EP3719151B1

EP3719151B1 - Production method for aluminum alloy-based composite material, and aluminum alloy-based composite material

Info

Publication number: EP3719151B1
Application number: EP18884716.4A
Authority: EP
Inventors: Hiroshi MITO; Kenji Watanabe
Original assignee: Advanced Composite Corp
Current assignee: Advanced Composite Corp
Priority date: 2017-11-30
Filing date: 2018-11-30
Publication date: 2023-06-07
Anticipated expiration: 2038-11-30
Also published as: CN111479940B; EP3719151C0; CN111479940A; JP2019099850A; JP6681079B2; EP3719151A1; WO2019107541A1; EP3719151A4

Description

Technical Field

The present invention relates to a method for producing an aluminum alloy-based composite material containing a reinforcement material distributed uniformly therein, and an aluminum alloy-based composite material.

Background Art

In the past, an aluminum alloy-based composite material containing a ceramic powder being a reinforcement material composited in an aluminum alloy has been known. As a method for producing this aluminum alloy-based composite material, Patent Literature 1, for example, describes a method for producing an aluminum alloy-based composite material, wherein a powder of aluminum borate is used as a ceramic powder being a reinforcement material, and a filled body of this powder is impregnated with a melt of an aluminum alloy. It is to be noted that such a production method is called a melt casting method or a high-pressure casting method.
The production method described in Patent Literature 1 includes: a step of filling an aluminum borate powder raw material, thereby obtaining a filled body; a step of preheating the filled body; a step of heating an aluminum alloy, thereby obtaining a molten aluminum alloy; and a step of pressurizing and penetrating the molten aluminum alloy into the filled body having been preheated. In such a conventional production method, a filled body is obtained by filling a ceramic powder, such as an aluminum borate powder raw material, into a container made of iron or SUS.

Citation List

Patent Literature

Patent Literature 1: Japanese Patent Laid-Open No. 2008-38172
JP H11 170027 A , US 3 877 884 A and JP S60 115361 A disclose methods for preparing a metal-ceramic composite.

Summary of Invention

Technical Problem

The following problems are left unsolved in the above-described conventional technique.
That is, in the conventional method for producing an aluminum alloy-based composite material, a ceramic powder 102 is filled in a metal container 103 made of iron or SUS to make a filled body, and a melt Al1 of an aluminum alloy is allowed to flow in the metal container 103 from an upper opening of this metal container 103 to impregnate the filled body of the ceramic powder 102 with the aluminum alloy, as shown in Figure 14(a) and Figure 14(b), and therefore there has been a problem that the impregnation ratio of the aluminum alloy is different between the vicinity of the opening portion in which the melt Al1 of the aluminum alloy flows in and the bottom portion far from the opening portion, so that the whole filled body of the ceramic powder 102 is not impregnated uniformly.
Therefore, it has been difficult to obtain a uniform composite material particularly having a complicated shape or a sheet-like shape.
The present invention has been completed in view of the previously described problem, and an object of the present invention is to provide a technique of producing an aluminum alloy-based composite material, the technique enabling uniform impregnation with an aluminum alloy.

