KR20210122413A - Manufacturing method carbon fiber reinforced metal composites and carbon fiber reinforced aluminum composites manufactured thereby - Google Patents

Abstract

The present invention relates to a manufacturing method of a carbon fiber-reinforced metal composite and a carbon fiber-reinforced aluminum composite manufactured thereby. The manufacturing method of a carbon fiber-reinforced metal composite in accordance with the present invention comprises the following steps of: coating silicon oxide (SiO_2) on a carbon fiber; attaching magnesium (Mg) powder to the coated carbon fiber; and mixing metal powder for a composite. Accordingly, the metal melting temperature applied to conventional hybridization of a carbon fiber and a metal can be reduced in manufacturing by using high-temperature local heat generated by a thermite reaction between the silicon oxide (SiO_2) and magnesium (Mg) powder and low wet-ability of a metal to a carbon fiber can be enhanced to produce a carbon fiber-reinforced aluminum composite having excellent interfacial bonding between the two materials.

Description

Manufacturing method of carbon fiber reinforced metal composite and carbon fiber reinforced aluminum composite manufactured therefrom

The present invention relates to a method for manufacturing a carbon fiber-reinforced metal composite and a carbon fiber-reinforced aluminum composite prepared therefrom, and more particularly, to a carbon fiber _{coated with silicon oxide (SiO 2} ), and magnesium (Mg) to the coated carbon fiber. ) After attaching the powder, it is prepared by mixing the metal powder for the composite material, but _{using the high-temperature local heat generated by the thermite reaction of the silicon oxide (SiO 2} ) and magnesium (Mg) powder is used for conventional carbon fiber and intermetallic composite. Manufacturing method of carbon fiber-reinforced metal composite, which is manufactured by lowering the applied molten metalization temperature and improved interfacial bonding strength between two materials by improving the low wet-ability of the metal to carbon fiber, and carbon fiber-reinforced aluminum manufactured therefrom It's about composites.

For the purpose of strengthening mechanical strength or improving thermal conductivity, various carbon-metal composite materials obtained by compounding carbon fibers and a matrix metal have been proposed.

Conventional composite of carbon fiber and matrix metal is a method of impregnating a molten metal in a porous preform formed of carbon fiber (melt impregnation method), but in the case of this method, when the temperature of the molten metal is high, the molten metal is carbon There are problems in that carbon fibers are easily aggregated due to poor wettability with fibers, a large amount of pores and impurities may be introduced during the stirring process, and undesirable products are generated at the interface between aluminum and carbon fibers. For example, when molten aluminum reacts with carbon fiber, deliquescent aluminum carbide Al ₄ C ₃ is produced.

As a representative carbon-metal composite material, carbon fiber-reinforced aluminum composite, a composite material in which carbon fibers are uniformly dispersed as a reinforcing material in an aluminum matrix metal as a metal matrix, is lightweight, high in strength and rigidity, and has excellent electrical and thermal conductivity, It has advantages of low coefficient of thermal expansion and excellent wear resistance and high temperature characteristics. Carbon fiber-reinforced aluminum composites with these advantages are of interest in a wide range of industries, such as structural materials for transport devices such as automobiles and aircraft, materials for machinery industry, materials for civil engineering and construction, materials for energy, materials for leisure and sports, and electrical and electronic materials. have.

The thermal, electrical and mechanical properties of the carbon fiber reinforced aluminum composite material can be influenced by the uniform dispersion technology of the carbon fiber reinforcement in the aluminum matrix metal, the bonding strength improvement technology at the aluminum and carbon fiber interface, and the suppression technology of internal defects of the composite material. have. In addition, the characteristics may be influenced by the type, size, shape, volume fraction, and manufacturing process of the added carbon fiber.

The manufacturing process technology of carbon fiber reinforced aluminum composite material can be broadly classified into a solid-phase manufacturing process of manufacturing aluminum, which is a base material, in a solid state, and a liquid-phase manufacturing process of manufacturing it in a liquid state.

