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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 = …NdFeB ingot exposed to hydrogen atmosphere due to the changes of hydride lattice parameters cracks. The process called HDDR (Hydrogenation - …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 ... Introduction. In the fields of sintered magnets, the hydrogen decrepitation (HD) technique has been widely used. The as-melted NdFeB bulk material becomes brittle after HD and decrepitates into powders, as a result of the large volume expansion of the lattice of both the Nd 2 Fe 14 B matrix and the intergranular Nd-rich phase [1]. Hydrogen …

May 8, 2023 · 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 ...

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 ... 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...

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).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 …Mar 14, 2016 · Hydrogen decrepitation (HD)/hydrogenation disproportionation desorption recombination (HDDR) is a process used in manufacturing REPM and carried out as pretreatment before green body sintering. During hydrogenation, the Nd-rich grain boundary phase in NdFeB magnets initially absorbs hydrogen forming Nd hydride: [ 49 ]. 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 …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.

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. …

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 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].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. 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. 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, 2020 · Hydrogen decrepitation (HD) can be used as a direct reuse approach and effective method of recycling process to turn solid sintered magnets into a demagnetised powder for further processing. There are many major production steps –plus numerous sub steps- in the manufacture of high-quality, high-tech Neodymium magnets. Each step is highly important, and each step is an essential part of a highly refined …

Nov 15, 1988 · 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 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 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) …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 ...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

Oct 1, 2013 · 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 describe the dynamic mechanism model of the ... Sadly, one of the most common RE magnets, NdFeB, is produced as powder by strip casting and jet milling or by hydrogen decrepitation process, both of which yield irregular/angular powders. Such irregular powders exhibit low flowability making them unfit for most advanced manufacturing techniques. This work presents the use of an induction ...

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 ...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 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 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 ...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 …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 treatment starts with a hydrogen decrepitation (HD) process to transform the as extracted waste magnets into an almost fully demagnetized powder for an easy separation of the magnetic fraction from the rest of the materials (corrosion protection layers or, depending on the device, the assembly where the magnet was fixed into) [6]. …

Rare earth magnets based upon neodymium-iron-boron (NdFeB) are employed in many high tech applications, including h... Skip to main content. Sign In Create account . Journal Article OPEN ACCESS. THE USE OF THERMAL HYDROGEN DECREPITATION TO RECYCLE Nd-Fe-B MAGNETS FROM ELECTRONIC WASTE. Piotrowicz A; Pietrzyk S; …

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 …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. 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. Anisotropic powder was prepared with precursor (NdDy)-(FeCoNbCu)-B sintered magnets by hydrogen decrepitation, desorption, and subsequent annealing treatment. The hydrogen desorption was performed in magnetic fields of 0, 1, 3, and 5 T. The orientation of tetragonal phase grains of the powder was evaluated from the …The decrepitation process and related changes in the sample temperature are analysed to explain the experimentally observed weight gain curve of a Nd–Fe–B sample due to hydrogen uptake. It is shown that the expansion of the specific surface resulting from decrepitation of the sample is the most important parameter controlling …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 absorption and desorption characteristics for high coercivity NdDyFeCoNbCuB sintered bulk magnets were studied, by differential scanning calorimetry (DSC) measurement and hydrogenation kinetics measurement. The DSC measurements showed that hydrogenation of Nd-rich phase occurred in the temperature range of …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 hydrogen decrepitation (HD) behaviors of various forms of the permanent magnet alloy Nd 1 6 Fe 7 6 B 8 and stoichiometric composition Nd 11.8 Fe 82.3 B 5.9 have been investigated to provide background information on the production of sintered magnets by the HD process. The influence of the initial microstructures of the alloys on …The hydrogen-absorbing NdFeB powder absorbs heat in the plasma and rapidly decomposes and dehydrogenates. At the same time, in the dehydrogenation process, the particles are cracked and broken to form fine NdFeB powder due to rapid heat absorption and release of a large amount of hydrogen, and the NdFeB powder is at a high …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 ...

Rare earth magnets based upon neodymium-iron-boron (NdFeB) are employed in many high tech applications, including h... Skip to main content. Sign In Create account . Journal Article OPEN ACCESS. THE USE OF THERMAL HYDROGEN DECREPITATION TO RECYCLE Nd-Fe-B MAGNETS FROM ELECTRONIC WASTE. Piotrowicz A; Pietrzyk S; …Jul 1, 2002 · The effective diffusivity of hydrogen in NdFeB magnets is reduced with Co and Ga additions and as a result of the texture induced in the microstructure via die-upsetting process. In addition to the results shown in Fig. 8 , the thermal desorption behaviour related to the hydrogenation of a die-upset MQU-G magnet is different for the two ... The treatment starts with a hydrogen decrepitation (HD) process to transform the as extracted waste magnets into an almost fully demagnetized powder for an easy separation of the magnetic fraction from the rest of the materials (corrosion protection layers or, depending on the device, the assembly where the magnet was fixed into) [6]. …Instagram:https://instagram. mollypercent27s country kennels inchow get crispy turkey skin 42718180intrstar net webmailradio kiskeya en direct d 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 ... 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. sprint trade in any condition 2022381382 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 … mochinut murrieta menu 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.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.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.