Solution to Problem

The present invention relates to the subject matter of claims 1 to 7, in particular adopts the following constitution in order to solve the previously described problem. That is, a method for producing an aluminum alloy-based composite material according to the invention is a method for producing an aluminum alloy-based composite material containing a ceramic powder being a reinforcement material composited in an aluminum alloy, the method characterized by including: a filling step of filling the ceramic powder into a porous container formed of a porous material, and tightly closing the porous container with a lid part; a step of placing the porous container in a mold, and pouring a melt of the aluminum alloy into the mold; and an impregnation step of applying pressure to the melt in the mold, thereby impregnating the ceramic powder inside the porous container with the melt through the porous container.
This method for producing an aluminum alloy-based composite material includes the impregnation step of impregnating the ceramic powder inside the porous container with the melt through the porous container, and therefore the melt of the aluminum alloy flows evenly in the porous container from almost all the directions through the porous material of the porous container, thereby enabling uniform impregnation of the whole ceramic powder.
The method for producing an aluminum alloy-based composite material according to an embodiment is characterized in that the porous container is formed of carbon graphite.
That is, in this method for producing an aluminum alloy-based composite material, the porous container is formed of carbon graphite, and therefore the coefficient of thermal expansion is smaller than that of a container made of iron or SUS, so that deformation of the container due to thermal expansion hardly occurs, which enables using a container having a complicated shape. In addition, the porous container is carbon graphite, and therefore the composite material and the porous container can easily be separated when the hardened composite material is taken out of the porous container after the impregnation step.
The method for producing an aluminum alloy-based composite material according to a further embodiment is characterized by further including a preheating step of preheating the porous container after the filling step.
That is, this method for producing an aluminum alloy-based composite material further includes the preheating step of preheating the porous container after the filling step, and therefore the interfacial energy of the particles of the filled ceramic powder is enhanced, so that the wettability with the melt of the aluminum alloy is ameliorated. Particularly, since the porous container is formed of carbon graphite, the coefficient of thermal expansion of the porous container is low, so that deformation of the container due to the preheating hardly occurs.
The method for producing an aluminum alloy-based composite material according to a further embodiment is characterized in that the ceramic powder is a powder of aluminum borate.
That is, in this method for producing an aluminum alloy-based composite material, the ceramic powder is the powder of aluminum borate, and therefore a composite material excellent in processability can be obtained by using the powder of aluminum borate having a relatively low hardness.
The method for producing an aluminum alloy-based composite material according to a further embodiment is characterized in that a powder of SiC is further added as the ceramic powder.
That is, in this method for producing an aluminum alloy-based composite material, the powder of SiC is further added as the ceramic powder, and therefore the coefficient of thermal expansion as a whole can be reduced and the hardness can be enhanced according to the proportion of the powder of SiC to be added, which has a lower coefficient of thermal expansion and a higher hardness than aluminum borate.
In addition, as an effect of the powder of SiC, the wettability with the powder of aluminum borate is satisfactory, and the interface with the aluminum borate powder is modified, so that a stronger joint can be obtained.
The method for producing an aluminum alloy-based composite material according to a further embodiment is characterized in that the powder of SiC is mixed with the powder of aluminum borate in a volume ratio of the powder of SiC to the powder of aluminum borate of 0.5 to 2.0:20 in the filling step.
That is, in this method for producing an aluminum alloy-based composite material, the powder of SiC is mixed with the powder of aluminum borate in a volume ratio of the powder of SiC to the powder of aluminum borate of 0.5 to 2.0:20 in the filling step, and therefore a composite material which has achieved both reduction of the coefficient of thermal expansion as a whole and satisfactory processability can be obtained.
It is to be noted that when the ratio of the powder of SiC to the powder of aluminum borate is less than 0.5:20 in terms of volume ratio, an effect of reducing the coefficient of thermal expansion is not obtained sufficiently, and when the ratio of the powder of SiC exceeds 1.5, the hardness as a whole is too hard, which makes the processability poor.
An aluminum alloy-based composite material according to a further embodiment is characterized by an aluminum alloy-based composite material containing a ceramic powder being a reinforcement material composited in an aluminum alloy, the aluminum alloy-based composite material containing the ceramic powder being the reinforcement material uniformly dispersed and distributed in an aluminum alloy matrix, wherein the aluminum alloy-based composite material is obtained by the method for producing an aluminum alloy-based composite material.

Advantageous Effects of Invention

According to the present invention, the following effects are exhibited.
That is, the method for producing an aluminum alloy-based composite material according to the present invention includes the impregnation step of impregnating the ceramic powder inside the porous container with the melt through the porous container, and therefore the melt of the aluminum alloy flows evenly in the porous container from almost all the directions through the porous material of the porous container, thereby enabling uniform impregnation of the whole ceramic powder.
Accordingly, by the production method of the present invention, an aluminum alloy-based composite material having uniform coefficient of thermal expansion and hardness as a whole can be obtained, and a uniform aluminum alloy-based composite material having a complicated shape or a sheet-like shape can be obtained.
The aluminum alloy-based composite material prepared by this production method of the present invention is light in weight and has a high Young's modulus, a high vibration damping factor, a high thermal conductivity, and a high wear resistance, and therefore is suitable as a material for an X-Y table of a bonding machine or the like, and a robot arm, a chip mounter, air-compressing scroll parts, and the like, which are used in a semiconductor production apparatus.

