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Sprecher, et al. [8] compared the environmental impact of producing virgin NdFeB magnets to producing recycled NdFeB magnets from waste computer hard disk drives (HDDs) using hydrogen decrepitation. The results showed that recycling in general was more favorable to the environment, and this was especially true for manual …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 …Seven methods of production have been summarized, starting with the conventional powder metallurgy route and ending by the Hydrogen Decrepitation (HD) route, as they are the most applicable routes in this field. The advantages and disadvantages of the reported routes were mentioned. In fact, the HD method was found to have the following ...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 …big drive towards recycling of NdFeB magnets due to supply constraints for rare earth metals. Workers at the University of Birmingham have previously shown that hydrogen …

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 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 …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 …

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 moreThe 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 …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 …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) …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.

High-temperature oxidation resistance of Nd–Fe–B magnetic powder is of great importance for its application in bonded magnet fields. In this work, the refinement and surface modification of Nd–Fe–B magnetic powders were integrated and achieved simultaneously. The effects of phosphoric acid, isopropyl tris-(dioctyl pyrophosphate …

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. …

Hydrogen decrepitation (HD) is an effective and environmentally friendly technique for recycling of neodymium-iron-boron (NdFeB) magnets. During the HD process, the …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.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 …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 …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 …The processing and characterisation of recycled NdFeB based magnets. S. Adrwish. Materials Science. 2013. The scrap magnets were turned into a powder using the HD process. The powder was milled for specific times and sintered for 1-3hrs at 1090 °C. The magnet samples were measured using a permeameter to…. Expand. PDF.

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 …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 …High-temperature oxidation resistance of Nd–Fe–B magnetic powder is of great importance for its application in bonded magnet fields. In this work, the refinement and surface modification of Nd–Fe–B magnetic powders were integrated and achieved simultaneously. The effects of phosphoric acid, isopropyl tris-(dioctyl pyrophosphate …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]. …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 …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 …

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.

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 …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. 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) …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]. 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 (HD) process and re-sintering NdFeB magnet scrap recycling by processing it in hydrogen, then milling, aligning, pressing and re-sintering it [38–40] Although different methods for NdFeB magnet recycling have been reported in the literature, only one piece of technology has been applied in practice by the Urban Mining

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 …

Nov 1, 2017 · Fig. 1. Illustration of the Hydrogen Decrepitation Press-Less Process (HD-PLP) recycling of anisotropic sintered NdFeB magnet. Passivated commercial N48M sintered magnets were used as starting material and hydrogen was applied to disintegrate the magnets inside a ball milling container. The hydride powder was both used directly and some powder ...

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 ... 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 …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 …Over the last ten years several groups have been carrying out research into metal injection moulding (MIM) of neodymium-iron-boron (NdFeB) powders to produce isotropic or …Nov 1, 2017 · Fig. 1. Illustration of the Hydrogen Decrepitation Press-Less Process (HD-PLP) recycling of anisotropic sintered NdFeB magnet. Passivated commercial N48M sintered magnets were used as starting material and hydrogen was applied to disintegrate the magnets inside a ball milling container. The hydride powder was both used directly and some powder ... Permanent magnets produce magnetic fields and maintain the field even in the presence of an opposing magnetic field. They are widely used in electric machines, electronics, and medical devices. Part I reviews the conventional manufacturing processes for commercial magnets, including Nd-Fe-B, Sm-Co, alnico, and ferrite in cast and …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 …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 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].(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 …Mar 1, 2019 · Fig. 1 shows the hydrogen decrepitation curves of Nd-Fe-B SC and SM at 288 K with different initial hydrogen pressure. Under the initial hydrogen pressure of 0.1–1 Mpa, the HD process composes of four stages of magnets surface activation, slow hydrogenation of Nd-rich grain boundary phase, quick hydrogenation of Nd 2 Fe 14 B main phase grains, and slow hydrogenation of inner part of the magnets.

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 …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 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 …Instagram:https://instagram. jasminemanana como va a estar el climamy in laws are obsessed with me chapter 55cullum 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) … eternal valley memorial park and mortuarydollar 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 … zavarelli Sprecher, et al. [8] compared the environmental impact of producing virgin NdFeB magnets to producing recycled NdFeB magnets from waste computer hard disk drives (HDDs) using hydrogen decrepitation. The results showed that recycling in general was more favorable to the environment, and this was especially true for manual …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 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.