JP2004211175A - Production method of copper composite material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for imparting excellent mechanical strength and thermal and electrical properties to a copper composite material. <P>SOLUTION: An alumina (Al<SB>2</SB>O<SB>3</SB>) powder and a titanium boride (TiB<SB>2</SB>) powder are mixed with a base material (Cu powder), and the mixed powder is subsequently shaped into a primary shaped body and laterally squeezed to apply a strain corresponding to ≥200% elongation. Lateral squeezing is repeated for 12 times under a condition wherein the mold temperature is 400-1,000°C and the squeezing rate is about 1 mm/sec. Squeezing under this condition also serves as aging treatment, which facilitates deposition of the ceramic particles as well as miniaturization. This results in a secondary shaped product having average particle sizes of the base material (Cu) and the ceramic particles (Al<SB>2</SB>O<SB>3</SB>, TiB<SB>2</SB>) of ≤20 μm and ≤500 nm, respectively. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for producing a copper composite material suitable as a welding electrode material or the like.
[0002]
[Prior art]
A copper alloy in which an oxide such as alumina is dispersed in a copper matrix is widely used for electric component materials because of its excellent conductivity and heat resistance, and many proposals have been made to improve the properties and manufacturing method of this copper alloy.
For example, it has been proposed to add not only aluminum as an element to be internally oxidized but also tin as a third element to improve conductivity and softening characteristics. (Patent Document 1)
Further, it has been proposed that particles of 50 μm or less become 70% by weight or more by using a copper alloy powder in which an easily oxidizable metal such as aluminum having a size of 300 μm or less manufactured by an atomizing method is used as a solid solution. (Patent Document 2)
Further, after the Cu-Al alloy powder is internally oxidized to convert Al to Al ₂ O ₃ , the surface of the alloy powder is smoothed, and then compacted into a compact, and the compact is heated at 600 to 1000 ° C. A hot forging method has been proposed. (Patent Document 3)
Further, after the plate-like copper alloy containing Al is internally oxidized to convert Al into Al ₂ O ₃ , the plate-like alloy is made into a coil shape, the coil-like alloy is sealed in a metal tube, and the metal tube is formed into a desired shape. A method of hot working at 900 ° C. has been proposed. (Patent Document 4)
Further, a method has been proposed in which a carbon mold is filled with an alloy powder obtained by internally oxidizing a chip of a Cu—Al alloy, and hot-pressed at 900 ° C. under a pressure of 400 kg / cm ² . (Patent Document 5)
Further, a method has been proposed in which an annular hard layer of Al ₂ O ₃ is present inside a Cu—Al alloy powder to enhance sinterability. (Patent Document 6)
[0003]
(Patent Document 1) JP-A-59-150043 Patent claims (Patent Document 2) JP-A-60-141802 Patent claims (Patent Document 3) JP-A-63-241126 Page 2 Upper right column, lines 6 to 11 (Patent Document 4) JP-A-2-38541, page 3, upper right column, line 16 to lower left column, last line (Patent Document 5), JP-A-2-93029, page 3, lower right column 15, Line to page 4, upper left column, line 17 (Patent Document 6) JP-A-4-80301
[Problems to be solved by the invention]
In any of the above-mentioned prior arts, since hot working is performed at a high temperature, the structure tends to become coarse due to grain growth. It is known as Hall-Petch's law that the mechanical strength is reduced when the crystal structure of the metal material is coarsened. According to the conventional method, a property required as an electrode material for welding is a hardness of 60 (HRB) or more. In addition, it is impossible to obtain a material having an electrical conductivity of 85 (IACS%) or more and a thermal conductivity of 350 (W / (m · K)) or more.
[0005]
Then, the present inventors applied a strain corresponding to elongation of 200% to the Cu—Cr alloy that had been subjected to the solution treatment, and aged to give both mechanical strength and thermal / electrical properties. Satisfactory copper composite materials have been proposed as Japanese Patent Application Nos. 2002-210152 and 2002-210153.
