JPS59225893A - Joining method of ti or ti alloy to al or al alloy - Google Patents

Abstract

PURPOSE:To form a joint part having high quality without intervention of a brittle intermetallic compd. by sputtering the surface of the joint part in a non-oxidative atmosphere then coating a material which is more hardly oxidized than Al and Ti and produces eutectic crystal with Al on the surface thereof. CONSTITUTION:Either one of Al or Al alloy material and Ti or Ti alloy material charged into a sample exchange chamber 2 is carried into a cleaning and surface treating chamber 1 where the surface is sputtered by an Ar ion beam and is then coated. The material is then returned to the chamber 2 and the other material is similarly treated in the chamber 1. The material is again returned to the chamber 2 and the joint surfaces of both materials are brought into tight contact with each other. The materials are then carried into a diffusion chamber 3 where the materials are joined. The coating in this case is formed on the surfaces in order to maintain the clean surfaces removed of oxide until joining and to permit easy joining. Ni, Cu, Si, etc. are used for coating. These coating materials melt by generating eutectic crystal with Al and are extruded in the stage of joining.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a method for joining Ti or Ti alloy and At or At alloy used in ultra-high vacuum chambers and the like.

[Background of the invention]

Conventionally, it has been extremely difficult to join dissimilar metals, particularly Ti or Ti alloy (hereinafter abbreviated as Ti) and At or At alloy (hereinafter abbreviated as Al). For example, when welding (fusion welding) is performed, an intermetallic compound of Ti and At is formed at the joint, making the joint fragile.

There is also a known solid-state diffusion bonding method, but it is difficult to bond At and TI because a strong oxide film is attached to the surface.

Therefore, as in the past, A, t between the Ti and At junctions
A method is known in which diffusion bonding is performed by interposing a sheet material made of an alloy of and Si, heating the sheet material to its melting temperature, and applying pressure. In this case, since the sheet material is melted, the purpose is to use this molten metal to destroy or dissociate the strong oxide film on the bonding surfaces of A, t and Ti. Furthermore, since the sheet material is pressurized while it is melted, part of the sheet material and the destroyed oxide film are pushed out to the joint surface, making it possible to join. However, even with this method, the oxide film on the bonding surface remains as microscopic inclusions in the bonded portion, making it impossible to achieve high quality bonding. Especially 10-' Torr
~1゛O-'' Torr is unsuitable for bonding ultra-high vacuum parts because leakage occurs.

In addition, there is also a method of vacuum brazing A t and S with a brazing filler metal after cleaning with nitric-fluoric acid, caustic soda, etc. as a pre-treatment for bonding, but since the pre-treatment is performed in the atmosphere, the bonding surfaces are quickly oxidized. That's a problem. In other words, it is difficult to employ this method for bonding in an ultra-high vacuum chamber for the same reason as mentioned above.

[Purpose of the invention]

In view of the above, an object of the present invention is to obtain a high-quality joint between Ti and A7 without the presence of a fragile intermetallic compound.

2 [Summary of the Invention] The present invention sputters the bonded surface of Ti and At in a non-oxidizing atmosphere, removes the strong oxide film, and then attaches the sputtered surface to the sputtered surface, which has less reactivity in the atmosphere than At and Ti. The method is characterized in that after being coated with a substance that is inert and has a eutectic reaction with At, it is heated to a temperature higher than the eutectic temperature and bonded under pressure.

To carry out this method, it is preferable to use a bonding apparatus that can process without contacting the atmosphere using the same vacuum chamber or a plurality of vacuum chambers separated by a gate pulp that can be opened and closed freely.

For example, if At, AES is used after normal pretreatment, A-r+
When inspected while sputtering, about 50 oxides were found attached. Therefore, bonding properties can be improved by removing the oxide with an Ar ion beam or the like and at the same time coating with an element that has a smaller oxide forming ability than At and which forms a eutectic. The coating is provided to remove the oxide and maintain a clean surface until bonding, and to facilitate bonding. In order to prevent oxidation after coating, A.
For G, Au, Nl, Cu, etc., adsorbed oxygen can be dissociated by heating in a diffusion furnace even at a pressure of about 10-' Torr, but
It is desirable that Si or the like be 10 −8 Torr or less. Regarding Zn, since its vapor pressure is high, it is difficult to bond with Ar after coating.
Any inert gas atmosphere is best. The coating is At
For the reasons mentioned above, it is desirable to perform this treatment on both sides of Ti and Ti.

After coating, At and Ti are superimposed and bonded by heating and pressing. Oxygen and the like adsorbed on the surface of the coating layer are dissociated by this heating, so that the bonding surfaces can be kept clean during bonding.

