RU2792488C1 - Method for producing a composite material based on an aluminosilicate binder - Google Patents

Abstract

FIELD: producing a composite material.

SUBSTANCE: method for producing a composite material based on an aluminosilicate binder. Composite material is stable at high temperatures (up to 1000°C) and can be used in the production of aviation equipment, construction and other industries. The method for producing a composite material includes cutting carbon fabric, impregnation with an aluminosilicate binder, laying and curing at a temperature of 50-90°C for 20-120 min, followed by heat treatment in vacuum at a temperature of 800-1300°C. Carbon fabric is pre-treated with an aqueous solution of sodium or potassium silicate and, after impregnation with an aluminosilicate binder and molding, is compacted in a vacuum bag. The composite material contains components in the following ratio, parts by weight: alkaline solution of sodium or potassium silicate 20-30, carbon fiber 100, aluminosilicate binder 90-110.

EFFECT: composite material based on an aluminosilicate binder with high heat resistance and tensile and bending strength.

1 cl, 5 ex, 2 tbl

Description

The invention relates to a method for producing a composite material based on an aluminosilicate binder, which is subjected to operation at high temperatures (up to 1000°C). The composite material can be used in the production of aviation equipment, construction and other industries.

1) The invention is known according to the patent CN107640975B "Three-dimensional carbon fiber preform for producing a ceramic composite based on aluminum and yttrium oxides and a method for producing it."

The invention discloses a method for producing a ceramic composite material based on a three-dimensional carbon fiber preform and an inorganic matrix based on aluminum and yttrium oxides. The composite material consists of a three-dimensional carbon fiber preform and a ceramic matrix based on a complex phase of aluminum and yttrium oxides. The preparation method includes the following operations:

1) preparation of yttrium oxide sol;

2) impregnation;

3) drying;

4) heat treatment;

5) repetition of steps (2)-(4).

Composite material has the following advantages: low porosity, high temperature resistance, good mechanical properties.

The disadvantage of this invention is the duration and complexity of the technological process of obtaining a composite material, due to repeated repetition of the stages of impregnation, drying and heat treatment.

2) An invention is known according to patent CN 105601309A "Composite material based on aluminum oxide, reinforced with a three-dimensional fibrous filler and a method for its manufacture." The fibrous filler in the described invention is carbon fiber or silicon carbide fiber. The method includes the following steps:

1) impregnation of the filler with a binder;

2) drying;

3) heat treatment;

4) repetition of the processes of impregnation, drying, heat treatment.

The 3D fiber reinforced alumina composite material has low porosity, high stability and high mechanical performance.

The disadvantage of this invention is the duration and complexity of the technological process of obtaining a composite material, due to the need to repeat the stages of impregnation, drying and heat treatment.

3) An invention is known according to the patent CN107640973B "Three-dimensional carbon fiber preform for producing a ceramic composite based on yttrium silicates and a method for producing it." The method for preparing a composite material includes the following steps:

1) preparation of Sol Y ₂ O ₃ -SiO ₂ ;

2) impregnation of the reinforcing material;

3) drying;

4) heat treatment;

5) repetition of the operations of impregnation, drying, heat treatment.

The disadvantage of this invention is the duration and complexity of the technological process of obtaining a composite material, due to the need to repeat the stages of impregnation, drying and heat treatment.

4) An invention is known according to patent CN108147797B "Three-dimensional composite ceramic material based on silicon dioxide and zirconium, reinforced with carbon fiber, and a method for producing it." The invention discloses a three-dimensional composite ceramic material based on silicon dioxide and zirconium dioxide, reinforced with carbon fiber, and a method for its production, including the following steps:

1) stabilization of the Sol SiO ₂ -ZrO ₂ ;

2) impregnation of a three-dimensional carbon fiber preform in a stabilized SiO ₂ -ZrO ₂ ash;

3) drying the three-dimensional carbon fiber preform;

4) heat treatment;

5) repetition of the processes of impregnation, drying, heat treatment.

The carbon fiber-reinforced ceramic composite material obtained according to the present invention has high thermal stability, oxidation resistance, high mechanical properties.

The disadvantage of this invention is the duration and complexity of the technological process of obtaining a composite material due to the need to repeat the stages of impregnation, drying and heat treatment.

5) The invention is known according to the patent CN108178648B "Three-dimensional composite material based on aluminum oxide and zirconium, reinforced with carbon fiber, and method for its production".

The invention discloses a bulk composite material of aluminum oxide and zirconium, reinforced with carbon fiber, and a method for its production, including the following steps:

1) stabilization of the sol based on aluminum oxide and zirconium;

2) vacuum impregnation of a three-dimensional carbon fiber blank;

3) drying the impregnated carbon fiber preform;

4) heat treatment;

5) repetition of the operations of impregnation, drying, heat treatment.