[0006]
However, Al ₂ O ₃ does not form a solid solution in Cu, and a treatment method for a Cu—Cr alloy cannot be applied to a Cu—Al alloy.
[0007]
Further, the amount of Al dissolved in Cu is small, and it is difficult to increase the mechanical strength while maintaining high conductivity by increasing the amount of fine Al ₂ O ₃ deposited by complexing by the internal oxidation method. Incidentally, an alloy in which the mixing ratio of Cu and Al is arbitrarily set can be manufactured by using a ball mill, a vibration mill, and an attritor. However, according to these methods, equipment problems such as a non-oxidizing atmosphere and impurities are considered. There is a drawback that the incorporation of phenomena cannot be avoided.
[0008]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, a method for producing a copper composite material according to the present invention comprises mixing a copper powder and a ceramic powder without performing a conventional internal oxidation treatment, and forming the mixed powder into a primary shape. By extruding the primary body while applying strain to the primary body, the particle diameter of the base material was reduced, and the ceramic particles were pulverized finely to obtain a uniformly dispersed secondary body.
[0009]
Extrusion, drawing, shearing, rolling, forging, and the like can be considered as means for imparting the strain. In the case of extrusion, side extrusion performed at a mold temperature of 400 to 1000 ° C. and an extrusion speed of 0.5 to 2.0 mm / sec is effective, and the number of extrusions needs to be repeated 10 to 20 times.
The reason why the extrusion mold temperature is set to 400 to 1000 ° C. or higher is that if the temperature is lower than 400 ° C., deformation resistance is large and extrusion is difficult, and sufficient bonding strength between the parent phase and the particles cannot be obtained. This is because the melting point exceeds the melting point of copper, and distortion cannot be imparted. Therefore, the above range is preferable.
The higher the extrusion speed, the easier the strain is to be introduced. However, the reason why the extrusion speed is set to 0.5 to 2.0 mm / sec is that if the extrusion speed is less than 0.5 mm / sec, the production time is unfavorably long. The above range is preferable because the friction with the mold increases and the life of the mold is extremely shortened.
In order to perform extrusion, it is necessary to form the alloy powder into a predetermined shape (primary shape). For this purpose, means such as compacting or filling a tube with a mixed powder may be considered.
[0010]
In addition, in order to satisfy the mechanical strength and thermal / electrical properties required as electrode materials for welding, the average particle size of the base material of the obtained copper composite material is 20 μm or less, and the average particle size of the ceramic particles is 20 μm or less. Preferably it is 500 nm or less. If the particle size is larger than this, deformation due to pressurization during welding (because the compressive strength of the material is low) will be large. In order to obtain the compressive strength necessary for preventing deformation during welding, it is preferable that the particle size is equal to or less than the above particle size.
For this purpose, the average particle size of the ceramic powder used as the material is set to 0.3 to 10 μm, and the strain applied to the primary shape body is equivalent to elongation of 200% or more. The reason why the diameter of the ceramic powder is set to less than 0.3 μm is that production is difficult and the cost is unreasonable.
[0011]
In the present invention, alumina or titanium boride is preferable as the ceramic powder added to the copper matrix.
[0012]
Extrusion, drawing, shearing, rolling, forging, and the like can be considered as means for imparting strain to the material. Particularly in the case of lateral extrusion, by setting the mold temperature to 400 to 1000 ° C. and the extrusion speed to 0.5 to 2.0 mm / sec, the particle bonding temperature is lowered and sufficient strength is obtained.
[0013]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a view for explaining a process of obtaining a copper composite material according to the present invention. First, alumina (Al ₂ O ₃ ) powder or titanium boride (TiB ₂ ) powder is mixed with a base material (Cu powder). The mixing ratio is 0.1 wt% to 5.0 wt%. If it is less than 0.1 wt%, the abrasion resistance is not improved, and if it exceeds 5.0 wt%, the electrical conductivity is reduced and the life of the mold is shortened.
