KR20210142422A - Fiber reinforced composite material and manufacturing method thereof - Google Patents

Abstract

One embodiment of the present invention provides a method for manufacturing a fiber-reinforced composite material. The method for manufacturing a fiber-reinforced composite material comprises: a first step (S100) of causing carbon fibers or silicon carbide fibers to be impregnated in a polymer solution and curing the polymer solution to form a fiber molded body; a second step (S200) of increasing the temperature of the fiber molded body from the room temperature to a first temperature in an air atmosphere while performing first carbonization heat treatment; and a third step (S300) of performing second carbonization heat treatment while increasing the temperature of the first carbonized heat-treated fiber molded body from the first temperature to a second temperature in an inert gas atmosphere. According to one embodiment of the present invention, the method for manufacturing a fiber-reinforced composite material can improve the carbonization yield and utilize various polymers.

Description

Fiber reinforced composite material and manufacturing method thereof

The present invention relates to a fiber-reinforced composite material and a method for manufacturing the same.

As technology advances, the need for new materials that go beyond the physical properties of existing materials has emerged, and to achieve high energy efficiency and high reliability, the development of materials for extreme environments that can achieve ultra-lightweight and ultra-high temperature materials became necessary

In accordance with such a necessity, the development of fiber-reinforced composite materials using high-strength carbon fibers or silicon carbide fibers as reinforcing materials in a ceramic or carbon matrix has been made. Materials that have been put into practical use include carbon fiber reinforced carbon (C/C) composites, carbon fiber reinforced silicon carbide (C/SiC) composites, and silicon carbide fiber reinforced silicon carbide fibers. There are reinforced silicon carbide (SiC/SiC) composites.

Carbon fiber reinforced carbon (C/C) composites are made of carbon fiber as a reinforcing material and carbon as a matrix, and can be used for a short time up to 3000 °C in an inert atmosphere.

Carbon fiber reinforced silicon carbide (C/SiC) composites are made of carbon fiber and silicon carbide as a matrix, and can be used for long and short periods up to 2000 °C in an inert and oxidizing atmosphere.

Silicon carbide fiber reinforced silicon carbide (SiC/SiC) composites are made of silicon carbide fibers and silicon carbide as a matrix, and can be used for a long time in an extreme environment with a strong oxidizing atmosphere.

They are widely used in energy, defense, aerospace, environment, automobile, semiconductor and general industries.

However, since the fiber-reinforced composite material has a large number of pores, it is necessary to increase the density while repeating the impregnation and carbonization process. Currently, the carbonization process is carried out at a temperature of 500° C. to 2000° C. in an inert atmosphere, and the carbonization yield varies depending on the type of polymer. In practice, there is a large restriction on the type of polymer that can be used to increase the carbonization yield.

In such a carbonization process, there is a need to increase the carbonization yield to avoid the repetition of the process to promote economy, and to research a technology that can lower the cost by using various polymers using existing facilities.

Republic of Korea Patent Publication No. 10-2015-0066176

The technical problem to be achieved by the present invention is to provide an economical method for manufacturing a fiber-reinforced composite material capable of avoiding repetition of processes and utilizing various polymers, and a fiber-reinforced composite material manufactured thereby.

The technical problems to be achieved by the present invention are not limited to the technical problems mentioned above, and other technical problems not mentioned can be clearly understood by those of ordinary skill in the art to which the present invention belongs from the description below. There will be.

In order to achieve the above technical problem, an embodiment of the present invention provides a method for manufacturing a fiber-reinforced composite material.

In an embodiment of the present invention, the method for manufacturing a fiber-reinforced composite material comprises: a first step of impregnating carbon fibers or silicon carbide fibers in a polymer solution and curing them to form a fiber molded body; a second step of heating the fiber molded body to a first temperature in an air atmosphere while performing a first carbonization heat treatment; and a third step of performing a second carbonization heat treatment while heating the first carbonized heat-treated fiber molded body from the first temperature to a second temperature in an inert gas atmosphere; includes

In an embodiment of the present invention, the carbon fiber may be a polyacrylonitrile (PAN)-based fiber, a rayon-based fiber, or a pitch-based fiber.

In an embodiment of the present invention, the silicon carbide fiber may be manufactured by a precursor method, a powder extrusion method, or a chemical vapor deposition (CVD) method.

In an embodiment of the present invention, the polymer solution may include a thermosetting resin or a thermoplastic resin.

