RU2596619C1 - Method of producing high-temperature resistance radioparent material (article) based phosphate binder and quartz fabric - Google Patents

Abstract

FIELD: technological processes.

SUBSTANCE: invention relates to production of high-temperature resistance radioparent materials. Method includes finishing quartz fabric with organosilicon resin, impregnation with a mixture chromium-aluminophosphate ligament and fine powder of alumina, placing on rigid mandrel a package with a given number of layers of quartz fabric. On surface of assembled package a 0.5-5.0 mm thick layer is applied from a mixture of chromium-aluminophosphate binder and an aqueous slurry of quartz glass of polydisperse composition from 0.1 to 500 mcm, wherein amount of solid phase in an aqueous slurry of quartz glass is equal to percentage composition of quartz fabric in package. Hardened and pressed simultaneously with pumping of water vapour and volatile, heat treated at temperature 350±5 °C for 1-2 hours. Then method includes impregnation with a mixture of sediment of aqueous slurry of quartz glass with particle size of not more than 1.0 mcm and silica sol in ratio 1:1, drying and heat treatment at temperature 350±5 °C for 1-2 hours.

EFFECT: protection of glass fabric from thermal decomposition, providing dielectric and strength characteristics of material in modes of one-sided heating to 1,200 °C at a rate of 100 degrees/s and higher and possibility of obtaining complex products without destruction of reinforcement mesh.

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Description

The invention relates to the field of production of highly heat-resistant radiolucent materials - inorganic fiberglass, intended for the manufacture of radiolucent and heat-protective products of aviation and space-rocket technology operating in the single-sided heating mode (radiotransparent windows, antenna fairings of high-speed rockets, etc.).

Known methods for producing radiolucent highly heat-resistant fiberglass and fiberglass, products from them using quartz or high-silica fabric and inorganic phosphate binder.

In the patent of the Russian Federation No. 2076086, class. C04B 35/80, dated 03/27/1997, a composition was proposed for the manufacture of high-temperature electrical insulating fiberglass, including fiberglass with a content of SiO _{2 of} at least 98%, sintered with 15% KM-9K silicone resin solution, aluminophosphate binder with a molar ratio of P ₂ O ₅ / Al ₂ O ₃ in the range of 3.0-3.2 and alumina powder with an α-Al ₂ O ₃ content of at least 98% with a grain size of M5-M20 in an amount of 56 parts by weight For the manufacture of the product, the package was laid out on the mold and pressed at a pressure of 10 kgf / cm ² and a temperature of 270 ° C with an exposure of 10-12 min per 1 mm of the thickness of the product. The disadvantage of the composition is the decrease in electrical resistance and the deterioration of dielectric characteristics, starting from a temperature of 500 ° C.

Closest to the claimed invention is a method for producing radio engineering material according to the patent of the Russian Federation No. 2220930, class. C04B 35/80, 28/34 dated January 10, 2004 (prototype), where a quartz or silica fiberglass, dressed with 3-7% alcohol solution of KM-9K silicone resin, was selected as a reinforcing filler, and a chromaluminophosphate mixture was used as a fabric impregnation composition ligaments of HAFS-3 and electrofused corundum powder in a ratio of 1: 1. Curing is carried out under a press at a pressure of 0.95-1.05 MPa and raising the temperature to 270 ° C at a speed of 17-18 degrees per hour.

The advantage of the prototype over the analogue is that the chromophosphate binder HAFS-3 with a relatively low molar ratio of P ₂ O ₅ / (0,6Al ₂ O ₃ + 0,4Cr ₂ O ₃ ) = 2.26 is taken as a phosphate binder its less aggressive towards corroding reinforcing filler. Positive is the choice of a less concentrated solution of KM-9K organosilicon resin when applying a sizing layer of only 3-7% (in the analogue of 15%).

However, the prototype has a number of significant disadvantages.

When heated to temperatures above 500-600 ° C, the organopolymer sizing degrades with the release of carbon, which, deposited on the porous structure of the material, worsens its radio-technical characteristics, and with high-speed single-sided heating to temperatures of 1000-1300 ° C, the outer layers of the glass packet break and peel off, due to the explosive nature of the pyrolysis of an organopolymer with free access of oxygen.

