Magnetic Field Dependent Damping of Magnetic Particle Filled Polypropylene

2012 ◽  
Vol 184 ◽  
pp. 449-454
Author(s):  
O.A. Lambri ◽  
D. Gargicevich ◽  
F. Tarditti ◽  
F.G. Bonifacich ◽  
Werner Riehemann ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Elastic Modulus ◽  
Internal Friction ◽  
Polymer Matrix ◽  
Volume Fraction ◽  
Alternating Magnetic Field ◽  
Internal Stresses ◽  
Dynamic Shear Modulus ◽  
Dc Magnetic Field ◽  
Damaged Zone

The behavior of internal friction Q-1 and dynamic shear modulus has been studied in polypropylene charged with either different volume fraction or size of magnetite (Fe3O4) particles, as a function of the applied magnetic field at 318 K. An increase of the alternating (AC) magnetic field oscillating with 50 Hz, leads to an increase of the internal friction. In addition, during the subsequently decreasing alternating magnetic field, the internal friction decreases, but a hysteretic behavior appeared. In fact, the internal friction of the decreasing part of magnetic field amplitude is found to be smaller than during the previously increasing amplitude part of the treatment with the alternating magnetic field. Subsequent magnetic treatment cycles, lead to successively decreasing internal friction. In contrast, during the increase of a direct (DC) magnetic field, the internal friction decreases and the elastic modulus increases. The behavior of the internal friction and the elastic modulus during the application of an oscillating magnetic field (AC) is discussed on the basis of the development of both, a new zone with different rheological characteristics than the matrix but of the same material (self-inclusion), and/or a deteriorated or damaged zone (chain’s cuts) of the polymer matrix in the neighborhood of the magnetite inclusion. These effects are promoted by the movement or small relative rotation of the magnetite particles related to the surrounding matrix controlled by the oscillating field. The behavior of the internal friction and elastic modulus during the application of a direct (DC) magnetic field is discussed on the basis of the increase of the internal stresses into the polymer matrix due to the promotion of the magnetomechanical stresses.

Effect of a magnetic field on the elastic modulus and internal friction of alloy oKh27YU5A

1981 ◽  
Vol 13 (11) ◽  
pp. 1393-1396
Author(s):  
T. G. Kovaleva ◽  
A. D. Shevchuk ◽  
P. I. Tereshchenko
Keyword(s):  
Magnetic Field ◽  
Elastic Modulus ◽  
Internal Friction

scholarly journals Heating ability of elongated magnetic nanoparticles

2021 ◽  
Vol 12 ◽  
pp. 1404-1412
Author(s):  
Elizaveta M Gubanova ◽  
Nikolai A Usov ◽  
Vladimir A Oleinikov
Keyword(s):  
Magnetic Field ◽  
Magnetite Nanoparticles ◽  
Volume Fraction ◽  
Low Frequency ◽  
Hysteresis Loops ◽  
Dipole Interaction ◽  
Alternating Magnetic Field ◽  
Particle Sizes ◽  
Order Of Magnitude ◽  
Elongated Nanoparticles

Low-frequency hysteresis loops and specific absorption rate (SAR) of various assemblies of elongated spheroidal magnetite nanoparticles have been calculated for a range of particle semiaxis ratios a/b = 1.0–3.0. The SAR of a dilute randomly oriented assembly of magnetite nanoparticles in an alternating magnetic field of moderate frequency, f = 300 kHz, and amplitude H0 = 100–200 Oe is shown to decrease significantly with an increase in the aspect ratio of nanoparticles. In addition, there is a narrowing and shift of the intervals of optimal particle diameters towards smaller particle sizes. However, the orientation of a dilute assembly of elongated nanoparticles in a magnetic field leads to an almost twofold increase in SAR at the same frequency and amplitude of the alternating magnetic field, the range of optimal particle diameters remaining unchanged. The effect of the magneto-dipole interaction on the SAR of a dilute assembly of oriented clusters of elongated magnetite nanoparticles has also been investigated depending on the volume fraction of nanoparticles in a cluster. It has been found that the SAR of the assembly of oriented clusters decreases by approximately an order of magnitude with an increase in the volume fraction of nanoparticles in a cluster in the range of 0.04–0.2.

