JPH0910962A - Method for joining aluminum material and stainless steel material - Google Patents

Abstract

PURPOSE: To provide a method for joining an aluminum material and stainless steel material which is easy in the joining method regardless of shapes and is adequately usable for production of an enclosure for an X-ray image multiplier tube, etc. CONSTITUTION: An Ag plating layer 9 is interposed into the joint surfaces between an input window 12 made of hemispherical planar aluminum of the enclosure 1 for the X-ray image amplifier tube and a stainless steel flange 3. These joint surfaces are diffusion joined by a hot pressurizing method. The Ag layer at the joint surfaces is diffused into the aluminum input window 2 by eutectic reaction and the intermetallic compd. layer of Fe-Al is formed at the joint boundary, by which the aluminum material and the stainless steel material are securely joined.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of joining dissimilar materials (aluminum material and stainless steel material), and is preferably used for manufacturing an envelope for an X-ray image intensifier tube.

In the text, "aluminum material" means pure aluminum material, aluminum alloy material and the like, and "stainless steel material" means various stainless steels.

[0003]

2. Description of the Related Art Conventionally, various kinds of joining methods have been proposed for joining different kinds of materials in consideration of application. Especially, it is not possible to perform usual welding on a combination of an aluminum material and a stainless steel material. Joining methods have been tried. That is, the surface to be joined is subjected to various surface treatments (plating or vapor deposition of various metals) and then brazing is performed, or an intermediate material is inserted between the two and then the explosive welding method or pressure method (or rolling) is performed.
The method of joining is adopted. For example, a method in which a stainless steel material is plated with Ni and then an aluminum brazing material is interposed to braze the aluminum material (JP-A-61-2).
No. 53166), or a method of brazing using Ag brazing on a stainless steel material and then using an aluminum brazing material for vacuum brazing (JP-A-60-133971), by inserting a Ti plate into an aluminum plate and a stainless steel plate. Explosion welding method, heating and pressurizing with Si compound interposed between stainless steel and aluminum, continuous rolling pressure welding of aluminum and stainless steel using a rolling roll (JP-A-1- No. 138078) is known.

[0004]

However, the Ni plating method described above requires special consideration in the selection of plating conditions, and the Ag plating method causes the Ag layer to remain porous at the bonding interface, so that vacuuming is not performed. It takes a long time to
When the Ag layer is used for manufacturing an envelope for an X-ray image intensifier tube and the like, there is a disadvantage that the formation of the photocathode is adversely affected. In addition, although the method of or has the merit when manufacturing a plate material, it has a complicated shape, for example, for joining a hemispherical plate and a cylindrical plate like an envelope for an X-ray image intensifier tube. Many steps are required for application, which leads to an increase in cost. In the case of the further method, the bonding force at the joint surface is weak and there is a problem in durability.

The present invention has been made in order to solve the above problems, and has a strong bonding force, can be easily evacuated and bonded regardless of the bonding shape, and can be used for an envelope for an X-ray image intensifier tube. It is an object of the present invention to provide a method for joining an aluminum material and a stainless material that can be suitably used for manufacturing and the like.

[0006]

In order to solve the above-mentioned problems, the method for joining an aluminum material and a stainless material according to the present invention includes an Ag layer on the joining surface of both materials.
It is characterized in that the two materials are diffusion-bonded by a hot pressing method with the Ag layer interposed therebetween.

Further, a better bonding can be realized by completely diffusing the Ag layer on the bonding surface into the aluminum material by the eutectic reaction so that the Ag layer does not remain alone.

Further, better bonding can be realized by forming an Fe-Al intermetallic compound layer at the bonding interface. The intermetallic compound consisting of Fe and Al means Fe ₃
Al, FeAl, FeAl ₂ , Fe ₂ Al ₅ , FeAl
₃ or a mixture of these.

[0009]

According to the above-mentioned method, the Ag layer sandwiched between the aluminum material and the stainless material diffuses into the aluminum material during hot pressing, and the two materials are bonded and fixed by the eutectic reaction.
Further, by completely diffusing the Ag layer in the aluminum material so that it does not remain as the Ag layer alone, it is easy to evacuate when used for manufacturing an envelope for an X-ray image intensifier tube. In addition, it is possible to realize a suitable bonding that does not cause the inconvenience of adversely affecting the formation of the photocathode.

Further, the Ag layer is diffused into an aluminum material by a eutectic reaction to form an Ag + Al layer, which reacts with Fe in stainless at the joint surface to form Fe- at the joint interface.
By forming the intermetallic compound layer of Al, both materials are more firmly bonded by the chemical bonding force.

[0011]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a cross-sectional view of an X-ray image intensifier tube envelope manufactured by applying the present invention. The envelope 1 for the X-ray image intensifier is composed of a hemispherical plate-shaped input window 2 made of aluminum,
It is composed of a flange 3 made of stainless steel, an envelope body 4 made of Kovar, and a container body 5 made of glass, and these parts together form a vacuum container. First, the glass container body 5 and the Kovar envelope body 4 are joined by glass sealing, and an electron optical system (not shown) is assembled inside the glass container body 5. Also, a hemispherical plate-shaped aluminum input is made by the joining method of the present invention. The window 2 and the stainless steel flange 3 are joined together through the Ag plating layer 9, and the stainless steel flange 3 and the Kovar envelope body 4 are welded (welded portion 6) by a melt welding method such as arc welding. An envelope 1 for an X-ray image intensifier tube is obtained.