The solid-state manufacturing process is a method of manufacturing in a solid state without melting the aluminum base metal, and may include, for example, a powder metallurgy process, a diffusion bonding process, a spray molding process, and the like. The solid-state manufacturing process has advantages in that the mechanical properties of the composite are superior to that of the liquid-phase manufacturing process, but has disadvantages in that it is expensive to manufacture and difficult to mass-produce.

The liquid phase manufacturing process is a method using molten aluminum as a raw material, and may include, typically, stir casting, mixing casting, squeeze casting, infiltration, and the like. Among the above-described liquid manufacturing processes, stir casting is evaluated as suitable for mass production because the process itself is very simple and can be molded into a thread shape.

However, due to the characteristics of the liquid phase manufacturing process, the difference in density between aluminum and carbon fibers is large, and the wettability of carbon by molten aluminum is poor, so carbon fibers are easily agglomerated, a large amount of pores and impurities can be introduced during the stirring process, and the interface between aluminum and carbon fibers has been pointed out that the weak Al ₄ C ₃ phase is easily formed.

Accordingly, Patent Document 1 is a method for mass production for the commercialization of carbon fiber-reinforced aluminum composites, wherein stir casting is applied, but the contact angle of carbon to aluminum by inputting carbon fibers while supplying current to liquid aluminum. Since the carbon fiber can be spontaneously dispersed by reducing the amount of carbon in the molten aluminum, it is possible to obtain a composite material in which carbon fibers are uniformly distributed inside the aluminum matrix metal, and aluminum carbide ( Al ₄ C ₃ ) Since the phase is not formed, a carbon fiber reinforced aluminum composite material manufacturing method for improving the mechanical properties of the composite material is disclosed.

Therefore, as a method of manufacturing a carbon fiber reinforced aluminum composite by a liquid-phase manufacturing process, while improving the wettability of carbon fibers to liquid aluminum, in order to suppress the formation of _{aluminum carbide (Al 4} C _{3 ) phase at the interface between aluminum and carbon fibers, various} Research has been ongoing.

Patent Document 2 discloses that when a carbon fiber-reinforced aluminum-based composite material is manufactured by impregnating an aluminum or aluminum alloy molten metal by molten metal forging into a preform composed of carbon fiber, a preform composed of carbon fiber open yarn coated with an alumina precursor is produced. By using it, the preheating temperature of the green body can be lowered from around 3000°C to 600-1200°C in the conventional range, the embrittlement of carbon fibers is prevented, the impregnation property of the matrix metal is improved, high mechanical strength, physical properties, cutting workability, etc. Disclosed is a method for producing an excellent carbon fiber-reinforced aluminum-based composite material.

However, in order to increase the interfacial bonding strength, the composite material is still manufactured at a high temperature of 1000°C, but the operation risk is high due to the high process temperature.

Therefore, for the commercialization of carbon fiber-reinforced aluminum composites, it is urgent to develop an economical manufacturing process suitable for mass production, standardize the properties of the composite and secure reliability.

Therefore, as a result of the present inventors' efforts to solve the conventional problems, the carbon fiber is _{coated with silicon oxide (SiO 2} ), and magnesium (Mg) powder is attached to the coated carbon fiber, and then the metal powder for the composite is mixed and manufactured. , Carbon fiber reinforced aluminum manufactured and manufactured by lowering the molten metalization temperature applied to the conventional carbon fiber and intermetallic composite by using the high-temperature local heat generated by the thermite reaction of the silicon oxide (SiO _{2 ) and magnesium (Mg) powder} By confirming the excellent physical properties of the composite material, the present invention was completed.

Korean Patent No. 1740883 (Notice on May 30, 2017) Japanese Laid-Open Patent Publication No. 2005-29813 (published on February 3, 2005)

It is an object of the present invention to provide a method for manufacturing a carbon fiber reinforced metal composite.

Another object of the present invention is to provide a carbon fiber-reinforced aluminum composite prepared by the above manufacturing method.

