Alumina Ceramic Texturing Induced by High Magnetic Field and its Microstructure

2012 ◽  
Vol 512-515 ◽  
pp. 339-343 ◽  
Author(s):  
Lin Feng Xu ◽  
Yun Feng Li ◽  
An Ze Shui ◽  
Yan Min Wang
Keyword(s):  
Magnetic Field ◽  
High Magnetic Field ◽  
Heating Temperature ◽  
Heating Time ◽  
Raw Material ◽  
Particle Orientation ◽  
Alumina Powder ◽  
Magnetic Field Direction ◽  
Magnetic Field Treatment ◽  
The Magnetic Field

Various textured alumina ceramics were prepared by colloidal processing in high magnetic field and heating from alumina powder as raw material in this study. The effects of the magnetic field strength, heating time and heating temperature on the particle orientation were systematically examined for these samples with scanning electron microscope (SEM) and X-ray diffraction (XRD) etc. The experimental results showed that alumina grains are polyhedral ball shape of, no textured structure exists in the sintered bodies without magnetic field treatment; the alumina grains align with the c-axis parallel the magnetic field direction under high magnetic field, the grains present strip shape in the sintered alumina bodies with the magnetic field treatment; the particle orientation degree increases with increasing the heating time and heating temperature; when the sintering temperature achieves about 1823K, the textured microstructure can be obviously observed in the sintered alumina bodies.

Sintering Shrinkage Anisotropy of Spherical Alumina Powder Compacts with Particle Orientation

2007 ◽  
Vol 334-335 ◽  
pp. 293-296 ◽  
Author(s):  
Yan Chun Liu ◽  
An Ze Shui ◽  
Xue Tan Ren ◽  
Ling Ke Zeng
Keyword(s):  
Magnetic Field ◽  
High Magnetic Field ◽  
Field Direction ◽  
Particle Orientation ◽  
Alumina Powder ◽  
Magnetic Field Direction ◽  
Axis Direction ◽  
Powder Compacts ◽  
Sintering Shrinkage ◽  
Spherical Alumina

Spherical alumina powder and dispersant were mixed with distilled and deionized water, and ball milled to make alumina slurry. The slurry was dried in a high magnetic field to make a compact. Subsequently, the compact was cold-isostatic-pressed (CIP) to enhance the homogeneity in particle packing density. Anisotropy of shrinkage during sintering was examined for the alumina compacts in detail. Particle orientation existed in the spherical alumina powder compacts prepared in 10T, and made them shrink anisotropically during sintering. Sintering shrinkage was larger in the direction parallel to magnetic field direction (i.e., the c-axis direction of alumina crystal) than that in its perpendicular direction. The particle orientation structure in the compacts was confirmed with the immersion liquid method of polarized light microscope, and the grain alignment structure in the sintered bodies was also observed with X-ray diffraction, the c-plane was perpendicular to the magnetic field direction. On the other hand, isotropic sintering shrinkage occurred in the spherical alumina powder compacts prepared in 0T, which did not hold the particle orientation. The experimental results indicate that sintering shrinkage of spherical alumina powder compact depends on alumina crystal axis direction. Origin of the sintering shrinkage anisotropy for the spherical alumina powder compacts can be attributed to the particle orientation caused by high magnetic field.

Effects of High Magnetic Field Heat Treatment on the Microstructure of Fe-0.76%C Alloy

2011 ◽  
Vol 704-705 ◽  
pp. 863-869 ◽  
Author(s):  
Ming Long Gong ◽  
Xiang Zhao ◽  
Chang Shu He ◽  
J.Y. Song ◽  
Liang Zuo
Keyword(s):  
Magnetic Field ◽  
High Magnetic Field ◽  
Lamellar Spacing ◽  
Field Direction ◽  
Magnetic Field Direction ◽  
High Carbon Content ◽  
Proeutectoid Ferrite ◽  
Alloy Microstructure ◽  
And Shifts ◽  
The Magnetic Field

