Dry and Wet Milling Comparison of Nd-Fe-B Magnets Based on Strip Cast Alloys

2017 ◽  
Vol 899 ◽  
pp. 567-571
Author(s):  
Fernando Maccari ◽  
R.V. Well ◽  
G. Eller ◽  
M.S.T. Hoffmann ◽  
Leonardo Ulian Lopes ◽  
...  
Keyword(s):  
Casting Process ◽  
High Energy ◽  
Milling Process ◽  
Grain Structure ◽  
Coarse Grained ◽  
High Coercivity ◽  
Wet Milling ◽  
Sintered Magnet ◽  
Energy Product ◽  
Cast Alloys

In this work, the influence of milling medium was investigated in order to achieve high energy-product Nd-Fe-B magnets, mostly by the remanence improvement related to the obtention of monocrystalline particles during milling. Nd-Fe-B alloy made by strip-casting process were used as starting material, which exhibits refined grain structure and demands special attention during milling in relation to coarse-grained, conventionally cast alloys. It was found that by using liquid medium during ball milling process, the mean particle size decreased, as well as the size distribution, which improved the particle alignment and hence the remanence in the sintered magnet. Texture was quantified by magnetic characterization based on reference isotropic magnets made in same conditions, and microstructure development was evaluated by optical microscopy. Moreover, after post-sintering treatment, the coercivity increased 20% compared to as sintered state without changing the remanence, providing an anisotropic magnet with high coercivity.

High-Energy Ball Milling and Sintering of Ti-2Ta-22Si-11B and Ti-6Ta-22Si-11B Powders Mixtures

2014 ◽  
Vol 802 ◽  
pp. 20-24 ◽  
Author(s):  
Lucas Moreira Ferreira ◽  
Luciano Braga Alkmin ◽  
Érika C.T. Ramos ◽  
Carlos Angelo Nunes ◽  
Alfeu Saraiva Ramos
Keyword(s):  
Ball Milling ◽  
Weight Ratio ◽  
High Energy ◽  
Milling Process ◽  
Wet Milling ◽  
X Ray Diffraction ◽  
Heat Treated ◽  
Equilibrium Structures ◽  
Rotary Speed ◽  
Steel Balls

The milling process of elemental Ti-2Ta-22Si-11B and Ti-6Ta-22Si-11B (at-%) powder mixtures were performed in a planetary Fritsch P-5 ball mill using stainless steel vials (225 mL) and hardened steel balls (19 mm diameter). Ball-to-powder weight ratio of 10:1 and a rotary speed of 300 rpm were adopted, varying the milling time. Wet milling (isopropyl alcohol) for 20 more minutes was used to increase the yield powder in to the vial. Following the Ti-Ta-Si-B powders milled for 600 min were heat-treated at 1100°C for 1 h in order to obtain the equilibrium structures. The milled powders and heat-treated samples were characterized by X-ray diffraction, scanning electron microscopy, and energy dispersive spectrometry. Supersaturated Ti solid solutions were formed during ball milling of Ti-Ta-Si-B powders while that the Ti5Si3 phase was formed after milling for 620 min of the Ta-richer powder mixture only. The particles sizes were initially increased during the initial milling times, and the wet milling provided the yield powder into the vials. A large amount of pores was found in both the sintered samples which presented the formation of the TiSS,(ss-solid solution) Ti6Si2B and TiB.

scholarly journals Microstructural Transitions during Powder Metallurgical Processing of Solute Stabilized Nanostructured Tungsten Alloys

Metals ◽  
2022 ◽  
Vol 12 (1) ◽  
pp. 159
Author(s):  
Nicholas Olynik ◽  
Bin Cheng ◽  
David J. Sprouster ◽  
Chad M. Parish ◽  
Jason R. Trelewicz
Keyword(s):  
Extreme Environments ◽  
High Energy ◽  
Grain Structure ◽  
Coarse Grained ◽  
Ultrafine Grain ◽  
Grain Boundary Engineering ◽  
Carbon Impurities ◽  
Grain Structures ◽  
Metallurgical Processing ◽  
Size Population

