Ndfeb hydrogen decrepitation.jpeg.

Sep 7, 2022 · We report investigations on the processing by Spark Plasma Sintering (SPS) of RE2Fe14B (RE = Nd, Pr…) powders obtained by hydrogen decrepitation of decommissioned magnets and the magnetic properties of the consolidated magnets. First experiments have been carried out with a commercial powder to make clear the mechanisms occurring during the powder densification. The magnetic properties of ... As noted above, the calculated Gibbs energy of reactions of individual REE with atomic hydrogen (Table 1) is strongly negative, thereby predictive of rapid chemical decrepitation of the two-phase Nd-magnet within the temperature range of interest. These reactions can be expected to take place immediately … See moreWe ascribe the volume expansion during ATF aging to the incorporation of hydrogen dissociated from the organic liquid ATF into the melt-spun NdFeB powder. Hydrogen is known to diffuse into the Nd2Fe14B crystal structure [2–4] and occupy interstitial sites to form the isomorphic hydride Nd2Fe14BHx with up to x=5 H per formula …Jan 1, 1991 · 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]. 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 …

Step 3: Hydrogen Decrepitation. Rare earth elements have hydrogen absorption effect. NdFeB magnet alloy sheets are placed in a vacuum tube rotary furnace. As hydrogen gas is filled, rare earth-rich phase in the grain boundary of NdFeB magnet alloy absorbs hydrogen gas. After hydrogen absorption saturated, the rare earth-rich phase turns 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.

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 ...Jun 27, 2014 · 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) bear the best magnetic properties (B r = 110.59 emu/g, H cj ...

room temperature in a custom-made gauge glass reactor, and the hydrogen decrepitation process was video-monitored in situ with a single frame camera at 0.1 frames per second (fps).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. 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 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 …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 …

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 points on their surface. Bulk corrosion studies in steam gave comparable results, the oriented sample …

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) …

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. 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 ...NdFeB sintered magnet material has been developed. The magnets are produced by powder metallurgy route involving hydrogen decrepitation technique for making fine powder. After melting and casting ...Magnetic powders for sintered NdFeB magnets have been prepared by using an advanced processing method including strip casting, hydrogen decrepitation, jet milling and rubber isotropic press. The effects of Dy, Ga and Co addition on the microstructure and magnetic properties of sintered magnets have been investigated. By adopting a suitable …Jan 1, 2022 · The SC alloy is converted into a fine powder by hydrogen decrepitation and then jet-milling (JM) to produce a fine powder consisting almost entirely of single crystal particles of the Nd 2 Fe 14 B phase. This powder is then filled into fills molds and pressed while a magnetic field is applied to orient the individual particles. The compacted ...

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 ... 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 …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 …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 …Oct 30, 2018 · 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 pressure, and the temperature on the hydrogen absorption are discussed. The ... The processing and characterisation of recycled NdFeB-type sintered magnets. M. Degri. Materials Science, Engineering. 2014. 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…. Expand.International Journal of Hydrogen Energy. Volume 24, Issues 2–3, 1 March 1999, Pages 257-261. Application of hydrogen vibration milling in theprocessing of NdFeB and (Nd, Pr)FeB permanent magnets. Author links open overlay panel R.S Mottram 1, V Yartys 2, P.W Guegan 1, I.r Harris 1. Show more.

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 process of hydrogen decrepitation (HD), which is used in the primary production and recycling of Nd magnets, takes place at low temperatures, even at room temperature, so that the entire microstructure decomposes only in powder form and the grain size is reduced.

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 …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 …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 …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 ultrafine magnet waste (particle size < 1 µm) contained around 50% rare earths mainly in the form of hydroxides as they are generated from the hydrogen decrepitation. The major phases in ultrafine NdFeB waste were Nd(OH) 3, Fe 2 O 3 and Fe phases. When ultrafine magnet waste was leached with hydrofluoric acid, all the iron …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 …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 …

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 ...

Dec 25, 2017 · Recycling of Nd-Fe-B magnets is one of the few solutions to alleviate the supply risks of certain rare earth elements (REE) such as Nd and Dy. 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 hydrogenated powder.

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 ...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 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 …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].Sep 14, 2000 · This way of powdering known as hydrogen decrepitation (HD) is a well-established stage of manufacturing technologies of sintered [2], [3] and bonded [4] Nd–Fe–B magnets. The interstitial hydrogen in the ferromagnetic Nd 2 Fe 14 B phase reduces significantly its anisotropy field H A. That is why desorption of hydrogen is necessary in order ... Jul 1, 2019 · Recycling of scrap sintered Nd–Fe–B magnets as anisotropic bonded magnets via hydrogen decrepitation process. 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…. 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 ...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. Coercivities up to 534 kA/m were obtained in porous samples based on powder size d < 100 µm. Adding a ball milling step resulted in full density …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) …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 …A high performance sintered NdFeB magnet with N52 was prepared by strip casting, hydrogen decrepitation, jet milling, rubber isostatic pressing with impulse magnetic field and vibrating. The structure of the magnet was investigated by XRD, optical microscope, TEM and SEM, and its demagnetization curve was tested by magnetograph. The results …0.5% -1%. Dysprosium (Dy) 0.8% -1.2%. The method of manufacture of Neodymium Iron Boron magnets is as follows: The Neodymium metal element is initially separated from refined Rare Earth oxides in an electrolytic furnace. The “Rare Earth” elements are lanthanoids (also called lanthanides) and the term arises from the uncommon oxide …

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. 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 ...Hydrogen decrepitation (HD) of Nd-Fe-B cast alloys is widely used in the processing of sintered magnets. The oxidation resistance under air of alloy powder …Instagram:https://instagram. liralincoln ln 25 pro parts list2017 6 17 11 8 41 a esos graciaslowepercent27s patio covers 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]. controller tmp Semantic Scholar extracted view of "Possible methods of recycling NdFeB-type sintered magnets using the HD/degassing process" by M. Zakotnik et al. ... The purpose of this thesis was to study the Hydrogen Decrepitation (HD) process as a way to recycle waste scraps of Nd-Fe-B sintered magnets into highly coercitive and anisotropic … quiz 6 1 similar figures proving triangles similar 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 …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 ... 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 (29