In order to achieve the above object, the present invention is a first step of coating _{silicon oxide (SiO 2 ) on carbon fiber,}

A second step of attaching magnesium (Mg) powder to the carbon fiber coated in the first step;

A third step of preparing a mixture by mixing the carbon fiber attached in the second step and the metal powder for the composite material; and

It provides a method for producing a carbon fiber-reinforced metal composite comprising a fourth step in which the mixture of the third step is reacted and melted at a temperature of 700 to 850° C. to impregnate the reinforced carbon fiber in a metal matrix.

The manufacturing method of the present invention may further perform a silicone oil coating step on the carbon fiber coated in the first step.

In the manufacturing method of the present invention, the metal powder for the composite material in the third step is to use any one selected from aluminum or magnesium. In this case, in the third step, it is preferable that the carbon fiber and the metal powder for the composite material are mixed in a volume ratio of 1: 2 to 1: 50.

In the manufacturing method of the present invention, in the fourth step, the mixture of the third step is melted by including the heat generated by the thermite reaction _{of silicon oxide (SiO 2 ) and magnesium (Mg) powder,} The silicon oxide (SiO ₂ ) and magnesium (Mg) powder are reacted in a molar ratio of 1:2.

By the thermite reaction, the silicon oxide (SiO ₂ ) is reduced to form carbon fiber-Si, and a composite in which the carbon fiber-Si is dispersed in a metal matrix by molten metal may be provided.

Accordingly, the present invention provides a carbon fiber reinforced aluminum composite in which carbon fibers are dispersed in an aluminum matrix from the above manufacturing method, and Si is dispersedly attached to the surface of the carbon fibers.

According to the manufacturing method of the carbon fiber reinforced metal composite material of the present invention, it is possible to improve the physical properties while lowering the high working temperature of 1000 ℃ or more for the conventional carbon fiber and metal composite.

Specifically, the method for producing a carbon fiber-reinforced metal composite of the present invention uses the high-temperature local heat generated due to the thermite reaction to lower the molten metalization temperature applied to the conventional carbon fiber and metal composite. It is possible to improve the physical properties of the composite material by securing the wettability of the liver.

In addition, it is possible to provide a carbon fiber reinforced metal composite with improved interfacial bonding strength between two materials from the manufacturing method of the present invention.

1 is a step-by-step schematic diagram for a method of manufacturing a carbon fiber reinforced metal composite.

Hereinafter, the present invention will be described in detail.

The present invention provides a method for manufacturing a carbon fiber reinforced metal composite.

1 is a schematic diagram showing a step-by-step schematic diagram for a method of manufacturing a carbon fiber reinforced metal composite, and will be described in detail with reference to the drawings, the present invention

The first step of coating the carbon fiber with silicon oxide (SiO _{2 ),}

A second step of attaching magnesium (Mg) powder to the carbon fiber coated in the first step;

A third step of preparing a mixture by mixing the carbon fiber attached in the second step and the metal powder for the composite material; and

It provides a method for producing a carbon fiber-reinforced metal composite comprising a fourth step in which the mixture of the third step is reacted and melted at a temperature of 700 to 850° C. to impregnate the reinforced carbon fiber in a metal matrix.

In the carbon fiber-reinforced metal composite manufacturing method of the present invention, in the case of the conventional carbon fiber-metal composite working temperature of 660 to 860°C, wet-ability is not observed at all, and at a temperature of 860°C or higher, the contact angle is 110 degrees It rises and carbide (eg, Al ₄ C ₃ ) is found, and the contact angle is rapidly decreased to 95 to 65 at a temperature of 1000° C. or higher, and thick carbide is generated at the interface.

Accordingly, the present invention was devised to improve the low wet-ability between carbon fiber and metal, and is generated by thermite reaction or Mgnesiothermic reduction reaction of _{silicon oxide (SiO 2 ) and magnesium (Mg) powder.} It is possible to lower the working temperature of 1000° C. or higher of molten metal applied to the conventional composite by using the high-temperature local heat.

