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The reaction speed in the typical hydrogenation run (Fig. 1b, 1d) is limited only by the rate of the gas diffusion into the sample.When the reaction proceeds in deficiency of hydrogen (Fig. 1b) only a part of the Nd transforms into neodymium hydride NdH y as it follows from the diffraction pattern displayed in Fig. 2d.That pattern includes …@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. …Hydrogen Decrepitation is a known process for breaking rare earth alloys such as NdFeB into powder, as described by Zakotnik et al. (“Hydrogen Decrepitation and Recycling of Sintered NdFeB-type Sintered Magnets”, Proceedings of 19 th International Workshop on Rare Earth Permanent Magnets & Their Applications; pp 289-295).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 …

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 Hydrogen Decrepitation is a process step used in the production of Neodymium magnets to create extremely small grains in the material. Neodymium magnets must have very small grains averaging about 5 micrometers in order to have the best magnetic properties. But the grain sizes after casting are much larger than that, so they must be ground down ...

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 …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].

T D ACCEPTED MANUSCRIPT The Use of Hydrogen to Separate and Recycle Neodymium-Iron-Boron-type Magnets from Electronic Waste A. Walton a, Han Yi , N.A. Rowson b, J.D. Speight , V.S.J. Mann a, R.S. Sheridan , A. Bradshaw a, I.R. Harris a, A.J. Williams School of Metallurgy and Materials a and School of Chemical Engineering b, …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.Fully dense, sintered NdFeB-type magnets have been subjected to the hydrogen decrepitation (HD) process. The resultant powder has been subsequently …Mar 1, 2019 · The Hydrogen Decrepitation process (HD) is used as an alternative method of powder preparation in the manufacturing process of sintered Nd Fe B magnets [ 1]. During the HD process a NdFeB-type material is hydrogenated by gaseous hydrogen at atmospheric (or elevated) pressure at room (or elevated) temperature.

Jul 15, 2015 · 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.

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.

calcium [12] and hydrogen decrepitation [1,13-19]. Many of these are under current development. Hydrogen decrepitation (HD) is based on the selective synthesis of …The intrinsic magnetic coercivity (Hci) of Nd‐Fe‐B‐based permanent magnet material is profoundly affected by hydrogen absorbed during the hydrogen decrepitation (HD) process for producing anisotropic powders from bulk anisotropic hot‐deformed MAGNEQUENCH (MQ) magnets. Hydrogen (H) content and x‐ray diffraction …The Hydrogen Decrepitation and the Hydrogen Disproportionation Desorption Recombination processes for the preparation and the recycling of the two industrially produced phases of SmCo alloys, SmCo5 and Sm2Co17, are reviewed. The effects of the chemical composition, the microstructure, the exposure time, the hydrogen …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.Hydrogen decrepitation as a highly efficient and excellent crushing method is widely used in the preparation of NdFeB magnets. ... Expand. 1. Save. The processing and characterisation of recycled NdFeB based magnets. S. Adrwish. Materials Science, Engineering. 2013; The scrap magnets were turned into a powder using the HD process. …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.Sep 17, 2021 · It is therefore expected that cracks are decreased by performing hydrogen decrepitation at higher temperature. To confirm this, the relationship between T dec (23°C–600°C) and the crack density D c was investigated. Here, D c was estimated by dividing the crack length in an SEM image by the cross-sectional area of the same image.

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 …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. The desorption of hydrogen from NdFeB powder and unmilled material produced using hydrogen decrepitation as a premilling technique was investigated using a mass spectrometer to monitor the hydrogen partial pressure in the system as the sample was heated under vacuum from room temperature to approximately 1000 degrees C. A …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 thisUnfortunately, the contained NdFeB magnets break up into a friable magnetized powder which then sticks to the ferrous scrap and the shredder itself. 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, …May 5, 2023 · The first is the hydrogen decrepitation (HD) process, which is already used in the primary production of NdFeB magnets to convert the alloy into powder form before further comminution. 46 The second process, named HDDR, which consists of two different steps, namely hydrogenation–disproportionation (HD) and desorption–recombination (DR), was ...

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].

