Project “Structured Composite Magnetically Active Materials with Controlled Electrophysical Properties”

RSF-Moscow Project No. 22-29-20176 “Structured Composite Magnetically Active Materials with Controlled Electrophysical Properties”

Head: Ph.D. Fionov A.S.

Report 2022.

In 2022, work was carried out to develop a technology for obtaining structured composite magnetically active materials based on elastomers with magnetic fillers in the presence of a magnetic field. As a result, a laboratory mold and a microprocessor control unit for the synthesis of magnetically active materials were created. The kinetics of the curing process of composite elastomeric materials based on sulfur-regulated polychloroprene and cold-curing polydimethylsiloxane with various fillers has been studied. The determination of rheokinetic parameters at different temperature conditions was carried out, which made it possible to select the optimal modes for manufacturing samples of magnetostructured composites based on various elastomeric matrices and the optimal concentration of the magnetic filler to obtain the most pronounced effect of structuring. The range of samples manufactured using the developed technology includes composite materials based on elastomeric matrices (chloroprene sulfur-regulated rubber – PCP and cold curing polydimethylsiloxane – SKTN-A) and magnetic fillers: hard magnetic (SmCo, NdFeB) and soft magnetic (natural magnetite Fe3O4, ZnNiCo- ferrite) in the concentration range of 30 … 100 mass parts per 100 mass parts of the elastomeric matrix, as well as composite materials based on PCP and magnetite in concentrations of 200 and 300 mass. parts. In this case, both structured and unstructured samples were obtained in order to compare their morphological, electrophysical, and magnetic properties. The total number of manufactured samples of composite materials exceeds 50 copies. It should be noted that the developed technology also makes it possible to manufacture samples based on plastisols, for example, based on the PVC-DOP system, and thermoplastic polymers, in the latter case, there is a need to additionally provide for the process of forced cooling of the samples to fix the magnetic structure. The morphological and structural properties of the obtained composite magnetoactive materials were studied. As a result, it was found that:

– according to scanning electron microscopy, the particle size distribution of finely dispersed (6…85 µm) magnetic fillers is multimodal;

– quantitative analysis of the distribution of elements, calculated on the basis of energy dispersive spectroscopy data, confirms the chemical composition of the magnetic powders declared by the manufacturer;

– the distribution of filler particles in the volume of the matrix is determined by the presence of a magnetic field during vulcanization and is statistically uniform for samples cured in the absence of a magnetic field, and structured for samples cured in a magnetic field. The structure thus obtained reflects the distribution of the magnetic field in the sample during vulcanization;

– filler particles tend under the influence of a magnetic field to form extended structures such as fibers;

– the residual magnetic moment, which demonstrates the degree of magnetic structure of the filler in the elastomeric composite, depends on the type of filler. For soft magnetic fillers (natural magnetite Fe3O4, ZnNiCo-ferrite), it does not exceed 0.3 mT, and is higher in the SKTN-A matrix than in PCP. In the case of hard magnetic (SmCo, NdFeB) fillers, structuredness is more pronounced, the residual magnetic moment reaches 0.4–0.7 mT in the PCP matrix and 0.8–1.6 mT in the SKTN-A matrix, and in both matrices higher values of the magnetic moment refer to the SmCo powder.

The magnetic properties of the obtained composite magnetoactive materials were also studied by magnetometric methods. The obtained magnetometric data allowed us to draw the following conclusions:

– structured samples (with the exception of PCP – Fe3O4) have a pronounced anisotropy of magnetic susceptibility relative to the direction of the external magnetic field;

– the degree of anisotropy is higher for the SKTN-A matrix than for PCP;

– the magnetic moment in a field of more than 4 kOe is higher for composites, both structured and unstructured, in the case of a PCP matrix;

– for composites based on hard magnetic fillers, the anisotropy fields in both matrices exceed 1 T.

To study the electrophysical characteristics of the created composite magnetically active materials in various frequency ranges, the following measuring stands were created:

– automated installation for research of electrical conductivity at direct current and dielectric parameters in the frequency range of 20 Hz … 2 MHz;

– automated installation for the study of dielectric parameters by the method of a quarter-wave resonator at a wavelength of 30 cm.

– automated setup for studying electrodynamic characteristics by quasi-optical and waveguide methods at frequencies of 0.5…40 GHz.

 

Published articles:

  1. Fionov, A.; Kraev, I.; Yurkov, G.; Solodilov, V.; Zhukov, A.; Surgay, A.; Kuznetsova, I.; Kolesov, V. Radio-Absorbing Materials Based on Polymer Composites and Their Application to Solving the Problems of Electromagnetic Compatibility. Polymers (2022) WOS SCOPUS Q1 RSCI RSCI
  2. Fionov A.S., Khachaturov A.A., Safonov S.S., Tlegenov R., Golovanov E.V., Surgai A.V., Kolesov V.V., Potapov E.E. Magnetically structured composites based on polychloroprene and magnetite. Ivanovo: ISPU im. IN AND. Lenin. Collection of scientific papers of the XX Anniversary All-Russian with international participation Plyos scientific conference on nanodispersed magnetic fluids (2022) RSCI
  3. Fionov A.S., Khachaturov A.A., Kolesov V.V., Potapov E.E., Surgay A.V. Functional elastomeric materials based on polychloroprene and magnetite Microwave engineering and telecommunication technologies. Sevastopol: SevSU Publishing House, 2022. (2022) RSCI