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Hydrogen decrepitation process has been applied for the first time for the direct recycling of SmCo 5 magnets. Industrially produced sintered SmCo 5 magnets were decrepitated by hydrogen gas at a pressure of 1 bar to 9.5 bar at room temperature in a planetary rotating jar. After decrepitation, the starting sintered magnets were reduced to …
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.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 …The Hydrogen Decrepitation process (HD) is used as an alternative method of powder preparation in the manufacturing process of sintered Nd Fe B magnets [ 1]. During the HD process a NdFeB-type material is hydrogenated by gaseous hydrogen at atmospheric (or elevated) pressure at room (or elevated) temperature.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 …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 ...
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) …
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 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 …
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 …This work could have implications with regard to the mechanism of hydrogen decrepitation of sintered NdFeB magnets during the well-established recycling process described by Walton et al. [19] and [20]. During this process, scrap sintered NdFeB magnets are damaged in air to expose a clean surface suitable for hydrogen decrepitation. …This paper studied the corrosion behavior of c ∥ and c ⊥ surfaces in sintered (Ce 0.15 Nd 0.85) 30 Fe bal B magnets. The conclusions are as follows: (1) The distribution of RE-rich phase is improved after Ce substitution compared with the sintered Nd-Fe-B magnets, and the value of A0 / A1 is approximate for both c ∥ and c ⊥ surfaces.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], …
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 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
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; …
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 …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 …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, …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 …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
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 ... 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 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].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 ...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 …
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 …
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 ].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 …The invention relates to a hydrogen decrepitation process for sintered Nd-Fe-B permanent magnets and belongs to the technical field of magnetic materials. The hydrogen decrepitation process includes melting metal materials, quickly solidifying the metal materials into cast pieces, activating the cast pieces under a certain condition, namely …NdFeB ingot exposed to hydrogen atmosphere due to the changes of hydride lattice parameters cracks. The process called HDDR (Hydrogenation - Decrepitation -D...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 …Jul 8, 2020 · 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 = 830 kA/m ... The U.S. Department of Energy's Office of Scientific and Technical Information
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 …
PDF (11 MB) Get e-Alerts SUBJECTS: Grain, Hydrogen, Hydrogenation, Magnetic properties, Organic reactions Abstract Regarding the restrictions recently imposed by China on the export of rare-earth elements (REEs), …
We report investigations on the processing by Spark Plasma Sintering (SPS) of RE2Fe14B (RE = Nd, Pr…) powders obtained by hydrogen decrepitation of …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 …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 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 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 …Jul 8, 2020 · 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 = 830 kA/m ... 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 …Aug 4, 2022 · Here, we describe a room temperature, electrolytic decrepitation process applied to sintered Nd 2 Fe 14 B magnet fragments taken from end-of-life computer hard disk drives. In this process, fine grain, Nd-magnet-hydride powder is rapidly produced by atomic hydrogen in a 2 M KOH electrolyte.
The invention relates to a hydrogen decrepitation process for sintered Nd-Fe-B permanent magnets and belongs to the technical field of magnetic materials. The hydrogen decrepitation process includes melting metal materials, quickly solidifying the metal materials into cast pieces, activating the cast pieces under a certain condition, namely …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 ...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 …Instagram:https://instagram. bloglocomotives schedule 2023vending machine for sale under dollar600flmy sksymenpercent27s haircut near my location 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 … craigslist mcallen domesticasopercent27reillypercent27s on dixie highway Aug 4, 2022 · Here, we describe a room temperature, electrolytic decrepitation process applied to sintered Nd 2 Fe 14 B magnet fragments taken from end-of-life computer hard disk drives. In this process, fine grain, Nd-magnet-hydride powder is rapidly produced by atomic hydrogen in a 2 M KOH electrolyte. 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 … 274073 Hydrogen decrepitation (HD) is an effective and environmentally friendly technique for recycling of neodymium-iron-boron (NdFeB) magnets. During the HD process, the NdFeB breaks down into a matrix phase (Nd2Fe14BHx) and RE-rich grain boundary phase. The grain boundary phase in the HD powder is <2 μm in size. Recycled NdFeB material has …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