In addition, one of the negative factors in obtaining materials according to the technology proposed in the prototype is the preservation in the structure of the material of a significant amount of water vapor from a phosphate binder and volatile organosilicon resins, sizing quartz fiberglass, which reduces moisture resistance and other properties of the material.

The solution to this problem can be provided by the timely exhaustion of vapors from the collected package when heated in the temperature range of 50-300 ° C.

The tasks solved by the present invention are:

- ensuring the dielectric and strength characteristics of inorganic fiberglass based on quartz fabric and a phosphate binder in single-sided heating modes at an outer surface temperature of 1200 ° C and a heating rate of 100 deg./s and above;

- providing the possibility of obtaining complex products with accurate dimensions in thickness and profile due to mechanical processing without destroying the reinforcing fiberglass.

The task is achieved in that:

1. A method of obtaining a highly heat-resistant radiolucent composite material (product) based on a phosphate binder and quartz fabric, comprising sizing quartz fabric with an organosilicon resin, impregnating with a mixture of chromium-phosphate binder and finely divided corundum powder, pressing and curing, characterized in that after impregnation of quartz-phosphate chromium with a mixture and finely dispersed corundum powder carry out the calculation on a rigid mandrel package with a given number of layers of quartz tk ani, apply a layer with a thickness of 0.5-5.0 mm from a mixture of chromaluminophosphate binder and an aqueous silica glass slip of polydisperse composition from 0.1 to 500 microns, while the amount of solid phase in the aqueous silica glass slip is equal to the percentage composition of quartz fabric in the bag, curing and pressing is carried out simultaneously with the pumping out of water and volatile vapors, heat treatment at a temperature of 350 ± 5 ° C for 1-2 hours, impregnated with a mixture of sludge from a water slurry of silica glass with a particle size of not more than 1 μm and silica in a ratio of 1: 1, dried and ter they are processed at a temperature of 350 ± 5 ° C for 1-2 hours.

2. The method according to p. 1, characterized in that the aqueous slurry of silica glass contains crushed silica glass fiber up to 500 microns in length or hollow glass microspheres in an amount of 5-10% of the solid phase.

The main advantage of the proposed method for producing a radiolucent material based on a phosphate binder and quartz fabric for products operating in the single-sided heating mode is the application of a ceramic layer with a thickness of 0.5-5.0 mm with low thermal conductivity on the surface of the collected material (product) package (0, 3-0.5 W / m ² ).

A layer performs several functions:

- protects fiberglass from thermal degradation of organosilicon sizing and thereby preserves the strength and dielectric characteristics of the material;

- allows mechanical processing of products and thus to obtain with great accuracy the profile and wall thickness of the workpiece to a predetermined one without damaging the reinforcing fabric; provides the ability to obtain an aerodynamically smooth and even outer surface of the product.

The second important advantage of the method of obtaining material (products) based on a phosphate binder and quartz fabric is the reduction of the acidity of the material obtained by impregnating it with a mixture of sludge from an aqueous silica glass slip with a particle size of not more than 1 μm, the pH of which is 4-6 units and alkaline silica, for example, KZ-TM-30 TU 2145-008-61801487-2010 with pH = 10 units in a ratio of 1: 1, followed by heat treatment. The material has a neutral reaction and interacts well with metals, organoplastics, etc. In addition, an increase in the temperature range of heat treatment of the material up to 350 ± 5 ° C (in the prototype and analog 270 ± 5 ° C) leads to the complete conversion of phosphates to a water-resistant form and increases moisture resistance material (product).

The thickness of the ceramic layer of 0.5-5.0 mm was determined by the requirements for heat protection of the organopolymer on quartz fabric and tolerance for machining by the thickness of the product.

The temperature range 300-350 ° C is selected based on the preservation of the properties of the material based on chromaluminophosphate binder. At a higher temperature, the sizing is degraded and the dielectric properties deteriorate; a lower temperature (less than 300 ° C) does not provide the final polycondensation of the aluminochromophosphate binder and its moisture resistance.