The disadvantage of this invention is the duration and complexity of the technological process of obtaining a composite material, due to the need to repeat the stages of impregnation, drying and heat treatment.

6) The invention is known according to the patent CZ20318U1 "High-strength geopolymer composite reinforced with carbon fiber". The invention relates to high-strength carbon fiber-reinforced geopolymers coated with epoxy resin. The invention discloses a high-strength geopolymer composite reinforced with carbon fiber, characterized in that it contains:

- 55-65 wt. geopolymer matrix containing 70-80 wt.% SiO ₂ , 5-8 wt.% Al ₂ O ₃ , 10-20 wt.% K ₂ O, 2-7 wt.% one of the oxides, which include P ₂ O ₅ and B ₂ O ₃ ;

- 35-45 wt.% carbon fibers, coated on the basis of epoxy resin with a content of from 1 to 1.5 wt.%;

The flexural strength of geopolymer composite samples, depending on the composition, ranges from 406 to 753 MPa, and the modulus of elasticity ranges from 67.5 to 87.7 GPa.

The disadvantage of the invention is the need to use an additional operation, which consists in applying an epoxy coating on the surface of carbon fibers, which complicates the manufacturing process of the composite material and increases time costs. In addition, the use of an epoxy resin coating limits the operating temperature of the geopolymer composite.

7) The closest in technical essence and achieved technical result , chosen by the applicant as a prototype, is the invention according to patent CN101531535B "Method of obtaining a reinforced composite material based on an inorganic polymer from a continuous fiber."

The method for preparing a composite material based on an inorganic polymer is carried out in accordance with the following steps:

1) kaolin is calcined for 1.5-2.5 hours at a temperature of 700-800°C, thus obtaining metakaolin;

2) metakaolin and silicate solution are mixed in a mass ratio of 46-62%, an inorganic polymer matrix is formed, then ceramic particles are added and an admixture of ceramic particles is obtained in an inorganic polymer matrix, where the weight ratio of the inorganic polymer matrix and ceramic particles is 1: 0.1- 1;

3) a continuous fiber fabric is impregnated with a mixture of inorganic polymer, sonicated for 5-12 minutes, a prepreg is obtained;

4) the prepreg is placed in a mold at a temperature of 50-90°C, hardens within 20-120 minutes,

5) the product obtained in step 4 is subjected to pyroprocessing in vacuum or inert gas, the processing temperature is 800-1300°C, and the processing time is 30-120 minutes.

Thus, a reinforced composite material based on an inorganic polymer from a continuous fiber is obtained.

The density of the composite material based on an inorganic polymer with a continuous fiber is 1.6-1.9 g/cm ³ , the three-point bending strength is 160-260 MPa, the tensile strength is 40-55 kJ ^. m ^-2 , operating temperature up to 1000°C.

The disadvantage of the invention is the low mechanical properties of the composite material in bending and stretching, which, apparently, is due to insufficient compaction of the prepreg layers and insufficient removal of air bubbles and moisture, since the prepreg is cured without vacuum.

The objective and technical result of the claimed technical solution is to develop a method for producing a composite material based on an aluminosilicate binder that eliminates the disadvantages of the prototype, namely:

- increasing the strength characteristics of the composite material.

The technical result is achieved by the fact that in the method of obtaining a composite material based on an aluminosilicate binder , a new feature is that the carbon fabric is pre-treated with an aqueous solution of sodium or potassium silicate and, after impregnation with an aluminosilicate binder and laying out in a mold, is compacted in a vacuum bag in the following ratio of components, wt. hours:

alkaline solution of sodium or potassium silicate 20-30 carbon fiber 100 aluminosilicate binder 90-110

The method for producing a composite material based on an aluminosilicate binder includes the following steps:

1) cutting carbon fabrics,

2) treatment of each tissue layer with an aqueous solution of sodium or potassium silicate, followed by exposure for 30 minutes;

3) preparation of aluminosilicate binder, which consists in mixing metakaolin and sodium or potassium silicate solution;

4) impregnation of each layer of carbon fiber with an aluminosilicate binder,

5) laying out impregnated layers,

6) sealing the assembled package under vacuum and curing at a temperature of 50-90°C for 20-120 minutes. To increase the heat resistance and operating temperature, heat treatment is additionally carried out in an inert gas atmosphere at a temperature of 800-1300°C.

The claimed sequence of actions is not identified from the prior art.

