JP3515192B2 - Brazing structure of porous metal body and method of manufacturing the same - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a metal member such as a filter member and a metal member with high accuracy and reliability.
In addition, the present invention relates to a brazing structure of a metal porous body bonded while preventing pores from being closed due to infiltration of a brazing material into the pores of the porous body, and a method for manufacturing the same.

[0002]

2. Description of the Related Art Porous metal bodies obtained by sintering metal powders, metal fibers, etc. are used for various applications such as filter devices, heat insulating materials, etc., and these metal porous bodies are usually welded to metal members such as housing members. Alternatively, they are used by being integrally connected by brazing or the like.

On the other hand, in recent years, high precision and miniaturization have become indispensable requirements for parts and devices. For example, a filter device, particularly a filter device for processing gas used for manufacturing semiconductors, suffers from low pressure loss. , Diameter 0.0
Complete removal of impurities such as ultrafine particles of 1 μm and water is desired, and its accuracy is at the PPT level. At the same time, in order to reduce the arrangement interval of gas pipes, filter members are housed in gas pipes, and it is also desired to downsize the filter device. It is rare.

On the other hand, in the above-mentioned semiconductor manufacturing apparatus,
To connect a tubular member such as a pipe, for example, as shown in FIG. 4, while forming a flange portion provided with ring-shaped projections a, a on the connecting end faces facing each other at the connecting ends of the tubular members A1 and A2, A so-called VCR joint structure by Cajon Corporation of the United States is known in which the ring-shaped projections a, a are pressed against each other to be connected by screwing a screw member B1 and a nut member B2 fitted on the outer peripheral surfaces of the tubular members A1, A2. ing.

In addition, the present inventor has a gasket D made of metal sandwiched between the connection end faces in this joint structure, and the gasket D and a filter member E which is a cup-shaped porous metal body fixed to the gasket D. And a filter device F (shown in FIG. 4) that is made up of the above, and that accommodates the filter member E in the tubular member by sandwiching the gasket D.

Regarding the filter member E used in such a filter device F, the inventor of the present invention first
According to W093 / 06912, a two-layer structure material composed of a support 3A having relatively large pores and a fine layer 3B arranged on the outer peripheral surface thereof and having pores smaller than the pores (see FIG. 4).
, Etc.) are proposed.

[0007]

However, when such a porous metal porous body is bonded to the metal member, which is the gasket D in this example, by welding, for example, the filter member itself is very small and the welding operation is difficult. In addition, the local heating during welding often causes metal fume and coloring. This metal fume adheres to the filter member E and floats along with the flow of the processing gas at the time of use, contributing to impurities. In addition, even when a highly accurate welding method such as electron beam is adopted in welding, local shrinkage, dents, cracks, etc. often occur in the porous metal body, and great care must be taken in the welding to improve work efficiency. Inferior.

Also, when the brazing material is joined by brazing instead of welding, the molten brazing material usually forms an infiltrated portion b deeply penetrating into the pores of the filter member E by the capillary phenomenon as shown in FIG. Easy to use, thereby blocking pores and reducing filtration area.

On the other hand, in order to completely prevent the leak between the filter member E and the gasket D, it is indispensable to make the bonding surfaces of the two flat and smooth, and to bring them into close contact with each other. In polishing the end surface of the filter member E, a high degree of skill is required to impart flatness. For example, when the filter member E having the two-layer structure is particularly polished, as shown in FIG. 5, a defective portion G is apt to occur due to polishing sag, chipping of a fine layer due to mishandling after polishing, etc. When a defective portion G occurs,
Only the support 3A having inferior filtering performance appears on the outer surface, and such a defective portion G cannot be completely repaired only by brazing, and leakage occurs, making microfiltration impossible.

An object of the present invention is to provide a brazing structure for a porous metal body and a method for producing the same, which can solve the above problems.

[0011]

According to the present invention, a porous metal having a pore diameter smaller than that of pores of the metal porous body is previously fixed to the bonding surface of the metal porous body to be bonded to the metal member by sintering. A brazing structure for a porous metal body, characterized in that the dense porous material having pores and the metal member are brazed and bonded together to prevent the pores of the porous metal body from being blocked by the infiltration of the brazing material. It is the body.