An aqueous silica glass slip contains crushed silica glass fibers up to 500 microns in length or hollow glass microspheres in an amount of 5-10% of the solid phase. This value provides mixing of the suspension and simplifies the application of the layer.

The proposed method for producing radiolucent material and products based on it includes the following technological steps:

- sizing of quartz fabric and fiberglass with organosilicon resin;

- the preparation of an inorganic binder based on chromium phosphate binder and finely divided corundum powder;

- applying an inorganic binder to the finished quartz fabric and assembling the package on a rigid mandrel from a given number of fabric layers;

- preparation of a ceramic mass on the basis of the same inorganic binder and water slip of silica glass, applying it to the surface of the collected package;

- curing and pressing of the material (product) is carried out simultaneously with the pumping of water vapor and volatile;

- heat treatment of the material (product) at a temperature of 350 ± 5 ° C for 1-2 hours;

- impregnation of the material (product) over the entire surface with a mixture of sludge from a slip of silica glass and silica sol;

- drying at room temperature;

- heat treatment at a temperature of 350 ± 5 ° C for 1-2 hours.

The TS 8/3-K-TO, TU 6-48-112-94 quartz fabric, which has good dielectric characteristics and high heat resistance, was selected as a fibrous filler. The fabric was dressed by dipping (manual method) or by passing through a bath with an alcoholic solution of organosilicon resin KM-9K, TU 1-596-490-2012 concentration of 3-7% for 2-3 minutes on an impregnating machine and drying in ovens at a temperature 30-60 ° C. Quality control of sizing was carried out by weight gain after drying - it should be 5-10%.

As an inorganic binder, the FOSCON 351 TU 2149-150-10964029-01 chromaluminophosphate binder was used, which was thoroughly mixed in a ball mill with powder filler from electrocorundum with a grain size of 3-20 μm TU 3988-075-00224450-99 in a 1: 1 ratio.

The application of a binder on fiberglass was carried out both by means of an impregnating machine with rollers, and manually by smearing the fabric on both sides with a spatula and aligning it with a rubber roller. To accelerate the process during the experimental development of the method on complex products, the application of the binder was carried out directly on the fabric blanks when a double-glazed window was set on a rigid mandrel. The alignment of the ligament layer after laying each layer of quartz fabric was carried out using a coating device according to the USSR copyright certificate No. 1426661, class. B05C 17/02 of 09/30/1988

After a set of a bag with a given number of layers of quartz fabric, impregnated with a mixture of chromaluminophosphate binder and finely divided corundum powder, a ceramic layer is applied with a thickness of 0.5-5.0 mm by spraying (thin), with a brush, spatula and roller (thick). A mixture of chromium-aluminum phosphate binder and an aqueous silica glass slip is a suspension obtained by wet grinding in a ball mill to a fineness of 0.1-500 microns. Such a grain composition of an aqueous slurry containing small and larger particles provides after heat treatment the integrity of the obtained ceramic layer. The aqueous slip was introduced into the chromaluminophosphate binder in an amount in the solid phase equal to the percentage of quartz tissue in the bag (20-30%) and mixed in a ball mill for at least 1-2 hours. To regulate and select the molding properties of an aqueous slurry and chromaluminophosphate binder, distilled water or dry quartz glass powder of the same grain composition can be added to the suspension.

Additionally, in order to reduce the thermal conductivity of the ceramic layer, crushed silica glass fibers up to 500 μm in length or hollow glass microspheres, for example, grade MS-8, can be added in an amount of 5-10% by solid phase. The mixture is mixed in a ball mill with a small amount of balls (10%) for 1-2 hours.

Pressing and curing of the material (products) was carried out simultaneously with the evacuation of water vapor and volatile during slow heating (E _t = 10 deg./h) at a temperature of 50-300 ° C and pressure up to 1 atm, then heat treatment was performed at a temperature of 350 ± 5 ° C for 1-2 hours.

