Enhancement of Magnetic Properties in Co-Sr Ferrite Nano Composites Prepared by an SHS Route

2013 ◽  
Vol 209 ◽  
pp. 164-168 ◽  
Author(s):  
Nital R. Panchal ◽  
Rajshree B. Jotania
Keyword(s):  
Spinel Ferrite ◽  
Exchange Interactions ◽  
Maximum Energy ◽  
Absorption Properties ◽  
Microwave Absorption Properties ◽  
Maximum Energy Product ◽  
Energy Product ◽  
High Density Magnetic Recording ◽  
Exciting Area

The preparation and characterization of composite materials containing nanometer-sized constituents is currently a very active and exciting area of research at laboratories around the world. In order to improve the magnetic and electromagnetic absorption properties of magnetic materials, composite of soft/hard ferrite is required in proper composition. For high-density magnetic recording, decrease in the coercive field and simultaneously increase in saturation magnetization has attracted much attention. To achieve these properties, new modified CoFe2O4-SrFe12O19 composite ferrite nanoparticles were prepared by using an SHS route. Composites of spinel: hexaferrite were prepared in the ratio 1:0, 1:2 and 0:1. The enhancement of maximum energy product BHmax is achieved by the addition of Spinel ferrite into M-type hexaferrite particles. The exchange interactions between hard and soft magnetic phases improve the microwave absorption properties. The parameters, Hc, σs, and particle size d, can easily be controlled by changing the content of spinel ferrite in the composite with Sr-M hexaferrite.

Microstructure of high-energy product Fe-Nd-B magnequench ribbons

1986 ◽  
Vol 44 ◽  
pp. 826-827
Author(s):  
Y. L. Chen
Keyword(s):  
Anisotropy Field ◽  
Microstructural Characterization ◽  
High Energy ◽  
Maximum Energy ◽  
Maximum Energy Product ◽  
Energy Product ◽  
High Anisotropy ◽  
Energy Products ◽  
Very High

Melt-spun Fe-Nd-B MAGNEQUENCH® ribbons have been produced by Croat et al. with energy products in excess of 10 MG.Oe using a relatively narrow window of composition and quenching speed. The hard magnetic phase has subsequently been identified as the Nd2Fe14B compound which has a very high anisotropy field. The microstructure of the MAGNEQUENCH® ribbon which has a maximum energy product of 14.1 MG•0e was found to consist of equiaxed Nd2Fe14B grains surrounded by a very thin intergranular film. This paper presents the results of some of our earlv work on the microstructural characterization of high energy product MAGNEQUENCH® ribbons having nominal compositions of Nd13Fe82.6B4.4 and Nd15Fe79.9B5.1. The purpose of this investigation was to characterize the microstructures of various MAGNEQUENCH® ribbons for correlation with their magnetic properties.

Influence of Alloying Elements Zr, Nb and Mo on the Microstructure and Magnetic Properties of Sintered Pr-Fe-Co-B Based Permanent Magnets

2018 ◽  
Vol 930 ◽  
pp. 440-444
Author(s):  
Melissa Rohrig Martins da Silva ◽  
R.G.T. Fim ◽  
S.C. Silva ◽  
Julio Cesar Serafim Casini ◽  
P.A.P. Wendhausen ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Permanent Magnets ◽  
Maximum Energy ◽  
Alloying Elements ◽  
Maximum Energy Product ◽  
Energy Product ◽  
Cast Alloys ◽  
Hydrogen Decrepitation ◽  
Microstructure And Magnetic Properties

