Efficiency of Magnetostatic Protection Using Nanostructured Permalloy Shielding Coatings Depending on Their Microstructure

The effect of microstructure on the efficiency of shielding or shunting of the magnetic fluxby permalloy shields was investigated in the present work. For this purpose, the FeNi shieldingcoatings with different grain structures were obtained using stationary and pulsed electrodeposition.The coatings’ composition, crystal structure, surface microstructure, magnetic domain structure, andshielding efficiency were studied. It has been shown that coatings with 0.2–0.6μm grains have adisordered domain structure. Consequently, a higher value of the shielding efficiency was achieved,but the working range was too limited. The reason for this is probably the hindered movement of thedomain boundaries. Samples with nanosized grains have an ordered two-domain magnetic structurewith a permissible partial transition to a superparamagnetic state in regions with a grain size of lessthan 100 nm. The ordered magnetic structure, the small size of the domain, and the coexistenceof ferromagnetic and superparamagnetic regions, although they reduce the maximum value ofthe shielding efficiency, significantly expand the working range in the nanostructured permalloyshielding coatings. As a result, a dependence between the grain and domain structure and theefficiency of magnetostatic shielding was found

Оптимизация излучающей катушки программно-аппаратного комплекса для исследования эффективности экранирования низкочастотного электромагнитного излучения

Optimization of the radiation coil of the hardware-software complex for studying the effectiveness of shielding of low-frequency electromagnetic radiation will make it possible to assess the effectiveness of shielding coatings at a higher level. This fact will make it possible to develop coatings with improved characteristics. The purpose of this work was to determine the optimal characteristics of the emitting coil which will ensure its stable operation and magnetic field strength in the frequency range up to 100 kHz.The parameters of the manufactured samples, such as inductance (L), active (R) and total resistance (Z), were obtained using an MNIPI E7-20 emittance meter. In practice, the coils with the optimal parameters calculated theoretically were connected to a current source and amplifier. To detect electromagnetic radiation, a multilayer inductor connected to a UTB-TREND 722-050-5 oscilloscope was used as a signal receiver.The results of measurements showed that the resistance of multilayer coils is approximately 1000 times higher than that of single-layer coils. Also, for multilayer coils, an avalanche-like increase in total resistance is observed starting from a frequency of 10 kHz, while for single-layer coils there is a uniform increase in total resistance over the entire frequency range up to 100 kHz.The paper presents results of research on the correlation of the performance of single-layer and multilayer inductors depending on their parameters in the frequency range from  20 Hz  to  100 kHz. Values of the voltage required to provide the magnetic field strength of 1, 5, 20 Oe at 25 Hz and 100 kHz have been calculated. After analyzing the data obtained, the optimal parameters of the inductor were found which ensure stable performance in the frequency range up to 100 kHz.Оптимизация излучающей катушки программно-аппаратного комплекса для исследования эффективности экранирования низкочастотного электромагнитного излучения позволит на более качественном уровне оценивать эффективность экранирующих покрытий. Данный факт даст возможность разрабатывать покрытия с улучшенными характеристиками. Целью данной работы являлось определение оптимальных характеристик излучающей катушки, которые обеспечат её стабильную работу и напряжённость магнитного поля в частотном диапазоне до 100 кГц.Параметры изготовленных образцов, такие как индуктивность, активное и общее сопротивление, были получены, используя измеритель иммитанса МНИПИ E7-20. На практике катушки с оптимальными параметрами, вычисленными теоретически, были подключены к источнику и усилителю тока. Для детектирования электромагнитного излучения в качестве приёмника сигнала использовалась многослойная катушка индуктивности, подключённая к осциллографу UTB-TREND 722-050-5.Результаты измерений показали, что сопротивление многослойных катушек приблизительно в 1000 раз больше сопротивления однослойных. Также у многослойных катушек наблюдается лавинообразный рост общего сопротивления, начиная с частоты 10 кГц, в то время как у однослойных катушек происходит равномерный рост общего сопротивления на всём диапазоне частот до 100 кГц. Представлены результаты исследований корреляции рабочих характеристик  однослойных  и многослойных  катушек  индуктивности  в  зависимости  от  их  параметров  в  частотном  диапазоне от 20 Гц до 100 кГц. Рассчитаны значения напряжения, необходимого для обеспечения напряжённости магнитного поля 1, 5, 20 Э при 25 Гц и 100 кГц. Проанализировав полученные данные, найдены оптимальные параметры катушки индуктивности, обеспечивающие стабильные рабочие характеристики в диапазоне частот до 100 кГц