The claimed technical solution is illustrated in Table. 1 - Tab. 2.

Table 1 shows the compositions of the claimed composite material and the prototype composite material.

Table 2 shows the properties of the claimed composite material and the prototype composite material.

The following is a description of the individual components of the claimed composite material.

The heat resistance of polymer composite materials is limited by the nature of the polymer matrix. To solve this problem, it is promising to use a geopolymer binder. Geopolymers are a class of aluminosilicate binders, which are polymers based on minerals synthesized by geosynthesis, that is, a chemical reaction between aluminosilicates and alkali metal polysilicates, which results in the formation of an Al-O-Si bond.

These materials have a wide range of useful properties: good mechanical properties, thermal stability, low shrinkage, fire and acid resistance, and they are environmentally friendly, which compares favorably with most synthetic resin-based polymer binders.

Carbon fibers provide high strength composite material. The filler used was a carbon cloth with a surface density of 100 g/m ² .

An aluminosilicate solution was used as a geopolymer binder. Metakaolins of the following grades were used as the initial component: VMK-45 with a mass fraction of SiO ₂ 51.4%, Al ₂ O ₃ >42%; VMK-VVu with a mass fraction of SiO ₂ 40-42%, Al ₂ O ₃ 30-32%, MK 1000 with a mass fraction of SiO ₂ 55%, Al ₂ O ₃ 40% (Synergo LLC, Russia). Si/Al ratio = 2…3. Alkaline solutions of sodium or potassium silicate containing 30-31% sodium or potassium silicate and 8-9% NaOH or KOH were used as an activating agent.

The mixing of the components was carried out in the temperature range from 0 to 20°C in order to reduce the rate of gelation of the mixture before the start of the impregnation process.

It is known from the literature that the geopolymer matrix has low adhesion to carbon fibers. In the proposed invention, to improve adhesion between the filler and the binder, the carbon fabric was pre-treated with an aqueous solution of sodium or potassium silicate containing sodium or potassium silicate 10-15% and 2.5-3% NaOH or KOH. The presence of alkali leads to partial oxidation of the carbon fiber surface, which leads to the formation of groups that chemically interact with the geopolymer matrix. As a result, the adhesive strength between the carbon fiber and the aluminosilicate matrix is increased.

The heat resistance of the composite material was determined by dynamic mechanical analysis on a DMA 242 E instrument (NETZSCH) at a heating rate of 5 K/min.

Tensile strength was determined according to GOST R 56785-2015 “Polymer composites. Tensile testing method for flat specimens”.

Bending strength was determined according to GOST R 56810-2015 “Polymer composites. Bending test method for flat specimens”.

Further, the applicant provides examples of the implementation of the claimed technical solution.

Example 1

At the first stage, the layers of carbon fabric are cut, the number of layers depends on the thickness of the products. Layers of carbon fabric are pre-treated with an aqueous solution of sodium silicate and incubated for 30 minutes. The composition of the aluminosilicate binder is prepared by mixing metakaolin and sodium silicate solution in a ratio of 1: 1.2. Layers of carbon fabric are impregnated with an aluminosilicate binder and laid out on a tooling. The vacuum bag is assembled and the workpiece is cured under vacuum at a temperature of 50-90°C for 20-120 minutes. To increase the heat resistance and operating temperature, heat treatment is additionally carried out in an inert gas atmosphere at a temperature of 800-1300°C.

Example 2

At the first stage, the layers of carbon fabric are cut, the number of layers depends on the thickness of the products. Layers of carbon fabric are pre-treated with an aqueous solution of potassium silicate and incubated for 30 minutes. The composition of the aluminosilicate binder is prepared by mixing metakaolin and potassium silicate solution in a ratio of 1: 1.2. Layers of carbon fabric are impregnated with an aluminosilicate binder and laid out on a tooling. The vacuum bag is assembled and the workpiece is cured under vacuum at a temperature of 50-90°C for 20-120 minutes. To increase the heat resistance and operating temperature, heat treatment is additionally carried out in an inert gas medium at a temperature of 800-1300°C.

Example 3

At the first stage, the layers of carbon fabric are cut, the number of layers depends on the thickness of the products. Layers of carbon fabric are pre-treated with an aqueous solution of sodium silicate and incubated for 30 minutes. The composition of the aluminosilicate binder is prepared by mixing metakaolin and sodium silicate solution in a ratio of 1: 1.1. Layers of carbon fabric are impregnated with an aluminosilicate binder and laid out on a tooling. The vacuum bag is assembled and the workpiece is cured under vacuum at a temperature of 50-90°C for 20-120 minutes. To increase the heat resistance and operating temperature, heat treatment is additionally carried out in an inert gas medium at a temperature of 800-1300°C.

