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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 …2.1. Introduction of this section. HDDR treatment is used to obtain Nd-Fe-B magnet powders with good magnetic anisotropy and high coercivity [6,8,19].Therefore, HDDR treatment has been used to produce anisotropic bonded magnets for high-performance motors in automobiles and electronic devices [20,21].In typical HDDR …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 …Received 21st February 2020, Accepted 5th March 2020. meric portion. The PA-free magnet powder was found to retain >90% of its original magnetic properties. Two epoxy-bonded magnets produced with this recycled magnet powder showed magnetic properties. DOI: 10.1039/d0gc00647e. The gravimetric measurements also confirmed that Dy additions increase both the initiation and absorption time for hydrogen decrepitation. Hence, a higher hydrogen pressure will be required to speed up the process. AB - Scrap containing NdFeB is a valuable resource for the production of NdFeB magnets as the demand for these materials grows.

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 ... 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 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 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.

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 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 …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 ... The fabrication of Nd-Fe-B sintered magnets is composed of quite a few processes mainly including strip casting, hydrogen decrepitation, jet-milling, magnetic alignment and pressing, sintering and subsequent heat treatment, machining, and surface coating. ... Possible methods of recycling NdFeB-type sintered magnets using the …

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 …

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 ...

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 …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 …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 …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 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 ...

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 …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 ... 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 corrosion and degradation of sintered Nd–Fe–B type magnets by hydrogen obtained from moisture in the environment has been termed the Negative Harris Effect. The residual hydrogen from the hydrogen decrepitation process in the manufacture of fully dense magnets is desorbed completely during the vacuum sintering …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 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 …

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 …

2.1. Introduction of this section. HDDR treatment is used to obtain Nd-Fe-B magnet powders with good magnetic anisotropy and high coercivity [6,8,19].Therefore, HDDR treatment has been used to produce anisotropic bonded magnets for high-performance motors in automobiles and electronic devices [20,21].In typical HDDR …Electrolytic Hydrogen Decrepitation of NdFeB Magnets Under Ambient Conditions. V. Kaplan, Y. Feldman, …, I. Lubomirsky. Journal of Sustainable Metallurgy • Volume 8, Issue 3 • 1 September 2022. 1 citation; Scopus record. Article. 2D Pb-Halide Perovskites Can Self-Heal Photodamage Better than 3D Ones.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 …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 ... Mar 1, 2019 · 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. 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; …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 …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 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 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 …

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 …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 …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 ... 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. 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, …May 11, 2020 · Metallurgical simulation and evaluation of the resource efficiency of whole production processes are of key importance for sound environmental impact assessments. Exergy dissipation analysis is suitable to quantify the theoretical limits of a process and pinpoint hotspots for improvements along the value chain. Production of NdFeB permanent magnets is evaluated herein using a simulation-based ... 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 …May 11, 2020 · Metallurgical simulation and evaluation of the resource efficiency of whole production processes are of key importance for sound environmental impact assessments. Exergy dissipation analysis is suitable to quantify the theoretical limits of a process and pinpoint hotspots for improvements along the value chain. Production of NdFeB permanent magnets is evaluated herein using a simulation-based ... We report investigations on the processing by Spark Plasma Sintering (SPS) of RE2Fe14B (RE = Nd, Pr…) powders obtained by hydrogen decrepitation of …@article{osti_37277, title = {Hydrogen decrepitation of sintered NdFeB magnets}, author = {Stiller, C and Roth, S and Binner, A}, abstractNote = {The kinetics of the hydrogen absorption and desorption behavior of a NdFeB sintered magnet is studied. Hydrogenation at temperatures above 200 C is used to crumble the Nd-enriched phase. …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

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 intrinsic magnetic coercivity (H ci) 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 …We report investigations on the processing by Spark Plasma Sintering (SPS) of RE2Fe14B (RE = Nd, Pr…) powders obtained by hydrogen decrepitation of …Instagram:https://instagram. sellers funeral home and cremation services obituariessaint tropez airbnbwkntqxlira 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) … this item isnteamvorstellung jan w. 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 … r 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 ... 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 …