In an embodiment of the present invention, the impregnation is resin transfer molding (RTM), high speed liquid molding (High speed RTM) or high pressure resin transfer molding (HP-RTM), vacuum resin transfer molding (VARTM) or vacuum impregnation (VI) process can be carried out.

In an embodiment of the present invention, the curing may be performed at a temperature of 25 °C to 180 °C.

In an embodiment of the present invention, between the first step and the second step, one or more carbides, nitrides or oxides selected from the group consisting of Si, Zr, Ta, BN (boron nitride) or Al It may further include the step of coating with.

In an embodiment of the present invention, the first temperature may be 300 °C to 600 °C.

In an embodiment of the present invention, the second temperature may be 400 °C to 2000 °C.

In an embodiment of the present invention, the inert gas may include nitrogen (N) or argon (Ar).

In an embodiment of the present invention, after the third step, a process of converting internal carbon into a ceramic by melt-infiltrating silicon at a high temperature (LSI) may be further included.

In an embodiment of the present invention, the fiber-reinforced composite material may be densified by repeating the first to third steps for the second carbonized heat-treated fiber molded body until the target density is achieved.

In order to achieve the above technical problem, another embodiment of the present invention provides a fiber-reinforced composite material manufactured by the above manufacturing method.

According to an embodiment of the present invention, it is possible to provide an economical fiber-reinforced composite material by reducing the repetition of the densification process by improving the carbonization yield in the fiber-reinforced composite material manufacturing process.

In addition, it is not limited to the type of polymer resin that can be used as a matrix, and a variety of polymer resins can be used. can be expanded

It should be understood that the effects of the present invention are not limited to the above-described effects, and include all effects that can be inferred from the configuration of the invention described in the detailed description or claims of the present invention.

1 is a flowchart of a method for manufacturing a fiber-reinforced composite material according to an embodiment of the present invention.
Figure 2 is a TGA graph of the epoxy resin according to the heat treatment atmosphere control, according to an embodiment of the present invention.
3 is a TGA graph of a phenolic resin in a nitrogen atmosphere, according to an embodiment of the present invention.

Hereinafter, the present invention will be described with reference to the accompanying drawings. However, the present invention may be embodied in several different forms, and thus is not limited to the embodiments described herein. And in order to clearly explain the present invention in the drawings, parts irrelevant to the description are omitted, and similar reference numerals are attached to similar parts throughout the specification.

Throughout the specification, when a part is said to be “connected (connected, contacted, coupled)” with another part, it is not only “directly connected” but also “indirectly connected” with another member interposed therebetween. "Including cases where In addition, when a part "includes" a certain component, this means that other components may be further provided without excluding other components unless otherwise stated.

The terms used herein are used only to describe specific embodiments, and are not intended to limit the present invention. The singular expression includes the plural expression unless the context clearly dictates otherwise. In this specification, terms such as "comprises" or "have" are intended to designate that the features, numbers, steps, operations, components, parts, or combinations thereof described in the specification exist, but one or more other features It should be understood that this does not preclude the existence or addition of numbers, steps, operations, components, parts, or combinations thereof.

A method for manufacturing a fiber-reinforced composite material according to an embodiment of the present invention will be described.

1 is a flowchart of a method for manufacturing a fiber-reinforced composite material according to an embodiment of the present invention.

Referring to FIG. 1, the method for manufacturing a fiber-reinforced composite material includes: a first step (S100) of impregnating carbon fibers or silicon carbide fibers in a polymer solution and curing them to form a fiber molded body; a second step (S200) of heating the fiber molded body to a first temperature in an air atmosphere while performing a first carbonization heat treatment; and a third step (S300) of performing a second carbonization heat treatment while heating the first carbonized heat-treated fiber molded body from the first temperature to a second temperature in an inert gas atmosphere; includes

In the first step, carbon fibers or silicon carbide fibers are impregnated in a polymer solution and cured to form a fiber molded body (S100).

The carbon fiber may be a polyacrylonitrile (PAN)-based fiber, a rayon-based fiber, or a pitch-based fiber, for example, a polyacrylonitrile-based fiber, but used in this field It is not particularly limited as long as it becomes

The silicon carbide fiber may be manufactured by a precursor method, a powder extrusion method (carborundum) or a CVD (chemical vapor deposition) method, for example, it may be prepared by a precursor method, but if it is used in this field It is not particularly limited.