Brief Description of Drawings

[Figure 1] Figure 1 is a perspective view showing a porous container before being filled with a ceramic powder and tightly sealed with a lid part in one embodiment of a method for producing an aluminum alloy-based composite material according to the present invention.
[Figure 2] Figure 2(a) is an exploded perspective view showing a porous container having a rectangular parallelepiped shape, and Figure 2(b) is an exploded perspective view showing a porous container having a cylindrical shape in the present embodiment.
[Figure 3] Figure 3(a), Figure 3(b), and Figure 3(c) are simple sectional views showing steps from a step of pouring a melt to a knockout step in sequence in the present embodiment.
[Figure 4] Figure 4(a), Figure 4(b), Figure 4(c), and Figure 4(d) are perspective views showing steps after the knockout step in sequence in the present embodiment.
[Figure 5] Figure 5 is a SEM image showing an aluminum alloy-based composite material obtained using aluminum borate as a ceramic powder in a method for producing an aluminum alloy-based composite material of a conventional example.
[Figure 6] Figure 6 is a SEM image obtained by further enlarging the image in Figure 5.
[Figure 7] Figure 7 is a SEM image showing an aluminum alloy-based composite material obtained using aluminum borate as a ceramic powder in an Example of a method for producing an aluminum alloy-based composite material according to the present invention.
[Figure 8] Figure 8 is a SEM image obtained by further enlarging the image in Figure 7.
[Figure 9] Figure 9 is a SEM image showing an aluminum alloy-based composite material obtained using a mixed powder of aluminum borate and SiC as a ceramic powder in an Example of a method for producing an aluminum alloy-based composite material according to the present invention.
[Figure 10] Figure 10 is a SEM image obtained by further enlarging the image in Figure 9.
[Figure 11] Figure 11 is a graph showing a damped vibration property of aluminum.
[Figure 12] Figure 12 is a graph showing a damped vibration property of an aluminum alloy-based composite material obtained using aluminum borate as a ceramic powder in a method for producing an aluminum alloy-based composite material of a conventional example.
[Figure 13] Figure 13 is a graph showing a damped vibration property of an aluminum alloy-based composite material obtained using aluminum borate as a ceramic powder in an Example of a method for producing an aluminum alloy-based composite material according to the present invention.
[Figure 14] Figure 14(a) is a sectional view showing a container filled with a ceramic powder, and Figure 14(b) is a sectional view showing a impregnation step with a melt of an aluminum alloy in a method for producing an aluminum alloy-based composite material of a conventional example.