Exploiting grain boundary engineering in the design of alloys for extreme environments provides a promising pathway for enhancing performance relative to coarse-grained counterparts. Due to its attractive properties as a plasma facing material for fusion devices, tungsten presents an opportunity to exploit this approach in addressing the significant materials challenges imposed by the fusion environment. Here, we employ a ternary alloy design approach for stabilizing W against recrystallization and grain growth while simultaneously enhancing its manufacturability through powder metallurgical processing. Mechanical alloying and grain refinement in W-10 at.% Ti-(10,20) at.% Cr alloys are accomplished through high-energy ball milling with transitions in the microstructure mapped as a function of milling time. We demonstrate the multi-modal nature of the resulting nanocrystalline grain structure and its stability up to 1300 °C with the coarser grain size population correlated to transitions in crystallographic texture that result from the preferred slip systems in BCC W. Field-assisted sintering is employed to consolidate the alloy powders into bulk samples, which, due to the deliberately designed compositional features, are shown to retain ultrafine grain structures despite the presence of minor carbides formed during sintering due to carbon impurities in the ball-milled powders.

Effect of Milling Process and Calcination Temperature on the Properties of BSCF-SDC Composite Cathode

2018 ◽  
Vol 791 ◽  
pp. 74-80
Author(s):  
Umira Asyikin Yusop ◽  
Hamimah Abdul Rahman ◽  
Suraya Irdina Abdullah ◽  
Dedikarni Panuh
Keyword(s):  
Calcination Temperature ◽  
Composite Cathode ◽  
High Energy ◽  
Milling Process ◽  
Dry Milling ◽  
Secondary Phases ◽  
Wet Milling ◽  
Composite Powders ◽  
Composite Cathodes ◽  
Solid Cathode

The ionic conductivity, super conductivity, ferroelectricity, and magnetic resistance of barium strontium cobalt ferrite (BSCF) make it a good solid cathode material. This study aims to investigate the influence of milling process and calcination temperature on the behaviour of nanocomposite cathode BSCF–samarium-doped ceria (SDC). The BSCF–SDC composite powders were mixed using two milling processes, namely, wet milling and dry milling. The composite cathode powders were mixed through wet milling by high-energy ball milling at 550 rpm for 2 hours. For dry milling, the powders were milled at 150 rpm for 30 minutes. The powders then underwent calcination at 900 °C, 950 °C, 1050 °C, and 1150 °C for 2 hours. The composite cathodes were examined on the basis of phase and microstructure through field emission scanning electron microscopy (FESEM) and X-ray diffraction (XRD), respectively. In conclusion, the selection of suitable milling process and calcination temperature is important in eliminating secondary phases in BSCF–SDC composite cathodes and in enhancing their properties.

Synthesis of Cathode Materials Fe-Doped NiS2 by Mechanical Alloying for Li/NiS2 Cells

2011 ◽  
Vol 287-290 ◽  
pp. 1428-1432
Author(s):  
Xiao Jing Liu ◽  
Dong Wook Park ◽  
Zhe Zhu Xu ◽  
Sang Dae Kang ◽  
In Shup Ahn ◽  
...  
Keyword(s):  
Mechanical Alloying ◽  
Cathode Materials ◽  
Lithium Ion ◽  
High Energy ◽  
Milling Process ◽  
High Energy Density ◽  
Tetraethylene Glycol ◽  
Wet Milling ◽  
Powder Particles ◽  
Normal Hexane