The addition of alloying elements on rare-earth permanent magnets is one of the methods used to improve the magnetic properties. This present work evaluates the influence of alloying elements such as Zr, Nb and Mo on the microstructure and magnetic properties of sintered Pr-FeCo-B based permanent magnets. The permanent magnets were produced by the conventional powder metallurgy route using powder obtained by hydrogen-decrepitation (HD) method from as cast alloys. In order to produce the magnet Pr16Fe66,9Co10,7B5,7Cu0,7 without alloying elements the mixture of alloys method was employed, mixing two compositions: Pr20Fe73B5Cu2 (33% w.t) and Pr14Fe64Co16B6 (67% w.t). With the purpose of evaluating the influence of the alloying elements, the Pr14Fe64Co16B6X0,1 (where X= Zr, Nb or Mo) (67% w.t) alloy was employed. The characterization of the alloys and the magnets was carried out using scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDXS) and the magnetic properties were measured using a permeameter. The magnet without any additions presented the highest intrinsic coercivity (μ0iHc = 748 KA.m-1) while the magnet with Nb addition presented higher remanence (Br = 1,04 T). The magnet with Zr addition presented the highest maximum energy product (BHmáx = 144 KJ.m-3), and the magnet with Mo addition showed the highest squareness factor (SF = 0,73).

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.

Effects of Magnetic Powder Loading on Mechanical Properties and Magnetic Properties of Natural Rubber

2006 ◽  
Vol 45 ◽  
pp. 1423-1428
Author(s):  
Somsak Woramongconchai ◽  
Chatchawan Lohitvisat ◽  
Aree Wichainchai
Keyword(s):  
Mechanical Properties ◽  
Magnetic Properties ◽  
Coercive Force ◽  
Natural Rubber ◽  
Barium Ferrite ◽  
Maximum Energy ◽  
Magnetic Powder ◽  
Elongation At Break ◽  
Maximum Energy Product ◽  
Energy Product

The effect of magnetic powders and powders loading on magnetic properties and mechanical properties of magnetic rubbers were studied. The natural rubber with magnetic powders, Barium ferrite, Neodymium iron boron, were used as starting materials to prepare magnetic rubbers. Barium ferrite (BaO.6F2O3) powders had been sintered at 1285 oC for 30 hours to improve its crystal structure. The physical properties of magnetic rubbers, residual flux density (Br), coercive force (Hc), maximum energy product (BHmax), hardness and density, had a trend to increase as enhancing magnetic powders loading. However, some properties such as, intrinsic coercive force (Hci), tensile strength and elongation at break, had a trend to decrease when the magnetic powder loading was increased. Magnetic properties of the anisotropic type, sintered powders, were higher than isotropic type, non-sintered powders, except the Hci because anisotropic magnetic rubber indicated crystal orientation in the same direction.

Replacement of NdFeB by Ferrite Magnets

2018 ◽  
Vol 912 ◽  
pp. 106-111
Author(s):  
Marcos Flavio de Campos ◽  
Daniel Rodrigues ◽  
Jose Adilson de Castro
Keyword(s):  
Wind Turbines ◽  
Maximum Energy ◽  
High Resistivity ◽  
Relevant Issue ◽  
Demagnetizing Field ◽  
Ndfeb Magnets ◽  
Electric Cars ◽  
Maximum Energy Product ◽  
Energy Product ◽  
Proper Volume

The replacement of NdFeB magnets by ferrite magnets is discussed. For motors, remanence is relevant, implying in a volume three times that of NdFeB, when the relevant index of merit is remanence. However, if the relevant issue is the BHmax (maximum energy product), the volume for replacement should be ten times larger. The high resistivity of ferrites is a big advantage for motors. The temperature of operation is also relevant, because NdFeB magnets loss coercivity even with small increase of temperature. Different applications are discussed, as for instance, motors for electric cars and wind turbines. The choice of the proper volume depends on the evaluation of demagnetizing field in the condition of operation.