Study on Sliding Friction Characteristics of Magnetorheological Elastomer - Copper Pair Affected by Magnetic-Controlled Surface Roughness and Elastic Modulus

2021 ◽  
Author(s):  
Rui Li ◽  
Di Wang ◽  
Xinyan Li ◽  
Ping-an Yang ◽  
Haibo Ruan ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Surface Roughness ◽  
Elastic Modulus ◽  
Friction Coefficient ◽  
Sliding Friction ◽  
Volume Fraction ◽  
Coupling Effect ◽  
Initial Surface ◽  
Friction Characteristics ◽  
Adjustable Range

Abstract To optimize the online friction coefficient adjustment, it is necessary to study the parameter change features of the magneto-sensitive polymer and its influence on the friction characteristics under magnetic field. A series of isotropic magnetorheological elastomers (MREs) with different initial surface roughness were prepared, and a sliding friction platform with MRE - copper block pair was built to carry out magnetic-controlled friction characteristic experiment. Results show that the sliding friction coefficient of MRE decreases with the increase of the magnetic field, but the degree of reduction is quite different under different initial surface roughness and elastic modulus. When the initial surface roughness of MRE is between 0.5 - 2.5 μm and the ferromagnetic particles volume fraction is between 10% - 15%, its magnetic-controlled friction coefficient has the largest reduced value of 22.75%. Moreover, features of elastic modulus and surface topography under magnetic field were tested and analyzed. By combining with the single peak contact model and the friction binomial law, the relationship between the surface roughness and elastic modulus of MREs and the sliding friction force is deduced, and it is proved that the friction coefficient is affected by the coupling effect of surface roughness and elastic modulus. The magnetic-controlled elastic modulus is the key factor, which determines the overall downward trend of the friction coefficient of MREs. Magnetic-controlled surface roughness also plays an important role in the adjustable range of friction coefficient, and reducing the initial surface roughness can increase the magnetic-controlled friction coefficient adjustable range.

Martensite Variant Reorientation of NiMnGa/Silicone Composites Containing Polystyrene Foam Particles

2011 ◽  
Vol 409 ◽  
pp. 645-650 ◽  
Author(s):  
Yui Watanabe ◽  
Motoki Okuno ◽  
Yoshinaka Shimizu ◽  
Hiroyasu Kanetaka ◽  
Tomonari Inamura ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Elastic Modulus ◽  
Volume Fraction ◽  
Parent Phase ◽  
Dominant Factor ◽  
Matrix Composites ◽  
Zone Method ◽  
Martensite Variant ◽  
Matrix Polymer ◽  
The Magnetic Field

Effect of elastic modulus of matrix on ferromagnetic motion of NiMnGa particles was investigated for NiMnGa particles embedded silicone matrix composites with or without containing polystyrene form particles (PFPs), which are regarded as pores. NiMnGa single crystal was fabricated by a floating zone method and a cube-shape particle was fabricated with the surface orientation parallel to [100], [010] and [001] directions at the parent phase state. The elastic modulus of matrix polymer was controlled by changing the number of PFPs. It was found that the elastic modulus of silicone was decreased with increasing the volume fraction of PFPs. The magnetic-field-induced martensite variant reorientation (MVR) was evaluated by the magnetization curves obtained using a vibration sample magnetometer, and the magnetic field required for the start of martensite variant reorientation was reduced by increasing the number of PFPs. The control of elastic modulus of matrix polymer is important and a dominant factor for the magnetic motion of NiMnGa/polymer composites.

scholarly journals Calculation of the Amplitude of Acoustic Waves in Nanoscale Magnets in an Alternating Magnetic Field Caused by Displacements of Domain Boundaries

2021 ◽  
pp. 47-52
Author(s):  
L.P. Petrova ◽  
N.M. Ignatenko ◽  
A.S. Gromkov
Keyword(s):  
Magnetic Field ◽  
Absorption Coefficient ◽  
Wave Vector ◽  
Carrier Frequency ◽  
Acoustic Waves ◽  
Spontaneous Magnetization ◽  
Alternating Magnetic Field ◽  
Internal Stresses ◽  
Generation Process ◽  
Domain Boundaries

