SU1709401A1 - Absorbing composite - Google Patents

Abstract

The invention relates to a composite absorbing material for use in the radio industry in the manufacture of parts for absorbing radio equipment. The purpose of the invention is to increase the absorption capacity by controlling the dielectric constant of the material. Absorbing material contains, in wt.%: Powder of nickel-zinc ferrite (50-60): iron or cobalt on the surface of ferrite particles

Description

The invention relates to magnetic materials, in particular to absorbing magnetic materials, and can be used in the radio industry in the manufacture of parts for absorbing devices of radio equipment.

The aim of the invention is to increase the absorption capacity by controlling the dielectric constant of the material.

The invention is based on the fact that the absorbing material containing ferrite powder and binder contains epoxy resin as a binder, and as a ferrite powder contains nickel zinc ferrite powder clad with iron or cobalt, with the following "-complete ratio, wt.%:

Nickel-zinc ferrite powder50-60 Iron or cobalt1-5 Epoxy resin Remaining Iron or cobalt, chemically deposited on the surface of the particles of nickel-zinc ferrite, change the dielectric constant of the material depending on their content in the shielding metal lay There is no change in the magnetic permeability of the material. Since the absorbing capacity of the material is proportional to the ratio of the dielectric and magnetic permeabilities. an increase in the dielectric constant with an almost unchanged value of the magnetic

permeability is equivalent to increasing the absorption capacity of the material.

The ability to control the dielectric constant allows it to be used for matching in microwave devices. The radio absorbing material shielding the metal surface must satisfy the matching condition

,

where d is the thickness of the shielding layer;

e, / - complex relative dielectric and magnetic permeability of the material;

I is the wavelength at which it is required to provide matching;

-1 - imaginary unit; I with e - e-1 / («+ 1 /.

The presence of a screening layer of iron or cobalt of a given thickness on the surface of ferrite particles (as determined by their content in the material) changes the dielectric constant within specified limits without affecting the magnetic permeability / g, which makes it possible to choose a material with such a ratio of components to ensure optimal fulfillment of the condition of agreement.

The table shows the compositions of the proposed material and its characteristics.

To obtain a composite absorbing material, Nl-Zn ferrite powder with a particle size of 0.9–1.3 µm was taken, it was plated with cobalt, for which, after activation and sensitization, they were placed in a cobalt bath (compounds 7–9) or iron oxide (compounds 1–4 ).

The bath contains components, g / l:

Cobalt sulfate25

Sodium citrate 9

Ammonium sulfate 42

Potassium hypophosphate 20

Cobalting was carried out at a pH of 9.3 and a temperature of 80 ± 2 ° C for 5–10 min; the thickness was varied within 0.100, 15 µm.

Iron cladding was carried out in a bath of composition, g / l;

Ferrous sulfate5

Sodium citrate 10

Sulfuric hydrazine6

at pH 8.5 and temperature 90 ± 2 ° С for 8-15 minutes. The thickness of the cladding layer of iron on ferrite particles ranged from 0.16 to 0.25 μm.

Nl-Zn ferrite powders chemically plated with iron or cobalt are injected into epoxy resin. Ratio

Components of the material are given in the table. The resulting mixture was evacuated to remove air bubbles for 60 minutes, after which it was molded. On the obtained samples, the values of f and Efiv are measured.

9 GHz frequency.

Compositions 2-4 and 6-8 relate to the proposed ratio of components of the absorbing material, compositions 1.5 and 9 to the material with the ratio of components,

beyond the scope of the invention. For comparison, the table shows the composition of a known material containing ferrite powder of the same composition in a binder.

As follows from the table proposed

the material allows (compounds 2–4, 6–8) compared with the known increase the absorption capacity by increasing and by 1.5–3.0 times and provides

This is the ability to control the absorption capacity in a given frequency range (9 GHz), while for a known material the absorption capacity can only have a fixed value

dielectric constant and. therefore, the absorption capacity.

Claims (1)

Claims of Composition Absorbing Material Containing Ferrite Powder and Binder, characterized in that, in order to increase the absorption capacity by controlling the dielectric constant of the material, it contains epoxy resin as a binder and contains ferrite powder, plated with nickel-zinc ferrite powder. cobalt or iron. With the following ratio of components, wt.%: Nickel-zinc ferrite powder50-60 Iron or cobalt1-5 Epoxy resin Resid