RU2300509C2 - Method of production of the composite heat-insulation material and the material manufactured by this method - Google Patents

Abstract

FIELD: aircraft industry; space-rocket industry; methods of production of the composite thermal insulation materials.

SUBSTANCE: the invention is pertaining to the field of aircraft industry and space-rocket industry. The technical result of the invention is production of the details possessing the radiotransparency, the increased thermal stability, the low value of the dielectric conductivity in the broad band of the temperatures, the small specific weight. The method of manufacture of the heat- insulation material provides for impregnation of the sintered silicon dioxide bar having the fibrous structure with the methylphenylspirosiloxane solution at its continuous gyration in two orthogonally related planes and drying within 1-3 hours with the subsequent polymerization at the temperature of 240-260°C within 2-4 hours. The material produced by this method contains the components in the following ratio (in mass %): silicon dioxide of the fibrous structure - 45.0-55.0, methylphenylspirosiloxane - 45.0-55.0.

EFFECT: the invention ensures production of the details possessing the radiotransparency, the increased thermal stability, the low value of the dielectric conductivity in the broad band of the temperatures, the small specific weight.

2 cl, 3 ex, 1 tbl

Description

The group of inventions relates to the aviation, rocket and space industry and can be used to create parts from structural materials, in particular for the manufacture of broadband antenna fairings for hypersonic missiles with a low dielectric constant in a wide temperature range and low specific gravity.

A known method of manufacturing mineral wool or glass wool products (USSR Author's Certificate No. 876623 C04B 43/02, publ. 10/30/1981), which consists in applying a binder solution to the fiber by spraying the fiber with the subsequent formation of a continuous mineral wool carpet, compacting it and heat treating it.

The disadvantage of this method is the uneven application of the binder, as a result of which the quality of the obtained material is not uniform throughout the volume of the material, i.e. not consistent with the physical, technical and radio characteristics of the claimed material.

The closest in technical essence to the claimed method for producing composite material in the group of inventions is the method (Russian Patent No. 2209494, IPC7 H01Q 1/42, publ. 07/27/2003), in which a sintered silicon dioxide having no fibrous structure is impregnated with a polymer .

The disadvantage of this method is that the material obtained in this way does not meet the necessary strength and dielectric properties.

Known composite material, including mineral and glass fibers, aluminophosphate binder and kaolin (USSR Author's Certificate No. 471349 С04В 43/04, publ. 03.09.1975). The disadvantage of this material is that due to the poor fluidity of the binder, the interfiber space is unevenly filled, which leads to an inhomogeneous density and permittivity of the material throughout the volume.

The closest in technical essence to the claimed material is the material (USSR Author's Certificate No. 607830 С04В 43/02, publ. 05.25.1978), consisting of mineral fiber, synthetic binder, foaming agent and water, in which urea-formaldehyde resin was used as a synthetic binder.

The disadvantage of this material is that due to the relatively low heat resistance of the binder, which degrades when a temperature is reached above 150 ° C with the release of a large number of volatile compounds, the physicomechanical and dielectric characteristics of the material are significantly impaired.

The technical result of the present invention is to obtain a composite thermal insulation material with improved physical and technical characteristics, capable of operating in the temperature range of 500-1000 ° C while maintaining the radio technical characteristics.

The specified technical result is achieved by the fact that

1. A method of manufacturing a composite heat-insulating material, including the impregnation of sintered silica with a solution of methylphenylspirosiloxane, characterized in that the sintered silica preform has a fibrous structure, the impregnated preform is dried in air for 1-3 hours with continuous rotation in two mutually perpendicular planes and polymerized at a temperature of 240-260 ° C for 2-4 hours.

2. Composite heat-insulating material made by the method according to claim 1, including sintered silica and methylphenylspirosiloxane, characterized in that the sintered silica has a fibrous structure, and the components are in the following ratio (wt.%):

silica fiber 45.0-55.0 structures methylphenylspirosiloxane 45.0-55.0

The used acetone solution of methylphenylspirosiloxane MFSS-8 (TU 6-02-13 52-87) is a silicon-organic oligomer of the spirocyclic structure of the polymerization type, without functional groups and cured without isolation of by-products with a high temperature of thermal oxidative degradation of 500 ° C. During the curing of methylphenylspirosiloxane, a chemical bond forms with the silica fiber.

The structural formula of methylphenylspirosiloxane is presented below:

The polymer content in the material varies only by the density of the acetone solution of methylphenylspirosiloxane and, to a lesser extent, by the impregnation time. The optimal content of methylphenylspirosiloxane in the proposed material is in the range of 45-55%. It was experimentally established that a polymer content of less than 45% does not provide the specified physical and mechanical properties, more than 55% significantly degrades the dielectric characteristics.

