Nanocomposites in the Systems Fe1−xO-Fe3O4 and MgO-MgFe2O4 Produced by Mechanical Alloying

1999 ◽  
Vol 581 ◽  
Author(s):  
A. Huerta ◽  
H. A. Calderon ◽  
H. Yee-Madeira ◽  
M. Umemoto ◽  
K. Tsuchiya
Keyword(s):  
Grain Size ◽  
Magnetic Properties ◽  
Mechanical Milling ◽  
Magnetic Particles ◽  
Milling Time ◽  
Volume Fraction ◽  
Low Energy ◽  
Nanocrystalline Ceramics ◽  
Plasma Sintering ◽  
Spark Plasma

ABSTRACTWtastite-magnetite and magnesia-magnesioferrite nanocrystalline ceramics have been prepared by mechanical milling and spark plasma sintering. As-milled powders have a nanocrystal-line structure in both systems. Low energy milling gives rise to an increasingly higher volume fraction of wfistite as a function of milling time in the Fe1−xO-Fe3O4 system. Similar results are obtained in the MgO-MgFe2O4 system with increasingly larger amounts of MgFe2O4 produced by milling. Composites of magnetic particles (Fe3O4 or MgFe2O4) in a nonconductive matrix (FeO or MgO, respectively) are found in the sintered samples. Measurement of magnetic properties can be used to determine conclusively the nature of the developed phases and the effect of grain size.

Production and Magnetic Properties of Nanocomposites made of Ferrites and Ceramic Matrices

2001 ◽  
Vol 703 ◽  
Author(s):  
H. A. Calderon ◽  
A. Huerta ◽  
M. Umemoto ◽  
K. Cornett
Keyword(s):  
Magnetic Properties ◽  
Magnetic Particles ◽  
Milling Time ◽  
Volume Fraction ◽  
Nanocrystalline Structure ◽  
Low Energy ◽  
Nanocrystalline Ceramics ◽  
Plasma Sintering ◽  
Spark Plasma ◽  
Ceramic Matrices

ABSTRACTThis investigation deals with the production of materials containing a dispersion of magnetic nanoparticles in an insulating matrix. Such a distribution of magnetic centers is expected to absorb electromagnetic radiation in a range of wavelengths. Wüstite-magnetite and magnesiamagnesioferrite nanocrystalline ceramics have been prepared by mechanical milling and spark plasma sintering. As-milled powders have a nanocrystalline structure in both systems. Low energy milling gives rise to an increasingly higher volume fraction of wüstite as a function of milling time in the Fe1-xO-Fe3O4 system. Similar results are obtained in the MgO-MgFe2O4 system with increasingly larger amounts of MgFe2O4 produced by milling. Composites of magnetic particles (Fe3O4 or MgFe2O4) in a nonconductive matrix (FeO or MgO, respectively) are found in the sintered samples. Measurement of magnetic properties can be used to determine conclusively the nature of the developed phases and the effect of grain size.

Nanostructured Ceramic Oxides Containing Ferrite Nanoparticles and Produced by Mechanical Milling.

2012 ◽  
Vol 1485 ◽  
pp. 71-76
Author(s):  
A. Huerta-Ricardo ◽  
K. Tsuchiya ◽  
T. Umemoto ◽  
H. A. Calderon
Keyword(s):  
Mechanical Milling ◽  
Magnetic Particles ◽  
Volume Fraction ◽  
Nanocrystalline Structure ◽  
Ceramic Materials ◽  
Matrix Composites ◽  
Vacuum Sintering ◽  
Ceramic Oxides ◽  
Plasma Sintering ◽  
Spark Plasma

ABSTRACTThis investigation deals with the production process and the characterization of ceramic materials consisting of magnetic particles in an insulating matrix. Composites made of magnetite particles (Fe3O4 or MgFe2O4) in a wüstite or magnesiowüstite matrix (FexO or Mg1-xFexO), respectively, have been produced by means of mechanical milling and spark plasma sintering. As-milled powders have a nanocrystalline structure in both systems. As a function of milling time, low energy milling gives rise to an increasingly higher volume fraction of wüstite in the FexO-Fe3O4 system while it promotes increasing amounts of magnesiowüstite (MgxFe1-xO). Sintering is performed from 673 to 1273 K in vacuum. Sintering at low temperatures allows retention of nanosized grains containing a fine dispersion of magnetic particles in a wüstite and magnesiowüstite matrix. Measurement of magnetic properties reflects the constitution of the sintered samples and the effect of grain size. It also allows determination of the transformation sequence both during mechanical milling and sintering

Study on Mechanical Alloying of TiB2 Particulate Reinforced Titanium Matrix Composites

2018 ◽  
Vol 875 ◽  
pp. 41-46 ◽  
Author(s):  
Yue Ying Li ◽  
Fu Wen Zhu ◽  
Zhen Liang Qiao
Keyword(s):  
Mechanical Alloying ◽  
Milling Time ◽  
Volume Fraction ◽  
Matrix Composites ◽  
Titanium Matrix ◽  
Titanium Matrix Composites ◽  
Plasma Sintering ◽  
Spark Plasma ◽  
Powder Particles ◽  
Particulate Reinforced

