Mobile magnetometer for rapid test of saturation magnetization of magnetic nanofluids
A.N. Bolotov, O.O. Novikova
Tver State Technical University
Abstract: The work is aimed at creating a magnetometric device for accurate determining the saturation magnetization of magnetic nanofluids and similar properties of functional dispersed materials. The device is based on a magnetometric method with the Hall induction transducers, improved taking into account the peculiarities of the physical and mechanical properties of liquids. The measuring magnetic system of the device is designed in such a way that with the help of permanent magnets it is possible to create a uniform magnetizing field up to (2 ÷ 4) · 105 A/m in a working gap where the cuvette with the studied magnetic nanofluid is installed. Under the cuvette with a magnetic nanofluid in its middle section is a Hall Converter, which serves to measure the strength of the magnetizing magnetic field. The second Hall Converter, designed to measure the magnetic field induction in a substance, is installed in a rectangular groove and is located in the center of the magnetic nanofluid in the cuvette. The relative error of measuring the magnetization on the device did not exceed 2 % for magnetic nanofluids with a magnetization in the range from 10 kA / m to 50 kA/m. The created device can be used for Express measurements in laboratory and industrial conditions and does not require special professional skills. It is shown that the additive component of the instrumental measurement error depends on the values of the residual voltage (nonequipotential EMF), side galvanomagnetic effects and thermo – EMF of the measuring Converter. The multiplicative component is related to the time and temperature instability of the conversion coefficient and the current or voltage supply. The methodic error of the magnetometer is caused by the fact that not a fully closed magnetic circuit is used for measuring the magnetic field induction. It is shown that the device meets international standards for magnetic measurements of soft magnetic materials in terms of their metrological parameters. The device allowed us to determine the magnetization of colloidal systems in magnetic fields of a start paraprocess, individual magnetization of nanoparticles of the dispersed phase, the aggregative stability of colloids in magnetic and gravity fields to estimate the size of the solvation shell of the nanoparticles.
Keywords: magnetic nanofluid, saturation magnetization, Hall converters, magnetic system, measurement error, numerical simulation
- Alexander N. Bolotov – Dr. Sc., Professor, Head of the Applied Physics Department, Tver State Technical University
- Olga O. Novikova – Ph. D., Docent, Docent of the Applied Physics Department, Tver State Technical University
Bolotov, A.N. Mobile magnetometer for rapid test of saturation magnetization of magnetic nanofluids / A.N. Bolotov, O.O. Novikova // Physical and chemical aspects of the study of clusters, nanostructures and nanomaterials. – Tver: TSU, 2020. — I. 12. — P. 557-570. DOI: 10.26456/pcascnn/2020.12.557. (In Russian).
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