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Hydrogen decrepitation process has been applied for the first time for the direct recycling of SmCo 5 magnets. Industrially produced sintered SmCo ... Nowadays, NdFeB magnets represent more than 90% of the REE permanent magnets production. But, SmCo magnets have much higher coercivity and better temperature resistance, and many experts expect ...Hydrogen decrepitation process has been applied for the first time for the direct recycling of SmCo 5 magnets. Industrially produced sintered SmCo 5 magnets were decrepitated by hydrogen gas at a pressure of 1 bar to 9.5 bar at room temperature in a planetary rotating jar. After decrepitation, the starting sintered magnets were reduced to …Oct 25, 2015 · End-of-life NdFeB magnets are important secondary RE sources. Several recycling methods for NdFeB magnets have been developed, such as direct reuse,4 hydrogen decrepitation (HD) and regeneration of new NdFeB,5–7 pyrometallurgical methods,8,9 hydrometallurgical methods,10–13 gas-phase extraction. Apr 15, 2022 · 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 range of 720–820 °C. Keywords: Finite difference method; Kinetics; Hydrogen decrepitation; NdFeB alloys; Diffusion 1. Introduction Sv (V ) expansion due to decrepitation results in a five orders of magnitude higher rate of hydrogen diffusion into The most popular recent application of hydrogen in the Nd–Fe–B alloy than into a theoretical bulk sample of that ...Hydrogen processing of magnetic scrap (HPMS) as one of the best approaches for magnet-to-magnet recycling is thoroughly reviewed in this study in terms …Abstract: Hydrogen decrepitation (HD) is an effective and environmentally friendly technique for recycling of neodymium-iron-boron (NdFeB) magnets. During the …Hydrogen decrepitation (HD) of the sintered block was used to return the annealed material back into a powder [33]. During this step, the material reacts with hydrogen resulting in volume expansion of both the Nd-rich phase, at triple junctions and grain boundaries, and the Nd 2 Fe 14 B matrix phase [34]. This expansion leads to …Abstract. This paper reports the room temperature hydrogen decrepitation (HD) of fully dense, 2/17-type sintered magnets based on the composition, Sm (Co 0.69 Fe 0.21 Cu 0.068 Zr 0.019) 7.49. These magnets absorb significant amounts of hydrogen over an extended period (∼48 h) at room temperature and at a pressure of 10 bar to give a …May 5, 2017 · 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]. The corrosion and degradation of sintered Nd–Fe–B type magnets by hydrogen obtained from moisture in the environment has been termed the Negative Harris Effect. The residual hydrogen from the hydrogen decrepitation process in the manufacture of fully dense magnets is desorbed completely during the vacuum sintering …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 Nd-Fe-B (Neomax) alloys and the ND-Dy-Fe-Nb-B high coercivity alloys. The magnets produced by the HD/JM process showed excellent coercivities when …Jan 1, 2006 · Several recycling methods for NdFeB magnets have been developed, such as direct reuse,4 hydrogen decrepitation (HD) and regeneration of new NdFeB,5–7 pyrometallurgical methods,8,9 hydrometallurgical methods,10–13 gas-phase extraction. Direct reuse is only suitable for large magnets, such as those used for wind turbines, electric motors, and ... 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. …In this paper it is demonstrated that hydrogen could play a vital role in this process. Fully dense sintered NdFeB-type magnets have been subjected to the hydrogen decrepitation (HD) process. magnets. The thermal and mechanical impact of the hydrogen decrepitation process was assessed during hydrogen processing. For all forms of sintered NdFeB scrap the surface condition of the magnets is important as oxidation has been shown to inhibit the onset of the hydrogen decrepitation process. In this Feb 5, 2009 · Abstract. Some fully dense, sintered NdFeB-type magnets (employed in VCM disc drives) have been subjected to a recycling process using the hydrogen decrepitation (HD) process. After a brief milling treatment, the powder was aligned, pressed and re-sintered and this procedure was repeated four times with a progressive fall in the density and in ... The subject of this paper is method (4) together with other aspects of the use of hydrogen in the processing of NdFeB-type magnets. 