RU2519244C1 - Carbon-containing formula for radioprotective materials - Google Patents

Abstract

FIELD: electricity.

SUBSTANCE: formula contains 5-16 wt % of ultradisperse active carbon with an average size of particles of 5-100 nm and specific surface are of 16-320 m²/g, a dispersing agent in the form of soda glass aqueous solution and a stabilising agent in the form of a saturated solution of . Finely-dispersed colloidal graphite can be introduced into the formula additionally. The invention uses the formula property to absorb radio-wave electromagnetic radiation at its equal distribution inside the hard matrix of a constructional material or at its application onto the surface of radar absorbent structures or constructional materials.

EFFECT: improving radioprotective properties of the material is the technical result of this invention.

2 cl, 3 tbl

Description

The invention relates to the field of radiation protective materials, in particular to materials for the absorption of electromagnetic radiation. The property of the inventive carbon-containing composition is used to absorb electromagnetic radiation of the radio wave range when it is directly distributed inside the solid matrix of building material, or applied to the surface of radar absorbing structures and building materials, or deposited on the surface of solid fillers for radar absorbing devices and radioprotective building materials.

Known composite material for the absorption of electromagnetic radiation, obtained by thermal expansion of a pre-combined mixture in thermal shock mode, consisting of a polymer binder selected from a number of polyolefins, and an electrically conductive powder filler, which is a graphite modification product with concentrated sulfuric and nitric acids (RU 2242487 C1, 26.06. 2003).

Known radar absorbing material, in which polyurethane foam is used as a binder, and carbon black as an absorbing filler. The mixture is mixed and then cured in the forms at a certain temperature regime (RU 2275719 C1, 09/06/2004). A known composition for coatings shielding electromagnetic radiation, containing as a polymer binder a solution of chlorosulfonated polyethylene in a hydrocarbon solvent, and as a filler a mixture of soot (10.0-12.0 wt.%) And graphite (20.8-25.0 wt. .%). The composition is applied to various substrates and surfaces (RU 2215764 C1, 11/13/2002).

The disadvantage of the above materials is the use of powder filler. Powder particles are distributed in the matrix of the polymer binder both in the form of individual particles (the smallest part) and in the form of aggregates of various sizes (most), while the size of the aggregates can reach tens and hundreds of microns (tens and hundreds of thousands of nanometers), which leads to heterogeneity of the material and affects the nonlinearity (oscillation) of the attenuation coefficient characteristics depending on the frequency of the electromagnetic field (EMF). The specific surface area of the filler particles in these materials does not exceed 0.05 square meters per 1 gram (m ² / g), which affects the efficiency of EMF absorption and requires the use of high concentrations of filler to obtain through conductivity (quantum effects). In addition, the disadvantages of these materials include the complexity of production, limited use, high toxicity of the combustion products of the binder material.

The closest analogue of the claimed material is the known carbon-containing composition - VKGS-0 preparation TU 113-48-52-89, which is an aqueous suspension of highly dispersed graphite stabilized by surface-active substances, which is used as a lubricant for medium and fine wire drawing of refractory metals and in other processes of hot metal forming (prototype).

The average particle size of graphite in the preparation is 1-2 microns (1000-2000 nm), specific surface area is up to 3 m ² / g. These technical parameters make it possible to obtain effective radiation shields (surfaces reflecting EMFs), since when the drug is applied to the surface of the material, the solvent evaporates and the graphite particles close together, forming a film with through conductivity. But to obtain a bulk radio-absorbing material (for example, building concrete), a high mass fraction of such particles in the matrix (7-20%) is required, which at the minimum value corresponds to the consumption of 150 kg of dry colloidal graphite or 500 kg of 30% aqueous suspension per 1 cubic meter of concrete. The amount of water introduced with the preparation is twice the allowable value for concrete in terms of water-cement ratio. All this leads to an increase in the cost of a unit volume of the material by 20 times and a 50% loss of strength.

The objective of the invention is to provide increased radioprotective properties to a wide range of building and structural materials.

EFFECT: creation of a highly effective non-combustible carbon-containing composition suitable for producing radiation shields and radar absorbing coatings, as well as bulky radar absorbing materials.

The technical result is achieved by the fact that, in contrast to the known technical solutions, an ultrafine active carbon with an average particle size of 0.005-0.1 μm (5-100 nm) and a specific surface of 16-320 m ² / g, dispersed, is used as a radar absorbing substance in the composition. in a mineral solvent. The composition of the solvent includes a solution of sodium liquid glass in water (dispersant) and ammonium lignosulfonate (stabilizer).

The ultrafine active carbon is dissolved in liquid glass diluted with water with a SiO ₂ concentration _of 8-15 wt.%. The lower concentration limit is due to the dispersion efficiency of active carbon, the upper one is due to practical expediency. The concentration of ultrafine active carbon in a colloidal solution of 5-16 wt.%. Using a concentration of less than 5% does not give the claimed effect, and at a concentration of more than 16%, the colloidal solution passes into a gel. The stabilizer, a saturated solution of ammonium lignosulfonate, is introduced last in the amount of 2-6 wt.% Depending on the concentration of active carbon.

A useful property of the proposed composition is the ability to further disperse in it up to 28 wt.% Highly dispersed colloidal graphite, which increases the overall concentration of radioprotective filler and expands the scope.