Description of Embodiments

Hereinafter, one embodiment of a method for producing an aluminum alloy-based composite material according to the present invention will be described with reference to Figure 1 to Figure 6.
The method for producing an aluminum alloy-based composite material of the present embodiment is, as shown in Figure 1 to Figure 3(a), Figure 3(b), and Figure 3(c), a method for producing an aluminum alloy-based composite material 1 containing a ceramic powder 2 being a reinforcement material composited in an aluminum alloy, and includes: a filling step of filling the ceramic powder 2 into a porous container 3 formed of a porous material; a step of placing the porous container 3 in a mold 4, and pouring a melt Al1 of the aluminum alloy into the mold 4; and an impregnation step of applying pressure to the melt Al1 in the mold 4, thereby impregnating the ceramic powder 2 inside the porous container 3 with the melt Al1 through the porous container 3.
In addition, the production method of the present embodiment includes a preheating step of preheating the porous container 3 after the filling step.
The porous container 3 is formed of a porous (open porous) material which does not melt even when the melt Al1 of the aluminum alloy is put thereinto and which has an infinite number of through holes. Particularly, it is preferable to form the porous container 3 with carbon graphite.
As the ceramic powder 2, a powder of aluminum borate (for example 9Al₂O₃·2B₂O₃) is used.
In addition, to obtain a composite material having a lower coefficient of thermal expansion and a higher hardness than aluminum borate, a powder of SiC (silicon carbide) is further added as the ceramic powder 2.
In such a case, it is preferable to mix the powder of SiC with the powder of aluminum borate in a volume ratio of the powder of SiC to the powder of aluminum borate of 0.5 to 2.0:20 in the filling step.
A case where the porous container 3 of carbon graphite is used, and a mixed powder of aluminum borate and SiC is used as the ceramic powder 2 in the production method of the present embodiment will be described in more detail. Firstly, the predetermined ceramic powder 2 is prepared and is filled into the porous container 3 of carbon graphite, as shown in Figure 1. It is to be noted that when the mixed powder of aluminum borate and SiC is used as the ceramic powder 2, both the powders are mixed in a predetermined ratio and are stirred and mixed sufficiently and uniformly with a rotating mixer or the like in advance.
As the aluminum alloy that can be utilized in the production method of the present embodiment, the alloy numbers such as, for example, A1050, A5052, A6061, A7075, AC4C, AC8A, and ADC12 can be adopted, and other types can also be adopted. Particularly, as an aluminum alloy which has satisfactory physical properties and with which impregnation trouble is unlikely to occur, AC4C, AC8A, and the like, which have a high thermal conductivity and a high strength, are preferable as an aluminum alloy. Examples of the chemical composition of such an alloy include an aluminum alloy containing Si: 6 to 13%, Mg: 0.2 to 1.3%, and Al: the balance each on a volume percentage basis.
It is preferable to set Si to be contained in such a way as to be in a range of a volume percentage of 6 to 12% because when the above-described content of Si is small, impregnation trouble easily occurs at the time of high-pressure impregnation. That is, the reason is that when Si has a volume percentage of less than 6%, the flow of the melt is poor, which makes it difficult for the melt of the aluminum alloy to penetrate among the ceramic powders 2 being a reinforcement material.
In addition, as the powder of aluminum borate which is utilized as the ceramic powder 2, a powder of aluminum borate having a center particle diameter of about 30 to about 50 µm, for example, is adopted, and as the powder of SiC, a powder of SiC having a center particle diameter of 2 to 4 µm, for example, is adopted.
As the porous container 3, porous containers using open porous carbon graphite blocks and having a various shapes can be adopted. For example, as shown in Figure 2(a), the porous container may be a container 3 having a rectangular parallelepiped shape, the container 3 composed of a main body 3a having a box shape, and a lid part 3b, or, as shown in Figure 2(b), a container 23 composed of a main body 23a having a bottomed cylindrical shape, and a lid part 23b may be adopted.
The pore diameter of the porous container 3 is desirably 10 µm or less. It is to be noted that the pore flow channels of the porous container 3 are complicated, and therefore the SiC powder having a particle diameter which is smaller than the pore diameter never flows outside along the pore flow channels.
When the ceramic powder 2 is filled into the porous container 3, the ceramic powder 2 can be filled in a state where gaps are unlikely to occur by packing the ceramic powder 2 while applying vibration to the porous container 3 with a vibrator or the like.
After the filling is completed, the ceramic powder 2 is put into a preheating furnace (such as muffle furnace) together with the porous container 3 in a state where the porous container 3 is tightly closed with the lid part 3b to perform preheating at 500 to 700°C, for example. This preheating step is a step for enhancing the interfacial energy of the ceramic powder 2 and ameliorating the wettability with the melt of the aluminum alloy.
A conventional container made of iron or SUS has an average thermal expansion coefficient of 14 to 17 ppm/k, and therefore there has been a problem that deformation of the container due to expansion occurs at the time of preheating. Particularly, the more complicated the container shape is, the more difficult the design taking thermal expansion into consideration is. In contrast, the porous container 3 of the present embodiment, using carbon graphite blocks, has an average thermal expansion coefficient of about 5 to about 7 ppm/k, and therefore has an advantageous point that the deformation of the container due to thermal expansion at the time of the preheating hardly occurs.