Another aspect of the present invention is to pre-sinter a dense porous material having pores having a pore diameter smaller than the pore diameter of the pores of the porous metal body on the bonding surface of the porous metal body bonded to the metal member. The brazing structure for a porous metal body characterized in that the brazing material is fixed between the dense porous material and the bonding surface of the metal member, and the brazing material is heated above the melting temperature of the brazing material. It is a body manufacturing method.

[0013]

[Function] Since the dense porous material is pre-sintered on the bonding surface of the porous metal body, the bonding surface of the porous metal body is covered with a finer dense porous material. Even if there is a deformation such as polishing sag or a defective portion, the deformation or the defective portion is repaired to improve the adhesion with the metal member. The dense porous material can be adhered to the bonding surface and sintered, for example, as a suspended sludge in which the powder is suspended in advance, and at that time, it can be covered without gaps regardless of the unevenness of the bonding surface. it can. In addition, the dense porous material also acts as a reinforcing member, preventing damage to the bonding surface, and since the dense porous material has already been sintered into a metal porous body, it prevents leakage from occurring between them and bonds. It can also maintain strength.

Moreover, by making the pore diameter of the dense porous material smaller than the pore diameter of the metal porous body, the infiltration of the brazing material in the molten state by the capillary phenomenon is substantially eliminated. The holes can be stopped in the pores, and for example, blocking of the effective pores due to flowing deep into the pores of the metal porous body is reduced, and the reduction of the filtration area can be suppressed.

Further, according to the third aspect of the present invention, by using a porous metal body having a bonding surface covered with a fine porous material having fine pores, the conventional planar polishing prior to bonding with the metal member is performed. High precision finishing is not required, which contributes to improvement of manufacturing efficiency and yield.

The term "pore diameter" means "mean pore diameter", and "mean pore diameter" means the median diameter measured by mercury porosimetry. When the porous metal body is composed of two or more layers instead of a single layer, the average value of both pore diameters, more preferably the smaller pore diameter, is adopted.

[0017]

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 brazing structure 1 of a porous metal body of the present invention.
Is used as an example of the filter device F that can be used in the semiconductor manufacturing apparatus shown in FIG.
FIG. 2 is a photomicrograph of the constituent members, and FIG. 3 is an enlarged photomicrograph of the joint portion.

In the brazed structure 1, the metal member 2 is bonded to the metal porous body 3 by brazing, and the bonding surface 5A of the metal porous body 3 is previously integrated with the dense porous material 6 by sintering. There is. The brazing structure 1 also removes impurities contained in the processing gas while the processing gas flowing from the central opening 4 of the metal member 2 passes from the inner peripheral surface to the outer peripheral surface of the cup-shaped porous metal body 3. It is captured and sent to the next process.

In the present embodiment, the porous metal body 3 is a multi-layer structure obtained by integrally sintering a support 3A, which is relatively coarse, for example, using metal powder, and a fine layer 3B covering the outer surface thereof. The layer 3B is relatively thin, for example, using a fine element such as a metal powder, a metal fiber, or a metal short fiber so as to have a high filtration accuracy and a low pressure drop that can substantially guarantee the filtration accuracy, for example, a metal porous body. It is formed to be 1/2 or less of the total thickness of No. 3, and more preferably about 1/4 to 1/20.

Further, in this example used in the filter device F for the process gas for semiconductor production, the fine layer 3B has a thickness of 0.5 to 10 μm and a thickness of 0. The thin layer has a thickness of about 1 to 2 mm (more preferably 0.3 to 0.8 mm). As a method for manufacturing such a multilayer structure, for example, the above-mentioned PCTW
As disclosed in O93 / 06912, a fine layer 3B is formed on the outer surface of a support 3A having coarse pores by suction-laminating a suspension in which fine elements are previously suspended, and is integrated by sintering. Can be used. It should be noted that a porous metal body using the above-mentioned short metal fibers or a mixed powder obtained by mixing the short metal fibers with fine metal powder can also provide a filter member with low pressure loss and high accuracy.

