Nanomodified composite magnetic materials and their molding technologies

Abstract

Advanced electro-magnetic machines and systems require new materials with improved properties. Heterogeneous 3D nanomodified soft magnetic materials could be efficiently applied. Multistage technology of iron particle surface nanomodification by sequential oxidation and Si-organic coatings will be reported. The thickness of layers is 0.5-5 nm. Compaction and annealing are the final steps of magnetic parts and components shaping. The soft magnetic composite material shows the features: resistivity is controlled by insulating coating thickness and equals up to ρ =10-4 Ω⋅m for metallic state and ρ =104 Ω⋅m for insulator state, maximum magnetic permeability is μm = 2500 and μm = 300 respectively, induction is up to Bm=2.1 T. These properties of composite soft magnetic material allow applying for transformers, throttles, stator-rotor of high-efficient and powerful electric machines in 10 kHz–1MGz frequency range. For microsystems and microcomponents application, good opportunity to improve their reliability is the use of nanocomposite materials. Electroplating technology of nanocomposite magnetic materials into the ultra-thick micromolds will be presented. Co-deposition of the soft magnetic alloys with inert hard nanoparticles allows obtaining materials with magnetic permeability up to μm=104, magnetic induction of Bs=(0.62–1.3) T. Such LIGA-like technology will be applied in MEMS to produce high reliable devices with advanced physical properties.

Investigation of the frequency characteristics of composite iron powders with insulating oxide coatings

“…This difference in the magnitude of the hysteresis losses is most likely because samples based on powders with a grain size of d>100 μm were studied. Therefore, it is advisable to use such a composite material in electrical products operating at frequencies up to 1 kHz [2,7,10,13]. Figure 4 shows the frequency dependences in the range of 50 Hz -1 MHz of a figure of merit and inductance for samples based on composites of Hoganes ASC100.29 powder after annealing in air, in water vapor and hydrogen at a temperature of 400 °C for two hours.…”

“…This difference can be explained by the fact that a material with a thin layer has a lower electrical resistivity, which means that the total electromagnetic losses will also be higher due to an increase in the contribution of losses to eddy currents. At the same time, the magnetic permeability at a frequency of 1 kHz differs by 30 units, and with an increase in frequency to 1 MHz, it decreases by 10-15% for both materials [10,11]. This makes it possible to use iron-based soft magnetic materials for electrical engineering…”

“…Magnetically soft materials include ferro-and ferrimagnets with low coercive force, high values of the initial and maximum magnetic permeability, and low losses for magnetization reversal in dc and ac fields [4,8,10]. Depending on the characteristics of devices, electrical machines and other devices, the following requirements are imposed on SMM:…”

Optimization of the method of oxide coating of metallic iron powder particles

“…In this regard, a combined method of obtaining oxide coatings on the surface of iron particles was proposed [2,4,5,8,10]. The proposed new method is based on the combined use of the above methods.…”

“…This is due to the fact that magnetic materials are widely used in various electrical devices (generators, electric motors, measuring equipment, inductance coils, etc.) [1][2][3].…”