JPH09184036A - Diamond reinforced aluminum alloy composite member with high thermal conductivity and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a diamond reinforces Al alloy composite member excellent in heat radiation characteristic in the normal service temp. region of the member and having high thermal conductivity. SOLUTION: This diamond reinforced Al alloy composite member with high thermal conductivity comprises an Al matrix composed of Al and diamond grains dispersed in the matrix. The member is a plastic worked article. Thermal conductivity C varies so as to draw a conic section with the increase in temp. The maximum value (Cmax) of the thermal conductivity (C) lies in the normal service temp. region (Rt) of the member, represented by 373K<=Rt<=573K.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high thermal conductivity diamond composite Al alloy member, and more particularly to a member composed of a matrix composed of one of Al and Al alloy and diamond particles dispersed in the matrix, and a method for producing the same. .

[0002]

2. Description of the Related Art Al is a metal material containing Ag, Cu,
It has the next highest thermal conductivity C after Au, but the thermal conductivity C decreases when alloyed to improve strength.

Therefore, conventionally, in the Al alloy matrix,
Diamond particles having a higher thermal conductivity C than that are dispersed to improve the thermal conductivity C (Japanese Patent Application Laid-Open No. Hei 4 (1999) -498).
-259305).

[0004]

Al alloy, for example, 60
The coefficient of thermal expansion of 61 material is about 23.6 × 10 ⁻⁶ K, and that of diamond is about 2 × 10 ⁻⁶ / K, and there is a relatively large coefficient of thermal expansion difference between them.

Under these circumstances, since the hot pressing method has been conventionally used for manufacturing the member, the molding temperature is relatively high, for example, set to about 873K.

However, when the molding temperature is set high as described above, a relatively large strain is generated in the member during cooling of the member due to the difference in the coefficient of thermal expansion, and such strain is caused by the heat conduction of the member. The rate of increase will be low because it will hinder the rate improvement.

Further, the thermal conductivity C of this kind of member changes so as to form a mountain shape as the temperature rises, but the maximum value Cmax of the thermal conductivity C in the conventional member is caused by the strain as described above. It is likely to appear in a high temperature range exceeding the limit operating temperature of Al alloy.

As a result, when the above-mentioned member is used as a heat-resistant member such as a piston for an internal combustion engine, its heat dissipation property is deteriorated due to its low thermal conductivity C in the normal temperature range, and durability due to overheating is caused. There is a problem that the sexual deterioration is remarkable.

[0009]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a member having a high thermal conductivity C and capable of exhibiting good heat dissipation in a member normal temperature range.

According to the present invention to achieve the above object,
In a high thermal conductivity diamond composite Al alloy member composed of a matrix composed of one of Al and Al alloy and diamond particles dispersed in the matrix, this member is a plastically worked product, and the thermal conductivity C is the temperature. As the temperature rises, it changes into a mountain shape, and the maximum value Cmax of its thermal conductivity C is the member normal temperature range Rt 37.
Provided is a high thermal conductivity diamond composite Al alloy member present in 3K ≦ Rt ≦ 573K.

Since the member is a plastically processed product, its forming temperature is relatively low, and therefore the strain generated during cooling of the member is small. This can greatly improve the thermal conductivity C of the member.

Further, since the maximum value Cmax of the thermal conductivity C is made to exist in the member normal temperature range Rt, it is possible to improve the heat dissipation in the temperature range Rt to avoid overheating of the member and enhance the durability of the member. You can

Further, the fact that the maximum value Cmax exists in the member normal temperature range Rt means that the thermal conductivity C of the member is low in a region lower than the lower limit temperature 373K of the temperature range Rt, and therefore the member is heated. It has the characteristic of being easy.

However, if the maximum value Cmax exists in a region lower than the lower limit temperature 373K of the member normal temperature range Rt, it becomes difficult to heat the member, while the maximum value Cmax is increased.
If max exists in a region exceeding the upper limit temperature 573K of the member normal temperature region Rt, overheating of the member is caused.

Another object of the present invention is to provide the above-mentioned manufacturing method capable of mass-producing the member.

According to the present invention to achieve the above object,
In producing a highly heat-conductive diamond composite Al alloy member composed of a matrix composed of Al and one of Al alloys and diamond particles dispersed in the matrix, one of the Al powder and the Al alloy powder and the volume fraction are used. A processing temperature T of 573K ≦ T ≦ 8 is applied to a material made of diamond powder having Vf of 25% ≦ Vf ≦ 60%.
Provided is a method for manufacturing a high thermal conductivity diamond composite Al alloy member which is subjected to plastic working under the condition of 23K.