In order to perform the above method more effectively, Ar'' ion sputtering, coating, and bonding must be performed in the same vacuum chamber.A schematic diagram of the processing equipment is shown in Figure 1.A
r 4- Consists of a clean surface processing chamber 1 for performing ion sputtering and coating processing, a sample exchange chamber 2, and a diffusion furnace 3. The clean surface treatment room is equipped with a mass spectrometer to evaluate cleanliness. Further, each chamber is connected to the chamber via a communication path having a gate pulp that can be freely opened and closed, and is provided with a conveyor for moving At and Ti between the chambers. In addition, A I- and T t were moved to the clean surface processing room 1 and the sample exchange room 2.
Equipped with a manubrator for lifting, lowering, and rotating.

One of the At and Ti charged into the sample exchange chamber 2 is first transported to the clean surface treatment chamber 1, where it is cis-battered by an Ar'' ion beam, coated, and transferred to the sample exchange chamber 2.
The opposing surfaces are then carried into the clean surface processing chamber 1, subjected to the above-mentioned processing, and returned to the sample exchange chamber 2, where the joining surfaces are brought into close contact with each other and carried into the diffusion furnace 3, where bonding is performed. A
The surface is cleaned by removing oxides by the r9 ion beam, and the mass spectrometer 7 in the clean surface processing chamber 1 determines whether the surface has been cleaned.

By using the above method and apparatus, a high-quality joint part that can be applied to joining ultra-high vacuum chambers and the like can be obtained.

Cleaning is also possible by using energy beams such as electron beams and laser beams instead of Ar+ ion beam sputtering.

[Embodiments of the invention] The present invention will be explained below by way of examples.

Pure TI (two types of titanium plates) and pure At (J I
S 1050 ) was used. After charging this into the sample exchange chamber 2 of the bonding apparatus shown in FIG. 1, it was evacuated to a vacuum of 10'''l'orr and Ti was first carried into the clean surface processing chamber 1 under 10''' Torr. After delivery, the Ar'' ion beam was incident at an angle of 45° to the joint surface, and 200 people/w
The etching speed was 10 minutes. After etching, the atmosphere was set to A r I F 3 Torr and S+ was coated. The coating was performed using a high frequency sputtering device 5 installed in the processing chamber.

The coating thickness was 5 μm. After coating, it is returned to the sample exchange chamber 2, and the opposing kt is carried to the clean surface treatment chamber 1, where it is treated under the same conditions as described above, and then Ti and At are brought into close contact with each other in the sample exchange chamber 2, and then carried to the diffusion furnace 3. did.

The bonding was performed at a bonding temperature of 600C, a bonding pressure of 0.2 Ky/constant 2, and a bonding time of 30 minutes. At this time, the degree of vacuum is 10
-6 Torr.

When heated at a bonding temperature of 600 C4, At, ':Si becomes molten due to a eutectic reaction and diffuses into p, Ti, and At. On the other hand, since the bonding material is pressurized, the molten part is
Part of it is pushed out from the bonding interface. Therefore, the liquid phase of the ht-si gold alloy at the bonding interface disappears, and in the process of being maintained at 600 tr, Tr, ht, s+
are mutually diffused, and At and Ti are integrated. The holding time depends on the bonding temperature, but care must be taken since a long holding time will involve the generation and growth of intermetallic compounds, and the preferred holding time is 30 minutes at 600C.

As shown in the micrograph shown in FIG. 2, good bonding can be achieved.

1 and 2, 4 is a sputter gun, 6 is a material to be joined (At/'Pi), 8 is a pressure system, 9 is a pressure jig, 1
0 is a heater, 11 is a vacuum system, 12 is a microcomputer, 13 is an Ar inlet, 14 is a high frequency sputtering power source, 1
5 represents At, 16 represents a joint, and 17 represents Ti.

Using Tl and A obtained above, an I(e IJ-ri test was conducted on a test piece with a bonded joint.Results 1
0” Torr-t/sec or less, airtightness iu,
It fully satisfied the specifications for ultra-high vacuum chambers/bars.

In this example, the case of Ti and At was explained, but k
It is possible to join any combination of dissimilar materials with A and t as the base, such as A and kl or At and stainless steel.

[Brief explanation of drawings]

Figure 1 is a schematic diagram of the device used in the bonding method of the present invention;
The figure is a micrograph of the joint. 1...Clean surface processing room, 2...Sample exchange room, 3...
Diffusion furnace, 4... Sputter gun, 5... High frequency sputtering device, 6... Material to be joined (including t/Ti), 7... Mass spectrometer, 8... Pressure system, 9...・・Pressure jig, 10・
··heater. -(9) 547- Continuation of Bai Daiichi Sada (Inventor Tatsube Ishizuka 3-1-1 Saiwaimachi, Hitachi City Stock% formula%

Claims (1)

[Claims] 1. In the dissimilar material diffusion bonding method of 'rt or Ti alloy and A or A, the joint surface is sputtered in a non-oxidizing atmosphere, and the sputtered surface has a higher reactivity in the atmosphere than At and Ti. is inert and At
Ti or Ti alloy and At or A-
How to join the alloy.