JPS59118292A - Formation of low melting point alloy layer for diffusion joining - Google Patents

Abstract

PURPOSE:To form uniformly a low melting point alloy layer for diffusion joining on joint surface by providing a film for preventing the formation of the low melting point alloy layer on the surface of a material to be joined except its joint surface then forming the low melting point alloy layer on the joint surface and removing the above-mentioned preventing film by an etching treatment. CONSTITUTION:A film 3 for preventing the formation of a low melting point alloy is formed on the part of a material to be joined 1 except its joint surface 2, then a low melting point alloy layer 4 is formed by a packing method on the surface 2. An etching preventive film 5 is formed on the surface of said layer 4 and is subjected to an etching treatment to remove the film 3. The film 5 is then removed by using a solvent so that the low melting point alloy layer for diffusion joining is formed only on the surface 2. The low melting point alloy layer is easily formed on the joint surface having an intricate shape by the above-mentioned method.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a method for forming a low melting point alloy layer for diffusion bonding, and in particular to a method for forming a low melting point alloy layer for bonding that is suitable for diffusion bonding of heat resistant alloys of complex-shaped parts. Concerning the method formed by the back method.

[Prior art]

Diffusion bonding methods are classified into two types: solid phase diffusion bonding methods and liquid phase diffusion bonding methods. In-phase diffusion bonding requires the application of relatively high pressure during bonding.

For this reason, it is not preferable to apply it to joining members where deformation must be avoided. In addition, in the case of joining parts with complex shapes, it is necessary to consider the equipment and pressure method required for joining, and at the same time, applying reliable and uniform pressure to the joint surfaces is a difficult task. .

On the other hand, in the liquid phase diffusion bonding method, by selecting an insert material that does not require applying pressure to the bonding surfaces, it becomes unnecessary to apply pressure to the bonding members.

A diffusion bonding method has been proposed in which an insert material is interposed between the bonding surfaces of bonding members. (U.S. Patent No. 36323
(No. 19, U.S. Pat. No. 3,678,570) However, since this method uses foil or powder as an insert method, in the case of parts with complex shapes or large shapes, the insert material tends to shift or break, resulting in poor bonding defects. The insert work process is also time consuming and has poor workability. Further, even if a low melting point alloy layer is formed on the joint surface of the materials to be joined by such a method, the low melting point alloy layer is also formed on a portion other than the joint surface, so it is necessary to cut this portion.

For this reason, workability is poor because dimensional processing and the like must be taken into account for the materials to be joined.

[Purpose of the invention]

The purpose of the present invention is to enable uniform formation of a low melting point alloy layer for diffusion bonding even on complex-shaped bonding surfaces, simplify the bonding work, prevent defective bonding, and obtain high-quality diffusion bonded parts. An object of the present invention is to provide a method for forming a low melting point alloy layer for diffusion bonding.

When forming a low melting point alloy layer for diffusion bonding by the pack method, the present invention provides a low melting point alloy layer forming film on parts other than the bonding surfaces of the materials to be joined, and then uses a back method to form a low melting point alloy layer on the bonding surfaces of the materials to be joined. After forming a melting point alloy layer and providing an etching prevention film on this low melting point alloy layer, the low melting point alloy formation prevention film is removed by etching treatment to form a low melting point alloy layer for diffusion bonding only on the joining surfaces of the materials to be joined. It is designed to form a .

Next, a method for forming a low melting point alloy layer for diffusion bonding according to the present invention will be explained based on FIG.

FIG. 1(A) shows a processed material 1 to be joined, and 2 in the figure is a joining surface for diffusion joining. A low melting point alloy layer formation prevention film 3 is formed on the workpiece 1 other than the joint surface 2 [Figure 1 (B
)]. Next, a low melting point alloy layer 4 is formed on the bonding surface 2 by the back method (FIG. 10).

An etching prevention film 5 is formed on the surface of the low melting point gold layer 4 formed on the bonding surface 2 [FIG. 1(D)].

