JP2011231374A - Method for manufacturing aluminum composite metallic material, and method for manufacturing aluminum composite metal product - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing technique in which a molding process for carbon fibers is unnecessary and which can obtain a composite molded article.SOLUTION: As shown in Fig.(d), when a specified amount of carbon fibers 12 is incorporated, the speed of a stirrer 14 is switched to a second speed V2 higher than a first speed V1. After stirring for several minutes, as shown in Fig.(e), the dispersion is separated into an upper layer part of the stirred article 15 in which a carbon fiber-rich mixture 16 contains the carbon fibers rich and a lower layer part of the stirred article 15 in which a carbon fiber-poor mixture 17 hardly contains the carbon fibers. As shown in Fig.(f), the carbon fiber-rich mixture 16 is transferred into a container 18. It is thereby possible to take out only the carbon fiber-rich mixture 16. The carbon fibers on which molding processing is not applied are incorporated into a semi-molten state metallic material. As it is unnecessary to mold the carbon fibers, it is possible to omit the molding process, and thereby to decrease the manufacturing cost of an Al composite metallic material.

Description

  The present invention relates to a technique for manufacturing an Al composite metal material or an Al composite metal product.

A heat sink is attached to the semiconductor substrate. Since this heat sink is literally a heat radiating component, high heat conductivity is required.
Since carbon has a higher thermal conductivity than metal, a composite molded product of a metal material and carbon fiber is recommended as a heat sink, and various manufacturing techniques thereof have been proposed (see, for example, Patent Document 1 (FIG. 2)). ).

Patent document 1 is demonstrated based on the following figure.
FIG. 5 is a diagram for explaining the basic principle of the conventional technique. A carbon fiber molded body 102 is placed on a die 101 and a molten metal 103 is poured into the die 101. Next, the molten metal 103 is pressurized with the punch 104. Then, the molten metal 103 soaks into the carbon fiber molded body 102. Thus, a composite molded product of metal and carbon fiber is obtained.

The carbon fiber molded body 102 is obtained by putting carbon fiber into a mold and compressing the carbon fiber. That is, a molding process is required to obtain a carbon fiber molded body. As a result, the manufacturing cost of the composite molded product increases.
In addition, because of the pressurization with the punch 104, the obtained composite molded product is limited to a simple shape such as a flat plate.

  There is a need for a manufacturing technique that does not require a carbon fiber molding step and that can obtain a complex molded article having a complicated shape.

JP 2001-58255 A

  It is an object of the present invention to provide a manufacturing technique that does not require a carbon fiber molding step and can obtain a complex molded article having a complicated shape.

The method for producing an Al composite metal material according to claim 1 includes a step of preparing a metal material using aluminum as a matrix and a carbon fiber as a reinforcing material;
A first stirring step of stirring at a first speed such that the carbon fibers are not scattered by a stirring means while adding the carbon fibers little by little while the metal material is put in a container and heated to a semi-molten state. When,
When the addition of the carbon fibers is completed, the speed of the stirring means is switched to a second speed that is higher than the first speed, and the upper layer portion of the stirring material is rich in carbon fibers containing the carbon fibers. A second agitation step of agitating the agitation for a predetermined time such that the mixture and a lower layer portion of the agitation are separated into a mixture of carbon fiber poors containing almost no carbon fiber;
In order to obtain the material of the Al composite metal product, the step of taking out the carbon fiber rich mixture from the container.

  In the method for producing an Al composite metal material according to claim 2, the Al composite metal material is composed of 15 to 40% by mass of carbon fiber and the remaining metal material.

  The method for producing an Al composite metal material according to claim 3 is characterized in that the carbon fiber added in the first stirring step is 3 to 5% of the metal material by mass ratio.

  According to a fourth aspect of the present invention, there is provided a method for producing an Al composite metal product, wherein a carbon fiber rich mixture obtained by the method for producing an Al composite metal material according to the first, second, or third aspect is directly converted into a die molding machine. And an Al composite metal product is obtained by molding with a cavity of a mold.

  The method for producing an Al composite metal product according to claim 5 is obtained by cooling the carbon fiber-rich mixture obtained by the method for producing an Al composite metal material according to claim 1, claim 2, or claim 3 to a solid state. Next, this solid state mixture is heated to a semi-molten state or a completely molten state, and is molded by a mold cavity to obtain an Al composite metal product.