The starting material for obtaining the claimed material can be any quartz fiber-based thermal insulation material having a rigid structure, i.e. molded and can be machined to size. Typically, such a material is anisotropic. Anisotropy is formed during the formation of the material. In the material of the fibrous structure, a strong and a weak direction are distinguished depending on the applied load during molding of the material. When impregnated, anisotropy is maintained.

One of the main requirements for the material for the manufacture of products for aviation and space purposes is its uniformity, which is possible only with a uniform distribution of the polymer throughout the volume of the material, the initial porosity of which is 95%. This can be achieved only under one condition: after the impregnation of the material, the material should periodically change its position in space to prevent the polymer solution from flowing over the entire drying time, i.e. within 1-3 hours. This time is enough to completely remove acetone from the polymer. Then the impregnated preform is placed in a thermostat and polymerized at a temperature of 240-260 ° C for 2-4 hours.

At this temperature, the spatial structure of the organosilicon resin is formed, and the formation of cycles of increased heat resistance depends not only on temperature, but also on the exposure time at this temperature. A holding time of 2-4 hours ensures the production of a composite material of a given strength and with dielectric characteristics not exceeding those allowed for products of this class.

The technological process of obtaining the claimed material consists of the following operations:

- heat-insulating material - sintered silica of a fibrous structure - in the form of preforms machined to size, was impregnated with a solution of methylphenylspirosiloxane with a density of 0.91-0.93 g / cm ³ for 1.5-5 minutes, dried in air for 1-3 hours with continuous rotation in two mutually perpendicular planes, then placed in a thermostat and polymerized at 240-260 ° C for 2-4 hours.

In this case, heat-protective material made of superthin quartz fiber TZMK-25 (TU 1-596-180-83) in the form of blocks measuring 325 × 325 × 150 mm was used.

Examples of specific embodiments of the invention

Example 1

- the workpiece from TZMK-25 is impregnated with a solution of methylphenylspirosiloxane with a density of 0.91 g / cm ³ for 1.5 minutes;

- dried in air for 1 hour with continuous rotation in two mutually perpendicular planes;

-polymerized at 240 ° C for 4 hours.

Example 2

- the workpiece from TZMK-25 is impregnated with an acetone solution of methylphenylspirosiloxane with a density of 0.92 g / cm ³ for 3 minutes;

- dried in air for 2 hours with continuous rotation in two mutually perpendicular planes;

- polymerized at 250 ° C for 3 hours.

Example 3

- the workpiece from TZMK-25 is impregnated with an acetone solution of methylphenylspirosiloxane with a density of 0.93 g / cm ³ for 5 minutes;

- dried in air for 3 hours with continuous rotation in two mutually perpendicular planes;

- polymerized at 260 ° C for 2 hours.

The properties of the obtained material are given in the table.

Table The name of indicators Claimed material Source Example Example Example material -one -2 -3 SiO ₂ - SiO ₂ - SiO ₂ - 55% fifty%, 45% IFSS IFSS IFSS 8-45% 8-50% 8-55% Bending strength, kgf / cm ² strong direction 52,4 60.3 111.9 18.3 weak direction 19.2 23,4 32,7 7.0 Compressive strength, kgf / cm ² strong direction 41.9 48.1 56.8 15.7 weak direction 32,0 34.2 36.8 11.3 Tensile strength, kgf / cm ² strong direction 13.0 13.8 14.5 12.0 weak direction 9.5 10.0 10.8 7.0 The dielectric constant 1.4 1.43 1.45 1.21 Density, g / cm ³ 0.38 0.4 0.42 0.25

As can be seen from the table, the proposed material has improved strength characteristics compared to the original, while the dielectric characteristics vary slightly.

A method has been developed that allows to obtain:

- composite heat-insulating material with a uniformly distributed binder throughout the volume of the source material;

A composite heat-insulating material based on superthin quartz fiber and methylphenylspirosiloxane with high heat-resistant and stable dielectric characteristics was obtained.

Using the present invention allows to create new wide-band antenna fairings and in the future solves one of the most important problems of rocket science.

Claims (2)

1. A method of manufacturing a heat-insulating material, including the impregnation of sintered silica with a solution of methylphenylspirosiloxane, characterized in that the preform of sintered silica has a fibrous structure, the impregnated preform is dried in air for 1-3 hours with continuous rotation in two mutually perpendicular planes and polymerized at a temperature of 240-260 ° C for 2-4 hours 2. Composite heat-insulating material made by the method according to claim 1, including sintered silica and methylphenylspirosiloxane, characterized in that the sintered silica has a fibrous structure, and the components are in the following ratio, wt.%: Silica fiber 45.0-55.0 the structure Methylphenylspyrosiloxane 45.0-55.0