The present studies are to investigate the microstructure features during transformation from austenite to ferrite without and with magnetic field on Fe-0.76%C alloy. It is found that the area fraction and numbers of proeutectoid ferrite grain as well as the lamellar spacing of pearlite in Fe-0.76%C alloy increased considerably with the increase of magnetic field intensity. The reason is that, the magnetic field increases the driving force of proeutectoid ferrite nuclei and shifts the eutectoid point to the side of high carbon content and high temperature, which increases the starting-temperature of the transformation from austenite to ferrite. The proeutectoid ferrite grains are elongated along the magnetic field direction, which can be explained as follows: the proeutectoid ferrite becomes the magnetic dipolar under high magnetic field, and then the polarized austenite atoms are much easier to diffuse into ferrite grains along the magnetic field direction. Key words: high magnetic field; Fe-0.76%C alloy; microstructure

Effect of High Magnetic Field on Diffusion Behavior of Carbon in Pure Iron

2011 ◽  
Vol 194-196 ◽  
pp. 67-70 ◽  
Author(s):  
Yan Wu ◽  
Yan Lu ◽  
Xiang Zhao ◽  
Liang Zuo
Keyword(s):  
Magnetic Field ◽  
High Magnetic Field ◽  
Field Intensity ◽  
Pure Iron ◽  
Magnetic Field Intensity ◽  
Carbon Diffusion ◽  
Field Direction ◽  
Magnetic Field Direction ◽  
Diffusion Behavior ◽  
The Magnetic Field

The effect of magnetic field on diffusion behavior of carbon in pure iron was investigated. The results showed that the magnetic field can accelerate the carbon diffusion when the magnetic field direction is perpendicular to the carburized direction, and this effect increases with the enhancement of magnetic field intensity.

Orientational Distributions and Rheological Properties of a Non-Dilute Colloidal Dispersion Composed of Rodlike Particles With Magnetic Moment Normal to the Particle Axis

2006 ◽  
Author(s):  
Yasuhiro Sakuda ◽  
Akira Satoh
Keyword(s):  
Magnetic Field ◽  
Magnetic Moment ◽  
Particle Interaction ◽  
Orientation Distribution ◽  
Field Direction ◽  
Particle Orientation ◽  
Magnetic Field Direction ◽  
Orientational Distribution ◽  
Rodlike Particles ◽  
The Magnetic Field

We have considered a semi-dense dispersion composed of ferromagnetic rodlike particles with a magnetic moment normal to the particle axis to investigate the rheological properties and particle orientational distribution in a simple shear flow as well as an external magnetic field. We have adopted the mean field approximation to take into account magnetic particle-particle interactions. The basic equation of the orientational distribution function has been derived from the balance of the torques and solved numerically. The results obtained here are summarized as follows. For a very strong magnetic field, the magnetic moment of the rodlike particle is strongly restricted in the field direction, so that the particle points to directions normal to the flow direction (and also to the magnetic field direction). This characteristic of the particle orientation distribution is also valid for the case of a strong particle-particle interaction, as in the strong magnetic field case. To the contrary, for a weak interaction between particles, the particle orientation distribution is governed by a shear flow as well as an applied magnetic field. When the magnetic particle-particle interaction is strong under circumstances of an applied magnetic field, the magnetic moment has a tendency to incline to the magnetic field direction more strongly. This leads to the characteristic that the viscosity decreases with decreasing the distance between particles, and this tendency becomes more significant for a stronger particle-particle interaction. These characteristics concerning the viscosity are quite different from those for a semi-dense dispersion composed of rodlike particles with a magnetic moment along the particle direction.

Effect of Magnetic Field Treatment on Dielectric Properties of LDPE Composites with Carbon Nanotube and Nanographite

2013 ◽  
Vol 873 ◽  
pp. 436-440
Author(s):  
Bao Zhong Han ◽  
Wei Zhou ◽  
Chang Lin Liu ◽  
Dan Liu ◽  
Xiang Wang
Keyword(s):  
Magnetic Field ◽  
Carbon Nanotube ◽  
External Magnetic Field ◽  
High Performance ◽  
Electrical Conductance ◽  
Research Field ◽  
Magnetic Field Direction ◽  
Field Development ◽  
Magnetic Field Treatment ◽  
The Magnetic Field

Magnetic phenomenon is one of the most fundamental phenomena of substances. All substances possess strong or weak magnetic property, and have different responds to external magnetic field. Development of high performance materials by using external magnetic field is an important research field of material science. In this study, a static magnetic field is applied during thermoforming processing of low density polyethylene (LDPE)/carbon nanotube (CNT), LDPE/nanographite composites. The effect of magnetic field treatment on dielectric property of these composites is investigated. Experimental results indicate that CNT and nanographite orientate in melted LDPE under the magnetic field. The electrical conductance, the dielectric constant and the dielectric loss angular tangent value of LDPE/CNT and LDPE/ nanographite composites along the magnetic field direction all increase.