TiB2 particulate reinforced titanium matrix composites were prepared by mechanical alloying and spark plasma sintering. Volume fraction of TiB2 powders in the composites are 5%, 10%, 15%. The effect of milling time and the volume fraction of reinforcement on microstructure and properties of the composites were studied. The results show that with increasing milling time, the size of powder particles decreases, quantity of them increases, and microstructure of the sintered samples becomes finer and more uniform. When milling time reaches 30h, the trend of powder agglomeration increases, the downward trend of the particle size becomes slowly. With the milling time, the density of titanium matrix composites is on the rise. The density of 10vol%TiB2 particulate reinforced titanium matrix composites can reach 4.799 g/cm3, with 30h milling time and sintering at 900°C. The density and hardness of the composites increase with increasing the volume fraction of TiB2. When the volume fraction of TiB2 is 15%, after milling 10h and sintered at 800°C, the density and hardness of the composites can reach 4.713g/cm3 and HV851.58.

Synthesis of nanostructured metal (Fe, Al)-C60 composites

2010 ◽  
Vol 1276 ◽  
Author(s):  
I. I. Santana García ◽  
V. Garibay Febles ◽  
H. A. Calderon
Keyword(s):  
Raman Spectroscopy ◽  
Mechanical Milling ◽  
Volume Fraction ◽  
High Volume ◽  
X Ray Diffraction ◽  
Nanostructured Composite ◽  
Plasma Sintering ◽  
Transmission Electron ◽  
Show Evidence ◽  
Spark Plasma

AbstractComposites of M-2.5 mol. % Fullerene C60 composites (where M= Fe or Al) are prepared by mechanical milling and Spark Plasma Sintering (SPS). The SPS technique has been used to consolidate the resulting powders and preserve the massive nanostructure. Results of X-Ray Diffraction and Raman Spectroscopy show that larger milling balls (9.6 mm in diameter) produce transformation of the fullerene phase during mechanical milling. Alternatively smaller milling balls (4.9 mm in diameter) allow retention of the fullerene phase. SEM shows homogeneous powders with different particle sizes depending on milling times. Sintering produces nanostructured composite materials with different reinforcing phases including C60 fullerenes, diamonds and metal carbides. The presence of each phase depends characteristically on the energy input during milling. Transmission Electron Microscopy (TEM) and Raman Spectroscopy show evidence of the spatial distribution and nature of phases. Diamonds and carbides can be identified for the sintered Fe containing composites with a relatively high volume fraction.

Spark Plasma Sintering of High-Energy Ball-Milled ZrB2 and HfB2 Powders with 20vol% SiC

2018 ◽  
Vol 941 ◽  
pp. 1990-1995
Author(s):  
Naidu V. Seetala ◽  
Cyerra L. Prevo ◽  
Lawrence E. Matson ◽  
Thomas S. Key ◽  
Ilseok I. Park
Keyword(s):  
Particle Size ◽  
Grain Size ◽  
Ball Milling ◽  
Milling Time ◽  
High Energy ◽  
Micro Hardness ◽  
Plasma Sintering ◽  
Spark Plasma ◽  
Energy Ball ◽  
Ball Milling Time

ZrB2 and HfB2 with incorporation of SiC are being considered as structural materials for elevated temperature applications. We used high energy ball milling of micron-size powders to increase lattice distortion enhanced inter-diffusion to get uniform distribution of SiC and reduce grain growth during Spark Plasma Sintering (SPS). High-energy planetary ball milling was performed on ZrB2 or HfB2 with 20vol% SiC powders for 24 and 48 hrs. The particle size distribution and crystal micro-strain were examined using Dynamic Light Scattering Technique and x-ray diffraction (XRD), respectively. XRD spectra were analyzed using Williamson-Hall plots to estimate the crystal micro-strain. The particle size decreased, and the crystal micro-strain increased with the increasing ball milling time. The SPS consolidation was performed at 32 MPa and 2,000°C. The SEM observation showed a tremendous decrease in SiC segregation and a reduction in grain size due to high energy ball milling of the precursor powders. Flexural strength of the SPS consolidated composites were studied using Four-Point Bend Beam test, and the micro-hardness was measured using Vickers micro-indenter with 1,000 gf load. Good correlation is observed in SPS consolidated ZrB2+SiC with increased micro-strain as the ball milling time increased: grain size decreased (from 9.7 to 3.2 μm), flexural strength (from 54 to 426 MPa) and micro-hardness (from 1528 to 1952 VHN) increased. The correlation is less evident in HfB2+SiC composites, especially in micro-hardness which showed a decrease with increasing ball milling time.

