scholarly journals Targeted patterning of magnetic microparticles in a polymer composite

2020 ◽  
Vol 378 (2171) ◽  
pp. 20190256 ◽  
Author(s):  
Dmitry Borin
Keyword(s):  
Magnetic Field ◽  
Three Dimensional ◽  
Soft Magnetic Materials ◽  
Soft Magnetic ◽  
Parameter Variations ◽  
The Matrix ◽  
Viscous Media ◽  
Experimental Findings ◽  
External Stimuli ◽  
Further Development

Structured and polymerized in a uniform external magnetic field, polymer composites based on magnetic soft microparticles are considered. Variations of magnetic field parameters and material composition provide a possibility of targeted micro-structural patterning of these composites. The influences of parameter variations on the resulting internal micro-structure of the low concentrated specimens are evaluated and visualized using optical microscopy and microcomputed tomography. The experimental findings are discussed in order to provide advanced possibilities of controlled patterning of soft magnetic materials. It is experimentally demonstrated that the final three-dimensional morphology of composite structure is determined mainly by the concentration of magnetic powder. The intensity of the applied magnetic field influences the rate of structuring of particles in initially viscous media and, therefore, may provide a potential opportunity to obtain non-ergodic microstructures when the matrix is polymerized before the particles have completed the structuring process. The results obtained can serve as a basis for further development of the engineering method of targeted patterning. The method is intended to obtain a material with the desired microstructure by selecting specific parameters of external stimuli and components of the composite. This article is part of the theme issue ‘Patterns in soft and biological matters’.

Three-dimensional atom probe study of Fe–B-based nanocrystalline soft magnetic materials

2009 ◽  
Vol 57 (15) ◽  
pp. 4463-4472 ◽  
Author(s):  
Y.M. Chen ◽  
T. Ohkubo ◽  
M. Ohta ◽  
Y. Yoshizawa ◽  
K. Hono
Keyword(s):  
Magnetic Materials ◽  
Three Dimensional ◽  
Atom Probe ◽  
Soft Magnetic Materials ◽  
Soft Magnetic

scholarly journals Sintering of Soft Magnetic Material under Microwave Magnetic Field

2012 ◽  
Vol 2012 ◽  
pp. 1-4 ◽  
Author(s):  
Sadatsugu Takayama ◽  
Jun Fukushima ◽  
Junichi Nishijo ◽  
Midori Saito ◽  
Saburo Sano ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Magnetic Material ◽  
Microwave Sintering ◽  
Power Level ◽  
Single Mode ◽  
Sintered Sample ◽  
Soft Magnetic Materials ◽  
Soft Magnetic Material ◽  
Soft Magnetic ◽  
Microwave Magnetic Field

We have developed a simple process for sintering of soft magnetization materials using microwave sintering. The saturated magnetization (Ms) of sintered magnetite was 85.6 emu/g, which was as high as 95% of magnetite before heating (90.4 emu/g). On the other hand, the averaged remanence (Mr) and coercivity (Hc) of the magnetite after heating were 0.17 emu/g and 1.12 Oe under measuring limit of SQUID, respectively. For the sintering process of soft magnetic materials, magnetic fields of microwave have been performed in nitrogen atmosphere. Therefore, a microwave single-mode system operating at a frequency of 2.45 GHz and with a maximum power level of 1.5 kW was used. We can sinter the good soft magnetic material in microwave magnetic field. The sample shrank to 82% theoretical density (TD) from 45%TD of green body. The sintered sample was observed the microstructure by TEM and the crystal size was estimated the approximate average size is 10 nm.

scholarly journals Динамические перестройки трехмерной топологической структуры движущейся доменной границы в магнитной пленке при наличии случайных возмущений

2019 ◽  
Vol 61 (11) ◽  
pp. 2070
Author(s):  
В.В. Зверев ◽  
Е.Ж. Байкенов ◽  
И.М. Изможеров
Keyword(s):  
Magnetic Field ◽  
Three Dimensional ◽  
Dynamic Processes ◽  
Soft Magnetic ◽  
Spatially Inhomogeneous ◽  
Plane Anisotropy ◽  
Wide Range ◽  
Micromagnetic Modeling ◽  
Magnetization Field ◽  
Topological Charges

