-B strips. Jiaying Jin G. Bai +4 authors M. Yan. ... Doping with Dy/Tb is a current solution to improve the coercivity and the operating temperature of NdFeB magnets, by increasing the magnetocrystalline anisotropy of the (Nd, Dy/Tb)2Fe14B (2:14:1) …This work could have implications with regard to the mechanism of hydrogen decrepitation of sintered NdFeB magnets during the well-established recycling process described by Walton et al. [19] and [20]. During this process, scrap sintered NdFeB magnets are damaged in air to expose a clean surface suitable for hydrogen decrepitation. …Hydrogen Decrepitation (HD) is a suitable method for recycling sintered neodymium-iron-boron magnets obtained from electronic scrap into a coercive powder [2][3][4][5][6][7][8][9]. ... Anisotropic ...At these elevated tempera- tures the decrepitation process proceeded rapidly and particles were ejected from the sample on all sides, V.A. Yartys et al. / Journal of Alloys and Compounds 239 (1996) 50-54 53 Fig. 2. Surface of a plate ejected from the [001 ] aligned sintered Nd16FeTaB8 magnet at the first stage of hydrogen decrepitation.H 2 can be used to extract NdFeB magnets from the automotive scrap, however, many challenges in the recycling are presented.. The importance of design choices, having negative impact on the recycling, are investigated in this work, so can be avoided. • Higher Dy additions slow down the kinetics of the hydrogen decrepitation …Sagawa obtained ultrafine NdFeB grain by innovative HD (hydrogen-decrepitation) + HDDR (hydrogenation-disproportionation-desorption-recombination) + helium jet milling process. It should be noted that the helium gas is more suitable than nitrogen gas to fabricate ultrafine powder due to its lighter mass fraction, and will also …
PDF (11 MB) Get e-Alerts SUBJECTS: Grain, Hydrogen, Hydrogenation, Magnetic properties, Organic reactions Abstract Regarding the restrictions recently imposed by China on the export of rare-earth elements (REEs), …big drive towards recycling of NdFeB magnets due to supply constraints for rare earth metals. Workers at the University of Birmingham have previously shown that hydrogen …Novel hydrogen decrepitation behaviors of (La, Ce)-Fe-B strips. Jiaying Jin G. Bai +4 authors M. Yan. ... Doping with Dy/Tb is a current solution to improve the coercivity and the operating temperature of NdFeB magnets, by increasing the magnetocrystalline anisotropy of the (Nd, Dy/Tb)2Fe14B (2:14:1) …At these elevated tempera- tures the decrepitation process proceeded rapidly and particles were ejected from the sample on all sides, V.A. Yartys et al. / Journal of Alloys and Compounds 239 (1996) 50-54 53 Fig. 2. Surface of a plate ejected from the [001 ] aligned sintered Nd16FeTaB8 magnet at the first stage of hydrogen decrepitation.
99.5%. The strips were employed in hydrogen decrepitation (HD) into coarse fragile particles. These coarse particles were then sent into jet milling (JM) procedure under a N. 2. gas flow. The dry powder was compacted of 14 mm diameter and 15 mm height with the alignment made with the maximum 2 T magnetic field. Over the last ten years several groups have been carrying out research into metal injection moulding (MIM) of neodymium-iron-boron (NdFeB) powders to produce isotropic or …These magnets were identical in every way apart from the orientation of the Nd 2 Fe 14 B grains. Each magnet was exposed to hydrogen and the decrepitation behaviour observed. The anisotropic samples were found to decrepitate exclusively from the ends of the rods whereas the isotropic magnets were attacked by the hydrogen at all ……
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The influence of the alloy granulation grade, temperature and surface oxidation on the kinetics and the course of the fracture processes during the hydrogenation of Nd16−xDyxFe76B8 (x=0–3) alloy was studied. The average particle sizes of the alloy were 1 mm, 5 mm and 3 cm and the temperature range between 20 and 200 °C. Pre-oxidation …This means that NdFeB magnets are prone to galvanic corrosion, in particular, intergranular corrosion attack. The corrosion mechanism as well as the hydrogen decrepitation behaviour of microcrystalline (i.e. sintered) magnets has been studied extensively [11], [12], [13], [14].