Accordingly, the manufacturing method of the present invention _{uses high-temperature heat temporarily generated by the thermite reaction of silicon oxide (SiO 2} ) and magnesium (Mg) powder, so that the compounding operation temperature is 850° C. or less while performing the complex between the carbon fiber and the metal. Wettability improvement can be achieved.

Accordingly, if the manufacturing method of the present invention is described step by step, the first step is a step of coating the _{carbon fiber with silicon oxide (SiO 2 ).}

Before coating the silicon oxide, the surface treatment step of the carbon fiber may be preceded by acid treatment. As a means for coating in the first step, in an embodiment of the present invention, silicon oxide (SiO ₂ ) is coated on carbon fiber using a sol-gel method using aminopropyl triethoxysilane (APTES) and Tetraethoxysilane (TEOS), but is not limited thereto. It may be employed without limitation in conventionally known methods.

In addition, the carbon fibers used in the first step are pitch-based carbon fibers, polyacrylonitrile-based carbon fibers, carbon nano fibers, multi-walled carbon nanotubes (MWCNTs), single-walled carbon fibers. A carbon nanotube (SWCNT, single walled carbon nano tube), a carbon nano yarn obtained by twisting the nanotubes, or a carbon nano sheet may be used.

Preferably, the carbon fibers are pitch-based carbon fibers having a length of 500 μm to 100 mm, polyacrylonitrile-based carbon fibers having a length of 500 μm to 100 mm, carbon nanofibers having a length of 500 nm to 2 mm, 500 nm to 500 μm Multi-wall carbon nanotubes having a length of , single-wall carbon nanotubes having a length of 500 nm to 500 μm, or carbon nano yarns having a length of 100 μm to 100 mm obtained by twisting the nanotubes may be used.

The manufacturing method of the present invention may further perform a silicone oil coating step on the carbon fiber coated with _{silicon oxide (SiO 2 ) after the first step.}

In the silicone oil coating step, the silicon oxide (SiO ₂ ) is coated with the surface of the coated carbon fiber and the in-situ component, and serves as a binder to help the adhesion with the magnesium (Mg) powder to be mixed in the next step. In particular, although magnesium (Mg) powder is explosive when it comes into contact with water, reaction stability can be secured by coating the carbon fiber surface coated with _{silicon oxide (SiO 2 ) with silicone oil.}

Then, in the second step of the present invention, magnesium (Mg) powder is attached to the carbon fiber coated in the first step.

At this time, the magnesium (Mg) metal powder is dispersed and mixed with the carbon fiber, so that it is partially attached to the surface of the carbon fiber.

In the manufacturing method of the present invention, the third step is a step of obtaining a mixture by mixing the carbon fiber to which the magnesium (Mg) powder is attached in the second step and the metal powder for the composite material. At this time, the metal powder for the composite material is to use any one selected from aluminum or magnesium, and in the embodiment of the present invention will be described using aluminum as a preferred example.

At this time, it is preferable that the carbon fiber and the metal powder for the composite material are mixed in a ratio of 1: 2 to 50 by volume. It is undesirable to generate a lot, and if the volume ratio exceeds 50, the amount of carbon fiber for reinforcement is too small, and there is a problem that the reinforcement effect of the composite material is low.

In the manufacturing method of the present invention, in the fourth step, the mixture of the third step is reacted and melted at a temperature of 700 to 850° C. to impregnate the reinforced carbon fiber in the metal matrix.

In the above reaction, a thermite reaction of silicon oxide (SiO ₂ ) and magnesium (Mg) powder, more precisely, a high temperature local heat is generated by a Mgnesiothermic reduction reaction, and the local heat is used in the molten metalization step. , by performing the overall working temperature in the range of 700 to 850 ℃, it is possible to manufacture a carbon fiber reinforced metal composite.

In general, in thermite reaction, when a metal oxide and a metal powder are ignited or heated, a large amount of heat is released due to the chemical bonding between the metal powder and the metal oxide. At this time, the metal oxide is boron (III) oxide, silicon (IV) oxide, chromium (III) oxide, magnesium (IV) oxide, iron (II, Ⅲ) oxide, copper (II) oxide and lead (II, III, IV) ) any one selected from the group consisting of oxides may be used.