Next, as shown in Figure 3(a), the preheated porous container 3 packed with the ceramic powder 2 is placed in the mold 4 preheated to 200 to 250°C in advance, and the melt Al1 of the aluminum alloy is poured into the mold 4.
On this occasion, a plurality of protruded portions may be provided at the bottom portion of the mold 4 to mount the porous container 3 on a plurality of the protruded portions in such a way that the melt Al1 flows to the lower bottom portion of the porous container 3. In this case, the porous container 3 can be placed in a state of raising the porous container 3 from the bottom portion of the mold 4, which enables the melt Al1 to flow to the lower bottom portion of the porous container 3. Thereby, penetration of the melt Al1 inside from all the directions in the porous container 3 is enabled.
After a constant amount of the melt Al1 of the aluminum alloy is poured into the mold 4, the melt Al1 of the aluminum alloy is pressurized at 80 to 140 MPa with a punch 5a of a press machine 5, as shown in Figure 3(b).
On this occasion, by the pressurization energy, the porous container 3 is impregnated with the melt Al1 of the aluminum alloy, and further, the ceramic powder 2 in the porous container 3 is impregnated with the melt Al1 of the aluminum alloy.
The pressurization is continued with the press machine 5 until this melt Al1 of the aluminum alloy solidifies completely.
When this impregnation speed with (flow rate of) the melt Al1 of the aluminum alloy is fast, turbulence occurs to move the ceramic powder 2, so that the distribution of the ceramic powder 2 is deviated, and insertion of aluminum, called metal vein, occurs, and therefore the impregnation speed is set to a low speed so that the turbulence will not occur. Accordingly, the pressurization force and the pressurization speed by the press machine 5 are adjusted according to the volume percentage and shape of the ceramic powder 2 in the porous container 3.
Next, when the impregnation is completed, and the temperature is lowered to about 200 to about 300°C, an integrally molded product 7 composed of the porous container 3, the aluminum alloy-based composite material 1 inside the porous container 3, and a hardened excess Al2 of the aluminum alloy is taken out of the mold 4 with a knockout 6 in the mold 4, as shown in Figure 3(c).
Further, the taken-out integrally molded product 7 is cut, for example, the integrally molded product 7 is cut along a cutting line C, with a band saw or the like, to remove the excess Al2, as shown in Figure 4(a), thereby exposing the porous container (3), as shown in Figure 4(b).
Next, the lid part 3b of the porous container 3 is detached, as shown in Figure 4(c), and further, the wall parts and bottom part of the porous container 3 are detached by cutting, as shown in Figure 4(d), thereby taking out the composite material 1. In the exemplified present embodiment, the porous container 3 is carbon graphite, and therefore the composite material 1 can easily be taken out.
The taken-out composite material 1 is processed into an intended shape by a milling cutter, grinding, NC processing, or the like. The aluminum alloy-based composite material 1 prepared in the exemplified present embodiment, contains an aluminum alloy as a parent material and, as reinforcement materials, 30 to 40% of aluminum borate and 1.5 to 2% of SiC each on a volume percentage basis, and is a composite material containing the ceramic powder 2, which is composed of a powder of aluminum borate and a powder of SiC, dispersed uniformly in an aluminum alloy matrix.
The method for producing an aluminum alloy-based composite material 1 of the present embodiment includes the impregnation step of impregnating the ceramic powder 2 inside the porous container 3 with the melt Al1 through the porous container 3, and therefore the melt Al1 of the aluminum alloy flows evenly in the porous container 3 from almost all the directions through the porous material of the porous container 3, thereby enabling uniform impregnation of the whole ceramic powder 2.
In addition, the porous container 3 is formed of carbon graphite, and therefore the coefficient of thermal expansion is smaller than that of a container made of iron or SUS, so that deformation of the container due to thermal expansion hardly occurs, which enables using a container having a complicated shape. In addition, the porous container 3 is carbon graphite, and therefore the composite material 1 and the porous container 3 can easily be separated when the hardened composite material 1 is taken out of the porous container 3 after the impregnation step.
In addition, since this method for producing an aluminum alloy-based composite material includes a preheating step of preheating the porous container 3 after the filling step, the interfacial energy of the particles of the filled ceramic powder 2 is enhanced, so that the wettability with the melt Al1 of the aluminum alloy is ameliorated. Particularly, since the porous container 3 is formed of carbon graphite, the coefficient of thermal expansion of the porous container 3 is low, and deformation of the container due to the preheating hardly occurs.
In addition, when the ceramic powder 2 is the powder of aluminum borate, a composite material excellent in processability can be obtained by using the powder of aluminum borate having a relatively low hardness.
In addition, when the powder of SiC is further added as the ceramic powder 2, the coefficient of thermal expansion as a whole can be reduced, and the hardness can be enhanced according to the proportion of the powder of SiC to be added, which has a lower coefficient of thermal expansion and a higher hardness than aluminum borate to be used together.
In addition, as an effect of using the powder of SiC together, the wettability with the powder of aluminum borate is satisfactory, and the interface with the aluminum borate powder is modified, so that a stronger joint can be obtained.
Particularly, by mixing the powder of SiC with the powder of aluminum borate in a volume ratio of the powder of SiC to the powder of aluminum borate of 0.5 to 2.0:20 in the filling step, and a composite material which has achieved both the reduction of the coefficient of thermal expansion as a whole and the satisfactory processability can be obtained.