[0014]
Next, the above-mentioned mixed powder is made into a primary shape body for lateral extrusion. In order to obtain a primary shape, for example, compacting or filling a mixed powder in a Cu (copper) tube is performed. The primary profile is then strained by side extrusion, corresponding to an elongation of 200% or more, preferably about 220%.
In FIG. 1, the diameter of the Cu tube is made larger than the diameter of the insertion hole formed in the side-extrusion die for the sake of easy understanding of the description. Are approximately equal, and are supported by using a jig or the like so that the Cu tube does not fall when the Cu tube is pushed in by a punch.
[0015]
As a specific condition of the lateral extrusion, an ECAE (equal-channel-angular extrusion) process of repeatedly extruding 12 times at a mold temperature of 400 to 1000 ° C. and an extrusion speed of about 1 mm / sec. By repetition of the above, the microstructure of the mother phase and the pulverization and dispersion of the ceramic occur.
[0016]
FIG. 2 shows a micrograph of the crystal structure of the copper alloy obtained by the ECAE treatment. 2A shows a composite material to which alumina powder is added, and FIG. 2B shows a composite material to which titanium boride powder is added. From these photographs, it is confirmed that alumina or titanium boride having a particle size of several nm is uniformly dispersed in the copper matrix.
[0017]
FIG. 3 is a graph comparing the weldability of the copper composite material according to the present invention and the conventional copper composite material by the number of continuous dots, and among the copper composite materials according to the present invention, a copper composite material in which alumina is dispersed is used as a welding tip. In this case, 1000 or more dots were possible, and when a copper composite material in which titanium boride was dispersed was used as a welding tip, 1400 dots were possible.
[0018]
【The invention's effect】
As described above, according to the method for producing a copper alloy according to the present invention, since the solution treatment is not a starting point, there is no limitation due to the solid solution limit, and the second element particles (Al ₂ O ₃₎ in the copper alloy are not limited. And TiB ₂ ) can be set arbitrarily, and characteristics that cannot be obtained with a conventional copper composite material can be obtained.
[0019]
That is, the purity of the matrix of the copper alloy is high, the electrical characteristics are excellent, and the particle size of Al ₂ O ₃ or TiB ₂ particles deposited at the interface of the matrix particles is in the nano order (500 nm or less) because the grain growth is suppressed. And the addition amount can be set arbitrarily.
[Brief description of the drawings]
FIG. 1 is a diagram illustrating a method for producing a copper composite material according to the present invention.
FIGS. 2A and 2B are micrographs showing a crystal structure of a copper alloy obtained by a production method according to the present invention, wherein FIG. 2A is a copper composite material to which alumina is added, and FIG. 2B is a copper composite material to which titanium boride is added. Shows the material.
FIG. 3 is a graph comparing the weldability of the copper composite obtained by the production method according to the present invention and the conventional copper composite by the number of continuous hit points.

Claims (5)

A copper powder and a ceramic powder are mixed, the mixed powder is made into a primary shape, and the primary shape is strained to reduce the diameters of the base material and the ceramic particles and combine with the secondary shape. A method for producing a copper composite material, comprising: The method for producing a copper composite material according to claim 1, wherein the means for imparting the strain is extrusion performed at a mold temperature of 400 ° C. or more and 1000 ° C. or less. The method for producing a copper composite material according to claim 1, wherein the primary shape body is obtained by compacting or filling a tube with a mixed powder. 3. The method for producing a copper composite material according to claim 1, wherein the ceramic powder has an average particle size of 0.3 to 10 μm, and a strain applied to the primary shape body corresponds to an elongation of 200% or more. And a mean particle size of the base material of the obtained secondary shape body is 20 μm or less, and a mean particle size of the ceramic particles is 500 nm or less. 4. The method for producing a copper composite material according to claim 1, wherein said ceramic powder is alumina or titanium boride.

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