Electromagnetic response of the three-layer construction on the basis of barium hexaferrite and a foam glass

This paper contains results of study of the frequency dependence of reflection coefficient of the ceramic surface coated with the construction consisting of following layers: metal, composite on the basis of ferrite with hexagonal structure, and foam glass. It is shown that foam glass layer reduces significantly the reflecting characteristics of the construction

Computer simulation of processes of radiation-thermal heating

In this work we present results of computer simulation of radiation-thermal heating of magnetic materials to change their structure. The energy source is a pulsed electron accelerator. The simulation results are presented in the form of the temperature distribution in the irradiated material, depending on the pulse duration, pulse repetition rate and the parameters of the material

Application of planetary ball mill for manufacturing of shielding composite coatings based on polyester powder paints and carbon fillers

Blend polyester powder paint and particulate carbon filler in the form of colloidal graphite and the carbon black product were investigated. Powder paint and carbon materials were treated together in a planetary ball mill. The data of the structural analysis and transmission coefficients of electromagnetic waves of terahertz range through the flat shape samples are presented

The foam-glass material for a radio frequency echoless chambers

The conducted experiment of foam glass modification by carbon nanotubes shows increased radio absorbing properties in comparison with a foam glass without additives. Addition of carbon nanodimensional tubes in number of 1,5 wt.% increases a tangent of dielectric losses angle by 2,5 times. The coefficient of electromagnetic radiation absorption in the range of frequencies of 120 - 260 GHz increases for a foam glass with carbon nanotubes (1,5 wt. %) twice in comparison with a foam glass without additives. The foam glass modified by carbon nanotubes is recommended as the effective radio absorbing material for the device of anechoic cameras. This material is fire safety, nonflammable, environmentally friendly, rather light-weight

Quasi-optical 2D system for non-contact non-destructive testing of defects in natural and artificial crystals

The results of development the automated system of two-dimensional diagnostics of defects of crystalline materials are presented. Used technology imaging. The structural scheme of the system is given, its main blocks are indicated, the approbation process is described, the software of the system is described

Characterization of porous glass-ceramic material as absorber of electromagnetic radiation

Investigations of a foam glass-ceramic material synthesized from raw siliceous earth material by the two-stage method at temperatures below 950°C have demonstrated the improvement of its physic mechanical properties in comparison with foam glass synthesized from glass cullet. This material actively interacts with microwaves and can be used for the development of protective screens reducing the adverse effect of microwaves on biological objects, anechoic chambers, and rooms with low level of electromagnetic background noise. Spectra of the transmission and absorption coefficients and of the complex dielectric permittivity for frequencies in the range 26-260 GHz are presented. The observed effects demonstrate the existence of regions with partial and total reflection arising on the glass-pore boundary and of the microwave interaction with ultradisperse carbon particles that remain after foaming with incomplete frothier transition from the soot to the gas phase

Analysis and reoperation of the magnetic permeability spectra of textured composite based on Z-type hexaferrite by using Cramers-Kronig relations

The frequency dependences of the magnetic permeability of textured composite based on Ba3Co2,4Fe23,2O41 ferrite are given. The magnetic permeability spectra were obtained by coaxial method in the frequency range 0.01–18 GHz. The expert judgement on the spectra was made by using Cramers – Kronig relations. It was shown, that the Cramers – Kronig relations can be used to correct magnetic permeability measurements by reciprocal recalculation of the frequency dependences of the real and imaginary parts

Radiation-thermal synthesis of W-type hexaferrites

The results of investigations of the phase composition, structural parameters, static and dynamic magnetic properties of BaCo0.7Zn1.3Fe16O27 hexaferrites obtained by the method of self-propagation high-temperature synthesis in combination with mechanochemical activation and radiation-thermal post-sintering are presented. The prospects of the proposed energy-saving approach for the production of ferrite ceramics with a hexagonal structure is shown