RU2352543C1 - Composite material and product made of it - Google Patents

Abstract

FIELD: construction.

SUBSTANCE: invention may be used in production of thermally loaded units and parts of aerospace equipment, in surface power engineering, oil-, gas pumping, transport systems and new fields of general and specialised machine building that operate under temperatures of up to 1550°C. Suggested composite material contains carbon fibers and matrix including the following components, wt %: Si 20-35, C 25-40, SiB₄ 0.1-1.5, SiO₂ 1-5, SiC - the rest.

EFFECT: increased heat resistance of products.

2 cl, 2 tbl

Description

The invention relates to ceramic composite materials and can be used in the manufacture of heat-loaded units and parts of aerospace technology, in ground energy, oil and gas, transport systems and new areas of general and special engineering, operating at temperatures up to 1550 ° C.

Known composite material, which consists of a reinforcing inorganic fiber and a matrix comprising 40-95 wt.% SiC phase and 5-60 wt.% Oxide phase. The oxide phase may be ZrSiO ₄ or a glass-ceramic phase of the compositions BaO-MgO-Al ₂ O ₃ -SiO ₂ or SrO-Al ₂ O ₃ -SiO ₂ . The average elemental composition of the SiC phase is, wt.%: 30-80 Si, 15-69 C, 0.005-20 O or 30-80 Si, 10-65 C, 0.005-25 O (US patent No. 6331496).

The disadvantage of this composite material is low heat resistance in air when exposed to a temperature of 1550 ° C for a long time.

A known composite material containing carbon fibers and a matrix consisting of silicon carbide, boron and pyrocarbon distributed in its volume and on the surface of the material in the following ratio of components in the matrix, wt.%:

SiC 10-50 AT 0.5-1.2 C (pyrocarbon)  rest

(RF patent No. 2203218).

Composite material can be used in the manufacture of products, such as o-rings, operating in aggressive environments and in air at a temperature of 900 ° C for 1 hour.

The disadvantage of the material and its products is insufficient heat resistance (high loss of mass) at a temperature of 1500 ° C.

Known composite material reinforced with SiC fibers with a ceramic matrix containing SiC in the form of crystals in an amount of up to 70 wt.% And SiC granules from a synthetic composite nanopowder (French application No. 2849022).

A disadvantage of the known composite material and products made of it is the low heat resistance in air when exposed to temperatures above 1200 ° C due to the formation of a protective amorphous SiO ₂ film and bubbles of gaseous oxidation products, resulting in mass loss over time.

To improve the properties of SiC _ox / SiC composite materials, interphase protective coatings based on boron-containing boron nitride compounds BN or В ₄ С on continuous SiC fibers were obtained, which serve not only to deflect matrix cracks, but also to increase oxidative stability, preventing fiber degradation.

Multilayer composite materials are obtained by controlled deposition of SiC, B _x C, Si-BC and Si-BN layers. Layered materials based on composite materials SiC-SiC with protective interfacial boron-containing coatings B ₄ C, BN, obtained in the ternary system Si-BC, Si-BN, have the ability to self-heal the matrix. The oxidation stability of a composite material of the type SiC _vol / BN / SiC with an interfacial coating of BN at moderate temperatures is improved compared to a composite material of the type SiC _vol / C / SiC not containing boron compounds. However, these composite materials do not retain oxidation stability at temperatures above 1500 ° C.

The closest analogue taken for the prototype is a composite material containing carbon fibers and a matrix including silicon, carbon, silicon tetraboride, silicon carbide in the following ratio of matrix components, wt.%:

Si 20-35 FROM 25-40 SiB ₄ 2-6 SiC rest

and an article made from it (RF patent No. 2297992).

The disadvantage of the composite material of the prototype and products from it is insufficient heat resistance (high loss of mass) at an operating temperature of 1550 ° C.

The technical task of the invention is to increase the heat resistance of the composite material and products made from it at an operating temperature of 1550 ° C for a long time.

The stated technical problem is achieved by the fact that the proposed composite material containing carbon fibers and a matrix including silicon, carbon, silicon tetraboride, silicon carbide, while the matrix additionally contains silicon dioxide in the following ratio of matrix components, wt.%:

Si 20-35 FROM 25-40 SiB ₄ 0.1-1.5 SiO ₂ 1-5 SiC rest

and an article made from it.

The authors found that the introduction of silicon dioxide into the matrix at the stated ratios and contents of the components leads to the formation of refractory high-silica glass when exposed to oxygen, which provides sealing of possible microdefects of the matrix in the form of microcracks, pores, etc., and thereby increases the heat resistance of the composite material and products from it when exposed to an operating temperature of 1550 ° C for a long time.

Examples of implementation

To obtain a composite material, the compositions of the proposed material (1-3) and the prototype material (4) were prepared, the ratio of components in which are shown in table 1.

Dispersed particles of a matrix of silicon carbide, silicon, carbon (SiC, Si, C) were mixed with particles of silicon tetraboride (SiB ₄ ) and carbon fibers in polyethylene drums. The carbon fiber UKNP-5000 was used as the carbon fiber material.

The resulting mixture was poured into the mold and pressed at temperatures of 120-150 ° C. Then the billet was subjected to high temperature heat treatment in a vacuum oven at a temperature of 1500 ° C.

After heat treatment in vacuo, the samples were impregnated with a silica sol of SiO ₂ with intermediate drying in air.

Analysis of the obtained results indicates that the heat resistance of the proposed composite material and products made from it is higher compared to the prototype material, which loses part of the carbon of the reinforcing filler during processing, which leads to its destruction after testing at 1550 ° C for 100 hours (see table 2).

The weight gain of the samples (1.8-4.3 wt.%) Associated with the formation of high-silica glass-bonded during heating in air at a temperature of 1550 ° C, confirms the protective effect of the matrix of the proposed compositions of the composite material for a long time (up to 500 hours), preventing the diffusion of air oxygen deep into the sample and preventing the oxidation of carbon fiber reinforcement.

Thus, the use of the proposed composite material in heavily loaded components and parts of aerospace engineering, ground-based energy and oil and gas pumping systems can increase their heat resistance at a working temperature of 1550 ° C for a long time and, accordingly, increase the reliability and resource of products.

Table 1 Name of components The composition according to examples, wt.% one 2 3 4 prototype Matrix:
Si
FROM
SiB ₄
SiO ₂
SiC 27
25
1,5
5
rest 35
32
0.8
3
rest twenty
40
0.1
one
rest 28
32
four
-
rest

table 2 The parameters of the test samples for heat resistance Change in mass of samples after heat resistance tests, wt.% Temperature ° C Time h one 2 3 4 prototype 1550 one hundred 1.8 3,1 2,4 - 5.8 sample destruction 200 2.7 3.6 2,8 sample failure 300 3,1 3.9 3.3 - "- 400 3.3 4.1 3.6 - "- 500 3.4 4.3 3.8 - "-

Claims (2)

1. A composite material containing carbon fibers and a matrix including silicon, carbon, silicon tetraboride, silicon carbide, characterized in that the matrix additionally contains silicon dioxide in the following ratio of matrix components, wt.%:
Si 20-35 FROM 25-40 SiB ₄ 0.1-1.5 SiO ₂ 1-5 SiC rest 2. A product of composite material, characterized in that it is made of material according to claim 1.