Of the above steps, the joining step of the hemispherical plate-shaped aluminum input window 2 and the stainless steel flange 3 by the joining method of the present invention will be described in detail with reference to FIG. The hemispherical plate-shaped input window 2 made of aluminum and the flange 3 made of stainless steel are sandwiched under pressure by the pressure jigs 7a and 7b, and heated to an appropriate temperature by the heater 8 to perform pressure bonding (diffusion bonding). At this time, Ag is previously formed on the joint surface of the stainless steel flange 3 side.
A plating layer 9 is formed. Ag interposed on the joint surface
The plating layer 9 is merely interposed in the state shown in FIG. 3A before joining, but by processing under, for example, the joining conditions described below, Ag layer 9 is formed as shown in FIG. 3B. Plating layer 9 is completely diffused into aluminum material 2 by a eutectic reaction to become Ag + Al layer 9a, and at the same time, Ag + Al layer 9a
At the bonding interface between the layer 9a and the stainless steel material 3, Fe-A
The intermetallic compound layer 9b of 1 is formed, and the aluminum material 2 and the stainless steel material 3 are firmly bonded. Further, when the bonding is completed, the Ag plating layer 9 is completely diffused into the aluminum material 2 so that the Ag layer does not remain as the sole Ag layer, so that the Ag layer is porous and remains at the bonding interface. This is particularly desirable when it is used for manufacturing an envelope for an X-ray image intensifier tube and the like because it can solve the inconvenience and does not cause a particular adverse effect on the formation of the photocathode.

The thickness of the Ag plating layer 9 is about 0.5 to several tens.
It may be in the μm range. The pressure applied by the pressure jigs 7a and 7b is preferably in the range of about 0.5 to 2 kgf / mm ² . Also, in this case, the joining temperature can be in the range of about 400 to 600 ° C. Since the bonding processing time depends on the diffusion reaction of the Ag layer 9, the diffusion (processing) time changes depending on the processing temperature. The proper joining time in the above example was 90 minutes at a joining temperature of 500 ° C.

The tensile shearing force at the joint between the hemispherical plate-shaped aluminum input window 2 and the stainless steel flange 3 of the X-ray image intensifier envelope manufactured by this method is 550 to 600 kg.
The shearing part was the aluminum input window 2. The envelope was able to withstand a high vacuum of 10 ^-7 to 10 ^-8 Torr. Furthermore, there was no adverse effect on the formation of the photocathode and sufficient brightness was obtained as an X-ray image intensifier tube.

In this embodiment, the Ag plating layer 9 was formed on the stainless steel flange 3 side, but this is for the purpose of interposing the Ag plating layer 9 on the joint surface, so it is formed on the aluminum input window 2 side. Of course, it doesn't matter. Also, Ag
The layer may be simply inserted as an insert material in the state of Ag foil on the joint surface.

In order to obtain good bonding strength, it is desirable that the Fe-Al intermetallic compound layer formed at the bonding interface is a thin layer of about several μm, so that the bonding temperature and bonding time do not become redundant and are proper. It is appropriately selected so that the layer thickness is formed.

[0018]

According to the joining method of the present invention, an aluminum material and a stainless steel material, which cannot be joined by a normal method, can be joined easily and firmly regardless of the joining shape. Furthermore, since an Fe-Al intermetallic compound layer is formed at the joining interface between both materials, a significantly stronger joining can be realized by this chemical bonding force as compared with the conventional joining method. In addition, by not allowing the Ag layer to remain alone when the bonding is completed, the inconvenience at the time of evacuation is eliminated, and the inconvenience of particularly adversely affecting the formation of the photocathode does not occur. Therefore, when the present joining method is applied to the manufacture of the envelope for an X-ray image intensifier, the quality and reliability thereof can be remarkably improved.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view of an X-ray image intensifier envelope which is an application example of a joining method of the present invention.

FIG. 2 is an explanatory view showing a joining method of the present invention.

FIG. 3 is an explanatory diagram showing a joined state of the present invention.

[Explanation of symbols]

 1 ・ ・ Enclosure for X-ray image intensifier 2 ・ ・ ・ Hemispherical plate aluminum input window 3 ・ ・ ・ Stainless steel flange 4 ・ ・ ・ ・ ・ ・ ・Envelope body made of Kovar 5 ... Glass container body 6 ... Welded portions 7a, 7b ... Pressurizing jig 8 ... Heater 9 ... .... Ag layer 9a ... Ag + Al layer 9b ... Fe-Al intermetallic compound layer

Claims (3)

[Claims] 1. A method for joining an aluminum material and a stainless steel material, wherein an Ag layer is interposed on a joint surface between the aluminum material and the stainless steel material, and the aluminum material and the stainless steel material are heated by sandwiching the Ag layer. A method for joining an aluminum material and a stainless material, characterized by performing diffusion bonding by a hot pressing method. 2. The aluminum material and the stainless steel material according to claim 1, wherein the Ag layer on the joint surface is completely diffused in the aluminum material by a eutectic reaction so that the Ag layer does not remain alone. How to join. 3. The method for joining an aluminum material and a stainless material according to claim 1, wherein an Fe-Al intermetallic compound layer is formed at the joining interface.