In the invention which concerns on Claim 1, the carbon fiber which has not performed the shaping | molding process is added to the metal material of a semi-molten state. Since it is not necessary to mold carbon fiber, the molding process can be omitted, and the production cost of the Al composite metal material can be reduced.
Although the carbon fibers are likely to be scattered, in the present invention, the carbon fibers are added little by little while stirring the semi-molten metal material at a low speed, so there is no fear that the carbon fibers are scattered.
Further, the metal material was not melted completely, but was in a semi-molten state. If it is in a semi-molten state, the free flow of the added carbon fiber is hindered. As a result, there is no fear that the carbon fibers are aggregated, and the carbon fibers are evenly dispersed in the metal material.

  In the invention according to claim 2, the Al composite metal material is 15 to 40% by mass of carbon fiber and the remaining metal material. When the addition ratio of the carbon fiber is less than 15% by mass, the Al composite metal material cannot obtain a desired thermal conductivity. On the other hand, when the addition ratio of the carbon fiber exceeds 40% by mass, the Al composite metal material becomes brittle, and it is difficult to perform the next molding and commercialization.

  In the invention which concerns on Claim 3, the carbon fiber added at a 1st stirring process was 3-5% of metal materials by mass ratio. If the carbon fiber is less than 3% of the metal material, it becomes difficult to separate the carbon fiber into a carbon fiber rich mixture and a carbon fiber poor mixture. Moreover, when carbon fiber exceeds 5% of a metal material, the time which stirring requires will become long and productivity will fall.

In the invention according to claim 4, the carbon fiber rich mixture is directly supplied to the mold molding machine and molded by the mold cavity. Since the process is continuous, mass production of Al composite metal products becomes possible, and the manufacturing cost of Al composite metal products can be reduced.
The cavity of the mold can have a complicated shape, and an Al composite metal product having a complicated shape can be easily obtained.

In the invention which concerns on Claim 5, the mixture rich in carbon fiber is cooled and made into a solid substance. Later, it is heated and partially melted or completely melted and molded by a mold cavity.
The carbon fiber rich mixture can be stored and moved in solid form. Since the solid material can be subjected to casting at a necessary time or a necessary place, it becomes easy to make a production plan for an Al composite metal product.
The cavity of the mold can have a complicated shape, and an Al composite metal product having a complicated shape can be easily obtained.

It is a flowchart explaining from the preparation process which concerns on this invention to a 2nd stirring process. It is a flowchart which manufactures Al composite metal products with a direct die-forming machine. It is a flowchart which manufactures Al composite metal product using the mixture of a solid state. It is a graph which shows the correlation with carbon fiber content rate and thermal conductivity. It is a figure explaining the basic principle of the prior art.

  Embodiments of the present invention will be described below with reference to the accompanying drawings.

Embodiments of the present invention will be described with reference to the drawings.
As shown to Fig.1 (a), the Al alloy ingot 11 as a metal material and the carbon fiber 12 called a carbon fiber are prepared (preparation process).
The carbon fiber 12 is a carbon fiber having a fiber diameter of 0.15 to 20 μm, a fiber length of 10 to 500 μm, and an aspect ratio of 5 to 500.

On the other hand, there is a carbon nanomaterial as a material similar to carbon fiber.
The carbon nanomaterial has a fiber diameter of 1.0 nm (nanometer) to 150 nm, that is, 0.001 to 0.15 μm, and is different from the carbon fiber 12 in size.
Therefore, in the present invention, the carbon nanomaterial is not included in the carbon fiber 12.

As shown in (b), the Al alloy ingot 11 is heated to a semi-molten state using a container (crucible) 13. A semi-molten state means a state in which a liquid phase and a solid phase are mixed.
As shown in (c), the carbon fiber 12 is added little by little while stirring the agitated material 15 at the first speed V1 with the stirrer 14. The first speed V1 is set to a low speed at which the carbon fibers 12 are not scattered. The operation is continued until the total amount of the predetermined amount of carbon fibers 12 is added (first stirring step).

  The metal material was not melted completely but in a semi-molten state. If it is a semi-molten state, the free flow of the added carbon fiber 12 is prevented. As a result, there is no fear that the carbon fibers 12 aggregate, and the carbon fibers 12 are evenly dispersed in the metal material.

As shown in (d), when a predetermined amount of carbon fiber 12 is added, the speed of the agitator 14 is switched to a second speed V2 that is higher than the first speed V1.
When stirred for several minutes, as shown in (e), the upper layer portion of the stirring material 15 becomes a carbon fiber-rich mixture 16 containing abundant carbon fibers, and the remaining portion (the lower layer portion of the stirring material 15) contains almost no carbon fibers. The agitated material 15 is separated up and down so as to be a carbon fiber poor mixture 17 (second agitating step).