Next, the low melting point alloy formation prevention film is removed by etching treatment [FIG. 1(E)]. Next, the etching prevention film 5 is removed using a solvent [FIG. 1(F)]. In this way, the low melting point alloy layer 4 for diffusion bonding is formed only on the bonding surface 2, and by bonding these low melting point alloy layers 4 to each other and performing a predetermined diffusion treatment, the materials to be bonded are firmly bonded. Ru. [FIG. 1 (G)] Here, the material to be joined 1 is preferably a heat-resistant alloy, particularly a heat-resistant alloy for complex-shaped parts. As heat-resistant alloys, especially Ni-based and Fe
Base heat-resistant alloys are preferable. The low melting point alloy formation prevention film 3 is stable at the pack temperature when forming the low melting point alloy layer by the back method, and has low bonding properties to the low melting point alloy layer formed by the back method and is easy to be etched. Something is desirable.

Therefore, the low melting point alloy formation prevention film 3 can be made of metal 1 alloy or other inorganic materials.

Further, as the film forming means, all surface coating layer forming methods such as plating, thermal spraying, CVD, etc. can be applied.

The low melting point alloy layer 4 is required to be an alloy having a melting point υ' lower than the in-phase line temperature of the heat-resistant alloy.

As such a low melting point alloy, when the material to be joined is an Nt-based heat-resistant alloy, an alloy containing B, which can lower the melting point by forming a eutectic with the Ni-based heat-resistant alloy and the main element NI, is desirable. . When the low melting point alloy layer is a layer of an alloy containing B,
The Cu plating layer is the most effective low melting point alloy formation prevention film. According to the plating method, a surface coating layer with a uniform thickness can be formed on a component having a complex shape at a lower cost than other methods of forming a surface coating layer such as a thermal spraying method or a CVD method. Furthermore, when forming a Cu surface coating layer by plating, Cu has a lower bonding property to NI-based heat-resistant alloys than alloys containing B, so it is difficult to efficiently remove only the Cu plating layer during etching. can. Further, since B has a high diffusion speed, the diffusion process can be shortened.

As the etching prevention film 5, an organic material is used that does not dissolve in the etching treatment solution but can dissolve in a specific organic solvent.

[Embodiments of the invention]

Examples of the present invention will be described below.

Table 1 shows the chemical composition of the test materials.

Table 1 The sample material is a precipitation-strengthened Ni-based heat-resistant alloy.
A low melting point alloy layer was formed by processing according to the steps shown in the figure. Table 2 shows the treatment conditions for the low melting point formation prevention film.

Table 2 A copper plating film of 30 μm was formed on the parts other than the bonding surfaces of the materials to be bonded under the processing conditions shown in Table 2.

Next, a boriding process was performed as a low melting point alloy layer forming process.

Table 3 shows the boriding treatment conditions.

Table 3: For the fertilizing treatment, first, the processing agent and the parts to be joined which have been subjected to the film forming treatment are placed alternately in a boriding treatment container, and the process is carried out under the conditions shown in Table 3. An alloy layer was formed on the surface.

Next, an alloy layer was formed on the joint surfaces of the materials to be joined, and then an acrylic resin was applied to the joint surfaces to form an etching prevention film. Next, the copper plating film was removed by etching under the conditions shown in Table 4.

Furthermore, the etched sample parts were immersed in methyl ethyl ketone to remove the acrylic resin and form a low melting point alloy layer only on the joint surfaces of the materials to be joined.

FIG. 2 shows the formation of the low melting point alloy layer. The thickness of the low melting point alloy layer is about 30 μm, and the melting point of the alloy layer is about 1135C. Solidus temperature of Ni-based heat-resistant alloy 125
Compared to 0t:', the melting point is lowered by about 115C, and the formation of an alloy layer by fertilizing treatment is effective for diffusion bonding. Moreover, the alloy layer could be accurately and uniformly formed only on the joint surfaces.

Next, the Ni-based heat-resistant alloys having alloy layers containing B formed on their joint surfaces were subjected to diffusion bonding under the conditions shown in Table 5 so that the surfaces of the alloy layers containing B were in contact with each other.

The diffusion bonded portion of the Ni-based heat-resistant alloy obtained by this diffusion bonding process is shown in FIG. According to FIG. 3, it can be seen that there are no defects such as poor bonding in the diffusion bonded portion of the Ni-based heat-resistant alloy, and a homogeneous bonded portion can be obtained within a bonding time of about 15 hours.