As the precursor method, a polycarbosilane (PCS) precursor, which is an organosilicon polymer, may be subjected to melt spinning and thermal decomposition to manufacture SiC fibers.

In the CVD method, a core wire (tungsten wire or carbon fiber) is transferred into a quartz reaction tube at a constant speed through a mercury contact, and an electric current flows through the input core wire to generate self-heating, such as methyl dichlorosilane. It can be manufactured by depositing SiC by adding silane gas and atmospheric gases Ar and H _{2 gas.}

In the powder extrusion method, submicron SiC powder and a sintering aid are mixed with an appropriate polymer to make a melt-spinning compound, extruded, stretched to a desired diameter, and sintered to manufacture SiC fibers.

The form of the carbon fiber or silicon carbide fiber is not particularly limited as long as it is used in this field, but it is preferably a woven fabric loosely woven by spinning, weaving, cotton weaving, etc. for the impregnation process performed in the subsequent process. The carbon fiber or silicon carbide fiber is more preferably manufactured by lamination of a two-dimensional woven fabric, but may be woven in a three-dimensional or four-dimensional manner.

The polymer solution may include a thermosetting resin or a thermoplastic resin.

The thermosetting resin may include epoxy, polyester, vinyl ester, phenol, or polyimide, and is not particularly limited as long as it is used in this field.

The thermoplastic resin may include nylon, thermoplastic polyester (PET, PBT), polyacetal, polyamide, polypropylene, polycarbonate, polyamide-imide, polyether ether ketone, polyphenyl sulfide or polyether imide. , it is not particularly limited as long as it is used in this field.

For example, the polymer solution may include epoxy.

In the conventional carbonization method, when an epoxy resin is used as the polymer solution, it is not easy to use because the carbonization yield is low. This can make use of the existing fiber reinforced plastic (FRP) resin system, which can lower the manufacturing cost and expand the use of low-pollution polymers.

In addition, the polymer solution may contain an additive or a solvent.

The additive may be a silicon powder, and the final product may be manufactured more densely by reacting primarily to form silicon carbide particles in the molded body.

The impregnation is resin transfer molding (RTM), high speed liquid molding (High speed RTM) or high pressure resin transfer molding (High pressure RTM, HP-RTM), vacuum assisted resin transfer molding (VARTM) Alternatively, it may be performed by a vacuum impregnation (VI) process, but is not limited thereto. For example, the impregnation may be performed by an RTM process.

The curing may be performed at a temperature of 25° C. to 180° C., but is not limited thereto. For example, the curing may be performed at 120°C. When the curing step is performed, the effect of fixing the shape of the impregnated fiber molded body appears.

In addition, the curing may be performed by a press process (press autoclave) process, but is not limited thereto.

Between the first step of forming the fiber molded body and the second step of performing the first carbonization heat treatment, the fiber molded body is formed of Si (silicon), Zr (zirconium), Ta (tantalum), BN (boron nitride, boron nitride). Alternatively, the method may further include coating with one or more carbides, nitrides or oxides selected from the group consisting of Al (aluminum).

The fiber molded body may be coated with one or more carbides, nitrides or oxides selected from the group consisting of Si, Zr, Ta, BN or Al, but is not limited thereto. For example, it may be coated one or more times using pyrolytic carbon (PyC) and silicon carbide. Since carbon fibers can be oxidized when exposed to high temperatures in the presence of oxygen, the coating can serve to inhibit oxidation.

In the second step, a first carbonization heat treatment is performed while the temperature of the fiber molded body is raised to a first temperature in an air atmosphere (S200).

The first temperature may be 300 °C to 600 °C.

The air contains oxygen, and the oxygen concentration may be at or above atmospheric pressure. For example, the concentration of oxygen may be about 21% by volume based on the total atmospheric volume.

For example, the fiber molded body may be first carbonized by heating while raising the temperature from room temperature to 500° C. in an air atmosphere.

The first carbonization yield obtained by the first carbonization heat treatment may be, for example, 50%.

In the third step, the second carbonization heat treatment is performed while the temperature of the first carbonized heat-treated fiber molded body is raised from the first temperature to the second temperature in an inert gas atmosphere (S300).

The second temperature may be 400 °C to 2000 °C.

The inert gas may include nitrogen (N) or argon (Ar).

For example, by heating the first carbonized heat-treated fiber molded body while raising the temperature from 500 °C to 1000 °C in a nitrogen atmosphere, the second carbonization can be achieved.

