416. Concentration of Gd-DTPA and signal intensity : effect of static magnetic field strength

AbstractWe report a systematic study of polarization and magnetic field effects on the optical response of Fe3O4-silicone elastomer composite. The Fe3O4 particles were aligned in a silicone elastomer matrix with an external static magnetic field. Films of composites containing 5wt% of 20nm ≤ d ≤ 30nm Fe3O4 particles aligned in- and out-of-plane in the elastomer host were prepared. The optical spectra of the films were measured with the Perkin-Elmer Lambda 950 UV/vis/NIR spectrometer. We observed a systematic redshift in the optical response of the outof-plane composite films with increasing static magnetic field strength, which saturated near 600 Gauss. We obtained a maximum redshift of ∼46 nm at 600 Gauss. The observed redshift in the optical response of the out-of-plane composite film is attributed to the effect of the magnetic field. This facilitated the formation of the highly aligned particles that induced strong electric dipole in the aligned particles. Interestingly, there were no observable shifts with increasing magnetic field strength in the in-plane films, suggesting that the orientation (polarization) of the magnetic dipole and the induced electric dipole play a crucial role in the optical response.

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Effect of external static magnetic field on the particle distribution, the metallurgical process and the microhardness of Sn3.5Ag solder with magnetic Ni particles

Soldering & Surface Mount Technology ◽

10.1108/ssmt-07-2021-0049 ◽

2021 ◽

Vol ahead-of-print (ahead-of-print) ◽

Author(s):

Jianhua Wang ◽

Hongbo Xu ◽

Li Zhou ◽

Ximing Liu ◽

Hongyun Zhao

Keyword(s):

Magnetic Field ◽

Field Strength ◽

Solder Joint ◽

Magnetic Field Strength ◽

Static Magnetic Field ◽

Particle Distribution ◽

Metallurgical Process ◽

Content Type ◽

Nickel Particles ◽

External Static Magnetic Field

Purpose This paper aims to investigate the mechanism of Ni particles distribution in the liquid Sn3.5Ag melt under the external static magnetic field. The control steps of Ni particles and the Sn3.5Ag melt metallurgical process were studied. After aging, the microhardness of pure Sn3.5Ag, Sn3.5Ag containing randomly distributed Ni particles and Sn3.5Ag containing columnar Ni particles were compared. Design/methodology/approach Place the sample in a crucible for heating. After the sample melts, place a magnet directly above and below the sample to provide a magnetic field. Sn3.5Ag with the different morphological distribution of Ni particles was obtained by holding for different times under different magnetic field intensities. Finally, pure Sn3.5Ag, Sn3.5Ag with random distributed Ni particles and Sn3.5Ag with columnar Ni particles were aged and their microhardness was tested after aging. Findings The experimental results show that with the increase of magnetic field strength, the time for Ni particle distribution in Sn3.5Ag melt to reach equilibrium is shortened. After aging, the microhardness of Sn3.5Ag containing columnar nickel particles is higher than that of pure Sn3.5Ag and Sn3.5Ag containing randomly distributed nickel particles. A chemical reaction is the control step in the metallurgical process of nickel particles and molten Sn3.5Ag. Originality/value Under the action of the magnetic field, Ni particles in Sn3.5Ag melt will be arranged into columns. With the increase of magnetic field strength, the shorter the time for Ni particles in Sn3.5Ag melt to arrange in a column. With the extension of the service time of the solder joint, if Sn3.5Ag with columnar nickel particles is used as the solder joint material, its microhardness is better than Sn3.5Ag with arbitrarily distributed nickel particles and pure Sn3.5Ag.

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Stress measurement based on magnetostrictive characteristic parameters

Insight - Non-Destructive Testing and Condition Monitoring ◽

10.1784/insi.2021.63.5.283 ◽

2021 ◽

Vol 63 (5) ◽

pp. 283-288

Author(s):

Entao Yao ◽

Fei Han ◽

Ping Wang ◽

Yuan Zhang

Keyword(s):

Magnetic Field ◽

Field Strength ◽

Magnetic Field Strength ◽

Static Magnetic Field ◽

Stress Measurement ◽

Maximum Relative Error ◽

Electromagnetic Acoustic Transducer ◽

Wide Range ◽

The Relationship ◽

Non Destructive

Non-destructive testing (NDT) involving stress measurement has found a wide range of applications in rail, pipeline, bridge and other engineering areas and it is therefore necessary to find a method to measure stress. In this paper, a non-destructive method is proposed to measure stress by observation of the magnetostrictive properties of the objects. Stress in the elastic range is applied to the ferromagnetic material, changing its lattice, while stress in the plastic range changes its microstructure. These are the reasons for the magnetostrictive coefficient variation of the material. An experimental platform was set up, using a cantilever beam with a strain gauge, to study the relationship between the SH wave, the static magnetic field strength and the applied uniaxial stress. The curve obtained shows the relationship between the amplitude of the electromagnetic acoustic transducer (EMAT) signal and the static magnetic field strength. The magnetostrictive parameters, sensitive to stress, were extracted from the curve. This method is verified through trials on test samples with a maximum relative error between experimental and predicted values of 8.06%.

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