Dynamic processes in a domain wall (DW) moving under a constant magnetic field in a soft-magnetic uniaxial film with in-plane anisotropy were studied using three-dimensional micromagnetic modeling. It was shown that the nature of the dynamics of topological transformations occurring in the DW can vary significantly due to disturbing factors depending randomly on coordinates or on time (spatially inhomogeneous anisotropy; magnetic field fluctuating in time). At the same time, typical configurations of the magnetization field in the vicinity of intrafilm vortex cores and singular (Bloch) points retain their appearance. The dependences of the energies and displacements of the DWs on time are found for a wide range of film thicknesses, temperatures, and magnetic fields. When analyzing the magnetization configurations, visualization methods based on the calculation of two types of topological charges were used.

Hardness and flexural performance of 3D orthogonal carbon/glass fibers hybrid composites under thermal-oxidative aging

2021 ◽  
pp. 152808372198927
Author(s):  
Juanzi Li ◽  
Wei Fan ◽  
Tao Liu ◽  
Lili Xue ◽  
Linjia Yuan ◽  
...  
Keyword(s):  
Failure Modes ◽  
Hybrid Composites ◽  
Glass Fibers ◽  
Flexural Modulus ◽  
Three Dimensional ◽  
Accelerated Aging ◽  
Flexural Performance ◽  
Flexural Failure ◽  
The Matrix ◽  
Experimental Findings

This study reports the hardness and flexural performance of the three-dimensional (3 D) orthogonal carbon/glass hybrid fiber/bismaleimide composites subjected to the accelerated aging conditions for 10, 30, 90, 120, and 180 days at 250 °C in an air environment. The rate of reduction in the flexural performance and failure modes were observed, in general, to be related to the aging time. The experimental findings revealed that the significant decline in the flexural performance of the samples aged for less than 30 days was predominantly attributed to the matrix degradation, while for the longer aging durations, the cracks in the composites and decomposition of the residual matrix were responsible for the gradual reduction in the flexural performance. The unaged and 30 days aged samples suffered a brittle failure represented by the macro-cracks and fiber breakage, while the cracked fiber/matrix interface and loosened fiber bundles were the main failure modes for the samples aged for longer times. The changes in the flexural failure modes resulted due to the severe degradation of the matrix under an extreme thermo-oxidative environment. Subsequently, a nonlinear relationship relating the flexural modulus to hardness was proposed.

The decay of wall-bounded MHD turbulence at low

2015 ◽  
Vol 783 ◽  
pp. 605-636 ◽  
Author(s):  
Alban Pothérat ◽  
Kacper Kornet
Keyword(s):  
Magnetic Field ◽  
Three Dimensional ◽  
Viscous Friction ◽  
Magnetic Reynolds Number ◽  
Two Dimensional ◽  
Mhd Turbulence ◽  
Velocity Gradients ◽  
Two Phases ◽  
Experimental Findings ◽  
The Magnetic Field

We present direct numerical simulations of decaying magnetohydrodynamic (MHD) turbulence at low magnetic Reynolds number. The domain considered is bounded by periodic boundary conditions in the two directions perpendicular to the magnetic field and by two plane Hartmann walls in the third direction. Regimes of high magnetic fields (Hartmann number of up to 896) are reached thanks to a new spectral method using the eigenvectors of the dissipation operator. The decay is found to proceed through two phases: first, energy and integral length scales vary rapidly during a two-dimensionalisation phase extending over approximately a Hartmann friction time. During this phase, the evolution of the former appears significantly more impeded by the presence of walls than that of the latter. Once the large scales are nearly quasi-two-dimensional, the decay results from the competition of a two-dimensional dynamics driven by dissipation in the Hartmann boundary layers and the three-dimensional dynamics of smaller scales. In the later stages of the decay, three-dimensionality subsists under the form of barrel-shaped structures. A purely quasi-two dimensional decay entirely dominated by friction in the Hartmann layers is not reached because of residual dissipation in the bulk. However, this dissipation is not generated by the three-dimensionality that subsists, but by residual viscous friction due to horizontal velocity gradients. In the process, the energy in the velocity component aligned with the magnetic field is found to be strongly suppressed, as is skewness. This result reproduces the experimental findings of Kolesnikov & Tsinober (Fluid Dyn., vol. 9, 1974, pp. 621–624), where, as in the present simulations, Hartmann walls were present.

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