The main purpose of the carbon-containing composition is to impart radioprotective properties to conventional radiolucent materials by coating the surface and (or) introducing radar absorbing particles into the bulk of the material. The particle size of active carbon is about 5-100 nm - this allows them to easily penetrate into the micropores and structural channels of the material, creating a nanoscale cross-section of elements and a macro-sized length electrical conductor frame, while the energy gap of the initial dielectric material decreases by more than an order of magnitude , there arises a set of transition energy levels providing broadband EMF absorption. The additional introduction of graphite particles with a size of 1000-2000 nm creates EMF scattering centers and leads to the formation of relay scattering structures and zones of various sizes, as a result of which the operating frequency range of the material is expanded and the level of EMF attenuation is increased, including by increasing the reflection coefficient. By changing the ratio of ultrafine active carbon / fine graphite in the composition, you can adjust the ratio of the reflection and absorption coefficients of the EMF material.

In the process of testing the inventive carbon-containing composition, cardboard samples were made on which a single-layer coating was applied, and concrete samples, in the manufacture of which the composition was introduced into the mixing water of the cement-sand mixture. Measurement of the reflection and attenuation coefficients of the electromagnetic field was carried out on a panoramic swirl meter VSWR P2-113. The measurement results are given in the tables.

Table 1 Corrugated fibreboard three-layer GOST 7376-89 Sample designation Frequency, GHz Measured Attenuation, dB (times) VSWR Reflection,% Absorption, dB (times) 0 4.0 0 1,02 0 0 one 4.0 7.3 (5.4) 3.30 28.6 5.2 (3.3) 2 4.0 4.7 (3.0) 2.49 18.2 3.8 (2.4) 3 4.0 8.8 (7.6) 4.06 36.6 5.6 (3.6)

Specification

0 - cardboard without coating;

1 - one-sided single-layer coating with a carbon-containing composition containing 15.9 wt.% Ultrafine active carbon;

2 - one-sided single-layer coating with a carbon-containing composition containing 8 wt.% Ultrafine active carbon;

3 - one-sided single-layer coating with a carbon-containing composition containing 13.5 wt.% Ultrafine active carbon and 5 wt.% Highly dispersed colloidal graphite.

table 2 Concrete Sample Number EMF frequency, GHz Measured EM attenuation, dB VSWR Reflection,% Absorption, dB Sample Thickness, cm Specific Absorption, dB / cm 0-1 4.0 7.2 3.6 32,0 4.9 5,0 1,0 1-1 4.0 10.8 3.8 34.0 7.1 4.0 1.8 1-2 4.0 35.8 4.1 37.0 22.6 4.7 4.8 1-3 4.0 42,4 4.6 41.3 24.9 5,0 5,0 1-4 4.0 32,0 6.1 51.6 15,5 2,5 6.2

Specification

All concrete samples had the same mass ratio of components of cement: sand: crushed stone: water: carbon-containing composition, the composition of the carbon-containing composition changed.

0-1 - control sample without a carbon-containing composition;

1-1 - carbon-containing composition with an ultrafine active carbon content of 5.9 wt.%;

1-2 - carbon-containing composition with an ultrafine active carbon content of 15.9 wt.%;

1-3 - a carbon-containing composition with an ultrafine active carbon content of 15.9 wt.% And 8 wt.% Highly dispersed colloidal graphite;

1-4 - a carbon-containing composition with an ultrafine active carbon content of 8 wt.% And 28 wt.% Highly dispersed colloidal graphite.

For the convenience of analyzing the results of table 2, table 3 contains the calculated values reduced to a concrete sample thickness of 3 cm.

Table 3 Batch number Specific Absorption, dB / cm EMF attenuation due to absorption by a layer 3 cm thick, dB (times) EMF attenuation due to reflection, dB (times) EMF attenuation total, dB (times) 0-1 1,0 3.0 (2) 1.4 (1.4) 4.4 (2.8) 1-1 1.8 5.4 (3.5) 2.8 (1.9) 8.2 (6.6) 1-2 4.8 14.4 (27.5) 8.5 (7) 22.9 (195) 1-3 5,0 15.0 (31.6) 10.6 (11.5) 25.6 (363) 1-4 6.2 18.6 (72) 19.8 (96) 38.4 (6900)

The compressive strength of the samples is 1.05-0.80 of the strength of the control sample. An increase in the cost of 1 m ^{3 of} concrete due to the addition of ultrafine active carbon 25-70% in combination with highly dispersed colloidal graphite - 200-400%. Graphite addition is useful in creating materials for shielding (radiation shields) EMF. To impart high radioprotective properties to general-purpose building materials, a carbon-containing composition containing only ultrafine active carbon is effective both technically and economically.

Claims (2)

1. Carbon-containing composition for radioprotective materials, including water, a dispersant in the form of an aqueous solution of sodium liquid glass, a radioprotective carbon filler and a stabilizer, characterized in that it contains ultrafine active carbon with an average particle size of 5-100 nm and a specific surface area of 16-320 m ² / g in the following ratio of components, wt.%:
SiO ₂ - 8-15, ultrafine active carbon - 5-16, a saturated solution of ammonium lignosulfonate - 2-6, water - the rest. 2. The carbon-containing composition according to claim 1, characterized in that it further comprises 5-28 wt.% Highly dispersed colloidal graphite.