In addition, any one selected from the group consisting of aluminum, magnesium, titanium, zinc, silicon and boron may be used as the metal powder.

Accordingly, in the present invention _{, the silicon oxide (SiO 2} ) is reduced (Si) and magnesium is oxidized (MgO) _{by a thermite reaction in which silicon oxide (SiO 2} ) as a metal oxide and magnesium powder as a metal powder are selected. At this time, the silicon oxide (SiO ₂ ) and magnesium (Mg) powder react in a molar ratio of 1:2.

Therefore, the carbon fiber-Si is formed on the surface by the reaction of _{the silicon oxide (SiO 2} ) partially attached to the carbon fiber surface and the magnesium powder.

Furthermore, the present invention provides a carbon fiber-reinforced aluminum composite material in which carbon fibers are dispersed in an aluminum matrix from the above manufacturing method, and Si is dispersedly attached to the surface of the carbon fibers.

The carbon fiber-reinforced aluminum composite obtained from the manufacturing method of the present invention has significantly higher tensile strength values than when manufactured without carbon fiber or when the composite is manufactured by the conventional method without thermite reaction [ Table 1 ], Due to the improvement of the wet-ability of aluminum, the interfacial bonding strength between the two materials is improved, which supports the result that the properties of the composite material are also improved.

Therefore, the carbon fiber-reinforced aluminum composite obtained from the manufacturing method of the present invention is provided as a composite material in which the physical properties of low tensile strength and flexural strength of aluminum are improved by complexing high-strength and light-weight carbon fibers with aluminum.

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

These examples are for explaining the present invention in more detail, and the scope of the present invention is not limited to these examples.

<Example 1>

50 g of 6 mm carbon fiber was first oxidized at 500° C. for 30 minutes to remove the sizing agent, and then surface oxidation was additionally performed for 12 hours by using a 6M aqueous nitric acid solution. After that, the carbon fiber was put in a mixed solution of 500 ml of ethanol and 10 ml of APTES (aminopropyl triethoxysilane) and reacted for 12 hours, immersed in 20 ml of TEOS (Tetraethoxysilane) and 500 ml, and then 5 ml of ammonia water was slowly added. The reaction was carried out for 24 hours. Thereafter, the carbon fibers were washed with ethanol and water and dried at 100° C. to obtain carbon fibers coated with silicon oxide.

After putting the silicon oxide-coated carbon fiber in silicone oil diluted 30 times with hexane, and taking it out, 50 μm of magnesium powder was sprayed and mixed with the carbon fiber, dried in a hood, and the magnesium powder was attached to a part of the carbon fiber surface.

10 g of the carbon fiber to which the magnesium powder was attached and 100 g of the aluminum powder were slowly mixed in an argon atmosphere in powder form. Then, 110 g of the mixture was put into an electric metal melting furnace and heated to 750° C. at a temperature increase rate of 10° C./min in an argon atmosphere to melt the mixture, thereby impregnating the matrix with reinforced carbon fibers. After pouring into a tensile specimen mold heated to 500° C., it was cooled slowly to prepare a carbon fiber reinforced aluminum composite specimen. The tensile test was performed after processing the test piece.

<Example 2>

20 g of the carbon fiber with magnesium powder and 100 g of aluminum powder prepared in Example 1 were slowly mixed in an argon atmosphere, and then 120 g of the mixture was put into an electric metal melting furnace and the temperature was raised to 750 at a rate of 10° C./min in an argon atmosphere. It was heated to ℃ to molten so as to be dissolved, so that the reinforced carbon fiber was impregnated in the matrix. Thereafter, the specimen was poured into a tensile specimen mold heated to 500° C., and cooled slowly to prepare a carbon fiber reinforced aluminum composite specimen.

<Comparative Example 1>

Put 120 g of pure aluminum powder without carbon fiber into an electric metal melting furnace and heat it to 750° C. at a heating rate of 10° C./min in an argon atmosphere to dissolve it. Then, pour it into a tensile specimen mold heated to 500° C., and cool the test piece slowly. prepared.