In order to synthesize the fine compound iron-doped nickel disulfide (NiS2) with environmentally friendly nickel, sulfur and iron powders, mechanical alloying (MA) was conducted for 8 hrs with SPEX Mill at a speed of 1000 rpm. In this process, stearic acid was added as a kind of process control agents (PCAs) to prevent the excessive cold welding. Meanwhile, for the purpose of getting nanocrystalline of Fe-doped NiS2powder particles to improve the contact areas between the active materials, the wet milling process was also done for 30 hrs with normal hexane (C6H14) as a solvent PCA. The prepared powders were characterized by FE-SEM, XRD, EPMA, EDS and TEM. Finally, the charge/discharge properties of Li/Fe-doped NiS2cells were investigated at room temperature by employing 1 M LiCF3SO3(lithium trifluoromethanesulfonate) dissolved in TEGDME (tetraethylene glycol dimethylether) as the electrolyte. The initial discharge capacity of Li/Fe-doped NiS2cell using wet milled powders as the cathode material is 792 mAh/g, which may indicate its high energy density and good future as cathode materials for lithium-ion batteries.

Synthesis and Characterization of Electromagnetic Material Based On Composite of Barium M-Ferrite and Zinc Oxide

2018 ◽  
pp. 78-82
Author(s):  
Verryon Harahap ◽  
Syahrul Humaidi ◽  
Perdamean Sebayang
Keyword(s):  
Zinc Oxide ◽  
Magnetic Properties ◽  
High Energy ◽  
Lattice Parameter ◽  
Milling Process ◽  
Raw Material ◽  
Wet Milling ◽  
Hexagonal Crystal ◽  
Milling Method ◽  
Energy Products

The making of composites BaFe12O19/ZnO has been done with Wet Milling method used media toluene. Barium M-Ferrit as a matrix and Zinc Oxide as a filler used as the main raw material for composite manufacturing. The milling process of Barium M-Ferrit was done for 12 hours using the High Energy Milling (HEM). Furthermore, the calcination process used furnace at 900 ° C for 4 hours. While Zinc Oxide is milled for 3 hours and calcined at a temperature of 500 oC for 3 hours. The results of Barium M-Ferrit and zinc Oxide mixed using wet milling touluene media for 15 minutes and dried for 1 hour at 200 oC. X-ray diffraction (XRD) showed that BaFe12O19 as a matrix and ZnO as filler with hexagonal crystal structure was formed and the peak showed a single phase, where each BaFe12O19 lattice parameter a = 5.8930 Å, c = 23.1940 Å and ZnO lattice parameter a = 3.2533 Å, c = 5.2073 Å. Characterization Vibrating Sample Magnetometer (VSM) obtained the value of magnetic properties BaFe12O19 powder (matrix) obtained (Ms) magnetic saturation 54.03 emu/g, (Mr) magnet remanent 33.06 emu/g, (Hcj) coercivity 2943 Oe and (BHmax) product energy 190 kGOe and Zinc Oxide as filler values (Ms) magnet saturation 7.84 emu / g, (Mr) magnet remanent 1.27 emu/g, (Hcj) coercivity 152.4 Oe and (BHmax) energy products 10 kGOe. The results of XRD on 50% mass of composites ZnO additions using match software have two phases, namely the presence of ZnO and BaFe12O19 phases which indicate that heterogeneous structures with hexagonal crystal structures. Composite magnetic properties obtained by adding 50% mass of ZnO were (Mr) magnet 39.40 emu/ g, coercivity 2728 Oe, (BHmax) product energy 110 kGOe and for composites 75% mass addition ZnO remanent 39.36 emu/g with coefficient of 1365 Oe and ( BHmax) product energy was 60 kGOe.

scholarly journals Synthesis And Electrochemical Characteristics Of Mechanically Alloyed Anode Materials SnS2 For Li/SnS2 Cells

2015 ◽  
Vol 60 (2) ◽  
pp. 1191-1194
Author(s):  
J.H. Hong ◽  
X.J. Liu ◽  
D.K. Park ◽  
K.W. Kim ◽  
H.J. Ahn ◽  
...  
Keyword(s):  
Ethylene Carbonate ◽  
Volume Ratio ◽  
High Energy ◽  
Milling Process ◽  
Diffraction Field ◽  
Electrochemical Characteristics ◽  
Wet Milling ◽  
Mechanically Alloyed ◽  
Mean Size ◽  
Increasing Demand

