KR101466910B1 - Fiber reinforced ceramic composite comprising oxidation barrier layer and manufacturing method - Google Patents

Abstract

The present invention relates to a method for producing a fiber-reinforced ceramic composite material and a fiber-reinforced ceramic composite material produced by the same. The method comprises the steps of: producing a composite material by laminating a carbon fiber and by laminating an oxidation preventing layer on the surface thereof; dipping the composite material in a polymer resin; carbonizing the dipped composite material; and dissolving metal silicon in order to permeate into the carbonized composite material. The thickness of the oxidation preventing layer is thinner than the thickness of an inner carbon fiber layer.

Description

FIELD OF THE INVENTION [0001] The present invention relates to a fiber reinforced ceramic composite material,

The present invention relates to a fiber-reinforced composite material comprising an antioxidant layer and a method of manufacturing the same.

Ceramic composite materials used for power generation facilities, aircraft, nuclear power industry, energy industry, and cook top radiating heaters have excellent thermal and structural characteristics. Such a composite material is produced by reinforcing a fiber to improve the characteristics of a matrix. Fiber-reinforced ceramic composite materials are materials made of polymeric resin matrix and reinforcing fibers, and are lightweight and have the advantage of excellent physical properties. As the base, natural resins or synthetic polymers are used. As the reinforcing fibers, inorganic fibers such as organic fibers or carbon fibers are used.

Particularly, as a reinforcing fiber, materials such as carbon (C) and silicon carbide (SiC) are often used. These materials react with oxygen when they are exposed at a high temperature for a long time and an oxide layer is formed, There is a problem, and an antioxidant layer is laminated in order to suppress oxidation. In order to improve the fracture toughness of the fiber-reinforced ceramic composite material, a material having a mechanical characteristic that is relatively weaker than that of the fiber may be laminated in order to induce a change in the path of the crack along the fiber interface. By such lamination, it is possible to improve the oxidation resistance even at a high temperature, to control the characteristics of the composite material, and to have the acid resistance characteristic and the excellent mechanical characteristic. That is, in the case of a conventional fiber-reinforced ceramic composite material, when exposed to a high-temperature oxidizing atmosphere of 500 ° C or higher, carbon fiber reacts with oxygen and is vaporized by carbon dioxide and deteriorates. In order to prevent such a phenomenon, oxidation / chemical chemical lamination is performed on the surface, however, since a separate lamination apparatus and a complicated chemical process must be performed, the manufacturing cost is increased. Further, the formed laminated layer is weak against external scratches and impacts, and peeling phenomenon occurs between the laminated layer and the composite material due to thermal fatigue repeated at a high temperature and a normal temperature, so that oxidation resistance is lost.

The present invention relates to a fiber reinforced ceramic composite material comprising an antioxidant layer on the surface of a carbon fiber so as not to cause damage to the internal composite material even at a high temperature or corrosive environment of 500 ° C or higher, And a method thereof.

In order to achieve the above object,

(1) preparing a composite material by laminating an antioxidant layer on the surface after laminating carbon fibers;

(2) impregnating the composite material with the polymer resin;

(3) carbonizing the impregnated composite material; And

(4) melting metallic silicon and infiltrating the inside of the carbonized composite material,

Wherein the thickness of the antioxidant layer in the step (1) is thinner than the thickness of the carbon fiber layer.

The present invention also provides a fiber-reinforced ceramic composite material produced by the above-described method.

The fiber-reinforced ceramic composite material including the antioxidant layer on the surface of the carbon fiber of the present invention can prevent the internal composite material from being damaged when exposed to a high temperature or corrosive environment of 500 ° C or more. Further, by manufacturing the antioxidant layer at an initial stage of manufacturing, the manufacturing cost can be reduced as compared with the conventional lamination technique, and the peeling phenomenon due to thermal fatigue does not occur.

FIG. 1 is a schematic view showing a fiber-reinforced ceramic composite material comprising an antioxidant layer on a surface thereof produced by the production method of the present invention.
Fig. 2 (a) is a fiber-reinforced ceramic composite material before oxidation, Fig. 2 (b) is a fiber-reinforced ceramic composite material of Example 1 after oxidation and Fig. 2 (c) is a photograph of a fiber-reinforced ceramic composite material of Comparative Example 1 after oxidation.
3 is a graph showing the density change of the fiber-reinforced ceramic composite material of Example 1 and Comparative Example 1 according to the oxidation time.
4 is a graph showing pore changes of the fiber-reinforced ceramic composite material of Example 1 and Comparative Example 1 according to the oxidation time.
5 is a graph showing changes in bending strength of the fiber-reinforced ceramic composite material according to Example 1 and Comparative Example 1 according to the oxidation time.