In order to neutralize acidity and at the same time additional harden the material (product) blanks were impregnated with a mixture of sludge from a quartz glass slurry with a particle size of not more than 1 μm and KZ-TM-30 alkaline silica in a ratio of 1: 1, followed by drying and heat treatment at a temperature of 350 ± 5 ° C for 1-2 hours. This operation can be performed either by layer-by-layer (3 times) application of the solution with a brush or by dipping, followed by drying at room temperature or in an oven. The absorption of the mixture is due to the porosity of the inorganic fiberglass and the resulting ceramic layer. Sludge was obtained by prolonged exposure (5-10 days) of an aqueous silica glass slip with a density of 1.75-1.85 g / cm ³ in a closed container and draining the upper layer.

Subsequently, the material (product) was processed on the corresponding machines (surface grinding, turning) with a bonded abrasive tool to the specified thickness of the ceramic layer. Various paints and varnishes can be applied to products, attached to metal, organocomposite or ceramic parts.

Examples of specific embodiments of the invention.

Example 1. On a quartz fabric TC 8/3-K-TO, sizing with a 3-7% alcohol-acetone solution of organosilicon resin KM-9K, a mixture consisting of 65 wt. % binder Foscon-351 and 35 wt. % powder filler from alumina with a grain size of 3-20 microns. A package was assembled with a given number of layers on a rigid mandrel, a mixture of chromium-phosphate binder and a water quartz slurry of a polydisperse composition from 0.1 to 500 μm was applied in an amount on the solid phase equal to the percentage of quartz fabric in the package. It was cured and pressed simultaneously with the evacuation of water vapor and volatile at temperatures up to 300 ° C, heat treated at 350 ± 5 ° C for 1-2 hours. It was cooled to room temperature, the material (product) was impregnated with a mixture of sludge from an aqueous quartz glass slip with a particle size of not more than 1 μm and KZ-TM-30 silica sol in a ratio of 1: 1, subjected to drying and heat treatment at a temperature of 350 ± 5 ° C for 1-2 hours.

Example 2. Example 2 was carried out analogously to example 1, the thickness of the layer of a mixture of chromaluminophosphate binder and an aqueous silica glass slip was 5.0 mm.

Example 3. Example 3 was carried out analogously to example 1, the layer thickness of the mixture of chromaluminophosphate binder and water slurry was 2.5 mm, crushed silica glass fiber with a length of up to 500 μm in the amount of 5-10% in the solid phase was introduced into the quartz slurry, the mixture was mixed in a ball mill with a small number of balls (10%) for 1-2 hours

The obtained experimental data are given in the table.

Samples of the material and product made in the form of flat panels and conical shells made by this method were tested for thermal cycling from -60 ° C to + 300 ° C in the amount of 15 heat shifts and for unilateral heating to an external surface temperature of 1200 ° C and heating rate at individual sites up to 100 deg./s. The dielectric properties of the material after thermal testing remained at the acceptable level. The dielectric constant and the dielectric loss tangent at a frequency of 10 ¹⁰ Hz before tests 3.07 and 0.006, after tests 3.21 and 0.016. The strength of the material based on chromium phosphate binder after testing has not changed.

Claims (2)

1. A method of obtaining a highly heat-resistant radiolucent composite material (product) based on a phosphate binder and quartz fabric, comprising sizing quartz fabric with an organosilicon resin, impregnating with a mixture of chromium-phosphate binder and finely divided corundum powder, pressing and curing, characterized in that after impregnation of quartz-phosphate chromium with a mixture and finely dispersed corundum powder carry out the calculation on a rigid mandrel package with a given number of layers of quartz tk ani, apply a layer with a thickness of 0.5-5.0 mm from a mixture of chromaluminophosphate binder and an aqueous silica glass slip of polydisperse composition from 0.1 to 500 microns, while the amount of solid phase in the aqueous silica glass slip is equal to the percentage composition of quartz fabric in the bag, curing and pressing is carried out simultaneously with the pumping out of water and volatile vapors, heat treatment at a temperature of 350 ± 5 ° C for 1-2 hours, impregnated with a mixture of sludge from an aqueous slurry of silica glass with a particle size of not more than 1 μm and silica in a ratio of 1: 1, dried and thermo work at a temperature of 350 ± 5 ° C for 1-2 hours 2. The method according to p. 1, characterized in that the aqueous slurry of silica glass contains crushed silica glass fiber up to 500 microns in length or hollow glass microspheres in an amount of 5-10% of the solid phase.