This paper proposes an algorithm that utilizes a macroscopic approach to calculate the amplitude of the total acoustic signal generated by an alternating magnetic field in ribbon-shaped nanocrystalline magnets (NCMs) with polydomain nanofibers at reversible displacements of domain boundaries. The calculations are made for the case with the wave vector directed along the magnetic field parallel to the tape plane. At the same time, the influence of anharmonicity on the displacements of the domain boundaries is considered for the carrier frequency. The orientation and frequency dependences for the wave vector and the signal absorption coefficient are found under the assumption that the rotation processes can be neglected. It is shown that the residual internal stresses in the (poly- or monodomain) nanograin NCMs have a significant effect on the absorption coefficient and the amplitude of the generated DG signal. The magnetic anisotropy constants decrease along with the size of the nanograins. In this case, the generation process due to the rotation of the spontaneous magnetization vectors is also significant, which must be considered in relation to the displacement processes. The proposed algorithm for calculating the amplitudes of the signals generated by a nanocrystalline magnet can be used to predict the friction properties of the developed promising NCM and calculate the amplitudes of the generated signals at the carrier frequency and harmonics.

Study on sliding friction characteristics of magnetorheological elastomer - copper pair affected by magnetic-controlled surface roughness and elastic modulus

2021 ◽  
Author(s):  
Rui Li ◽  
Di Wang ◽  
Xinyan Li ◽  
Changrong Liao ◽  
Ping-an Yang ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Surface Roughness ◽  
Elastic Modulus ◽  
Friction Coefficient ◽  
Sliding Friction ◽  
Volume Fraction ◽  
Coupling Effect ◽  
Initial Surface ◽  
Friction Characteristics ◽  
Adjustable Range

Abstract To optimize the online friction coefficient adjustment, it is necessary to study the parameter change features of the magneto-sensitive polymer and its influence on the friction characteristics under magnetic field. A series of magnetorheological elastomers (MREs) with different initial surface roughness were prepared, and a sliding friction platform with MRE - copper block pair was built to carry out magnetic-controlled friction characteristic experiment. Results show that the sliding friction coefficient of MRE decreases with the increase of the magnetic field, but the degree of reduction is quite different under different initial surface roughness and elastic modulus. When the initial surface roughness of MRE is between 0.5 - 2.5 μm and the carbonyl iron particles (CIPs) volume fraction is between 10% - 15%, its magnetic-controlled friction coefficient has the largest reduced value of 22.75%. Moreover, features of elastic modulus and surface topography under magnetic field were tested and analyzed. By combining with the single peak contact model and the friction binomial law, the relationship between the surface roughness and elastic modulus of MREs and the sliding friction force is deduced, and it is proved that the friction coefficient is affected by the coupling effect of surface roughness and elastic modulus. The magnetic-controlled elastic modulus is the key factor, which determines the overall downward trend of the friction coefficient of MREs. Magnetic-controlled surface roughness also plays an important role in the adjustable range of friction coefficient, and reducing the initial surface roughness can increase the magnetic-controlled friction coefficient adjustable range.

scholarly journals Heating ability of elongated magnetic nanoparticles

2021 ◽  
Author(s):  
Elizaveta M Gubanova ◽  
Nikolai A Usov ◽  
Vladimir A Oleinikov
Keyword(s):  
Magnetic Field ◽  
Magnetite Nanoparticles ◽  
Volume Fraction ◽  
Low Frequency ◽  
Hysteresis Loops ◽  
Dipole Interaction ◽  
Alternating Magnetic Field ◽  
Particle Sizes ◽  
Order Of Magnitude ◽  
Elongated Nanoparticles

Low-frequency hysteresis loops and specific absorption rate (SAR) of various assemblies of elongated spheroidal magnetite nanoparticles have been calculated for a range of particle semiaxis ratios a/b = 1.0 – 3.0. The SAR of a dilute randomly oriented assembly of magnetite nanoparticles in an alternating magnetic field of moderate frequency, f = 300 kHz, and amplitude H0 = 100 - 200 Oe is shown to decrease significantly with an increase in the aspect ratio of nanoparticles. In addition, there is a narrowing and shift of the intervals of optimal particle diameters towards smaller particle sizes. However, the orientation of a dilute assembly of elongated nanoparticles in a magnetic field leads to an almost twofold increase in SAR at the same frequency and amplitude of the alternating magnetic field, the range of optimal particle diameters remaining unchanged. The effect of the magneto-dipole interaction on the SAR of an assembly of oriented clusters of elongated magnetite nanoparticles has also been investigated depending on the volume fraction of nanoparticles in a cluster. It has been found that the SAR of the assembly of oriented clusters decreases by approximately an order of magnitude with an increase in the volume fraction of nanoparticles in a cluster in the range 0.04 - 0.2.

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