Examples

Figure 7 to Figure 10 show SEM images of aluminum alloy-based composite materials actually prepared based on the above-described production method of the embodiment.
Figure 7 and Figure 8 each show a SEM image of an aluminum alloy-based composite material using only aluminum borate as a ceramic powder. In addition, Figure 9 and Figure 10 each show a SEM image of an aluminum alloy-based composite material using a mixed powder of aluminum borate and SiC as a ceramic powder. It is to be noted that an aluminum alloy of alloy number AC4C was used in both cases.
Further, Figure 5 and Figure 6 each show a SEM image of an aluminum alloy-based composite material prepared based on a conventional production method shown in Figure 14(a) and Figure 14(b). This conventional example is an aluminum alloy-based composite material using only aluminum borate as a ceramic powder.
As can be found from these images, the powder of aluminum borate and aluminum around the powder can be distinguished by distinct light and shade, and the boundaries of structures are clear in the material obtained in the conventional example, but in both of the materials of the Examples, prepared according to the production method of the present embodiment, the light and shade between the powder of aluminum borate and aluminum around the powder are not distinct and the boundaries of structures are not clear, as compared to the conventional example. It is found that the tendency is more remarkable particularly in the material of the Example of the present invention, in which the powder of SiC was mixed. It is considered that this is because the bond between aluminum borate and aluminum is strong in the materials of the Examples of the present invention, as compared to the material of the conventional example, which makes the boundaries of each other vague, and particularly in the material of the Example, in which the SiC powder was mixed, it is considered that the wettability is more improved and the bond is thereby strengthened further.
In addition, it is found that in any of the materials which were prepared by the production method of the present embodiment, the ceramic powder is dispersed and distributed uniformly in the aluminum alloy matrix.
Next , results obtained by measuring the Young's modulus, density, specific Young's modulus, thermal conductivity, vibration damping property, and processability of the aluminum alloy-based composite material prepared as the Example of the present invention using the mixed powder of aluminum borate and SiC as a ceramic powder by the production method of the previously described embodiment are shown in Table 1. It is to be noted that the aluminum alloy-based composite material according to the Example of the present invention is written as "development article" in Table 1. In addition, for comparison, the same properties of cast iron FC100, an alumina ceramic, an aluminum alloy-based silicon carbide-reinforced composite material according to a conventional production method, and an aluminum alloy-based aluminum borate-reinforced composite material according to a conventional production method, as "conventional articles", are also described together in Table 1.

[Table 1]

