JPH06134569A - Brazing method for particle dispersed copper - Google Patents

Abstract

PURPOSE:To prevent the embrittleness generated by segregation of ceramic particles by incorporating an active metal, for example, Ti, into a brazing filler metal in such a manner that the brazing filler metal is wet in the ceramic particles when the brazing filler metal melts and brazing a material to be welded by using this active metal. CONSTITUTION:A material 11 to be combined and a material 12 to be combined are the alumina dispersion reinforced copper formed by dispersing the fine particles of Al2O3 of submicron order into pure copper matrix to reinforce the copper. The active metal brazer 13 is inserted between the joint surfaces thereof. The active metal brazer contg. the active metal Ti (at least one kind among Ti, Zr and Hf) in an Au-Cu eutectic brazer is used as the active metal brazer. The materials 11, 13 which are to be joined and are prepared in such a manner are held at and for a prescribed vacuum degree, temp. and time. As a result, the ceramic particles infiltrating the inside of the brazing filler metal from the slightly molten base materials are put into the state of being wetted and dispersed with and into the brazer at the time of solidifying the brazing filler metal and, therefore, the segregation of the ceramic particles in the final solidification and the embrittleness are prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a brazing method of copper or a copper alloy in which fine particles are dispersed in a matrix to strengthen the matrix, and particularly, to prevent brittleness of a brazed portion after brazing. Brazing method suitable for

[0002]

2. Description of the Related Art Copper is a material having good thermal conductivity and electrical conductivity. However, it has lower mechanical strength than other materials such as steel materials. Furthermore, 10 to 15 kgf / mm ² at 400 ° C The tensile strength will decrease to some extent. Therefore, Cu-Cr, C
Although precipitation strengthening alloys such as u-Cr-Zr alloys have been developed, their strength also decreases at high temperatures.

In recent years, ceramic particle dispersion strengthened copper has been developed which has an electric conductivity similar to that of pure copper and has a small decrease in strength even at high temperatures. Alumina dispersion strengthened copper is such a material. In order to utilize this material, joining is indispensable as with conventional materials. Like pure copper, fusion welding, pressure welding, brazing, etc. can be considered for joining.

[0004]

When the alumina dispersion strengthened copper is joined by a fusion welding method such as electron beam welding or arc welding, alumina is present in the molten pool. When the pool is solidified, the alumina is difficult to wet the molten copper, so that the alumina is likely to segregate in the final solidified portion, and the joint portion may be embrittled.

On the other hand, in the pressure welding method, since the material does not melt, the above-mentioned embrittlement does not occur. However, the pressure welding is generally difficult to widely use because there are restrictions on the shape and size of the bonding material.

Also, the brazing method is one of the most effective joining methods for alumina-dispersion-strengthened copper because it has no restrictions on the shape and size as the pressure welding and does not melt the base metal as much as fusion welding.
However, even in brazing, the surface layer of the base material in contact with the brazing material is molten. As a result, alumina may penetrate into the brazing material and segregate in the final solidified portion of the brazing layer, causing embrittlement.

An object of the present invention is to disperse a ceramic material in which ceramic particles are dispersed in a brazing material so as to prevent the ceramic particles infiltrated into the brazing material from segregating and solidifying during solidification of the brazing material. It is to provide a method of brazing copper.

[0008]

According to the present invention, when brazing a ceramic particle dispersion strengthened copper, a brazing material containing an active metal in the brazing material is used for brazing.

[0009]

[Function] The ceramic particles infiltrate into the brazing material from the base material slightly melted during brazing. Since the brazing material contains an active metal, the ceramic particles have good wettability. Therefore, when the brazing material is solidified, the ceramic particles are not discharged from the solution and are fixed in the solidified layer, so that the ceramic particles are not segregated and embrittlement of the brazed portion can be prevented.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows a set-up state in one embodiment of the present invention. The materials 11 and 12 to be bonded are alumina dispersion strengthened copper reinforced by dispersing Al ₂ O ₃ fine particles of submicron order in a pure copper matrix. Is. Al ₂ O ₃
Although various contents of are commercially available, 0.5 wt% Al ₂ O ₃ was used in this embodiment. An active metal brazing material 13 is inserted between these joint surfaces. In this embodiment, as the active metal brazing material, the T of the active metal is contained in the Ag—Cu eutectic brazing material.
A material containing 4 wt% of i dispersed therein was used. The materials 11 and 13 thus prepared are set in a vacuum furnace.

Next, the inside of the vacuum furnace is heated to 800 to 850 ° C. while maintaining the degree of vacuum at 10 ⁻⁴ to 10 ⁻⁵ Torr. Active metal wax
Since the melting point of 13 is about 790 ° C., the active metal braze 13 melts when kept at 800 to 850 ° C. (shown in FIG. 2- (a)). If the molten wax 14 is kept at the same temperature as it is,
The surface layer 15 of the materials 11 and 12 made of alumina dispersion strengthened copper, which is in contact with the molten brazing material 14, mutually diffuses and melts with the brazing material (FIG.
-(B)). When the materials 11 and 12 to be bonded are melted, the Al ₂ O ₃ fine particles 16 contained therein are dispersed in the molten brazing material 14 (FIG. 2- (c)). After the brazing material has sufficiently wetted the materials to be joined 11, 12, it is cooled in a vacuum furnace. The molten solder solidifies at temperatures below about 750 ° C. As is apparent from the fact that the Ti-containing active metal brazing material is also used for joining alumina bulk materials, it shows good wettability to alumina. Therefore, the Al ₂ O ₃ fine particles are dispersed in the solidification part 17 while being wetted by the molten solder when the molten solder is solidified (FIG. 2- (d)). FIG. 2 (e) shows a structural diagram after all the molten brazing solidifies to form the solidified thickness 18. When a shear test piece was prepared, the conventional Ag-C
The brazed u-Sn brazing material was peeled off during the mechanical finishing process. In this embodiment, about 20 kgf / mm ² The shear strength of According to this embodiment, when the brazing material is solidified, Al
_{Since the 2} O ₃ fine particles wet the brazing material and are dispersed in the brazing material, the brazing layer does not become brittle. When an Cu-Ag-Sn-Ti system having a lower brazing temperature is used as the active metal braze,
The deterioration of the base material can be further reduced. The combination of the materials to be joined is not limited to the alumina dispersion strengthened copper, and the combination of the alumina dispersion strengthened copper and another material is also possible. The dispersion strengthening material for copper is not limited to alumina, but other ceramics can be used. The same effect can be obtained with Zr and Hf as the active metal, not limited to Ti.

[0012]

As described above, according to the present invention, the ceramic particles, which have penetrated into the brazing material from the base material that is slightly melted by the molten brazing material, are wet and dispersed in the brazing material when the brazing material is solidified. Therefore, it is possible to prevent the ceramic particles from being segregated in the final solidified portion and embrittled.

[Brief description of drawings]

FIG. 1 is a process explanatory view showing a setup state of a material to be joined according to the present invention.

FIG. 2 is a process explanatory view showing a brazing process of the present invention.

[Explanation of symbols]

11, 12 ... Joined material 13 ... Active metal brazing material 14 ... Melting brazing material 15 ... Surface layer 16 ... Al ₂ O ₃ fine particles 17 ... Solidification part 18 ... Solidification layer

Claims (1)

[Claims] 1. When brazing copper or copper alloys in which ceramic particles are dispersed, or another material, in order to wet the brazing material to the ceramic particles when the brazing material melts, Ti, Zr, and Hf are added. A brazing method for particle-dispersed copper, characterized in that at least one active metal selected from the group is contained in a brazing material, and brazing is performed using this brazing material.