scholarly journals TOWARD LOW-ENERGY SPARK PLASMA SINTERING OF HOT-DEFORMED Nd-Fe-B MAGNETS

2021 ◽  
Vol 12 (2) ◽  
Author(s):  
Matic Korent ◽  
Marko Soderžnik ◽  
Urška Ročnik ◽  
Sandra Drev ◽  
Kristina Žužek Rožman ◽  
...  
Keyword(s):  
Energy Consumption ◽  
Spark Plasma Sintering ◽  
Deformation Process ◽  
Remanent Magnetization ◽  
Maximum Energy ◽  
Low Energy ◽  
Maximum Energy Product ◽  
Energy Product ◽  
Plasma Sintering ◽  
Spark Plasma

In this work, we present a newly developed, economically efficient method for processing rare-earth Nd-Fe-B magnets based on spark plasma sintering. It makes us possible to retain the technologically essential properties of the produced magnet by consuming about 30% of the energy as compared to the conventional SPS process. A magnet with anisotropic microstructure was fabricated from MQU F commercial ribbons by low energy consumption (0.37 MJ) during the deformation process and compared to the conventionally prepared hot-deformed magnet, which consumed 3-times more energy (1.2 MJ). Both magnets were post-annealed at 650 °C for 120 min in a vacuum. After the postannealing process, the low-energy processing (LEP) hot-deformed magnet showed a coercivity of 1327 kAm-1, and remanent magnetization of 1.27 T. In comparison, the highenergy processing (HEP) hot-deformed magnet had a coercivity of 1337 kAm-1 and a remanent magnetization of 1.31 T. Complete microstructural characterization and detailed statistical analyses revealed a better texture orientation for the HEP hot-deformed magnet processed by high energy consumption, which is the main reason for the difference in remanent magnetization between the two hot-deformed magnets. The results show that, although the LEP hot-deformed magnet was processed by three times lower energy consumption than in a typical hot-deformation process, the maximum energy product is only 8 % lower than the maximum energy product of a HEP hot-deformed magnet.

Fabrication of Deep-Sub-Millimeter-Thick Compacts Using Spark Plasma Sintering

2007 ◽  
Vol 534-536 ◽  
pp. 521-524
Author(s):  
T. Tanaka ◽  
T. Ohashi ◽  
Kazunori Oshiro ◽  
Hirotaka Fujimori ◽  
H. Kurisu ◽  
...  
Keyword(s):  
Spark Plasma Sintering ◽  
Remanent Magnetization ◽  
Maximum Energy ◽  
Maximum Energy Product ◽  
Energy Product ◽  
Plasma Sintering ◽  
Spark Plasma ◽  
Large Maximum ◽  
Sintering Method

Nd-Fe-B type powder was sintered using spark plasma sintering method. Fabricated compact sintered at the temperature of 700 °C, is found to be a composite magnet with Nd-Fe-Co-B and α-Fe. The compact sintered at 700 °C shows slightly low coercivity and large remanent magnetization comparing to the compact sintered at 600 °C due to the formation of α-Fe phase, resulting in the large maximum energy product. Maximum energy product tends to decrease with decreasing thickness of sintered compacts below 0.5 mm in thickness.

NdFeB/αFe Nanocomposite Permanent Magnets with Enhanced Properties Prepared by Spark Plasma Sintering

2011 ◽  
Vol 672 ◽  
pp. 229-232
Author(s):  
Marian Grigoraş ◽  
M. Lostun ◽  
Nicoleta Lupu ◽  
Horia Chiriac
Keyword(s):  
Spark Plasma Sintering ◽  
Permanent Magnets ◽  
High Energy ◽  
Maximum Energy ◽  
Maximum Energy Product ◽  
Energy Product ◽  
Plasma Sintering ◽  
Spark Plasma ◽  
Energy Ball ◽  
Melt Spun Ribbons

Nanocomposite NdFeB/αFe magnets were obtained by spark plasma sintering technique using high energy ball-milled Nd-Fe-B melt-spun ribbons mixed in different weight ratios with Fe commercial powders. The remanence of SPS nanocomposite magnets increases with the Fe powders content from 6.1 for 4 wt.% Fe to 6.4 kG for 5 wt.% Fe, while the estimated maximum energy product is also increased from 9.0 to 10.6 MGOe.

Consolidation Behavior and Magnetic Properties of Nanocrystalline Nd-Fe-B Magnets Prepared by Spark Plasma Sintering

2017 ◽  
Vol 899 ◽  
pp. 559-562
Author(s):  
Frederico Orlandini Keller ◽  
Juliano Assis Baron Engerroff ◽  
Leonardo Ulian Lopes ◽  
Nério Vicente Jr. ◽  
Paulo Antônio Pereira Wendhausen
Keyword(s):  
Magnetic Properties ◽  
Spark Plasma Sintering ◽  
Constant Pressure ◽  
Maximum Energy ◽  
Processing Temperature ◽  
Sintering Process ◽  
Maximum Energy Product ◽  
Energy Product ◽  
Plasma Sintering ◽  
Spark Plasma

Spark Plasma Sintering (SPS) was studied as a means to consolidate Nd-Fe-B powders, previously subjected to grain refinement by HDDR (Hidrogenation–Disproportionation–Dessorption–Recombination). The sintering process was carried out under 60 MPa constant pressure, varying the maximum processing temperature from 500 °C to 900 °C with a holding time of 5 min. Densification was observed above 600 °C related to the melting of Nd-rich phase. The magnetic properties are clearly related to microstructure coarsening associated with the SPS temperature regime. A monotonic decrease for coercivity (Hcj) was observed as a function of maximum SPS operating temperature with values varying from maximum of 750 kA/m at 500 °C to less than 200 kA/m for SPS at 900 °C. Remanence (Br) and maximum energy product (BH)max showed optimum values for intermediate temperatures, since these properties benefit from the densification developed by SPS.