  The specific gravity of Al is about 2.7, and the specific gravity of carbon is about 2.3. Since the carbon fibers are lighter than the Al alloy that is the matrix, the carbon fibers gather at the upper part of the matrix, so that it is estimated that the mixture is separated into the mixture 16 and the mixture 17.

  As shown in (f), the carbon fiber rich mixture 16 is transferred to a suitable container (for example, ladle) 18 (removal step). Thus, only the carbon fiber rich mixture 16 could be taken out.

The use of the extracted carbon fiber rich mixture 16 will be described with reference to FIGS.
As shown in FIG. 2A, the mixture 16 is supplied directly to the metal forming machine 21. The metal forming machine 21 is used to pour molten metal into the cavities 23 of the dies 22 and 22. By opening the dies 22, 22, an Al composite metal product 24 can be obtained as shown in FIG.
Furthermore, by subjecting the Al composite metal product 24 to hot rolling or hot extrusion, the metal structure can be refined and the mechanical characteristics and thermal characteristics can be improved.

Since the steps of FIGS. 1 and 2 are continuous, the mass production of the Al composite metal product becomes possible, and the manufacturing cost of the Al composite metal product can be reduced.
The cavity 23 of the mold 22 can have a complicated shape, and an Al composite metal product 24 having a complicated shape can be easily obtained.

  Alternatively, as shown in FIG. 3A, a mixture 16 is cast into a casting mold 25 to obtain a solid material (solid-state mixture) 26 as shown in FIG. This solid material 26 can be stored or transported to a remote location.

When necessary or at a necessary place, as shown in (c), the solid material 26 is made into a melt 28 in a semi-molten or completely melted state by the heating container 27. As shown in (d), the molten metal 28 is supplied to the metal forming machine 21. The metal forming machine 21 is used to pour molten metal into the cavities 23 of the dies 22 and 22. By opening the dies 22, 22, an Al composite metal product 24 can be obtained as shown in (e).
Furthermore, by subjecting the Al composite metal product 24 to hot rolling or hot extrusion, the metal structure can be refined and the mechanical characteristics and thermal characteristics can be improved.

  Experiments were conducted to verify the mixing ratio of the metal material and carbon fiber, the first speed and the second speed related to stirring. Details of the experiment will be described next.

(Experimental example)
Experimental examples according to the present invention will be described below. Note that the present invention is not limited to experimental examples.

○ Preparation process:
1000g aluminum alloy (JIS AC2B), 50g or 110g carbon fiber (fiber diameter 8μm, fiber length about 200μm), and 50g carbon nanomaterial (fiber diameter 0.15μm, fiber length about 15μm) for reference And prepared.

○ First stirring step:
• 1000 g of aluminum alloy is melted in a graphite crucible at 750 ° C.
-Thereafter, the molten metal is lowered to 585 ° C to be in a semi-molten state.
The semi-molten molten metal is stirred with a stirring blade made of silicon nitride that rotates at 350 rpm (first speed).
-During this stirring, a small amount (the amount is shown in Table 1) of carbon fiber is added to the molten metal.
Continue until the addition of the prescribed amount (amount shown in Table 1) is complete.

○ Second stirring step:
-The semi-molten molten metal is stirred for a predetermined time (time is shown in Table 1) with a silicon nitride stirring blade rotating at 500 revolutions per minute (second speed).
When a predetermined time has elapsed, a carbon fiber rich mixed portion is separated and formed on the top of the agitated material.

○ Extraction process:
Increase the container temperature to 700 ° C.
• Skim off the carbon fiber rich mixture.

○ Casting process:
-Supply a carbon fiber rich mixture to a high pressure casting machine to obtain an Al composite metal product.
○ Thermal conductivity measurement:
-The thermal conductivity of the obtained Al composite metal product was measured.
The reference index is the thermal conductivity of an aluminum alloy (JIS AC2B) that does not contain carbon fiber. This thermal conductivity is 144 W / mK.

  Sample 1: 110 g of carbon fiber was added to a 1000 g aluminum alloy at a rate of 1.8 g per minute. It took about 61 minutes to add the whole amount. The second stirring was not performed. A sample was prepared by high-pressure casting the mixture obtained only by the first stirring. The carbon fiber content of this sample was 10% by mass, and the thermal conductivity was 138 W / mK. The carbon fiber ratio is calculated as a percentage of (carbon fiber / (metal material + carbon fiber)).