According to the above method, the maximum value C of the thermal conductivity C
max is a member normal temperature range Rt, 373K ≦ Rt ≦
The member existing at 573K can be mass-produced.

However, the volume fraction Vf of diamond powder
When Vf <25%, the thermal conductivity C of the member does not change like the mountain shape as described above, while when Vf> 60%, the strength of the member decreases. Further, when the working temperature T is T <573K, plastic working cannot be performed, while when T> 823K, the thermal conductivity C of the member is caused by the large strain as described above.
Of the thermal conductivity C is the highest value Cma
x exists in a region exceeding the upper limit temperature 573K of the member normal temperature region Rt.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In FIG. 1, a high thermal conductivity diamond composite Al alloy member 1 is an extruded material as a plastic work product, and one of Al and Al alloys, in the illustrated example, A
The matrix 2 is composed of 1 and the diamond particles 3 dispersed in the matrix 2.

FIG. 2 shows the relationship between the thermal conductivity C and the temperature of diamond, Al and the member 1. In the member 1, the volume fraction Vf of diamond powder is Vf =
50%, and the extrusion temperature (processing temperature) T is T = 673.
Each set to K.

The thermal conductivity C of diamond decreases as its temperature rises, and the thermal conductivity C of Al is substantially constant regardless of its temperature change.

The thermal conductivity C of the member 1 exists between both the thermal conductivity C of diamond and Al according to the composite rule. The calculated value of the thermal conductivity C decreases as the temperature of the member 1 rises, but the measured value of the thermal conductivity C changes as follows.

The coefficient of thermal expansion of diamond is about 2 × 10 ^-6 /
K, while that of Al is about 25 × 10 ⁻⁶ / K, and there is a relatively large coefficient of thermal expansion difference between the two. Due to this, distortion occurs in the member 1 during cooling of the member 1 after extrusion, and this distortion becomes a factor that hinders the improvement of the thermal conductivity of the member 1. Therefore, the measured value of the thermal conductivity C is , The temperature of the member 1 is from room temperature (293K) to the extrusion temperature K = 67.
When it is in the range of less than 3K, the difference Δ is larger than the calculated value.
It becomes smaller by C. On the other hand, the temperature of the member 1 is the extrusion temperature T
= 673K, the distortion disappears, so ΔC
= 0, the measured value becomes equal to the calculated value.

The measured value is that the thermal conductivity C at a temperature of 473K.
As the maximum value Cmax of C.sub.max appears, the temperature changes to form a mountain shape.

The amount of strain of the member 1 changes depending on the extrusion temperature T when the volume fraction Vf of the diamond powder is constant. In FIG. 3, when Vf = 30%, the extrusion temperature T is T =
The thermal conductivity C when set to 573K and when set to T = 873K is shown. When the extrusion temperature T is set to T = 573K, the amount of strain of the member 1 is smaller than that when it is set to 873K, and as a result, the thermal conductivity C is high and the maximum value Cmax is located on the low temperature side.

The present invention provides the diamond composite A as described above.
In the 1-alloy member 1, it is essential that the maximum value Cmax of the thermal conductivity C exists in the member normal temperature range Rt of 373K ≦ Rt ≦ 573K. This is because the member 1 is applied to a heat resistant member such as a piston for an internal combustion engine.

In the production of the member 1, an extrusion temperature T is 573K on a material composed of Al powder and diamond powder having a volume fraction Vf of 25% ≤Vf≤60%.
Extrusion processing is performed under the condition of ≦ T ≦ 823K.

The member 1 is an extruded material, and the extrusion temperature T thereof is relatively low, so that the strain generated during cooling of the member 1 is small. Thereby, the thermal conductivity C of the member 1 can be greatly improved.

Further, since the maximum value Cmax of the thermal conductivity C is made to exist in the member normal temperature range Rt, the heat dissipation of the temperature range Rt is improved to avoid the overheating of the member 1 and the durability of the member 1 is improved. Can be increased.

Further, the fact that the maximum value Cmax exists in the member normal temperature range Rt means that the heat conductivity of the member 1 is low in a region lower than the lower limit temperature 373K of the temperature range Rt, and therefore the member 1 is heated. It has the characteristic that it is easy to be affected.

The average particle diameter d of the diamond particles 3 is 1 μm.
It is desirable that ≦ d ≦ 60 μm. Average particle size d is d
> 60 μm, the strength of member 1 decreases, while d <1 μ
With m, the thermal conductivity C of the member 1 decreases because there are too many interfaces.

