JPH05302161A - Vacuum flange - Google Patents

Abstract

PURPOSE:To provide an aluminum-alloy vacuum flange with the seal surface coated with a surface protective film excellent in durability. CONSTITUTION:The surface protective film has a structure, in which a metallic phase and a hard phase are intermixed, and is formed by vapor deposition on the seal surface of an aluminum-alloy flange to be used as a vacuum flange. The metallic phase preferably consists of an alloy contg. Ni and Co or Ni or Co. The hard phase consists of the nitride, carbide or boride of at least one kind among groups IVa, Va and VIa transition metals, Al and Si. The metallic phase is preferably formed with an Fe-Ni alloy, and the hard phase is formed with an Fe-Cr-N double nitride. The content of the metallic phase in the protective film is preferably controlled to 5-85wt.%.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an aluminum alloy flange used in a vacuum container, and in particular, it has two phases of a metal phase and a hard phase on its sealing surface, and one phase has the other phase dispersed therein. The present invention relates to a vacuum flange coated with a protective film having a textured state.

[0002]

2. Description of the Related Art Conventionally, stainless steel has been mainly used as a material for vacuum equipment. In recent years, however, the size of equipment and ultra-high vacuum have been increasing mainly for accelerators and semiconductors. The vacuum vessel made of stainless steel has excellent corrosion resistance and mechanical strength, but has a large weight, and has a limit as a material for ultra-high vacuum. Further, when used in a particle accelerator, there is a problem that considerable residual radioactivity is generated.

On the other hand, the vacuum container made of aluminum alloy is light in weight, has a higher ultimate vacuum than stainless steel, and is attracting attention as a container for ultra-high vacuum. Moreover, when used as an accelerator, the reduction rate of residual radioactivity is one digit lower than that of stainless steel.

However, the aluminum alloy has a big drawback that it is soft, and is easily scratched during handling, and particularly when the sealing surface of the flange is scratched, the sealing performance is directly affected. Therefore, at present, the sealing surface is protected by coating with a hard protective film of titanium nitride, chromium nitride, titanium carbide or the like.

[0005]

By the way, since the aluminum alloy has a very high coefficient of thermal expansion and a low melting point, it is very difficult to coat a good quality hard coating with good adhesion. Further, these hard films have a high hardness, but have a low coefficient of thermal expansion and a low toughness, and therefore, when the flange is repeatedly attached and detached, cracks and peeling occur in the hard film,
In terms of sealing performance, it lacks reliability and durability, which is a major obstacle to expanding the market for aluminum alloy vacuum equipment.

The present invention has been made in view of the above circumstances, and it is an object of the present invention that the weight is low, the ultimate vacuum is high, and the surface, especially the sealing surface is not easily scratched during handling, and the baking is repeated. Another object of the present invention is to provide a vacuum flange that does not deteriorate even when used for desorption.

The inventors of the present invention have conducted extensive experiments as a result of the hardening of the sealing surface of the flange, which has been a problem as described above, and as a result of earnest research, use of an evaporation method such as an ion plating method as an evaporation source. , A metal that will precipitate as a metal phase without reacting with the atmosphere gas, and a metal that will react with the atmosphere gas to precipitate as a hard phase, or an alloy of these metals will be used. It was found that the coating film obtained by vapor-depositing the alloy is very effective as a hard protective film on the surface of the flange, particularly on the sealing surface, and further studied the structure of the coating film to complete the present invention.

[0008]

According to the vacuum flange of the present invention, the coating formed on the sealing surface of the aluminum alloy flange component comprises two phases of a metal phase and a hard phase, and
Structure in which one phase is dispersed in the other phase, that is, a surface protective film having a structured structure in which the metal phase is dispersed in the hard phase or the hard phase is dispersed in the metal phase (hereinafter, the metal phase and the hard phase). It is referred to as a surface protective film composed of a mixed phase with a phase). Further, the means for solving the above-mentioned problems is that the surface protective film is formed by a vapor deposition method.

The metal phase is Ni or Co, or an alloy containing one of Ni and Co, and the hard phase is a transition metal of Group IVa of the periodic table and Va of the periodic table. It is preferably a transition metal of Group VI, a transition metal of Group VIa of the periodic table, or a nitride, carbide or boride of at least one of Al and Si. Furthermore, it is preferable that the metal phase is a Fe—Ni alloy. Further, it is preferable that the hard phase is a Fe-Cr-N composite nitride. Then, in the surface protective film composed of the mixed phase of the metal phase and the hard phase, the metal phase is 5 wt% to 85 wt% with respect to the entire surface protective film, and the balance of the surface protective film other than the metal phase is It is preferable that the composition is composed of a hard phase and inevitable impurities.