Bulk Nanocrystalline Permanent Magnets by Selective Laser Melting

2021 ◽  
Vol 58 (10) ◽  
pp. 630-643
Author(s):  
F. Trauter ◽  
J. Schanz ◽  
H. Riegel ◽  
T. Bernthaler ◽  
D. Goll ◽  
...  
Keyword(s):  
Additive Manufacturing ◽  
Field Strength ◽  
Selective Laser Melting ◽  
Permanent Magnets ◽  
Maximum Energy ◽  
Laser Melting ◽  
Maximum Energy Product ◽  
Energy Product ◽  
Bulk Nanocrystalline ◽  
Micrometer Scale

Abstract Fe-Nd-B powders were processed by additive manufacturing using laboratory scale selective laser melting to produce bulk nanocrystalline permanent magnets. The manufacturing process was carried out in a specially developed process chamber under Ar atmosphere. This resulted in novel types of microstructures with micrometer scale clusters of nanocrystalline hard magnetic grains. Owing to this microstructure, a maximum coercive field strength (coercivity) μ0Hc of 1.16 T, a remanence Jr of 0.58 T, and a maximum energy product (BH)max of 62.3 kJ/mm3could, for example, be obtained for the composition Nd16.5-Pr1.5-Zr2.6-Ti2.5-Co2.2-Fe65.9-B8.8.

scholarly journals High-Throughput Screening of Rare-Earth-Lean Intermetallic 1-13-X Compounds for Good Hard-Magnetic Properties

Metals ◽  
2019 ◽  
Vol 9 (10) ◽  
pp. 1096 ◽  
Author(s):  
Georg Krugel ◽  
Wolfgang Körner ◽  
Daniel F. Urban ◽  
Oliver Gutfleisch ◽  
Christian Elsässer
Keyword(s):  
Rare Earth ◽  
High Throughput ◽  
High Throughput Screening ◽  
Spontaneous Magnetization ◽  
Anisotropy Field ◽  
Structure Type ◽  
Anisotropy Constant ◽  
Maximum Energy ◽  
Maximum Energy Product ◽  
Energy Product

By computational high-throughput screening, the spontaneous magnetization M s , uniaxial magnetocrystalline anisotropy constant K 1 , anisotropy field H a , and maximum energy product ( B H ) max are estimated for ferromagnetic intermetallic phases with a tetragonal 1-13-X structure related to the LaCo 9 Si 4 structure type. For SmFe 13 N, a ( B H ) max as high as that of Nd 2 Fe 14 B and a comparable K 1 are predicted. Further promising candidates of composition SmFe 12 AN with A = Co, Ni, Cu, Zn, Ga, Ti, V, Al, Si, or P are identified which potentially reach (BH) max values higher than 400 kJ/m 3 combined with significant K 1 values, while containing almost 50% less rare-earth atoms than Nd 2 Fe 14 B.

Effect of Dysprosium Content on the Magnetic Properties of Nanocrystalline (Pr0.25Nd0.75)10-xDyxFe82Co2B6 Alloys

2014 ◽  
Vol 789 ◽  
pp. 28-31 ◽  
Author(s):  
He Wei Ding ◽  
Chun Xiang Cui ◽  
Ji Bing Sun
Keyword(s):  
Magnetic Properties ◽  
Melt Spinning ◽  
Maximum Energy ◽  
Vibrating Sample Magnetometer ◽  
X Ray ◽  
Maximum Energy Product ◽  
Energy Product ◽  
Intrinsic Coercivity ◽  
Electronic Microscope ◽  
Microstructure And Magnetic Properties

(Pr0.25Nd0.75)10-xDyxFe82Co2B6(x=0~0.3) ribbons were prepared by melt spinning at 25m/s and subsequent annealing. The effect of Dy content on the microstructure and magnetic properties of the ribbons has been investigated by X-ray diffractometer (XRD), scanning electronic microscope (SEM) and vibrating sample magnetometer (VSM). The magnetic properties related to the Dy content were characterized. Intrinsic coercivity of 598kA/m, remanence of 0.58T, and the maximum energy product (BH)max of 43kJ/m3 were achieved in (Pr0.25Nd0.75)9.8Dy0.2Fe82Co2B6 after annealing at 700°C for 10 minutes.

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