Mechanical properties of Mg-based materials fabricated by mechanical milling and spark plasma sintering

2018 ◽  
Vol 233 (10) ◽  
pp. 1972-1984 ◽  
Author(s):  
Mutlu Karasoglu ◽  
Serdar Karaoglu ◽  
Gursoy Arslan
Keyword(s):  
Grain Size ◽  
Yield Strength ◽  
Spark Plasma Sintering ◽  
Mechanical Milling ◽  
Microstructural Analysis ◽  
Compressive Yield Strength ◽  
X Ray ◽  
Plasma Sintering ◽  
Spark Plasma ◽  
Hardness Values

In this work, magnesium powders of different grain sizes were synthesized by mechanical milling for periods ranging from 0.5 to 30 h. Subsequent to milling, powders were consolidated by spark plasma sintering at 550 ℃ for 10 min. Before and after sintering, microstructural changes were investigated by analytical methods including X-ray diffraction (XRD), X-ray spectrometer, optical and electron microscopy. Analyses showed that nanocrystalline sizes were achieved by mechanical milling for milling times exceeding 5 h. Additionally, it was recognized that grain growth occurred during sintering, but to a limited extent. Mechanical test results displayed reasonable improvements in both compressive yield strength and hardness values with increasing milling times up to 5 h, where these reached their maximum values (245.5 MPa and 75.9 HV). The enhancement in these properties with increased milling time up to 5 h was attributed to both the extent of grain refinement and the formation of MgO together with incorporation of Fe particles, originating from the milling process, into the matrix. On the other hand, a substantial decrease in yield strength and hardness values in the samples milled in excess of 5 h were recorded, which in turn was related to the accompanying decline in bulk density of the samples. Microstructural analysis of the deformed samples revealed that grain size reduction suppressed twin formation, which elucidates the enhancement in ductility with decreasing grain size.

scholarly journals Fe-Si/MnZn(Fe2O4)2 Core-shell Composites with Excellent Magnetic Properties by Mechanical Milling and Spark Plasma Sintering (SPS)

Metals ◽  
2018 ◽  
Vol 8 (7) ◽  
pp. 553 ◽  
Author(s):  
Liang Yan ◽  
Biao Yan
Keyword(s):  
Magnetic Properties ◽  
Spark Plasma Sintering ◽  
Mechanical Milling ◽  
Core Shell ◽  
Magnetic Composite ◽  
Soft Magnetic ◽  
Magnetic Composites ◽  
Plasma Sintering ◽  
Soft Magnetic Composites ◽  
Spark Plasma

The Fe-Si/MnZn(Fe2O4)2 composite powders are synthetized by means of the mechanical milling, and Fe-Si/MnZn(Fe2O4)2 soft magnetic composites are prepared by spark plasma sintering (SPS). The impact of milling time on particle size, phase structure and magnetic properties of the investigative core-shell structure powders along with that of sintering temperature on microstructure and magnetic properties of FeSi-MnZn(Fe2O4)2 soft magnetic composite are studied by X-ray diffraction (XRD), scanning electron microscopy (SEM), and vibrating sample magnetometer (VSM). The experimental results demonstrate a layer of MnZn(Fe2O4)2 forming a coating on the surface of Fe-Si powder after mechanical milling, and the soft magnetic composites exhibiting excellent magnetic performance at 900 °C: 212.49 emu/g for saturation magnetization, with 6.89 Oe for coercivity, 3 × 10−4 Ω.m for electrical resistivity and stable amplitude permeability and low core loss over a wide frequency range. Therefore, SPS offers a convenient and swift way to enhance performance of soft magnetic composites using magnetic materials as insulting layer.

Magnetic Properties of Nd-Fe-B-M (M=Si, C) Bulk Nanocomposite Magnets Prepared by the Spark Plasma Sintering Method

2007 ◽  
Vol 1032 ◽  
Author(s):  
Tomokazu Fukuzaki ◽  
Keisuke Tanaka ◽  
Kazue Nishimoto ◽  
Yuji Muro ◽  
Keishi Nishio ◽  
...  
Keyword(s):  
Grain Size ◽  
Magnetic Properties ◽  
Magnetic Phase ◽  
The Other ◽  
Soft Magnetic ◽  
Grain Sizes ◽  
Nanocomposite Magnets ◽  
Plasma Sintering ◽  
Spark Plasma ◽  
Sintering Method

AbstractWe have prepared Nd2Fe14B/Fe3B bulk nanocomposite magnets at the compositions of Nd4Fe77.5B18.5-xMx (M=Si, C) by substitution of other elements M for B. For the sample substituted with 1 at.%Si and sintered at 600 oC, the coercivity exhibits the highest value of 227 kA/m. It has also been found that the grain sizes of the Nd2Fe14B and the Fe3B phases depend on the ramp-up time and the reduction of the grain size leads to an increase of the coercivity. On the other hand, the samples substituted with C exhibit soft magnetic behaviors, which is attributed to the suppression of the precipitation of the Nd2Fe14B hard magnetic phase.

Sign in / Sign up

Export Citation Format

Share Document