The present invention will be described in detail below. That is, a vapor deposition method such as an ion plating method or a reactive sputtering method is used as a film forming method, and as an evaporation source, a metal that does not react with the atmosphere gas and is deposited as a metal phase reacts with the atmosphere gas. Using a metal that will be precipitated as a hard phase, or an alloy containing these metals, the structure of the coating film obtained by depositing these metals or their alloys is analyzed by the electron probe micro-partial analysis method.
(Electron Probe Micro Analysis), X-ray diffraction analysis method (X-
ray Diffraction Analysis), X-ray photoelectron spectroscopy (X-ray
It was found by analysis such as Photoelectron Spectroscopy) that a metallic phase and a hard phase existed. It was confirmed that the microstructure of this coating is a mixed phase in which a metal phase and a hard phase are present in a disordered state.

The metal serving as the metal phase on the sealing surface of the aluminum alloy flange is an atmospheric gas (a mixed gas of Ar and N2, a mixed gas of Ar and CH4, Ar and B) during vapor deposition.
Ni or Co, or an alloy containing Ni, Co is preferable as a metal that does not easily react with (a mixed gas of 2H6, etc.).

Further, as the metal of the metal compound which becomes the hard phase, there are group IVa of the periodic table which reacts with the atmosphere gas,
Group Va and Group VIa transition metals (these transition metals are
Ti, Zr, Hf, V, IVa, Va, VIa group of the periodic table
Nb, Ta, Cr, Mo, W and the like. Depending on the periodic table, the transition metals may be group IVB, group VB, or group VI.
(Although sometimes described as B group), Al and Si are preferable.

Ni, Co, or N serving as the metal phase
At the same time, an alloy containing one of i and Co and at least one of transition metals of the IVa group, the Va group, and the VIa group of the periodic table, Al, and Si, which become the hard phase, are evaporated at the same time. By doing so, only the metal that becomes the hard phase selectively reacts with the atmospheric gas. Then, the metal forming the hard phase reacts with the atmosphere gas to form a nitride, a carbide or a boride.

Then, a metal that does not easily react with the atmospheric gas is vapor-deposited as a metal phase on the sealing surface of the aluminum alloy flange, and a metal that reacts with the atmospheric gas becomes a nitride, a carbide or a boride, and these compounds serve as a hard phase of the aluminum alloy. Evaporate on the sealing surface of the flange. In this way, the surface protective film composed of the mixed phase of the metal phase and the hard phase is formed on the surface of the aluminum alloy.

As described above, the vacuum flange formed by the ion plating or the sputtering treatment with the surface protective film made of the mixed phase of the metal phase and the hard phase on the sealing surface of the aluminum alloy flange is handled. It is not easily scratched, has high corrosion resistance, and is unlikely to cause peeling or cracks on its sealing surface even after repeated baking and removal.

In the present invention, the composition of the mixed phase forming the surface protective film is preferably 5 to 85 weight% of Ni or Co or an alloy containing either Ni or Co as the metal phase. %, And the rest is periodic table IVa, V
It is at least one nitride or carbide or boride of a, VIa group transition metals, Al, and Si and unavoidable impurities. An effective vacuum flange is provided by providing a surface protective film composed of a mixed phase having such a composition on an aluminum alloy flange component.

That is, the metal phase of the surface protective film is 5% by weight.
If less than, the thermal expansion coefficient of the protective film is low, which causes a large internal strain between the base material and the toughness of the protective film is low. Peeling and cracking are easy to occur, and if it exceeds 85 wt%,
The hardness of the protective film is low, and scratches easily occur, which is not preferable.

The vacuum flange of the present invention was obtained by applying a surface protective film having the above composition to the sealing surface of an aluminum alloy flange and conducting a leak test as a thermal cycle test by repeating baking and desorption 50 times or more. It turned out that it has a good sealing performance.

Therefore, in the vacuum flange of the present invention, an aluminum alloy flange having improved sealing surface strength can be obtained, and further damage to the sealing surface can be prevented, and thus reliability and durability of sealing performance are problems. It can be applied to aluminum alloy flanges that have become.

[0020]

EXAMPLES Examples of the vacuum flange of the present invention will be specifically described below based on experimental examples, but the present invention is not limited thereto.