  Sample 2: 50 g of carbon fiber was added to a 1000 g aluminum alloy at a rate of 5 g per minute. It took 10 minutes to add the whole amount. The second stirring at 500 rpm was performed for 1 minute. A sample was prepared by high-pressure casting 250 g of the carbon fiber-rich mixture obtained by the second stirring. The carbon fiber content of this sample was 10% by mass, and the thermal conductivity was 144 W / mK.

  Sample 3: 50 g of carbon fiber was added to 1000 g of aluminum alloy at a rate of 5 g per minute. It took 10 minutes to add the whole amount. The second stirring at 500 rpm was performed for 2 minutes. A sample was prepared by high-pressure casting the carbon fiber-rich mixture obtained by the second stirring. This sample had a carbon fiber content of 15% by mass and a thermal conductivity of 155 W / mK.

  Sample 4: 50 g of carbon fiber was added to 1000 g of aluminum alloy at a rate of 5 g per minute. It took 10 minutes to add the whole amount. The second stirring at 500 rpm was carried out for 3 minutes. A sample was prepared by high-pressure casting the carbon fiber-rich mixture obtained by the second stirring. The carbon fiber content of this sample was 20% by mass and the thermal conductivity was 172 W / mK.

  Sample 5: 100 g of carbon fiber was added to 2000 g of aluminum alloy at a rate of 5 g per minute. It took 20 minutes to add the whole amount. The second stirring at 500 rpm was performed for 5 minutes. A sample was prepared by high-pressure casting the carbon fiber-rich mixture obtained by the second stirring. This sample had a carbon fiber content of 40% by mass and a thermal conductivity of 180 W / mK.

  Sample 6: 150 g of carbon fiber was added to a 2000 g aluminum alloy at a rate of 2.1 g per minute. It took 70 minutes to add the whole amount. The second stirring at 500 rpm was performed for 5 minutes. The carbon fiber rich mixture obtained by the second stirring was brittle and could not be transferred to the next casting. Therefore, measurement of thermal conductivity was not performed.

  Sample 7: 50 g of carbon nanomaterial was added to 1000 g of aluminum alloy at a rate of 2 g per minute. It took 25 minutes to add the whole amount. The second stirring at 500 rpm was carried out for 3 minutes. A sample was prepared by high-pressure casting the carbon fiber-rich mixture obtained by the second stirring. The carbon fiber content of this sample was 20% by mass, and the thermal conductivity was 130 W / mK.

The correlation between the carbon fiber content and the thermal conductivity was examined by taking the carbon fiber content described in Table 1 on the horizontal axis and the thermal conductivity on the vertical axis.
As shown in FIG. 4, a curve that rises to the right can be obtained.
The thermal conductivity of the aluminum alloy (AC2B) not including carbon fiber is 144 W / mK. Then, sample 7 (using carbon nanomaterials) cannot be employed because its thermal conductivity is too low. Moreover, since the sample 2 has the same thermal conductivity as that of the aluminum alloy (AC2B) that does not contain carbon fiber, there is no meaning of adding carbon fiber.
Samples 3, 4, and 5 have high thermal conductivity. Therefore, it was confirmed that the preferable carbon fiber content is in the range of 15% by mass to 40% by mass.

By the way, in Table 1, the time required for the first stirring was 10 minutes to 70 minutes. The longer the first stirring time, the longer the production time and the lower the productivity.
Therefore, it was decided to carry out an additional experiment focusing on the time required for the first stirring. The contents and results of this experiment are described in Table 2.

  Sample 8: 10 g of carbon fiber was added to 1000 g of an aluminum alloy at a rate of 5 g per minute. The reinforcement / metal material (percentage) is 1%. It took 2 minutes to add the whole amount, and the dispersion state in the first stirring was good. Next, 2nd stirring was implemented for 3 minutes at 500 rpm. However, the carbon fiber rich mixture did not separate from the carbon fiber poor mixture. Therefore, the evaluation was x.

  Sample 9: Carbon fiber was increased to 20 g with respect to Sample 8. The reinforcing material is 2% of the metal member. However, the carbon fiber rich mixture did not separate from the carbon fiber poor mixture. Therefore, the evaluation was x.

Sample 10: Carbon fiber was increased to 30 g with respect to Sample 8. The reinforcing material is 3% of the metal member. The time required for the first stirring is 6 minutes, which is shorter than the target time (less than 20 minutes). The second agitation provided a good separation of the carbon fiber rich mixture from the carbon fiber poor mixture. Therefore, evaluation was set as (circle).
Sample 11: Carbon fiber was increased to 50 g with respect to Sample 8. The reinforcing material is 5% of the metal member. The time required for the first stirring is 10 minutes, which is shorter than the target time (less than 20 minutes). By the second stirring, the mixture was separated into a carbon fiber rich mixture and a carbon fiber poor mixture. Therefore, evaluation was set as (circle).

