RU2249572C1 - Method for production of composite material - Google Patents

Abstract

FIELD: inorganic fibrous building materials for spacecraft and machine engineering industry.

SUBSTANCE: claimed method includes impregnation of article from ceramic fiber with inorganic sol, forming and dehydration by its deformation and subsequent drying, wherein inorganic sol is additionally contains 1-30 % of fine dispersed MgO powder. After drying article is subjected to heat treatment at 150-350°C for 1-3 h. Obtained material has density of 0.3-1.7 u/cm³, bending strength of 10-110 MPa, thermal conductivity of 0.25-0.8 V/m*K, heat resistance increased by 3-5 times at operating temperatures of 1000-1750°C.

EFFECT: composite material with increased heat resistance without losses in physical and mechanical properties.

2 cl, 2 tbl, 1 ex

Description

The invention relates to the field of inorganic fibrous materials for structural purposes for products of the aerospace and engineering industries.

A known method of producing a heat-insulating material, according to which refractory fibers are dispersed in a colloidal solution of aluminosilicon, are squeezed by vacuum from an excess of a bonding agent, the material is formed into rectangular plates or products. The molded products are dried at 150-200 ° C to a residual moisture content of not more than 1% (Av. St. USSR 1564147).

A known method of producing heat-resistant and heat-resistant molded material from ceramic fiber materials, which consists of the following operations: mixing the components for 20 minutes, molding at a pressure on the press of 2 bar, vacuum treatment, drying at 110-180 ° C (German Patent No. 3444397) .

A disadvantage of the known methods is the low temperature resistance of the materials obtained up to 1300 ° C.

The closest analogue taken as a prototype is a method for producing a composite material, including impregnation of a ceramic fiber preform with inorganic sol, molding and dewatering the preform by deformation followed by drying, while deformation is carried out to reduce the volume by 30-70% (RF Patent No. 2031889 )

The disadvantage of the prototype method is the lack of heat resistance of the material at operating temperatures.

The technical task of this invention is the creation of a composite material with increased heat resistance at operating temperatures of 1000-1750 ° C while maintaining the physical and mechanical properties of the material.

The stated technical problem is achieved by the fact that the proposed method for producing a composite material, including impregnating a ceramic fiber preform with an inorganic sol, molding and dewatering the preform by deforming it, followed by drying, in which the inorganic sol additionally contains fine MgO powder, and after drying the preform is subjected to heat treatment. The content of fine MgO powder in the ash is 1-10 wt.%, Heat treatment is carried out at 150-350 ° C for 1-3 hours.

The authors found that the additional introduction of finely dispersed MgO powder into the sol and heat treatment of the preform at 150-350 ° C led to an increase in the heat resistance of the composite material at operating temperatures of 1000-1750 ° C for 10 hours. The increase in heat resistance is due to the formation of phase systems of solid solutions of spinel MgOAl ₂ O ₃ , γ-Al ₂ O ₃ and a solid solution of MgO in ZrO ₂ .

Examples of implementation

Example 1

A blank of ceramic fibers of the Al ₂ O ₃ —SiO _{2 system was} impregnated with an inorganic sol into which finely dispersed MgO powder 1 wt.% Was previously introduced, then the blank was molded and dehydrated by deformation. The obtained preforms were dried in an oven at a temperature of 50 ° C for 3 hours and heat treated in an electric furnace at a temperature of 150 ° C for 3 hours. The resulting composite material was tested for heat resistance and physical and mechanical properties.

A method of obtaining a composite material of Al ₂ O ₃ / Zr O ₂ -MgO, SiC / Zr SiO ₄ -MgO systems shown in table 1 (examples 2,3) was carried out analogously to example 1.

The compositions of the proposed composite material and the method for its preparation are shown in tables 1, 2.

Table 1 Example No. Type of fiber The composition of the sol phase Drying mode T °, h Heat treatment mode, T °, h 1 Offers Al ₂ O ₃ -SiO ₂ Al₂O₃
MgO-1 wt.% 50 ° -3h 150 ° -3h 2 Offers SiC ZrSiO₄
MgO-5 wt.% 65 ° -2h 250 ° -2h 3 Offers Al ₂ O ₃ -50 Zro₂
MgO-10 wt.% 80 ° -1h 350 ° -1h. Prototype 4 Al ₂ O ₃ -SiO ₂ ZrO ₂ 12 -

table 2 No measure Composite Material Properties The presence of defects Density,
g / cm ³ Bending Strength, MPa Thermal conductivity, V / (m · K) Test temperature ° C 20-1000-20 20-1500-20 20-1750-20 Heat resistance - number of cycles Suggestion 1
KM 2
3 1,2
0.6
1.7 twenty
110
65 0.3
0.8
0.25 10
10
10 10
10
10 10
10
10 No defects, samples removed from testing without destruction Prototype 4 0.51-1.56 16-102 0.3 2 2 1 Samples collapsed, removed from testing

From table 2 it is seen that the heat resistance of the proposed composite materials Al ₂ About ₃ -SiO ₂ / Al ₂ About _3- MgO, Al ₂ About ₃ / Zr O ₂ -MgO, SiO ₂ / SiO ₂ -MgO, SiC / Zr SiO ₄ - MgO at test temperatures, ° C: 20-1000-20, 20-1500-20, 20-1750-20 5-10 times higher while maintaining physical and mechanical properties, respectively, of the composite material of the prototype Al ₂ O ₃ -SiO ₂ / ZrO ₂ .

The proposed method allows to obtain a composite material with increased heat resistance, ensuring reliability and increasing the service life of products at temperatures of 1000-1750 ° C.

Claims (2)

1. A method of obtaining a composite material, comprising impregnating a ceramic fiber preform with an inorganic sol, molding and dewatering the preform by deforming it, followed by drying, characterized in that the inorganic sol additionally contains 1-10 wt.% Fine MgO powder, and after drying, the preform is subjected heat treatment. 2. The method of producing a composite material according to claim 1, characterized in that the heat treatment is carried out at 150-350 ° C for 1-3 hours