Hereinafter, embodiments will be described. (A) Al powder of 99.9% purity manufactured by the air atomizing method and Al composed of 6061 material
Alloy powder was prepared. The average particle size of these powders is 25 μm
It is. Further, a diamond powder having an average particle diameter d of d = 20 μm manufactured by the high pressure synthesis method was prepared. (B) The Al alloy powder and the volume fraction Vf are each 10 by the mixing process for 24 hours using a V-type blender.
%, 20%, 25%, 30%, and 50% mixed powder of diamond powder, and a mixed powder of Al alloy powder and diamond powder having a volume fraction Vf of 30% were prepared. (C) A billet (material) having a diameter of 35 mm and a length of 50 mm was formed by performing CIP (Cold Isostatic Press) method using each mixed powder under the condition of 4000 kgf / cm ² .
The relative density of each billet was 92-98%. (D)
Using each billet, the extrusion temperature T is set to room temperature,
Examples 1 to 9 of a plurality of diamond composite Al alloy members were set by setting 473K, 573K, 673K, 823K, and 873K, and extruding by setting the extrusion ratio to 9.8.
I got In addition, when the extrusion temperature T was set to room temperature and 473K, extrusion processing could not be performed.

A test piece having a diameter of 10 mm and a thickness of 2 mm was prepared from Examples 1 to 9 and the thermal conductivity C of each test piece was measured by the laser flash method. The results shown in FIG. 4 were obtained. Data regarding Al is also shown in FIG. 4 as Example 10.

As is clear from FIG. 4, in Examples 1 to 6 in which the volume fraction Vf of the diamond powder is set to 25% ≤Vf≤60% and the extrusion temperature T is set to 573K≤T≤823K, respectively. The conductivity C is high, and the maximum value Cmax of the thermal conductivity C exists in the member normal temperature range Rt, that is, 373K ≦ Rt ≦ 573K.

In Example 7, the maximum value Cmax exceeds the member normal temperature range Rt. This is because the extrusion temperature T is T> 873.
Due to being K. Further, the thermal conductivity C of Examples 8 and 9 changes substantially flatly, so that the maximum value Cmax does not appear in the member normal temperature range Rt. This is because the volume fraction Vf of diamond powder is Vf <25%.

From FIG. 4, it is desirable that the thermal conductivity C in the member normal temperature range Rt is C> 260 W / mK,
It can be said.

[0037]

EFFECTS OF THE INVENTION According to the present invention, with the above-mentioned constitution, it is possible to provide a diamond composite Al alloy member having high thermal conductivity and good heat dissipation in the member normal temperature range.

Further, according to the present invention, it is possible to provide a manufacturing method capable of mass-producing the diamond composite Al alloy member.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a diamond composite Al alloy member.

FIG. 2 Diamond, Al and diamond composite A
It is a graph which shows the relationship between the temperature and thermal conductivity regarding a 1-alloy member.

FIG. 3 is a graph showing the relationship between temperature and thermal conductivity for diamond composite Al alloy members having different extrusion temperatures.

FIG. 4 is a graph showing the relationship between temperature and thermal conductivity for various diamond composite Al alloy members.

[Explanation of symbols]

 1 Diamond composite Al alloy member 2 Matrix 3 Diamond particles

Claims (4)

[Claims] 1. A highly heat-conductive diamond composite Al comprising a matrix composed of one of Al and Al alloy and diamond particles dispersed in the matrix.
In the alloy member, this member is a plastically worked product, and the thermal conductivity C changes into a mountain shape with an increase in temperature,
Further, the high thermal conductivity diamond composite Al alloy member is characterized in that the maximum value Cmax of its thermal conductivity C exists in a member normal temperature range Rt of 373K ≦ Rt ≦ 573K. 2. The high thermal conductivity diamond composite Al alloy member according to claim 1, wherein the thermal conductivity C in the member normal temperature range Rt is C> 260 W / mK. 3. The average particle diameter d of the diamond particles is 1
μm ≦ d ≦ 60 μm, and its volume fraction Vf is 2
The high thermal conductivity diamond composite Al alloy member according to claim 1, wherein 5% ≦ Vf ≦ 60%. 4. A high thermal conductivity diamond composite Al composed of a matrix composed of one of Al and Al alloy and diamond particles dispersed in the matrix.
In manufacturing the alloy member, one of Al powder and Al alloy powder and diamond powder having a volume fraction Vf of 25% ≦ Vf ≦ 60% is used as a material, and the processing temperature T is 5
A method for producing a highly heat-conductive diamond composite Al alloy member, characterized by performing plastic working under the condition of 73K ≦ T ≦ 823K.