2. The hydrogen decrepitation process The manufacture of rare earth-transition metal magnets by the HD route was first proposed in a 1978 patent by Harris et al. [7].May 1, 2023 · The hydrogen absorbed by the whole alloy and, in particular, by the Nd 2 Fe 14 B phase decreases with temperature. Below 150 °C, the hydrogen absorbed by the Nd 2 Fe 14 B phase produces a significant transgranular cracking that is undesirable for particle shape. At 300 °C, the fast and limited absorption of hydrogen by the Nd-rich phase ... Jan 1, 1991 · Abstract. In this paper we describe and discuss the use of hydrogen in the processing ofNdFeB-type magnets. The roles of hydrogen in the hydrogen decrepitation (HD) and hydrogenation, disproportionation, desorption and recombination (HDDR) processes are considered together with the characteristics of the magnets produced by these routes. 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 obtained strips were pulverized and further milled into ∼5 μm powder using hydrogen decrepitation and jet milling, respectively. These powders were pressed in a magnetic field of 1.8 T under a pressure of 8.0 MPa. Afterward, the green compacts were sintered at 1070°C for 3 h in vacuum, cooled by Ar quenching. ... NdFeB sintered …hydrogen uptake (2043.76 μmol∙g-1) was received for conditions 4 bar and room temperature, while the lowest (925.27 μmol∙g -1 ) for 1 bar at 400 0 C (Figure 4). At room temperature (29Feb 5, 2009 · Abstract. Some fully dense, sintered NdFeB-type magnets (employed in VCM disc drives) have been subjected to a recycling process using the hydrogen decrepitation (HD) process. After a brief milling treatment, the powder was aligned, pressed and re-sintered and this procedure was repeated four times with a progressive fall in the density and in ... Mar 1, 1985 · 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 alignment, which can ... So exposure at LOW temperature to hydrogen leads the NdFeB pieces to react via intergranular fracturation (decrepitation), the mass of Nd2Fe14B grains forminfg a metal hydride with max ... Jan 1, 2007 · The rapid cooling of the strip flakes suppresses the growth of soft α-Fe branch crystal grains. The thickness of the strip flakes was about 0.25–0.35 mm. Hydrogen decrepitation (HD), which uses the expansion of hydrogen to break up the flakes, was followed by milling in a jet mill (JM). The particles were then accelerated to supersonic ... The high- and standard-grade material can be processed using either an HD/HDDR process or a sintering process, both of which are being tested in the course of this project. HD/HDDR stands for hydrogen decrepitation (HD) and hydrogen-disproportionation decomposition-recombination (HDDR). The HD/HDDR pulverised …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 …So exposure at LOW temperature to hydrogen leads the NdFeB pieces to react via intergranular fracturation (decrepitation), the mass of Nd2Fe14B grains forminfg a metal hydride with max ...Fully dense sintered NdFeB-type magnets have been subjected to the hydrogen decrepitation (HD) process. The resultant powder has been subsequently processed in one of two ways in order to produce ...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 …Hydrogen decrepitation (HD) is an effective and environmentally friendly technique for recycling of neodymium-iron-boron (NdFeB) magnets. During the HD process, the …The corrosion and degradation of sintered Nd–Fe–B type magnets by hydrogen obtained from moisture in the environment has been termed the Negative Harris Effect. The residual hydrogen from the hydrogen decrepitation process in the manufacture of fully dense magnets is desorbed completely during the vacuum sintering …The initial step for manufacturing NdFeB plated permanent magnets in this unit process is NdFeB alloying and strip casting. NdFeB alloy is composed of 72% iron, 27% neodymium, and 1% boron from boron carbide (Sprecher et al., 2014). In order to stop free iron from forming, a small amount of iron formed between NdFeB crystals, the alloy is ...Hydrogen is already used to process cast NdFeB in the Hydrogen Decrepitation (HD) process. The HD process is used extensively to reduce bulk (or strip) cast NdFeB ingots to friable, hydrogenated NdFeB granules/powder, prior to the production of jet milled powder which is then aligned, compressed and sintered to form fully dense …(DOI: 10.1016/S0925-8388(99)00443-0) The corrosion and degradation of Nd–Fe–B magnets by hydrogen from moisture in the environment has been termed the Negative Harris Effect. In order to provide more information on this phenomenon, different density Nd–Fe–B magnets have been subjected to vacuum desorption, XRD and …NdFeB-based alloys and magnets also react readily with hydrogen, and this has been exploited by the hydrogen decrepitation (HD) process [4]. During HD the material is exposed to hydrogen (at room temperature) and initially the Nd-rich phase absorbs hydrogen (represented approximately by Eq.Mar 1, 2019 · Fig. 1 shows the hydrogen decrepitation curves of Nd-Fe-B SC and SM at 288 K with different initial hydrogen pressure. Under the initial hydrogen pressure of 0.1–1 Mpa, the HD process composes of four stages of magnets surface activation, slow hydrogenation of Nd-rich grain boundary phase, quick hydrogenation of Nd 2 Fe 14 B main phase grains, and slow hydrogenation of inner part of the magnets. A production-scale plant in Germany planned to go onstream in 2024 and a pilot plant launched a few months ago in the UK, expected to graduate to production-scale in 2023, are using the hydrogen-enabled process in efforts to commercialize it. At the center of both efforts is HyProMag Limited, closely tied to the University of Birmingham and an ...The scrap sintered Nd–Fe–B magnets were recycled as the raw materials for bonded magnets using the hydrogen decrepitation (HD) process. The HD powders have the lowest oxygen and hydrogen content by hydrogenation at 150 °C with 1 bar H2 pressure and dehydrogenation at 600 °C. The powders with the largest particle size (>380 μm) …Oct 1, 2015 · Hydrogen is already used to process cast NdFeB in the Hydrogen Decrepitation (HD) process. The HD process is used extensively to reduce bulk (or strip) cast NdFeB ingots to friable, hydrogenated NdFeB granules/powder, prior to the production of jet milled powder which is then aligned, compressed and sintered to form fully dense sintered magnets ... Michihide Nakamura, Masashi Matsuura, Nobuki Tezuka, Satoshi Sugimoto, Yasuhiro Une, Hirokazu Kubo, Masato Sagawa; Preparation of ultrafine jet-milled powders for Nd-Fe-B sintered magnets using hydrogenation–disproportionation–desorption–recombination and hydrogen …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 …Hydrogen decrepitation (HD) is based on the selective synthesis of neodymium hydrides though the reaction of hydrogen gas with neodymium located in the Nd-Fe-B magnet. HD process was originally designed and patented by Harris et al. (1979) as a way to break down SmCo and Sm 2(Co,Fe,Cu,Zr) alloys. 5 17.Hydrogen absorption/adsorption properties of high coercivity NdDyFeCoNbCuB sintered magnets were determined. Hydrogenation kinetics were analyzed using both differential scanning calorimetry (DSC) and X-ray diffraction (XRD). Hydrogenation of the Nd-rich intergranular phase results in a rather broad and large peak …An essential information about history and applications of Hydrogen Decrepitation has been generally reported. Very important technical details about the HD route were summarized, as well as fabrication procedure of Nd16Fe76B8 permanent magnet. Some micro strucural of SEM images of hydride and sintered magnets were given to …The obtained strips were pulverized and further milled into ∼5 μm powder using hydrogen decrepitation and jet milling, respectively. These powders were pressed in a magnetic field of 1.8 T under a pressure of 8.0 MPa. Afterward, the green compacts were sintered at 1070°C for 3 h in vacuum, cooled by Ar quenching. ... NdFeB sintered …The reactions and phase changes occurring during sintering of NdFeB permanent magnet alloys were studied by differential thermal analysis and scanning electron microscopy. The powders were produced by hydrogen decrepitation and on heating, hydrogen evolution occurred in two stages: firstly from the matrix phase (∼170 °C) and …Mar 1, 2016 · The hydrogen decrepitation (HD) process for cast NdFeB alloys [1] has also been shown to be a technically and economically effective method for breaking down scrap sintered NdFeB magnets into a powder [2] and hence, for instance, for the separation of NdFeB-based magnets from end-of-life hard disk drive assemblies [3], [4]. Received 21st February 2020, Accepted 5th March 2020. meric portion. The PA-free magnet powder was found to retain >90% of its original magnetic properties. Two epoxy-bonded magnets produced with this recycled magnet powder showed magnetic properties. DOI: 10.1039/d0gc00647e. magnets from electrical and electronic equipment. These materials are then processed using hydrogen decrepitation to transform the NdFeB magnets into a hydrogenated powder. This powder can then be extracted mechanically from the obsolete devices, and can then be processed further to produce either sintered or bonded rare earth magnets.Hydrogen decrepitation (HD) is based on the selective synthesis of neodymium hydrides though the reaction of hydrogen gas with neodymium located in the Nd-Fe-B