Even when used for filtration of gases other than semiconductor process gas, such as various liquids such as molten polymer, the porous metal body can be arbitrarily selected in its structure according to the characteristics of each fluid. For example a single layer structure,
Structures with three or more layers, moreover, those using single or heterogeneous fine elements, and their shapes are pipes,
It may be in the shape of a tube, a cone, a pyramid, an irregular shape provided with a fold, or a sheet or a block.

The material of the metallic porous body 3 is determined in consideration of the corrosion resistance to the fluid to be treated, the conditions of use, the mechanical characteristics, etc. Usually, nickel or its alloys such as Hastelloy (registered trademark) and Inconel (registered trademark) are used. In addition to the above, stainless steel (316, 316L, etc.), and a sintered body composed of single or mixed elements appropriately selected from silver or the like, or a sintered body having a multilayer structure can be adopted.

Particularly, stainless steel can be preferably used because it is relatively easy to form and has excellent corrosion resistance and heat resistance. When such a porous metal body 3 is bonded to the metal member 2 functioning as a gasket in the VCR joint structure, as described above, the bonding surface 5A of the porous metal body 3 is densely packed to a predetermined thickness. The porous material 6 is integrally sintered.

The dense porous material 6 basically does not need to have a filtering function, but rather the bonding surface 5 of the metal porous body.
A, the brazing material intervening between the joining surfaces 5B of the metal member 2 functions as a brazing material that prevents the molten brazing material from flowing into the porous metal body 3 by a capillary phenomenon. Therefore, the pores are smaller than the pore diameter of the porous metal body 3, for example, 0.30 to 0.99 times the pore diameter of the porous metal body 3, and more preferably about 0.6 to 0.9 times. It is preferable to set it so that it has pores of the same diameter.

It should be noted that the dense porous material 6 is made of the same kind of metal element as the metal porous body 3 because it has excellent sinterability and the thickness t is 0.2 to 2.0 mm.
The stainless steel is sintered and integrated with the bonding surface 5A of the porous metal body 3 at a temperature of about 900 to 1200 ° C., for example, about 0.5 to 1.0 mm.
In order to improve the bondability between the metal member 2 and the metal porous body 3, the surface of the brazing surface is polished and ground in advance in order to eliminate unevenness and smooth the surface. In the ring-shaped dense porous material 6, a small defective portion of the porous metal body is repaired and adhered by deformation of both due to pressing during sintering.

As described above, the dense porous material 6 may be a molded product formed in advance into a flat plate ring shape. Alternatively, for example, suspended sludge in which fine metal particles are previously suspended in water is attached to the bonding surface 5A. It can also be formed by sintering. In this case, in the polishing process in which the brazing surface is made a smooth flat surface as required, it is not necessary to finish the entire surface with high precision as in the conventional case, and the yield is improved and the productivity is improved.

On the other hand, in the present example, the metal member 2 is a disk-shaped base body 7 which functions as a gasket which seals by pressing both surfaces of the ring-shaped projections a, a on the connecting end surfaces of the tubular bodies A1, A2. In addition, a concave portion 9 which is a ring body provided with the central opening 4 and into which the outer peripheral surface of the porous metal body 3 is fitted is provided on one surface.

The inner surface of the recess 9 forms a connecting surface 5B for connecting the porous metal body 3 and is connected to the inner peripheral surface of the cup-shaped porous metal body 3 by the opening 4. The metal member 2 has, on the other surface of the concave portion 9, a reinforcing boss portion 11 that bulges opposite to the concave portion 9. The metal member 2 has a thickness T of, for example, 0.5 to 2.0 in the outer peripheral portion.
The outer diameter is about 8 mm to about 20 mm.

The recessed portion 9 loosely fits the porous metal body 3 to prevent the brazing material from spreading due to heating and also to prevent the porous metal body 3 from falling when brazing.

The metal member 2 is the tubular member A1,
The ring-shaped projections a are pressed by A2 to form a slight recess on the surface thereof, and the strength and hardness are set to such a level that leakage can be prevented by surface contact. Therefore, preferably H
For example, nickel, aluminum, silver, etc. having a surface hardness of v50 to 250, preferably Hv90 to 200 can be preferably used, and stainless steel and various nickel alloys are also used.

