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. 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.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 …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 ... Various anti-corrosion coatings used on commercially available NdFeB-type magnets were comparatively examined for their durability and suitability for magnet reprocessing by hydrogen-assisted recycling (HPMS). Layer thickness and structure were determined by systematic microstructural analysis, and a standardized corrosion test …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 ...Jul 14, 2000 · 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 the hydrogen ... The behavior of hydrogen absorption and release in hydrogen decrepitation (HD) process of Nd-Fe-B alloys were investigated. The results reveal that the reactivity and the amount of hydrogen absorption in HD process are related to the surface activity of the alloy so that the fresh and active surface has a higher efficiency. The presence of Nd-rich phase at the …Hydrogen Decrepitation (HD) has been used as an efficient and economical method in producing coarse NdFeB powder. This article studied the effects of hydrogen on the Nd-Dy-Fe-B magnets, such as HD ...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 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 …(2020) Piotrowicz et al. Journal of Mining and Metallurgy, Section B: Metallurgy. Rare earth magnets based upon neodymium-iron-boron (NdFeB) are employed in many high tech applications, including hard disk drives (HDDs). The key elements in manufacturing NdFeB magnets are rare earth elements (REE... 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 basic compound for most Neodymium magnets is Nd2Fe14B. In practice, the actual chemical reaction used can be more complicated. A commonly used reaction is: 57 Fe + 8 B + 10 Fe2O3 + 7.5 Nd2O3 ...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. 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]. 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 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 = …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 …During the hydrogenation process, a volume expansion takes place, which promotes the formation of transgranular and intergranular cracks, causing the breakup of the material [29].Fig. 1 shows the different types of fracture that can occur during the hydrogen decrepitation process. The hydrogenation of the grain boundary phase can lead to an …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 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 …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 …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. Dec 20, 2020 · After the hydrogen decrepitation, the hydrogenated NdFeB powder needs to be purified to remove all the impurities. This purification process has to be done in an inert atmosphere to avoid oxidation. Various authors have noted that both oxygen and carbon have been shown to have detrimental effects on the sintering process for NdFeB ( Lopes et al ... 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.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. 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 ... The extracted NdFeB powder is of a purity whereby it can be re-processed into new magnetic materials or rare earth alloys. HyProMag Ltd will be targeting a wide range of end of life applications. Illustration of the HPMS process applied to the voice coil assembly of a hard disk drive. Pilot HPMS reactor capable of processing 5kg of NdFeB.Fully dense, sintered NdFeB-type magnets have been subjected to the hydrogen decrepitation (HD) process. The resultant powder has been subsequently …Fully dense, sintered NdFeB-type magnets have been subjected to the hydrogen decrepitation (HD) process. The resultant powder has been subsequently …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 ... The use of 3-D laser confocal microscopy to visualise hydrogen interactions in-sit; The use of hydrogen decrepitation to extract NdFeB magnets from electronic assemblies; In-situ removal of magnets from large magnetic assemblies using hydrogen; Corrosion protection for NdFeB magnets; Recycling of rare earth magnets; Strip casting …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; …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 …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 (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. 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 …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]. 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. 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 ... 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 ... 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 = …Originated by Professor Rex Harris, the hydrogen decrepitation method, which is used to reduce NdFeB alloys to a powder, is now ubiquitously employed in worldwide magnet processing.(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 …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 ...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 ...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.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.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. Jul 14, 2000 · 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 the hydrogen ... 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 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 …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 ...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. 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 thisWe 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 …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 ...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 ... 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. 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]. Due to the high strength and very compact structure of sintered NdFeB magnets, hydrogen decrepitation is a necessary step to break down the magnet mass. On the other hand, the resin-bonded NdFeB magnets have very low strength and can be easily crushed by heating and removing the resin and epoxy used in their fabrication. 39. 3.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. 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 …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. 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 …Unfortunately, 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, …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 …Hydrogen Decrepitation (HD) has been used as an efficient and economical method in producing coarse NdFeB powder. This article studied the effects of hydrogen on the Nd-Dy-Fe-B magnets, such as HD ...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 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 …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 ]. 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 …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 …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 ...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 …Dec 20, 2020 · After the hydrogen decrepitation, the hydrogenated NdFeB powder needs to be purified to remove all the impurities. This purification process has to be done in an inert atmosphere to avoid oxidation. Various authors have noted that both oxygen and carbon have been shown to have detrimental effects on the sintering process for NdFeB ( Lopes et al ... 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 …Ndfeb hydrogen decrepitation.jpeg, lvquntaalc, kansas football jayhawkspercent22
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. . Ndfeb hydrogen decrepitation.jpeg