The second carbonization yield obtained by the second carbonization heat treatment may be, for example, 19%.

The second temperature may be higher than the first temperature, and may be a process of carbonizing while continuously increasing the temperature.

At the first temperature, the carbonization yield is higher in an air atmosphere than in a nitrogen atmosphere, and at the second temperature, the carbonization yield is higher in a nitrogen atmosphere than in an air atmosphere. Therefore, it is possible to reduce the process of repeating the above steps in order to increase the carbonization yield of the polymer while appropriately controlling the gas atmosphere and temperature, thereby densifying the polymer.

After the second carbonization heat treatment, a process of converting internal carbon into a ceramic by performing liquid silicon infiltration (LSI) into silicon at a high temperature may be further included.

The LSI method uses a slurry made of carbon fiber or silicon carbide fiber or a carbon source of a fiber fabric or a slurry made of a carbon source/silicon carbide powder to form a matrix phase to prepare a prepreg and laminate it to form a molded body. It is a method of forming a silicon carbide matrix phase by infiltrating molten Si after manufacturing.

By the LSI process, the internal carbon of the fiber molded body subjected to the second carbonization heat treatment is converted to SiC, so that the fire resistance or oxidation resistance is increased C/SiC (SiC is used as a matrix in carbon fiber reinforcement) or SiC/SiC (silicon carbide) A composite material can be formed (with SiC as a matrix in the fiber reinforcement).

The carbon-to-ceramic conversion process is not limited to LSI, and may be performed by a Chemical Vapor Infiltration (CVI) or Polymer Infiltration and Pyrolysis (PIP) process.

Until the target density is achieved, the fiber-reinforced composite material can be densified by repeating the first to third steps for the second carbonized heat-treated fiber molded body until the target density is achieved. have.

For example, the first step of re-impregnating and curing the second carbonized heat treatment-treated fiber molded body that has undergone the first to third steps in a polymer solution, the second step of performing the first carbonization heat treatment, and the second step of performing a second carbonization heat treatment Step 3 may be repeated again to manufacture a fiber-reinforced composite material.

By filling the pores of the fiber-reinforced composite material with a carbon matrix by the densification process, mechanical properties can be improved.

The present invention provides a method for economically manufacturing a fiber-reinforced composite material by increasing the carbonization yield to reduce the number of densification processes.

A fiber-reinforced composite material manufactured by the above manufacturing method (S100 to S300) according to another embodiment of the present invention will be described.

The fiber-reinforced composite material of the present invention is a fiber molded article formed by impregnating carbon fiber or silicon carbide fiber in a polymer solution and curing it, while raising the temperature to a first temperature in an air atmosphere, a first carbonization heat treatment, and then in an inert gas atmosphere By manufacturing including the step of heat-treating the second carbonization while raising the temperature from the first temperature to the second temperature, it is possible to provide a fiber-reinforced composite material with an improved carbonization yield.

By improving the carbonization yield of the fiber-reinforced composite material, it is possible to reduce the repetition of the densification process, which is economical, and it is possible to utilize various polymers that were not previously available due to the low carbonization yield.

Preparation Example 1

The carbon fiber was impregnated in a solution containing an epoxy resin and cured to form a fiber molded body. The fiber molded body was heated from room temperature to 400° C. in an air atmosphere, and then carbonized by heating from 400° C. to 1000° C. in a nitrogen atmosphere to prepare a fiber-reinforced composite material.

Preparation Example 2

The carbon fiber was impregnated in a solution containing an epoxy resin and cured to form a fiber molded body. The fiber molded body was heated from room temperature to 500° C. in an air atmosphere, and then carbonized by heating from 500° C. to 1000° C. in a nitrogen atmosphere to prepare a fiber-reinforced composite material.

Comparative Example 1

A fiber-reinforced composite material was prepared by carbonizing an epoxy resin by heating it at room temperature to 1000°C in an air atmosphere.

Comparative Example 2

A fiber-reinforced composite material was prepared by carbonizing the epoxy resin by heating it at room temperature to 1000°C in a nitrogen atmosphere.

Experimental example

2 is a TGA graph of the epoxy resin according to the heat treatment atmosphere control, according to an embodiment of the present invention.