The effect of heat treatment on the microstructure and mechanical properties of 2d nanostructured au/nife system

Nanostructured NiFe film was obtained on silicon with a thin gold sublayer via pulsed electrodeposition and annealed at a temperature from 100 to 400◦C in order to study the effect of heat treatment on the surface microstructure and mechanical properties. High-resolution atomic force microscopy made it possible to trace stepwise evolving microstructure under the influence of heat treatment. It was found that NiFe film grains undergo coalescence twice—at ~100 and ~300°C—in the process of a gradual increase in grain size. The mechanical properties of the Au/NiFe nanostructured system have been investigated by nanoindentation at two various indentation depths, 10 and 50 nm. The results showed the opposite effect of heat treatment on the mechanical properties in the near-surface layer and in the material volume. Surface homogenization in combination with oxidation activation leads to abnormal strengthening and hardening-up of the near-surface layer. At the same time, a nonlinear decrease in hardness and Young’s modulus with increasing temperature of heat treatment characterizes the internal volume of nanostructured NiFe. An explanation of this phenomenon was found in the complex effect of changing the ratio of grain volume/grain boundaries and increasing the concentration of thermally activated diffuse gold atoms from the sublayer to the NiFe film. © 2020 by the authors. Licensee MDPI, Basel, Switzerland.Funding: The work was supported by Act 211 Government of the Russian Federation, contract № 02.A03.21.0011

Combined Effect of Microstructure, Surface Energy, and Adhesion Force on the Friction of PVA/Ferrite Spinel Nanocomposites

Nanocomposite films based on spinel ferrite (Mg0.8Zn0.2Fe1.5Al0.5O4) in a PVA matrix were obtained. An increase in the spinel concentration to 10 wt.% caused an avalanche-like rise in roughness due to the formation of nanoparticle agglomerates. The lateral mode of atomic force microscopy (AFM) allowed us to trace the agglomeration dynamics. An unexpected result was that the composite with 6 wt.% of filler had a low friction coefficient in comparison with similar composites due to the successfully combined effects of low roughness and surface energy. The friction coefficient decreased to 0.07 when the friction coefficient of pure PVA was 0.72. A specially developed method for measuring nano-objects’ surface energy using AFM made it possible to explain the anomalous nature of the change in tribological characteristics. © 2022 by the authors. Licensee MDPI, Basel, Switzerland.National University of Science and Technology, MISISAlex V. Trukhanov thanks NUST MISIS for support within the framework of the «Priority 2030»

Влияние габаритных параметров цилиндрического экрана на эффективность экранирования

Study of dimensional parametersʼ influence on shielding properties of cylindrical shields will allow to optimise the fusion process, as well as to reduce production costs by reducing the material used. The purpose of this work was to compare results of theoretical calculation of shielding effectiveness of an infinite cylindrical shield with the data obtained in real conditions.A cylindrical Ni-Fe shield was synthesised by electrochemical deposition with length of 32 cm, diameter of 4.5 cm and shielding thickness of ≈ 100 µm. The cylinder length was then reduced from 32 cm to 6 cm in 4 cm increments and for each cylinder length shielding effectiveness was measured using three-coordinate Helmholtz field-forming system.The measurement results show that the calculation of shielding effectiveness of infinite cylindrical shield is valid for cylinder lengths l ≥ 18–20 cm. Shielding effectiveness is markedly reduced at values of l ˂ 15 cm.Analysis of data obtained allowed to conclude that it is necessary to determine the correction factor when calculating a cylindrical screen shielding efficiencyИзучение влияния габаритных параметров на экранирующие свойства цилиндрических экранов позволит оптимизировать процесс синтеза, а также снизить затраты на производство, за счёт уменьшения используемого материала. Целью данной работы было сравнение результатов теоретического расчёта эффективности экранирования бесконечного цилиндрического экрана и данных, полученных в реальных условиях.Методом электрохимического осаждения был синтезирован цилиндрический экран Ni-Fe, длина которого составила 32 см, диаметр 4,5 см, толщина экранирующего покрытия составила≈ 100 мкм. Затем длина цилиндра уменьшалась от 30 до 6 см с шагом в 4 см, для каждой длины цилиндра была измерена эффективность экранирования с помощью полеобразующей системы трёхкоординатных катушек Гельмгольца.Результаты измерений показали, что расчёт эффективности экранирования бесконечного цилиндрического экрана справедлив при длине цилиндра l ≥ 18–20 см. При значениях l ˂ 15 см эффективность экранирования заметно снижается.Анализ полученных данных позволил сделать вывод о необходимости определения поправочного коэффициента при расчётах эффективности экранирования цилиндрического экрана