Jan 1, 2018 · High-temperature demagnetization can, however, cause melting of components, e.g., plastics, glue, etc. Hydrogen decrepitation (Table 8.3), a more efficient alternative, has been suggested for processing of HDDs [34], [35]. The NdFeB magnets absorb hydrogen, expanding in volume with about 5%, which causes breaking into coarse granules or powder. A study of the processing and characterisation of sintered NdFeB magnets made from recycled feed stock was undertaken. Initially the hydrogen decrepitated (HD) powder was investigated using two different milling techniques ball milling and burr milling. The powders were analysed with optical microscopy, with the aid of a magnetic field.
Hydrogen decrepitation and recycling of NdFeB Feb 9, 2023 · Abstract The process of hydrogen decrepitation of the (Nd, Pr, Dy)(Fe, Co)2.6 alloy in wide temperature and pressure ranges has been studied. The choices of the chemical composition of the (Nd, Pr, Dy)(Fe, Co)2.6 alloy and the method of production of the initial alloy based on out-of-furnace calcium–thermal reduction are substantiated. The introduction of dysprosium into the alloy ... A combination of hydrogen decrepitation (HD) and jet milling (JM) has been used to produce powder for the processing of permanent magnets. ... The procedure has proved to be very successful for both NdFeB (Neomax) alloys and the NdDyFeNbB high coercivity alloys. The magnets produced by the HD/JM process showed excellent … The extracted NdFeB powder is of a purity whereThe processing and characterisation of recycled NdFeB-ty NdFeB magnets are used in wind turbines and hybrid electric vehicles and are instrumental in progression toward a low-carbon economy. Recycling rare-earth elements (REEs) from NdFeB magnet waste is an important step toward building a sustainable REE supply chain. In this study, we describe an electrochemical process to selectively extract REEs from NdFeB magnet waste at room temperature. First ... Hydrogen decrepitation and recycling of NdFeB-type sintered magnets. M Zakotnik, E Devlin, IR Harris, AJ Williams. Journal of iron and steel research, international 13, 289-295, 2006. 57: 2006: Life cycle assessment of emerging technologies on value recovery from hard disk drives. Hydrogen decrepitation and recycling of NdF The nature of hydrogen decrepitation when applied to a cast Nd-Fe-B permanent magnet alloy has been studied by following the microstructural changes on polished surfaces of the material exposed to hydrogen at a pressure of 4 bar. The milling of the material decrepitated at a pressure of 10 bar has also been studied by determining …These magnets were identical in every way apart from the orientation of the Nd 2 Fe 14 B grains. Each magnet was exposed to hydrogen and the decrepitation behaviour observed. The anisotropic samples were found to decrepitate exclusively from the ends of the rods whereas the isotropic magnets were attacked by the hydrogen at all … Hydrogen Decrepitation is a process step used in tThe reaction speed in the typical hydrogenation run In this paper we describe and discuss the use of hydrogen in the p The hydrogen decrepitation (HD) process are studied in detail based on these results. The hydrogen absorption mechanism of Sm(CoFeCuZr) 7.6 alloy can be regarded as a hydrogen dissolution process without phase transformation. In addition, the existence of a large amount of fine grains in the SC has an adverse effect on the … During the hydrogenation process, a volu May 11, 2020 · Metallurgical simulation and evaluation of the resource efficiency of whole production processes are of key importance for sound environmental impact assessments. Exergy dissipation analysis is suitable to quantify the theoretical limits of a process and pinpoint hotspots for improvements along the value chain. Production of NdFeB permanent magnets is evaluated herein using a simulation-based ... The corrosion and degradation of sintered Nd–Fe–B type[As starting materials, magnets of different grades Hydrogen Decrepitation is a process step used 2.1. Introduction of this section. HDDR treatment is used to obtain Nd-Fe-B magnet powders with good magnetic anisotropy and high coercivity [6,8,19].Therefore, HDDR treatment has been used to produce anisotropic bonded magnets for high-performance motors in automobiles and electronic devices [20,21].In typical HDDR …The hydrogen decrepitation (HD) process are studied in detail based on these results. The hydrogen absorption mechanism of Sm(CoFeCuZr) 7.6 alloy can be regarded as a hydrogen dissolution process without phase transformation. In addition, the existence of a large amount of fine grains in the SC has an adverse effect on the …