<Comparative Example 2>

After 10 g of carbon fiber and 100 g of aluminum powder were mixed slowly in an argon atmosphere, 110 g of the mixture was put in an electric metal melting furnace and heated to 750° C. at a temperature increase rate of 10° C./min. After pouring into a tensile specimen mold, it was cooled slowly to prepare a carbon fiber reinforced aluminum composite specimen.

<Comparative Example 3>

After 20 g of carbon fiber and 100 g of aluminum powder were mixed slowly in an argon atmosphere, 120 g of the mixture was put in an electric metal melting furnace and heated to 750° C. at a temperature increase rate of 10° C./min. After pouring into a tensile specimen mold, it was cooled slowly to prepare a carbon fiber reinforced aluminum composite specimen.

<Experimental Example 1> Physical property evaluation

The results for the tensile strength of the carbon fiber reinforced aluminum composite specimens prepared in Examples 1 to 2 and Comparative Examples 1 to 3 are shown in Table 1 below.

From the results of Table 1, the carbon fiber-reinforced aluminum composites of Examples 1 and 2 prepared at a molten metalization temperature of 750° C. using the thermite reaction of _{silicon oxide (SiO 2 ) and magnesium (Mg) powder did not contain carbon fibers.} Based on the tensile strength of Comparative Example 1, the tensile strength value was increased by 54 to 86%.

On the other hand, _{the carbon fiber-reinforced aluminum composites of Comparative Examples 1 and 2, which were prepared without the thermite reaction of silicon oxide (SiO 2} ) and magnesium (Mg) powder, were 52 to 52 to higher than the tensile strength of Comparative Example 1 not including carbon fibers. The tensile strength value was reduced by 80%. That is, in the case of Comparative Examples 1 and 2, it was confirmed that due to the low wet-ability of aluminum to carbon fibers, the interfacial bonding force between the two materials was low, so that even if it was made into a composite material, it was confirmed that a low physical property value was shown.

In the above, the present invention has been described in detail only with respect to the described embodiments, but it is obvious to those skilled in the art that various modifications and variations are possible within the scope of the technical spirit of the present invention, and it is natural that such variations and modifications belong to the appended claims.

1: carbon fiber
2: Silicon oxide
21: silicone oil
3: Magnesium powder
4: aluminum powder
11: Reinforced carbon fiber
41: aluminum matrix

Claims (8)

The first step of coating the carbon fiber with silicon oxide (SiO _{2 ),}
A second step of attaching magnesium (Mg) powder to the carbon fiber coated in the first step,
A third step of preparing a mixture by mixing the carbon fiber attached in the second step and the metal powder for the composite material; and
A method for producing a carbon fiber reinforced metal composite comprising a fourth step in which the mixture of the third step is reacted and melted at a temperature of 700 to 850° C. to impregnate the reinforced carbon fiber in a metal matrix. The method of claim 1, wherein a silicone oil coating step is further performed on the carbon fiber coated in the first step. The method of claim 1, wherein the metal powder for the composite material in the third step is any one selected from aluminum and magnesium. The method of claim 1, wherein in the third step, the carbon fiber and the metal powder for the composite material are mixed in a volume ratio of 1: 2 to 1: 50. According to claim 1, wherein in the fourth step, the mixture of the third step is molten by including the heat generated by the thermite reaction _{of silicon oxide (SiO 2 ) and magnesium (Mg) powder.} A method of manufacturing a carbon fiber reinforced metal composite. The method of claim 5, wherein the silicon oxide (SiO ₂ ) and magnesium (Mg) powder are reacted in a molar ratio of 1:2. The method of claim 5, wherein the silicon oxide (SiO ₂ ) is reduced by the thermite reaction to form carbon fiber-Si. A carbon fiber-reinforced aluminum composite in which carbon fibers are dispersed in an aluminum matrix from the method for manufacturing the carbon fiber-reinforced metal composite of any one of claims 1 to 7, and Si is dispersedly attached to the surface of the carbon fibers.

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