FIG. 3 is a photomicrograph of the joint portion magnified 50 times, showing that the dense porous material 6 between the joint surface 5B of the metal member 2 and the joint surface 5A of the porous metal body 3 is a brazing material. 12
On the other hand, the brazing material does not substantially flow into the pores of the porous metal body 3, and the pores are not blocked even near the interface. Therefore, it can be understood that the infiltration of the molten brazing material is stopped in the pores of the dense porous material 6, and the extent to which the brazing material penetrates the dense porous material is
It may be in the form of a layer having the entire depth or an arbitrary depth.

This is because the pore diameter of the dense porous material 6 is set smaller than that of the metal porous body 3.

In this example, as the brazing material, a Ni-based amorphous foil (having a thickness of 10 to 100 μm, preferably 20 to 7) is used.
A brazing material foil piece having a thickness of 0 μm) was adopted and arranged between the metal member 2 and the dense porous material 6.

Since such a brazing material has a small thickness and also has extremely high flatness and deformation recovery property, the brazing material can be easily arranged and a reliable connection without a gap can be obtained. Further, Ni wax is excellent in corrosion resistance and high temperature strength and can be applied to a wide range of applications. In addition to this, for example, gold or silver wax can be adopted.

In the brazing process of the brazing material, it is desirable to appropriately set the material and heating conditions so that the viscosity in the molten state does not become low. 1000-10
It is also desirable to heat at 50 ° C. for about 2 to 20 minutes and further pressurize as necessary to make the bonding (adhesion) more reliable. The above conditions also change depending on the heat capacity of the porous metal body or the like.

The structure thus brazed is
As shown in FIG. 3, the infiltration of the brazing material stops inside the pores of the dense porous material 6 and suppresses the reduction of the effective filtration area of the porous metal body 3, and the brazing material also penetrates the pores of the dense porous material. It is good enough to allow sufficient penetration. Further, since the dense porous body 6 and the metal porous body 3 have been previously sintered,
There is no lack of strength such as peeling and the hole accuracy can be improved.

By adopting such a method and structure, it is possible to solve the problems of deformation, shrinkage and cracks due to local heat, which have been a problem in conventional welding, and also the problem of metal fume contamination. Also, the reduction of the effective filtration area due to the blockage of pores due to the brazing is suppressed, the flow of the processing fluid largely bypassing it is improved, and the retention thereof can be prevented. Further, the dense porous material can be configured so as to be able to restore sagging due to polishing on the bonding surface of the metal porous body, and at this time, the polishing work is streamlined to improve production efficiency and yield.

[0038]

As described above, the brazing structure and the method for producing the same according to the present invention efficiently prevent the pores from being closed due to brazing by interposing the dense porous material, while efficiently adhering the metal porous body and the metal member. Can be surely combined.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an example of the method of the present invention and a brazing structure obtained by the method.

FIG. 2 is an exploded view thereof.

FIG. 3 is a microscope enlarged photograph showing a joint portion in detail.

FIG. 4 is a cross-sectional view illustrating a usage state.

FIG. 5 is a cross-sectional view illustrating an example of a conventional brazed joint portion.

[Explanation of symbols]

2 metal members 3 Porous metal 5A, 5B Bonding surface 6 Dense porous material

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Claims (3)

(57) [Claims] 1. A dense porous material having pores having a pore diameter smaller than the pore diameter of the pores of the porous metal body, which is fixed to the bonding surface of the porous metal body bonded to the metal member by sintering in advance. A brazing structure for a porous metal body, characterized in that pores of the porous metal body are prevented from closing due to infiltration of a brazing material by brazing and bonding the metal member. 2. The multi-layered metal porous body comprises a support having relatively coarse pores and a fine layer of pores formed on at least an outer surface thereof and having a pore diameter smaller than the pores of the support. The brazing structure for a metal porous body according to claim 1, which is a structure. 3. A dense porous material having pores having a pore diameter smaller than the pore diameter of the pores of the porous metal body is fixed to the bonding surface of the porous metal body bonded to the metal member by previously sintering. In addition, a brazing material is disposed between the dense porous material and the bonding surface of the metal member, and the brazing material is heated to a melting temperature of the brazing material or higher, and a method for producing a brazing structure for a porous metal body. .