magnet. …Aug 4, 2022 · One of the most promising solutions with regards to extraction of end-of-life (EOL) magnets is to apply hydrogen decrepitation and to physically separate the Nd-Fe-B as a demagnetized... The MMG has been active in the field of rare earth alloys and processing of permanent magnets using hydrogen for over 40 years. Originated by Professor Emeritus Rex Harris, the hydrogen decrepitation method, which is used to reduce NdFeB alloys to a powder, is now ubiquitously employed in worldwide magnet processing. Semantic Scholar extracted view of "A study of the effects of the addition of various amounts of Cu to sintered NdFeB magnets" by O. Ragg et al. ... from an Nd/sub 17/-Fe/sub 76.5/-B/sub 5/-Cu/sub 1.5/ alloy by a two-step heat treatment at 1370 K and 870 K following hydrogen decrepitation (HD)-processing. …The fabrication of Nd-Fe-B sintered magnets is composed of quite a few processes mainly including strip casting, hydrogen decrepitation, jet-milling, magnetic alignment and pressing, sintering and subsequent heat treatment, machining, and surface coating. ... Possible methods of recycling NdFeB-type sintered magnets using the …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. It should be noted that hydrogen already plays a vital role in the production of sintered NdFeB-type magnets [1].The bulk alloy absorbs around 0.4 wt.% of hydrogen during the initial decrepitation stage and this hydrogen is desorbed during the subsequent vacuum sintering.Every tonne of alloy produces around 40 cubic meters of hydrogen …The scrap sintered Nd–Fe–B magnets were recycled as the raw materials for bonded magnets using the hydrogen decrepitation (HD) process. The HD powders have the lowest oxygen and hydrogen content by hydrogenation at 150 °C with 1 bar H2 pressure and dehydrogenation at 600 °C. The powders with the largest particle size (>380 μm) …The gravimetric measurements also confirmed that Dy additions increase both the initiation and absorption time for hydrogen decrepitation. Hence, a higher hydrogen pressure will be required to speed up the process. AB - Scrap containing NdFeB is a valuable resource for the production of NdFeB magnets as the demand for these materials grows.Step #5 Hydrogen Decrepitation While the grains are very small from strip casting, the material from strip casting comes out of the caster in sheets that must be reduced to powder in order to make magnets. The next step after this is Hydrogen Decrepitation –a process that introduces hydrogen to purposely disintegrate the magnet material. Jan 1, 2007 · The rapid cooling of the strip flakes suppresseThe processing and characterisation of recycled NdFeB-ty The hydrogen decrepitation (HD) process for cast NdFeB alloys [1] has also been shown to be a technically and economically effective method for breaking down scrap sintered NdFeB magnets into a powder [2] and hence, for instance, for the separation of NdFeB-based magnets from end-of-life hard disk drive assemblies [3], [4].Jan 1, 2006 · In this paper it is demonstrated that hydrogen could play a vital role in this process. Fully dense, sintered NdFeB-type magnets have been subjected to the hydrogen decrepitation (HD) process. The resultant powder has been subsequently processed in one of two ways in order to produce permanent magnets. Hydrogen Decrepitation and Recycling of NdFeB-ty 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.Hydrogen decrepitation (HD) is based on the selective synthesis of neodymium hydrides though the reaction of hydrogen gas with neodymium located in the Nd-Fe-B magnet. HD process was originally designed and patented by Harris et al. (1979) as a way to break down SmCo and Sm 2(Co,Fe,Cu,Zr) alloys. 5 17. High-temperature oxidation resistance of Nd–...

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Semantic Scholar extracted view of "A study of the effects of the addition of various amounts of Cu to sintered NdFeB...

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Hydrogen Decrepitation (HD) is a suitable method for recycling sintered neodymium-iron-boron magnets obta...

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Hydrogen Decrepitation is a known process for breaking rare earth alloys such as NdFeB into powder,...

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The initial step for manufacturing NdFeB plated permanent magnets in this unit process is NdFeB alloying and strip cas...

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2.1. Introduction of this section. HDDR treatment is used to obtain Nd-Fe-B magnet powders wi...

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