The powders were produced by hydrogen decrepitation and on heating, hydrogen evolution occurred in two stages: firstly from the matrix phase (~170 ~ and then from the neodymium-rich phase (350-750 ~ The neodymium-rich phase melted at ~630 ~ and no significant microstructural changes occurred below this temperature.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 …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... Hydrogen decrepitation (HD) is an effective and environmentally friendly technique for recycling of neodymium-iron-boron (NdFeB) magnets. During the HD process, the …The powders were produced by hydrogen decrepitation and on heating, hydrogen evolution occurred in two stages: firstly from the matrix phase (~170 ~ and then from the neodymium-rich phase (350-750 ~ The neodymium-rich phase melted at ~630 ~ and no significant microstructural changes occurred below this temperature.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 …May 5, 2017 · Typically, alloys are processed using the Hydrogen Decrepitation process (HD) [5], [6] where the cast NdFeB alloys are exposed to hydrogen at room temperature causing them to react exothermically, and consequently, decrepitating into a highly friable powder which can then be jet-milled, aligned, compressed and liquid phase sintered to form a ... The Hydrogen Decrepitation and the Hydrogen Disproportionation Desorption Recombination processes for the preparation and the recycling of the two industrially produced phases of SmCo alloys, SmCo5 and Sm2Co17, are reviewed. The effects of the chemical composition, the microstructure, the exposure time, the hydrogen …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 ...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 …

The hydrogen treatment of the Nd‐Fe‐B alloy ingots was found to produce magnet powders with good magnetic properties. Typical magnetic properties of these powders are as follows; 4πIs = 9.5 kG, Br = 7.7 kG, iHc = 9.4 kOe, and (BH)max = 12.2 MGOe. Microstructural studies of these powders showed that they are made of fine …

Abstract. This paper reports the desorption of hydrogen from NdFeB powder, and unmilled material, produced using hydrogen decrepitation as a pre-milling technique, investigated using a mass spectrometer to monitor the hydrogen partial pressure in the system as the sample was heated under vacuum from room temperature to …

Hydrogen decrepitation and recycling of NdFeB-type sintered magnets Zakotnik M, Devlin E, Harris IR, Williams AJ ... Environmental degradation of NdFeB magnets Yan GL, McGuiness PJ, Farr JPG, Harris IR Journal of Alloys and Compounds 2009;478:188-92 Oxidation of NdFeB-type magnets modified with additions of Co, Dy, Zr and V ...Hydrogen Decrepitation is a known process for breaking rare earth alloys such as NdFeB into powder, as described by Zakotnik et al. (“Hydrogen Decrepitation and Recycling of Sintered NdFeB-type Sintered Magnets”, Proceedings of 19 th International Workshop on Rare Earth Permanent Magnets & Their Applications; pp 289-295).The HD-process converts the magnets possible to recover the hard magnetic powder from a to a powder due to the expansion of the material on particular device (e.g. hard disk drive or electric motor) hydrogen absorption. Recycling of NdFeB magnets by by simply exposing the complete system to a hydrogen this means has been proposed by Rivoirard ...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. 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... 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. Absorption and desorption of hydrogen by the permanent magnet material Nd 2 Fe 1 4 B have been studied using a microcomputer‐controlled, thermomanometric analyzer with an initial hydrogen pressure of approximately 1 bar. Primary absorption occurs in the range 200–300 °C and results in the formation of a stable hydride with …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. …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. 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) …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.

Finely divided loose Nd2Fe14BHx, x≤5, hydride powder (particle size ≤1 μm is synthesized by washing Nd2Fe14B crystallites embedded in calcium and other by‐products (during a reduction‐diffusion‐reaction performed using excess calcium) in water. The calcium reacts thereby with the water and produces, Ca+H2O CaO+H2, native …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 …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 …Broadening the knowledge about the hydrogen decrepitation of the NdFeB type materials is needed to better service the process e.g. for recycling (at room temperature only 4 out of 10 scrap magnets undergo decrepitation which is likely to be the result of the number and character of pin holes in the electroplated coatings and/or to possible ...Instagram:https://instagram. prenotazionerxroewkrvending machine for sale under dollar60036891 Nov 14, 2017 · Abstract: Hydrogen decrepitation (HD) is an effective and environmentally friendly technique for recycling of neodymium-iron-boron (NdFeB) magnets. During the HD process, the NdFeB breaks down into a matrix phase (Nd2Fe14BHx) and RE-rich grain boundary phase. The grain boundary phase in the HD powder is <2 m in size. The Nd 2 Fe 14 B phase is the main component of sintered NdFeB magnets. The ternary NdFeB phase diagram (Fig. 5.1(a)) shows that there are five phases in addition to the Nd 2 Fe 14 B (T1) phase: Fe, Nd 2 Fe 17, Nd 5 Fe 17, Nd 1.1 Fe 4 B 4 (T2), and Nd.Sintered NdFeB magnets are produced by the liquid phase sintering process and the … tiersegnungennameerror name spark is not defined 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 ... rich piana uncensored 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. Hydrogen Decrepitation is a process step used in the production of Neodymium magnets to create extremely small grains in the material. Neodymium magnets must have very small grains averaging about 5 micrometers in order to have the best magnetic properties. But the grain sizes after casting are much larger than that, so they must be ground down ...