  Sample 12: Carbon fiber was increased to 60 g with respect to Sample 8, and the addition rate was changed to 3 g / min. The reinforcing material is 6% of the metal member. The time required for the first stirring was 20 minutes, which slightly exceeded the target time (less than 20). Therefore, the evaluation was △.

Sample 13: Carbon fiber was increased to 100 g with respect to Sample 8, and the addition rate was changed to 1.7 g / min. The reinforcing material is 10% of the metal member. The time required for the first stirring was 60 minutes, far exceeding the target time (less than 20). Therefore, the evaluation was x.
Sample 14: Carbon fiber was increased to 110 g with respect to Sample 8, and the addition rate was changed to 1.6 g / min. The reinforcing material is 11% of the metal member. The time required for the first stirring was 70 minutes, far exceeding the target time (less than 20). Therefore, the evaluation was x.

  Sample 15: Carbon fiber was increased to 120 g with respect to Sample 8, and the addition rate was changed to 1.5 g / min. The reinforcing material is 12% of the metal member. The time required for the first stirring was 80 minutes, far exceeding the target time (less than 20). In addition, carbon fiber was excessive and did not disperse. Therefore, the evaluation was x.

  If the preferable time required for the first stirring is within 10 minutes, the samples 10 and 11 are applicable, and the reinforcing material has a mass ratio of 3 to 5% of the metal member. That is, the carbon fiber added in the first stirring step was 3 to 5% of the metal material by mass ratio. If the carbon fiber is less than 3% of the metal material, it becomes difficult to separate the carbon fiber rich mixture and the carbon fiber poor mixture into two, and if the carbon fiber exceeds 5% of the metal material, Although the time required for stirring becomes longer and the productivity is lowered, these problems are solved by setting the content in the range of 3 to 5%.

  In addition, if the preferable required time in 1st stirring shall be less than 20 minutes, the samples 10, 11, and 12 will correspond, and a reinforcement will be 3 to 6% of a metal member by mass ratio.

  In addition, if Al as a metal material is aluminum and an aluminum alloy, a kind will not be limited. Various methods such as die casting, high pressure casting, low pressure casting, die casting, and sand casting can be applied to the casting method of the Al composite metal product.

  The present invention is suitable for producing an Al composite metal product composed of aluminum and carbon fiber.

  DESCRIPTION OF SYMBOLS 11 ... Metal material (Al alloy ingot), 12 ... Carbon fiber, 13 ... Container (crucible), 14 ... Stirrer, 15 ... Stirrer, 16 ... Carbon fiber rich mixture (Al composite metal material), 17 ... Carbon fiber Poor mixture, 21 ... metal forming machine, 22 ... mold, 23 ... cavity, 24 ... Al composite metal product.

Claims (5)

Preparing a metal material containing aluminum as a matrix and carbon fiber as a reinforcing material;
A first stirring step of stirring at a first speed such that the carbon fibers are not scattered by a stirring means while adding the carbon fibers little by little while the metal material is put in a container and heated to a semi-molten state. When,
When the addition of the carbon fibers is completed, the speed of the stirring means is switched to a second speed that is higher than the first speed, and the upper layer portion of the stirring material is rich in carbon fibers containing the carbon fibers. A second agitation step of agitating the agitation for a predetermined time such that the mixture and a lower layer portion of the agitation are separated into a mixture of carbon fiber poors containing almost no carbon fiber;
A method for producing an Al composite metal material, comprising the step of taking out the carbon fiber-rich mixture from the container in order to obtain a material for the Al composite metal product.   2. The method for producing an Al composite metal material according to claim 1, wherein the Al composite metal material is composed of 15 to 40% by mass of the carbon fiber and the remaining metal material.   The said carbon fiber added at a said 1st stirring process is 3-5 mass% of the said metal material by mass ratio, The manufacturing method of Al composite metal material of Claim 1 characterized by the above-mentioned.   The carbon fiber-rich mixture obtained by the method for producing an Al composite metal material according to claim 1, 2 or 3 is directly fed to a mold molding machine and molded by a mold cavity. A method for producing an Al composite metal product, comprising obtaining an Al composite metal product.   The carbon fiber-rich mixture obtained by the method for producing an Al composite metal material according to claim 1, claim 2, or claim 3 is cooled to a solid state, and then the solid state mixture is converted into a semi-solid state. A method for producing an Al composite metal product, characterized in that an Al composite metal product is obtained by heating to a molten state or a completely molten state and molding by a mold cavity.

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