(Experimental example) A reactive sputtering method was used as a vapor deposition method, and an Fe-Ni-Cr alloy, a Ni-Cr alloy, and C having different compositions as an anti-cathode material (target) were used.
o-W alloy or Ni-V alloy was used.
Plasma is generated in an atmosphere of r-N2, Ar-CH4, Ar-B2H6, and coatings having various compositions are coated with two aluminum alloy flanges of ICF70φ (A2219-T8).
The sealing surface of 52) was covered and a heat cycle test was conducted.
However, the gasket is pure aluminum (A1050-H
24) was used.

Tables 1 to 4 show the results of the thermal cycle test of the aluminum alloy flange coated with the surface protective film composed of the metal phase and the hard phase, which was obtained by the above experiment.

[0023]

[Table 1]

[Table 2]

[Table 3]

[Table 4]

The composition analysis of the surface protective film is carried out by electron probe micro analysis,
It was performed by X-ray diffraction analysis and X-ray photoelectron spectroscopy. Then, in the heat cycle test, it was confirmed whether or not the sealing performance was maintained after repeating baking and removal of the flange. The mark indicating that there was no leak up to 50 times in the repeating of baking and desorption was indicated by a circle, and the mark indicating the number of leaks in the middle was indicated.

As shown in Tables 1 to 4, the metal phase is Fe-Ni alloy and the hard phase is Fe-Cr-.
A surface protective film composed of a mixed phase of N composite nitride, a surface protective film composed of a mixed phase of Ni as a metal phase and Cr2N as a hard phase, and a mixed phase of Co as a metal phase and WC as a hard phase Each of the aluminum alloy flanges having a surface protective film made of Ni, and a surface protective film made of a mixed phase having Ni as a metal phase and VB2 as a hard phase has a composition ratio of the metal phase of 5% by weight to 85% by weight. In this case, the durability is up to 50 times in the heat cycle test. As described above, the vacuum flange of the present embodiment, the sealing surface has excellent durability,
When used in a vacuum container, it can exhibit excellent properties.

[0026]

As described in detail above, the vacuum flange of the present invention has the following remarkable technical effects. It is possible to provide a vacuum flange made of an aluminum alloy which is less likely to be damaged during handling, has less deterioration in sealing performance, and is less likely to cause peeling and cracks in the surface protective film of the seal even after repeating baking and detaching. b. Therefore, it is possible to provide a vacuum flange capable of coping with the recent increase in size and ultra high vacuum of accelerators and semiconductor-related vacuum equipment.

C. At the same time, the demand for aluminum alloy vacuum equipment is greatly increased, and the vacuum flange of the present invention can greatly contribute to the development of the accelerator and semiconductor-related industries using the vacuum flange. d. Aluminum alloy flanges for which the strength of the sealing surface has been improved, and further, damage to the sealing surface can be prevented, and thus reliability and durability of sealing performance are problems Applicable to flange.

Claims (6)

[Claims] 1. A surface protective film comprising a two-phase metal phase and a hard phase and having a structure in which the other phase is dispersed in one phase is formed on the sealing surface of an aluminum alloy flange component. Vacuum flange characterized by 2. A vapor deposition method for forming a surface protective film on a sealing surface of an aluminum alloy flange component, the structure comprising two phases, a metal phase and a hard phase, and a structure in which the other phase is dispersed in one phase. A vacuum flange characterized by being formed by. 3. The metal phase is Ni or Co, or an alloy containing one of Ni and Co, and the hard phase is a transition metal of Group IVa of the periodic table and V of the periodic table.
a transition metal of group a, transition metal of group VIa of the periodic table, Al,
The vacuum flange according to claim 1 or 2, which is a nitride, a carbide, or a boride of at least one of Si. 4. The vacuum flange according to claim 1, wherein the metallic phase is an Fe-Ni alloy. 5. The vacuum flange according to claim 1, claim 2, claim 3, or claim 4, wherein the hard phase is an Fe-Cr-N composite nitride. 6. A two-phase structure comprising a metal phase and a hard phase,
The surface protective film having a structure in which the other phase is dispersed in one phase is such that the metal phase is 5 wt% to 85 wt% with respect to the entire surface protective film, and the metal phase of the surface protective film is The vacuum flange according to claim 1, claim 2, claim 3, claim 4, or claim 5, wherein the remaining part has a composition consisting of a hard phase and unavoidable impurities.