Example 4

At the first stage, the layers of carbon fabric are cut, the number of layers depends on the thickness of the products. Layers of carbon fabric are pre-treated with an aqueous solution of potassium silicate and incubated for 30 minutes. The composition of the aluminosilicate binder is prepared by mixing metakaolin and potassium silicate solution in a ratio of 1:1.1. Layers of carbon fabric are impregnated with an aluminosilicate binder and laid out on a tooling. The vacuum bag is assembled and the workpiece is cured under vacuum at a temperature of 50-90°C for 20-120 minutes. To increase the heat resistance and operating temperature, heat treatment is additionally carried out in an inert gas medium at a temperature of 800-1300°C.

Example 5

At the first stage, the layers of carbon fabric are cut, the number of layers depends on the thickness of the products. Layers of carbon fabric are pre-treated with an aqueous solution of sodium silicate and incubated for 30 minutes. The composition of the aluminosilicate binder is prepared by mixing metakaolin and sodium silicate solution in a ratio of 1:1. Layers of carbon fabric are impregnated with an aluminosilicate binder and laid out on a tooling. The vacuum bag is assembled and the workpiece is cured under vacuum at a temperature of 50-90°C for 20-120 minutes. To increase the heat resistance and operating temperature, heat treatment is additionally carried out in an inert gas medium at a temperature of 800-1300°C.

The results are shown in Table 1. Table 1 also shows data on the prototype for comparison.

From the data given in Table 1, it can be seen that the compositions of the claimed composite material based on the aluminosilicate binder were obtained in the entire range of the declared values of the content of the components.

Table 2 shows the properties obtained in Examples 1-5 composite material based on aluminosilicate binder and prototype for comparison.

As can be seen from Table 2, the claimed composite material (Examples 1-5) has:

- high heat resistance (up to 1000°С);

- high bending strength (180-265 MPa);

- high tensile strength (232-242 MPa), which corresponds to a tensile strength of 560-582 kJ/m ² .

Thus, from the above, we can conclude that the applicant has achieved the objectives and the claimed technical result , exceeding the technical result of the prototype, namely:

- a method has been developed for producing a composite material based on an aluminosilicate binder, including preparation of carbon fabric, preparation of an aluminosilicate binder, impregnation of carbon fabric with a binder, laying out, vacuum forming and curing,

- it is shown that the proposed composite material based on aluminosilicate binder has a high heat resistance, higher values of bending and tensile strength compared to the prototype.

The claimed technical result is achieved by the fact that such a method for obtaining a composite material based on an aluminosilicate binder has been developed, which made it possible to obtain a material with high heat resistance and high physical and mechanical characteristics.

The composition of the composite material based on aluminosilicate binder and prototype

Table 1 The content of components (wt.h.) in the composition of the examples Prototype 1 2 3 4 5 Alkaline sodium silicate solution (dry residue) - 20 - 25 - thirty Alkaline solution of potassium silicate (dry residue) - - 22 - 27 - carbon fiber 38-54 100 100 100 100 100 Aluminosilicate binder composition at the ratio of components:
- metakaolin
- solution of potassium or cesium silicate
- sodium silicate solution
- potassium silicate solution
- ceramic particles 46-62
1
1-5
-
-
0.1-1 90
1
-
1.2
-
- 95
1
-
-
1.2
- 100
1
-
1.1
-
- 105
1
-
-
1.1
- 110
1
-
1
-
-

Properties of a composite material based on an aluminosilicate binder and a prototype

table 2 Characteristic Prototype Properties by Example 1 2 3 4 5 Operating temperature, °С 1000 1000 1000 1000 1000 1000 Bending strength, MPa 160-260 180 183 187 190 265 Breaking work, kJm ^-2 40-55 - - - - - Tensile strength, MPa - 242 240 237 235 232

Claims (2)

A method for producing a composite material based on an aluminosilicate binder, which consists in cutting carbon fabric, preparing an aluminosilicate binder, impregnating each layer of carbon fabric with an aluminosilicate binder, laying out the impregnated layers, compacting the assembled package under vacuum and curing at a temperature of 50-90 ° C for 20-120 minutes subsequent heat treatment in a vacuum at a temperature of 800-1300°C, characterized in that after cutting, it is pre-treated with an aqueous solution of sodium or potassium silicate and, after impregnation with an aluminosilicate binder and laying out in a mold, it is compacted in a vacuum bag in the following ratio of components, parts by weight: alkaline solution of sodium or potassium silicate 20-30 carbon fiber 100 aluminosilicate binder 90-110