Study of Static Magnetic Properties of Transformer Oil Based Magnetic Fluids for Various Technical Applications Using Demagnetizing Field Correction

Oana Maria Marinica

doi:10.1155/2017/5407679

Abstract

Static magnetization data of eight transformer oil based magnetic fluid samples, with saturation magnetization ranging in a large interval from 9 kA/m to 90 kA/m, have been subjected to the demagnetizing field correction. Using the tabulated demagnetization factors and the differential magnetic susceptibility of the samples, the values of the radial magnetometric demagnetization factor were obtained in the particular case of VSM880 magnetometer. It was found that the demagnetizing field correction keeps the saturation magnetization values unchanged, but instead the initial magnetic susceptibility of the magnetic fluid samples varies widely. The mean magnetic diameter, obtained through magnetogranulometry from the measured data, is higher than that obtained from the corrected ones and the variation rate increases with the magnetic particle volume fraction growth.

Highlights

IntroductionThe saturation magnetization, the initial magnetic susceptibility, magnetization curves or the reduced ones, and magnetogranulometric analysis of the magnetic fluids with different concentrations of the magnetic particle content allow the study of various microstructural characteristics
Static magnetization data of eight transformer oil based magnetic fluid samples, with saturation magnetization ranging in a large interval from 9 kA/m to 90 kA/m, have been subjected to the demagnetizing field correction
It was found that the demagnetizing field correction keeps the saturation magnetization values unchanged, but instead the initial magnetic susceptibility of the magnetic fluid samples varies widely

Summary

Introduction

The saturation magnetization, the initial magnetic susceptibility, magnetization curves or the reduced ones, and magnetogranulometric analysis of the magnetic fluids with different concentrations of the magnetic particle content allow the study of various microstructural characteristics. More precise values were tabulated for cylindrical samples They were obtained by numerical calculation of Nf,m, as a function of the magnetic susceptibility and the length-diameter ratio, with −1 ≤ χ < ∞ and 0.01 ≤ γ ≤ 500 in axial direction and −1 ≤ χ < ∞ and 0.01 ≤ γ ≤ 1 in radial direction [10]. As it is known, there is a strong connection between the microstructural properties of the magnetic fluids and their macroscopic behavior, which qualifies them to be used in various technical applications [11], magnetofluidic devices such as rotating seals [12, 13], bearings [14], sensors, and transducers [15, 16], or even in thermal applications [17]. A proper design of a magnetofluidic device implies detailed data on various properties of magnetic fluids, including the static magnetic ones, studied by applying the demagnetizing field correction

Experimental

Results and Discussion

Conclusion