Abstract With the increasing demand for efficient and economic energy storage, tin disulfide (SnS2), as one of the most attractive anode candidates for the next generation high-energy rechargeable Li-ion battery, have been paid more and more attention because of its high theoretical energy density and cost effectiveness. In this study, a new, simple and effective process, mechanical alloying (MA), has been developed for preparing fine anode material tin disulfides, in which ammonium chloride (AC), referred to as process control agents (PCAs), were used to prevent excessive cold-welding and accelerate the synthesis rates to some extent. Meanwhile, in order to decrease the mean size of SnS2 powder particles and improve the contact areas between the active materials, wet milling process was also conducted with normal hexane (NH) as a solvent PCA. The prepared powders were both characterized by X-ray diffraction, Field emission-scanning electron microscopeand particle size analyzer. Finally, electrochemical measurements for Li/SnS2 cells were takenat room temperature, using a two-electrode cell assembled in an argon-filled glove box and the electrolyte of 1M LiPF6 in a mixture of ethylene carbonate(EC)/dimethylcarbonate (DMC)/ethylene methyl carbonate (EMC) (volume ratio of 1:1:1).

High Velocity Nano Alumina Wet Milling in Zirconia and Corundum Mills

2011 ◽  
Vol 83 ◽  
pp. 255-260 ◽  
Author(s):  
Yusoff M.S. Meor ◽  
Paulus Wilfred ◽  
Muslimin Masliana
Keyword(s):  
Crystallite Size ◽  
Lattice Strain ◽  
High Energy ◽  
Milling Process ◽  
Alumina Powder ◽  
Wet Milling ◽  
Optimum Conditions ◽  
X Ray Diffraction ◽  
Nano Alumina ◽  
Tangent Method

The paper presents a study on the effect of high energy milling to the crystallite size and lattice strain of α-alumina in zirconia and corundum mills. A Fritsch Pervesette 7 which has a maximum milling speed of 1100 rpm was used for this comparison. Milled samples were analyzed using the X-Ray Diffraction (XRD) technique to calculate for the crystallite size using the Scherrer method while lattice strain was determined by the Tangent method. Scanning electron microscope (SEM) was also used to determine changes in the morphology of the alumina powder sample after the milling process. Zirconia was found to be the better abrasive material and the optimum conditions used to obtain the smallest crystallite size of 51.2 nm are milling speed and time of 1100 rpm and 180 minutes respectively.

scholarly journals Preparation of strontium hexaferrite magnets from celestite and blue dust by mechanochemical route

2008 ◽  
Vol 44 (1) ◽  
pp. 91-100 ◽  
Author(s):  
R.K. Tiwary ◽  
S.P. Narayan ◽  
O.P. Pandey
Keyword(s):  
Iron Ore ◽  
Single Phase ◽  
High Energy ◽  
Strontium Hexaferrite ◽  
Ferrite Powder ◽  
Sintered Magnet ◽  
X Ray ◽  
Energy Product ◽  
Long Time ◽  
Iron Ore Fines

In the present investigation celestite (natural ore of strontium) and blue dust (iron ore fines) have been used for the preparation of strontium hexaferrite powder. The mechanical alloying process has been adopted to prepare strontium hexaferrite powder. The celestite after chemical upradation and physically upgraded blue dust alongwith sodium carbonate was taken for the preparation of strontium hexaferrite in this experiment. The high-energy planetary ball mill with tungsten carbide jar and ball was used to prepare strontium hexaferrite powder. A long time of ball milling for different duration has led to displacement solid-state reaction. At the end of each experiment the product was washed thoroughly and dried. The X-ray diffaction study after annealing shows the development of single-phase strontium hexaferrite after 40 hrs. of milling. The resultant powder was compacted under magnetic field and sintered to prepare the magnet after annealing the ferrite powder. The magnetic properties were measured by Pulse magneto meter. The moderate value of coercivity, remanence and energy product were observed in this sintered magnet. The work illustrates the feasibility to prepare strontium hexaferrite magnetic powders directly from natural ores which can reduce the total cost of production as compared to conventional method.