A 3 T superconducting magnet for long-run magnetic Compton-scattering experiments

1998 ◽  
Vol 5 (3) ◽  
pp. 937-939 ◽  
Author(s):  
Nobuhiko Sakai ◽  
Hiroshi Ohkubo ◽  
Yasushi Nakamura
Keyword(s):  
Magnetic Field ◽  
Low Temperature ◽  
Compton Scattering ◽  
Superconducting Magnet ◽  
Field Direction ◽  
Compton Profile ◽  
Magnetic Field Direction ◽  
Long Run ◽  
Radiation Shields ◽  
The Magnetic Field

A 3 T superconducting magnet has been designed and constructed for magnetic Compton-profile (MCP) measurements with the new capabilities that the magnetic field direction can be altered quickly (within 5 s) and liquid-He refill is not required for more than one week. For the latter capability, two refrigerators have been directly attached to the cryostat to maintain the low temperature of the radiation shields and for the recondensation of liquid He. The system has been satisfactorily operated for over one week.

scholarly journals Enhanced X-ray emission arising from laser-plasma confinement by a strong transverse magnetic field

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Evgeny D. Filippov ◽  
Sergey S. Makarov ◽  
Konstantin F. Burdonov ◽  
Weipeng Yao ◽  
Guilhem Revet ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Transverse Magnetic ◽  
Radiative Properties ◽  
Magnetic Field Direction ◽  
Solid Target ◽  
Total Plasma ◽  
Plasma Confinement ◽  
X Ray ◽  
Magnetic Compression ◽  
The Magnetic Field

AbstractWe analyze, using experiments and 3D MHD numerical simulations, the dynamic and radiative properties of a plasma ablated by a laser (1 ns, 10$$^{12}$$ 12 –10$$^{13}$$ 13 W/cm$$^2$$ 2 ) from a solid target as it expands into a homogeneous, strong magnetic field (up to 30 T) that is transverse to its main expansion axis. We find that as early as 2 ns after the start of the expansion, the plasma becomes constrained by the magnetic field. As the magnetic field strength is increased, more plasma is confined close to the target and is heated by magnetic compression. We also observe that after $$\sim 8$$ ∼ 8  ns, the plasma is being overall shaped in a slab, with the plasma being compressed perpendicularly to the magnetic field, and being extended along the magnetic field direction. This dense slab rapidly expands into vacuum; however, it contains only $$\sim 2\%$$ ∼ 2 % of the total plasma. As a result of the higher density and increased heating of the plasma confined against the laser-irradiated solid target, there is a net enhancement of the total X-ray emissivity induced by the magnetization.

scholarly journals Combined laser and magnetic field treatment of YFeO3—containing films grown by spray-pyrolysis

2004 ◽  
Vol 2 (1) ◽  
pp. 188-195
Author(s):  
N. Mihailov ◽  
O. Vankov ◽  
N. Petrova ◽  
D. Kovacheva
Keyword(s):  
Magnetic Field ◽  
Spray Pyrolysis ◽  
Pulse Duration ◽  
Fused Silica ◽  
Crystallite Sizes ◽  
Citric Complexes ◽  
Magnetic Field Treatment ◽  
Glycol Solution ◽  
The Magnetic Field ◽  
Post Deposition

AbstractThin films (50–1200 nm) of YFeO3 were deposited on fused silica substrates by spray-pyrolysis using ethylene glycol solution of Y-Fe(III) citric complexes. The films were post deposition annealed at 750°C in static air for 2 h. Films obtained in this way were afterwards irradiated by a burst mode operated Nd-YAG laser (pulse energy 650 mJ, pulse duration 700 μs, energy density 110 mJ/cm2). The laser’s onset was synchronized with that of a magnetic field pulse of nearly square shape (magnetic induction 0.5 T, pulse duration 900 μs). The samples were placed normally to the direction of the magnetic field. The treatment does not affect the phase composition of the film but significantly increases the crystallite sizes of the phases presenting in the sample. The saturation magnetization of the films decreases as a result of the laser and magnetic field treatment and the coercive force increases by 50%.

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