Referring to FIG. 2, TGA curves of Preparation Examples 1 and 2 and Comparative Examples 1 and 2 can be confirmed. In Comparative Example 1, carbon was not completely oxidized at about 650°C, and in Comparative Example 2, the carbon remaining when heating to 1000°C was 1% to 2% or less, whereas Preparation Examples 1 and 2 were left when heating to 1000°C. It can be seen that carbon is about 17% and 19%, respectively.

3 is a TGA graph of a phenol resin in a nitrogen atmosphere, according to an embodiment of the present invention.

Referring to FIG. 3 , it can be seen that the residual carbon amount is about 60% when the phenol resin is heated to 1000° C. in a nitrogen atmosphere. Currently, phenolic resin is the most preferred polymer for composite materials requiring a carbon matrix.

According to an embodiment of the present invention, it is possible to provide an economical fiber-reinforced composite material by reducing the repetition of the densification process by improving the carbonization yield in the fiber-reinforced composite material manufacturing process.

In addition, it is not limited to the type of polymer resin that can be used as a matrix, and various polymer resins can be used, so that the existing FRP resin system can be utilized to lower the manufacturing cost, and the possibility of using low-pollution polymers can be expanded

The above description of the present invention is for illustration, and those of ordinary skill in the art to which the present invention pertains can understand that it can be easily modified into other specific forms without changing the technical spirit or essential features of the present invention. will be. Therefore, it should be understood that the embodiments described above are illustrative in all respects and not restrictive. For example, each component described as a single type may be implemented in a dispersed form, and likewise components described as distributed may be implemented in a combined form.

The scope of the present invention is indicated by the following claims, and all changes or modifications derived from the meaning and scope of the claims and their equivalents should be construed as being included in the scope of the present invention.

Claims (13)

A first step of impregnating carbon fibers or silicon carbide fibers in a polymer solution and curing to form a fiber molded body;
a second step of heating the fiber molded body to a first temperature in an air atmosphere while performing a first carbonization heat treatment; and
a third step of heating the first carbonized heat-treated fiber molded body from the first temperature to a second temperature in an inert gas atmosphere while performing a second carbonization heat treatment; Fiber-reinforced composite material manufacturing method comprising a. The method of claim 1, wherein in the first step,
The carbon fiber is a fiber-reinforced composite material manufacturing method, characterized in that the polyacrylonitrile (PAN)-based fiber, rayon-based fiber or pitch-based fiber. The method of claim 1, wherein in the first step,
The silicon carbide fiber is a fiber-reinforced composite material manufacturing method, characterized in that produced by a precursor method, powder extrusion method or chemical vapor deposition (CVD) method. The method of claim 1, wherein in the first step,
The polymer solution is a fiber-reinforced composite material manufacturing method, characterized in that it contains a thermosetting resin or a thermoplastic resin. The method of claim 1, wherein in the first step,
The impregnation is characterized in that it is performed by a resin transfer molding (RTM), high speed liquid molding (High speed RTM) or high pressure resin transfer molding (HP-RTM), vacuum resin transfer molding (VARTM) or vacuum impregnation (VI) process. A method for manufacturing a fiber-reinforced composite material. The method of claim 1, wherein in the first step,
The curing is a fiber-reinforced composite material manufacturing method, characterized in that carried out at a temperature of 25 ℃ to 180 ℃. According to claim 1,
Between the first step and the second step,
Fiber-reinforced composite material manufacturing method, characterized in that it further comprises the step of coating the fibrous body with one or more carbides, nitrides or oxides selected from the group consisting of Si, Zr, Ta, BN (boron nitride) or Al. According to claim 1, In the second step,
The first temperature is a fiber-reinforced composite material manufacturing method, characterized in that 300 ℃ to 600 ℃. According to claim 1, In the third step,
The second temperature is a fiber-reinforced composite material manufacturing method, characterized in that 400 ℃ to 2000 ℃. According to claim 1, In the third step,
The inert gas is a fiber-reinforced composite material manufacturing method, characterized in that it contains nitrogen (N) or argon (Ar). According to claim 1,
Fiber-reinforced composite material manufacturing method, characterized in that after the third step, further comprising the step of converting the internal carbon into ceramic by melt infiltration (LSI) silicon at a high temperature. According to claim 1,
Until the target density is achieved, the fiber-reinforced composite material manufacturing method, characterized in that the fiber-reinforced composite material is densified by repeating the first to third steps for the second carbonized heat-treated fiber molded body. A fiber-reinforced composite material manufactured by the method of claim 1 .

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