Figure 4 shows the mechanical properties of the diffusion bond. As is clear from FIG. 4, the mechanical properties (tensile strength, elongation, 0.2% proof stress) of the diffusion bonded portion are comparable to those of the base material.

(9) In the above-mentioned embodiments, a method was described in which the fertilization treatment was performed by burying the material in a packing agent made of powder, but a method in which a slurry-like packing agent is applied to the joining surfaces of the materials to be joined may also be used.

〔Effect of the invention〕

As described above, according to the present invention, the insert foil or powder can be applied to complex-shaped and large-sized parts without causing displacement or damage of the insert foil or powder unlike the conventional method in which the insert foil or powder is interposed between the joining surfaces of the materials to be joined. The work is simple and high-quality joints can be obtained. Further, since the low melting point alloy layer can be formed uniformly and with high dimensional accuracy only on the surfaces to be joined of complex-shaped and large-shaped parts, there is no need to perform finishing processing after forming the low melting point alloy. Furthermore, when diffusion bonding the materials to be joined obtained by the present invention, the diffusion bonding process can be performed with a low load, without requiring high loads as in the conventional solid phase diffusion bonding method, so that deformation of the materials to be joined can be avoided. It is possible to obtain a good diffusion bonding portion while preventing the diffusion.

[Brief explanation of drawings]

(10) Figure 1 is an explanatory diagram showing the process order of the low melting point alloy layer forming method of the present invention, and Figure 2 is a microscope showing the cross-sectional structure of the welded material on which the low melting point alloy layer obtained in the example was formed. The photograph, Fig. 3 is a micrograph showing the cross-sectional structure of the diffusion bonded part of the materials to be joined shown in Fig. 2, and Fig. 4 is a graph showing the mechanical properties of the diffusion bonded part and the base material shown in Fig. 3. . DESCRIPTION OF SYMBOLS 1... Member to be joined, 2... Joining surface, 3... Low melting point alloy layer formation prevention film, 4... Low melting point alloy layer, 5... Etching prevention film. (11) ＼ rtsu″i
-3 drawings, 2 drawings/QQ tiles, words, seagulls and words -←Join Nomen Riichiichi' L 0 1200'Cx 15 Procedural amendment (method) Showa 518 4', 7 The case of Mr. Kazuo Wakasugi, Commissioner of the Japan Patent Office Indication: Patent Application No. 225892 filed in 1982 Name of the invention: Method for forming a low-melting point alloy layer for diffusion bonding Relationship with the case concerning the person making amendments Patent applicant address: 5-1 Marunouchi-chome, Chiyoda-ku, Tokyo
1510) Hitachi, Ltd. Representative 3
1) Osamu Katsu Shigeyo Residence Address: 5-1 Marunouchi-chome, Chiyoda-ku, Tokyo ``Drawings'' subject to amendment Contents of amendment Figures 2 and 3 of the drawings will be revised as shown in the attached sheet. Kaya 2 E Kaya 3 Eyes 505

Claims (1)

[Scope of Claims] 1. In a method of forming a low melting point alloy layer for diffusion bonding on the joining surface of materials to be joined by a back method, the formation of the low melting point alloy layer on a portion other than the joining surface of the materials to be joined is prevented. A film is provided, and then a low melting point alloy layer is formed on the bonding surface of the materials to be joined by a back method, and an etching prevention film is provided on this low melting point alloy layer, and then the low melting point alloy layer formation prevention film is formed by an etching process. A method for forming a low melting point alloy layer for diffusion bonding, characterized in that the low melting point alloy layer for diffusion bonding is removed and the low melting point alloy layer for diffusion bonding is formed only on the bonding surfaces of the materials to be bonded. 2. The low melting point for diffusion bonding according to claim 1, wherein the low melting point gold layer formation prevention film is a copper film, and the low melting point alloy layer is an alloy layer containing B. Alloy layer formation method. 3. In claim 2, the material to be joined is N.
A method for forming a low melting point alloy layer for diffusion bonding, characterized in that it is an i-based heat-resistant alloy.