Spark Plasma Sintering Nd2Fe14B/α-Fe Bulk Exchange-Spring Magnets

2005 ◽  
Vol 475-479 ◽  
pp. 2161-2164 ◽  
Author(s):  
Ming Yue ◽  
Meng Tian ◽  
Wei Qiang Liu ◽  
Jiu Xing Zhang
Keyword(s):  
Magnetic Properties ◽  
Spark Plasma Sintering ◽  
Sintering Temperature ◽  
Xrd Analysis ◽  
Maximum Energy ◽  
Energy Product ◽  
Exchange Spring ◽  
Plasma Sintering ◽  
Spark Plasma ◽  
Exchange Spring Magnets

The Nd2Fe14B/α-Fe bulk exchange-spring magnets have been prepared by spark plasma sintering melt spun Nd9.8Dy0. 4Fe78.4Co5.6B5.8 flakes under different temperatures and pressures. It was found that higher sintering temperature improved the densification of the magnets, while deteriorated their magnetic properties simultaneously. An increased compressive pressure can restrain the grain growth remarkably and then leads to better magnetic properties and higher density for the magnet at same sintering temperature. XRD analysis showed that with the increase of sintering pressure, some peaks indicating c-axis texture such as (006) and (105) became dominant. As a result, the bulk magnet exhibited higher remanence and maximum energy product than starting powders.

Microstructure and Magnetic Properties of Hot-Pressed and Hot-Deformed Composite Magnets Produced by Spark Plasma Sintering Method

2011 ◽  
Vol 686 ◽  
pp. 740-744 ◽  
Author(s):  
Yi Long Ma ◽  
Deng Ming Chen ◽  
Qian Shen ◽  
Peng Jun Cao
Keyword(s):  
Magnetic Properties ◽  
Spark Plasma Sintering ◽  
Hot Pressing ◽  
Magnetic Energy ◽  
Pressing Temperature ◽  
Energy Product ◽  
Plasma Sintering ◽  
Spark Plasma ◽  
Energy Products ◽  
Fe Addition

Bulk isotropic and anisotropic Nd13.5Fe80.4Ga0.5B5.6 and Nd13.5Fe80.4Ga0.5B5.6/Fe magnets were synthesized by applying spark plasma sintering (SPS) technique. The effect of hot-pressing temperature on the magnetic properties of hot-pressed (HP) and hot-deformed (HD) magnets without additive and with 5% Fe addition was investigated. With increasing sintering temperature for HP magnets, the grain grew gradually. For HD magnets, the optimal magnetic properties could be obtained at hot-pressing temperature 680°C due to the development of desired c-axis texture and uniform microstructure, which resulted from the appropriate and uniform grain size in HP magnets. Fe addition could enhance remanence (Br) and magnetic energy products ((BH)m) of HP and HD magnets. However, the maximum magnetic energy product of HD magnets decreased when hot-pressing temperature was higher than 650°C.

scholarly journals Toward Low-Energy Spark-Plasma Sintering of Hot-Deformed Nd-Fe-B Magnets

2021 ◽  
Vol 10 (5) ◽  
pp. 98
Author(s):  
Matic Korent ◽  
Marko Soderznik ◽  
Urska Rocnik ◽  
Sandra Drev ◽  
Kristina Zuzek Rozman ◽  
...  
Keyword(s):  
Spark Plasma Sintering ◽  
Low Energy ◽  
Plasma Sintering ◽  
Spark Plasma

Reducing electric current and energy consumption of spark plasma sintering via punch configuration design

2017 ◽  
Vol 43 (18) ◽  
pp. 17225-17228 ◽  
Author(s):  
Liqing Huang ◽  
Ma Qian ◽  
Haibo Lu ◽  
Yong Sun ◽  
Lihua Wang ◽  
...  
Keyword(s):  
Energy Consumption ◽  
Electric Current ◽  
Spark Plasma Sintering ◽  
Configuration Design ◽  
Plasma Sintering ◽  
Spark Plasma

EM of rapidly solidified permanent magnets

1992 ◽  
Vol 50 (1) ◽  
pp. 198-199
Author(s):  
Raja K. Mishra
Keyword(s):  
Melt Spinning ◽  
Permanent Magnets ◽  
Dark Field Image ◽  
Dark Field ◽  
Maximum Energy ◽  
Quench Rate ◽  
Maximum Energy Product ◽  
Energy Product ◽  
Annular Dark Field ◽  
Rapidly Solidified

The discovery of a new class of permanent magnets based on Nd2Fe14B phase in the last decade has led to intense research and development efforts aimed at commercial exploitation of the new alloy. The material can be prepared either by rapid solidification or by powder metallurgy techniques and the resulting microstructures are very different. This paper details the microstructure of Nd-Fe-B magnets produced by melt-spinning.In melt spinning, quench rate can be varied easily by changing the rate of rotation of the quench wheel. There is an optimum quench rate when the material shows maximum magnetic hardening. For faster or slower quench rates, both coercivity and maximum energy product of the material fall off. These results can be directly related to the changes in the microstructure of the melt-spun ribbon as a function of quench rate. Figure 1 shows the microstructure of (a) an overquenched and (b) an optimally quenched ribbon. In Fig. 1(a), the material is nearly amorphous, with small nuclei of Nd2Fe14B grains visible and in Fig. 1(b) the microstructure consists of equiaxed Nd2Fe14B grains surrounded by a thin noncrystalline Nd-rich phase. Fig. 1(c) shows an annular dark field image of the intergranular phase. Nd enrichment in this phase is shown in the EDX spectra in Fig. 2.

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