High Coercivity Mechanism Of The Die-Upset Hard Magnets Re13.75Fe80.25B6 (Re = Nd, Pr): Possible Correlation To Specific DefectMicrostructure

1999 ◽  
Vol 5 (S2) ◽  
pp. 42-43
Author(s):  
V.V. Volkov ◽  
Y. Zhu
Keyword(s):  
Magnetic Structure ◽  
Permanent Magnets ◽  
Materials Science ◽  
High Energy ◽  
High Coercivity ◽  
Energy Product ◽  
Hard Magnets ◽  
Energy Products ◽  
Processing Techniques

The magnetic properties of permanent magnets are sensitive to their microstructure. In particular, for the family of Nd(Pr)-Fe-B magnets a very different coercivity and energy products may be obtained by several processing techniques. It was experimentally found that a small excess of Nd over the exact phase composition of Nd2Fe14B plays an important role in obtaining high-energy products during the die-upset processing of the anisotropic hard magnets. However the specific role of the Nd excess on both magnetic structure and microstructure of these die-upset magnets is unclear and controversial. Answers to these questions may help to correctly address some major issues in materials science, e.g. how microstructure is related to magnetic structure of hard magnets, and how to optimize the performance of hard magnets.In-situ TEM magnetizing experiments combined with Lorentz magnetic microscopy in Fresnel-Foucault modes were used to characterize the magnetic structure of die-upset, high energy-product hard magnets Nd13.75Fe80.25B6 and Pr13.75Fe80.25B6.

Structural Evaluation of Ti-Cr-Si-B Powders Produced by High-Energy Ball Milling and Sintering

2017 ◽  
Vol 899 ◽  
pp. 499-504
Author(s):  
Luiz Otávio Vicentin Maruya ◽  
Paulo Atsushi Suzuki ◽  
Alfeu Saraiva Ramos
Keyword(s):  
Ball Milling ◽  
Weight Ratio ◽  
High Energy ◽  
Milling Process ◽  
Wet Milling ◽  
Mechanically Alloyed ◽  
Structural Evaluation ◽  
Structural Applications ◽  
Rotary Speed ◽  
Steel Balls

Multicomponent Ti6Si2B-based alloys are potentially attractive for structural applications due to the low Ti6Si2B crystallographic anisotropy, and their oxidation resistance are higher than the Ti5Si3-based alloys. There is a limited amount of information on effect of alloying on stability of Ti6Si2B. The present work reports on the structural evaluation during ball milling and subsequent sintering of Ti-2Cr-22Si-11B and Ti-7Cr-22Si-11B (at-%) powders. The milling process was carried out in a planetary Fritsch P-5 ball mill under Ar atmosphere using hardened steel balls (19 mm diameter), stainless steel vials (225 mL), rotary speed of 300 rpm, and a ball-to-powder weight ratio of 10:1. Samples were collected after different milling times: 20, 60, 180, 300, 420 and 600 min. Addicional wet milling (isopropyl alcohol) for 20 more minutes was adopted to increase the yield powder into the vials. Following, the powders milled for 620 min were uniaxially compacted (20 MPa) in order to obtain cilinder green bodies with 10 mm diameter and subsequently sintered under vacuum at 1100°C for 240 min. The milled powders were characterized by X-ray diffraction, and scanning electron microscopy. The chromium addition have contributed to form a large amount of Ti6Si2B in the mechanically alloyed and sintered Ti-2Cr-22Si-11B and Ti-7Cr-22Si-11B alloys.

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