Hereinafter, the present invention will be described in more detail.

The present invention relates to a method of manufacturing a fiber-reinforced ceramic composite material comprising an antioxidant layer on a surface of a carbon fiber, and more particularly, to a method of manufacturing a composite material capable of preventing damage to an internal composite material even when exposed to a high- To a method for manufacturing a fiber-reinforced ceramic composite material.

The method for producing the fiber-reinforced composite material includes

(1) preparing a composite material by laminating an antioxidant layer on the surface after laminating carbon fibers;

(2) impregnating the composite material with the polymer resin;

(3) carbonizing the impregnated composite material; And

(4) melting metallic silicon and infiltrating the inside of the carbonized composite material,

In the step (1), the thickness of the antioxidant layer should be smaller than the thickness of the carbon fiber layer.

The step (1) is a step of laminating the carbon fibers and then laminating an antioxidant layer on the surface thereof to produce a composite material.

The carbon fiber is a fiber having poor oxidation and chemical resistance. The carbon fiber is not particularly limited as long as it is used in the art, and among them, polyacrylonitrile-based fiber, rayon-based fiber or pitch-based fiber can be used. The method for producing the carbon fiber is not particularly limited as long as it is used in the art, but it is preferable that the woven fabric loosely woven by spinning, scouring, cotton, etc. for the polymer impregnation process performed in the step (2). It is more preferable that the carbon fibers are produced by lamination of two-dimensional woven fabrics, but they may be woven in three dimensions or four dimensions.

As the oxidation preventing layer, fibers having excellent oxidation and chemical resistance are used, and silicon carbide is preferably used. When the composite material is produced by laminating the antioxidant layer on the surface of the carbon fiber, the composite material can be protected from deterioration and peeling occurring in a high temperature and corrosive environment of 500 ° C or higher. The thickness of the antioxidant layer should be thinner than the thickness of the inner fiber layer. If the thickness of the antioxidant layer is thicker than the thickness of the internal carbon fiber layer, the fracture caused by the difference in thermal expansion between the inside and outside is likely to be induced on the surface, and cracks that can penetrate the outside oxygen are generated, .

The step (2) is a step of impregnating the composite material with the polymer resin. The polymer resin is at least one polymer resin selected from the group consisting of a phenolic resin and a pitch, and is preferably a phenolic resin.

Examples of the method of impregnating the polymer resin include a method selected from the group consisting of a Vacuum Assisted Resin Transfer Molding (VARTM) method, a Resin Transfer Molding (RTM) method, and a Vacuum Impregnation (VI) It is preferable to carry out the method with one method and the prepreg.

The method of manufacturing a fiber-reinforced ceramic composite material of the present invention preferably further comprises the step of curing the impregnated composite material at 60 to 200 ° C after the step (2). When the curing step is carried out, the effect of fixing the shape of the impregnated composite material occurs.

In the step (3), the impregnated composite material is carbonized, and the organic material of the cured polymer is removed so that only the carbon component is present. The carbonization is preferably performed at a temperature of 600 to 2,200 ° C in a nitrogen or vacuum atmosphere (10 ^-2 torr or more). Further, it is more preferable to raise the temperature to 1,000 ° C or less at 0.05 to 0.2 ° C / min. The carbonization process can be performed by burning the organic material contained in the polymer resin in the temperature range to leave only the carbon component.

In the step (4), the metal silicon is melted and penetrated into the carbonized composite material to produce the fiber reinforced ceramic composite material. The cracks generated inside the carbonized composite material in the step (3) become the passages of molten metal silicon to be infiltrated thereafter. In the step (4), metallic silicon is filled in the outside of the composite material, and the metal silicon is melted by heating in a vacuum atmosphere (10 ^-1 torr or more) at 1,500 to 1,700 ° C to infiltrate the carbon fiber. In this temperature range, the metal silicon is melted without being volatilized and can penetrate smoothly into the composite material.

The present invention provides a fiber-reinforced ceramic composite material produced by the above production method. The fiber-reinforced ceramic composite material includes an antioxidant layer at an initial stage of manufacturing, and can be manufactured at a reduced cost since it is not subjected to an additional apparatus and a complicated chemical process. Further, the composite material can be protected even at a high temperature and corrosive environment of 500 DEG C or more, and no peeling phenomenon between the oxidation preventing layer and the inner carbon fibers is caused.