directions to nearest sherwin williamsHydrogen 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. 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 …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 …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 ... Feb 1, 1997 · Hydrogen decrepitation of Nd-Fe-B type magnet alloys is a two stage process. Firstly, the hydrogen reacts with the Nd-rich phase at or close to room temperature. This is an exothermic reaction [4] and the heat evolved then allows the second stage to proceed in which the hydrogen is absorbed by the Nd^FeuB matrix phase. 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 …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 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 ... In this paper, the hydrogen processing of scrap magnets has been demonstrated as an extraction method for NdFeB from automotive rotors for the first time, with the aim to …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 …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 …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. 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 ... 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 ... 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 ... In this paper, the hydrogen processing of scrap magnets has been demonstrated as an extraction method for NdFeB from automotive rotors for the first time, with the aim to …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 ...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 …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 …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).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 …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 …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 …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 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 …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. 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]. 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 ... Feb 1, 1997 · Hydrogen decrepitation of Nd-Fe-B type magnet alloys is a two stage process. Firstly, the hydrogen reacts with the Nd-rich phase at or close to room temperature. This is an exothermic reaction [4] and the heat evolved then allows the second stage to proceed in which the hydrogen is absorbed by the Nd^FeuB matrix phase. 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 …As starting materials, magnets of different grades were used, which were processed by hydrogen decrepitation and blending the powder with NdH x. Composition inhomogeneity in the Nd 2 Fe 14 B-based magnetic phase grains in the recycled magnets and the existence of a core-shell structure consisting of a Nd-rich (Dy-depleted) core and …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 ... During the hydrogenation process, a volume expansion takes place, which promotes the formation of transgranular and intergranular cracks, causing the breakup of the material [29].Fig. 1 shows the different types of fracture that can occur during the hydrogen decrepitation process. The hydrogenation of the grain boundary phase can lead to an …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. …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].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 …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 ]. The hydrogen decrepitation (HD) behaviors of various forms of the permanent magnet alloy Nd{sub 16}Fe{sub 76}B{sub 8} and stoichiometric composition Nd{sub 11.8}Fe{sub 82.3}B{sub 5.9} have been investigated to provide background information on the production of sintered magnets by the HD process. ... The procedure …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 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. Dec 20, 2020 · Extraction of NdFeB from rotors using hydrogen. Seven semi-embedded rotors and non-embedded rotors were processed separately in two experiments. All the magnets in individual slots were scored in concentric circles using an angle grinder to provide a fresh surface for the hydrogen, as shown in Fig. 3, 15–30 min before being loaded into the ... 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 …NdFeB permanent magnets have different life cycles, depending on the applications: from as short as 2–3 years in consumer electronics to 20–30 years in wind turbines. The size of the magnets ranges from less than 1 g in small consumer electronics to about 1 kg in electric vehicles (EVs) and hybrid and electric vehicles (HEVs), and can be …We 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 …In recent years, under the background of global low-carbon development, the production of NdFeB magnets has increased dramatically. With the end of magnet life, a large number of discarded products will be produced in the future. At the same time, 6–73% of industrial waste will be produced in the manufacturing process of magnets. The rare …Oct 1, 2020 · INET-3 is efficient to recover and separate Dy, Nd, and Co from NdFeB leachates. Its ΔpH 0.5 values of Fe-Dy, Dy-Nd, and Nd-Co are 0.35, 0.79, and 2.49, respectively. It is better to remove Fe 3+ by selective leaching and precipitation before Dy, Nd, and Co recovery and separation. 98% of Dy 3+ is recovered after four-stage counter-current extraction at A/O = 1:2 and equilibrium pH = 2.52. 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 ...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 oxidation kinetics in air of a commercial NdFeB magnet have been investigated over the temperature range 335–500°C. The oxide microstructure has been characterized by SEM, XRD and cross-sectional TEM. The results show that the external scale formed consists of an outer layer of Fe2O3 and an inner layer of Fe3O4 but that the principal degradation …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 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 …International Journal of Hydrogen Energy Volume 22, Issues 2–3 , February–March 1997 , Pages 241-244 Technical and operating features of interaction between hydrogens and alloys and magnets on the basis of rare earth metalscalcium [12] and hydrogen decrepitation [1,13-19]. Many of these are under current development. 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. …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 …1. Introduction. 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], …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 …Originated by Professor Rex Harris, the hydrogen decrepitation method, which is used to reduce NdFeB alloys to a powder, is now ubiquitously employed in worldwide magnet processing.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 ...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 = …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 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. The basic compound for most Neodymium magnets is Nd2Fe14B. In practice, the actual chemical reaction used can be more complicated. A commonly used reaction is: 57 Fe + 8 B + 10 Fe2O3 + 7.5 Nd2O3 ...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. 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) …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 …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 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 ...Feb 1, 1997 · Hydrogen decrepitation of Nd-Fe-B type magnet alloys is a two stage process. Firstly, the hydrogen reacts with the Nd-rich phase at or close to room temperature. This is an exothermic reaction [4] and the heat evolved then allows the second stage to proceed in which the hydrogen is absorbed by the Nd^FeuB matrix phase. 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.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 ... 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 …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.. Weather san jose california 10 day, and id come back if you