Оптимизация излучающей катушки программно- аппаратного комплекса для исследования эффективности экранирования низкочастотного электромагнитного излучения

Optimization of the radiation coil of the hardware-software complex for studying the effectiveness of shielding of low-frequency electromagnetic radiation will make it possible to assess the effectiveness of shielding coatings at a higher level. This fact will make it possible to develop coatings with improved characteristics. The purpose of this work was to determine the optimal characteristics of the emitting coil which will ensure its stable operation and magnetic field strength in the frequency range up to 100 kHz. The parameters of the manufactured samples, such as inductance (L), active (R) and total resistance (Z), were obtained using an MNIPI E7-20 emittance meter. In practice, the coils with the optimal parameters calculated theoretically were connected to a current source and amplifier. To detect electromagnetic radiation, a multilayer inductor connected to a UTB-TREND 722-050-5 oscilloscope was used as a signal receiver. The results of measurements showed that the resistance of multilayer coils is approximately 1000 times higher than that of single-layer coils. Also, for multilayer coils, an avalanche-like increase in total resistance is observed starting from a frequency of 10 kHz, while for single-layer coils there is a uniform increase in total resistance over the entire frequency range up to 100 kHz. The paper presents results of research on the correlation of the performance of single-layer and multilayer inductors depending on their parameters in the frequency range from 20 Hz to 100 kHz. Values of the voltage required to provide the magnetic field strength of 1, 5, 20 Oe at 25 Hz and 100 kHz have been calculated. After analyzing the data obtained, the optimal parameters of the inductor were found which ensure stable performance in the frequency range up to 100 kHz

Influence of Cylindrical Shield Dimensions on Shielding Effectiveness

Study of dimensional parametersʼ influence on shielding properties of cylindrical shields will allow to optimise the fusion process, as well as to reduce production costs by reducing the material used. The purpose of this work was to compare results of theoretical calculation of shielding effectiveness of an infinite cylindrical shield with the data obtained in real conditions. A cylindrical Ni-Fe shield was synthesised by electrochemical deposition with length of 32 cm, diameter of 4.5 cm and shielding thickness of ≈ 100 μm. The cylinder length was then reduced from 32 cm to 6 cm in 4 cm increments and for each cylinder length shielding effectiveness was measured using three-coordinate Helmholtz field-forming system. The measurement results show that the calculation of shielding effectiveness of infinite cylindrical shield is valid for cylinder lengths l ≥ 18–20 cm. Shielding effectiveness is markedly reduced at values of l ˂ 15 cm. Analysis of data obtained allowed to conclude that it is necessary to determine the correction factor when calculating a cylindrical screen shielding efficiency

Efficiency of Magnetostatic Protection Using Nanostructured Permalloy Shielding Coatings Depending on Their Microstructure

The effect of microstructure on the efficiency of shielding or shunting of the magnetic fluxby permalloy shields was investigated in the present work. For this purpose, the FeNi shieldingcoatings with different grain structures were obtained using stationary and pulsed electrodeposition.The coatings’ composition, crystal structure, surface microstructure, magnetic domain structure, andshielding efficiency were studied. It has been shown that coatings with 0.2–0.6μm grains have adisordered domain structure. Consequently, a higher value of the shielding efficiency was achieved,but the working range was too limited. The reason for this is probably the hindered movement of thedomain boundaries. Samples with nanosized grains have an ordered two-domain magnetic structurewith a permissible partial transition to a superparamagnetic state in regions with a grain size of lessthan 100 nm. The ordered magnetic structure, the small size of the domain, and the coexistenceof ferromagnetic and superparamagnetic regions, although they reduce the maximum value ofthe shielding efficiency, significantly expand the working range in the nanostructured permalloyshielding coatings. As a result, a dependence between the grain and domain structure and theefficiency of magnetostatic shielding was found