Hereinafter, the present invention will be described in detail with reference to examples.

However, the following examples are illustrative of the present invention, and the present invention is not limited to the following examples.

Example  1. Fabricated fiber-reinforced ceramic composites containing an antioxidant layer on the surface

Two sheets of silicon carbide, 20 sheets of carbon fiber, and two sheets of silicon carbide were laminated in this order to produce reinforcing fibers, wherein the silicon carbide fibers serve as an antioxidant layer. In order to facilitate the flow of the phenolic resin on the laminated reinforcing fibers, RDM (Resin Distribution Mat) was laminated, and a fill ply was laminated to smooth the surface of the composite material, followed by battling with a vacuum film. Phenolic resin was impregnated into the laminated fiber using vacuum pressure by Vacuum Assisted Resin Transfer Molding (VARTM) method and cured at a temperature of 120 ℃ to prepare fiber reinforced composite material. Then, the fiber-reinforced composite material removed from the mold was carbonized at a temperature of 1000 ° C or higher and in an inert atmosphere to convert it into a fiber-reinforced / carbon composite material. The silicon-silicon reaction was induced by infiltrating the silicon into the fiber-reinforced / carbon composite material in a vacuum atmosphere at 1600 ° C to finally obtain a fiber-reinforced ceramic composite material. The fiber-reinforced ceramic composite material is a carbon fiber / silicon carbide composite material in which the outside is protected by a silicon carbide fiber reinforced / silicon carbide composite material.

Comparative Example  1. Fabricated fiber-reinforced ceramic composite material without oxidation-resistant layer on the surface

A fiber-reinforced ceramic composite material free from an oxidation-preventive layer was prepared in the same manner as in Example 1 except for the step of laminating silicon carbide.

Experimental Example  One. Example  1 and Comparative Example  1 Physical Properties of Fiber Reinforced Ceramic Composites after Oxidation

The surface of the fiber-reinforced ceramic composite material prepared in Example 1 and Comparative Example 1 was exposed to an oxidizing atmosphere at 1000 캜. In the fiber-reinforced ceramic composite material of Example 1 including the antioxidant layer, the inner carbon fibers remained intact by the oxidation-preventive layer, but the fiber-reinforced ceramic composite material of Comparative Example 1 not containing the oxidation- And all of them were left as large pores.

Density, pore and bending strength were measured with the oxidation time. The fiber-reinforced ceramic composite material of Example 1 including the antioxidant layer had a very small reduction in density and did not significantly increase porosity. On the other hand, the fiber-reinforced ceramic composite material of Comparative Example 1, which does not include the oxidation-preventive layer, showed a large change in density and porosity. The flexural strength of the fiber-reinforced ceramic composite materials of Example 1 and Comparative Example 1 was greatly reduced, but the flexural strength of the fiber-reinforced ceramic composite material of Comparative Example 1, which did not include the oxidation preventing layer, Layer of the fiber-reinforced ceramic composite material of Example 1 maintained a strength of about 60 MPa.

Claims (7)

(1) preparing a composite material by laminating an antioxidant layer on the surface after laminating carbon fibers;
(2) impregnating the composite material with the polymer resin;
(3) carbonizing the impregnated composite material; And
(4) melting metallic silicon and infiltrating the inside of the carbonized composite material,
Wherein the thickness of the antioxidant layer in the step (1) is smaller than the thickness of the carbon fiber layer in the step (1), so that peeling due to thermal fatigue does not occur. The method for producing a fiber-reinforced ceramic composite material according to claim 1, wherein the polymer resin in step (2) is at least one polymer resin selected from the group consisting of a phenolic resin and a pitch. The method for impregnating a polymeric resin according to claim 1, wherein the polymer resin is impregnated in the step (2), comprises a vacuum resin transfer molding (VARTM) method, a resin transfer molding (RTM) Vacuum Impregnation) method. The method of manufacturing a fiber-reinforced ceramic composite material according to claim 1, [4] The method of claim 1, further comprising the step of curing the impregnated composite material at a temperature of 60 to 200 [deg.] C after the step (2). [4] The method of claim 1, wherein the carbonization in the step (3) is performed at a temperature of 600 to 2,200 ° C in a nitrogen or vacuum atmosphere. [4] The method of claim 1, wherein the step (4) comprises melting the metal silicon at a temperature of 1,500 to 1,700 DEG C in a vacuum atmosphere, and infiltrating the metal silicon into the composite material. A fiber-reinforced ceramic composite material produced by the method of claim 1.

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