The vibration damping property was measured with an FFT analyzer in such a way that vibration was applied with an impulse hammer to a test piece (10 × 10 × 100 mm) of the composite material, hung with a string, and resultant vibration was detected with an accelerometer. A damping ratio was calculated from a multiplier coefficient and a frequency based on plotting of peaks of a damped wave of each composite material, thereby performing evaluation.
Figure 13 shows the vibration damping property of the aluminum alloy-based composite material prepared in the Example of the present invention. In addition, for comparison, Figure 11 shows the vibration damping property of aluminum, and Figure 12 shows the vibration damping property of the aluminum alloy-based composite material prepared by the method of the conventional example shown in Figure 14(a) and Figure 14(b).
The processability was evaluated by observing, with a metallurgical microscope, a rake face and a front flank of a tool used when three-dimensional cutting of each composite material was performed with a NC lathe under a predetermined condition, and measuring width of flank face friction.
From these measurement results, it was ascertained that the aluminum alloy-based composite material of the Example of the present invention has significantly higher properties as compared to the cast iron, that is, has a Young's modulus about two times that of the cast iron, has a density about 40% higher than the cast iron, and has a thermal conductivity about 2.5 times that of the cast iron.
In addition, it was found that the aluminum alloy-based composite material of the Example of the present invention has a satisfactory processability about the same level as the processability of 2000 series aluminum, as compared to the alumina ceramic.
Moreover, the aluminum alloy (T6 treatment) of the alloy number A6061 had a tensile strength at 300°C of about 30 MPa, but the aluminum alloy-based composite material of the Example of the present invention had a high tensile strength, as high as 90 MPa.
Further, the aluminum alloy-based composite material (aluminum alloy-based aluminum borate-reinforced composite material) obtained using only aluminum borate having a low coefficient of thermal expansion, as low as 8 to 10 w/m·k, as a ceramic powder according to the conventional production method had a low thermal conductivity and a poor heat dissipation. In contrast, the aluminum alloy-based composite material of the Example prepared by the production method of the present invention, in which SiC was further added, had more improved thermal conductivity and mechanical property than the material of the conventional example. Moreover, the processability of the aluminum alloy-based composite material of the Example of the present invention was satisfactory because the processing property was hardly changed even though SiC was added.
In addition, it is found that the vibration damping property of the aluminum alloy-based composite material obtained by the production method of the present embodiment are improved as compared to that of the aluminum alloy-based aluminum borate-reinforced composite material obtained by the conventional production method. The conventional aluminum alloy-based silicon carbide-reinforced composite material has an excellent vibration damping property but has a poor processability, but the aluminum alloy-based composite material of the Example of the present invention not only has an excellent vibration damping property but also has a satisfactory processability.
With respect to the vibration damping property of aluminum, shown in Figure 11, the vibration is hard to be damped, but in the aluminum alloy-based composite material of the Example of the present invention, shown in Figure 13, damping occurs quickly, and therefore a satisfactory vibration damping property is obtained. In addition, it was ascertained that a lot of noises occur in a damped waveform of the aluminum alloy-based composite material of the conventional example, shown in Figure 12, but the number of noise components is small in the aluminum alloy-based composite material of the Example of the present invention, shown in Figure 13.
It is considered that noises occur in the damped waveforms in the aluminum alloy-based composite materials of the conventional examples because bonding in a texture is insufficient in some parts and bonding strength is nonuniform as a whole, and damped waveforms with less noise components are obtained in the aluminum alloy-based composite material of the Example of the present invention because bonding in a texture is uniform and strong.
Accordingly, the aluminum alloy-based composite material prepared by the production method of the present invention is suitable as a material which is used for an X-Y table of a bonding machine or the like, a robot arm and the like being used in a semiconductor production apparatus, or the like, in which not only light weight and a high Young's modulus are required, but also high vibration damping property and processability are required.
It is to be noted that the technical scope of the present invention is not limited to the above-described embodiments and Examples.
According to the invention a powder of aluminum borate, or a mixed powder of aluminum borate and silicon carbide are used as a ceramic powder.

Reference Signs List

1: Aluminum alloy-based composite material
2, 102: Ceramic Powder
3, 23: Porous container
4: Mold
6: Knockout
103: Metal container
All: Melt of aluminum alloy

Claims

A method for producing an aluminum alloy-based composite material comprising a ceramic powder being a reinforcement material composited in an aluminum alloy, the method comprising:
a filling step of filling the ceramic powder into a porous container formed of a porous material, and tightly closing the porous container with a lid part;

a step of placing the porous container in a mold, and pouring a melt of the aluminum alloy into the mold; and

an impregnation step of applying pressure to the melt in the mold, thereby impregnating the ceramic powder inside the porous container with the melt through the porous container,

wherein the ceramic powder is a powder of aluminum borate, or a mixed powder of aluminum borate and silicon carbide.
The method for producing an aluminum alloy-based composite material according to claim 1, wherein the porous container is formed of carbon graphite.
The method for producing an aluminum alloy-based composite material according to claim 1 or 2, further comprising a preheating step of preheating the porous container after the filling step.
The method for producing an aluminum alloy-based composite material according to any one of claims 1 to 3, wherein the ceramic powder is a powder of aluminum borate.
The method for producing an aluminum alloy-based composite material according to claim 4, wherein a powder of SiC is further added as the ceramic powder.
The method for producing an aluminum alloy-based composite material according to claim 5, wherein the powder of SiC is mixed with the powder of aluminum borate in a volume ratio of the powder of SiC to the powder of aluminum borate of 0.5 to 2.0:20 in the filling step.
An aluminum alloy-based composite material comprising a ceramic powder being a reinforcement material composited in an aluminum alloy, the aluminum alloy-based composite material comprising the ceramic powder being the reinforcement material uniformly dispersed and distributed in an aluminum alloy matrix, wherein
the aluminum alloy-based composite material is obtained by the method for producing an aluminum alloy-based composite material according to any one of claims 1 to 6,

wherein the ceramic powder is a powder of aluminum borate, or a mixed powder of aluminum borate and silicon carbide, and

wherein the vibration damping property of the aluminum alloy-based composite material measured with an FFT Analyzer is higher, and a damped waveform has fewer noises, as compared to a vibration damping property of aluminum.