JPH0251478A - Method for bonding metal and ceramic - Google Patents

Abstract

PURPOSE:To relieve the stress between the metal and ceramic and to obtain a bonded body having excellent strength by arranging a member for controlling the thermal expansion of a metal in parallel with the bonding surface of the metal to be bonded to a ceramic in the vicinity of the bonding surface. CONSTITUTION:A metal and a ceramic are bonded as described below by the title method such as brazing, diffusion bonding, and bonding by an active metal, etc. Namely, a member for controlling the expansion of the metal is arranged in parallel with the bonding surface, and the member having a lower thermal expansion coefficient than the metal is used. Since the member is thus arranged, the thermal expansion of the metal is controlled in conformity to the thermal expansion coefficient of the member. The difference in the thermal expansion between the ceramic and metal is reduced in the heating for bonding, the contraction margin of the bonded metal is diminished, and the residual stress in the vicinity of the bonding surfaces is decreased.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a metal/ceramics bonding method, and in particular, to bond metals and ceramics by brazing, diffusion bonding, active metals, etc., and to improve the heat resistance of ceramics. A metal that has properties such as insulation and wear resistance, as well as the toughness, electrical conductivity, and thermal conductivity of metals, and is used to obtain joined bodies suitable for use in fields such as high-temperature engines and offshore development.・Related to ceramic bonding method.

[Conventional technology]

Bonded bodies of metal and ceramics have both the characteristics of metals and the characteristics of ceramics, and are being applied and researched in various fields.

In order to obtain a high-strength joint between metal and ceramics, the first step is to
The first is that the reaction layer at the bonding surface of the two has excellent crystal bonding properties and mechanical properties at the interface, and the second is that during the bonding operation of the two,
When the materials are heated to the temperature required for bonding and then cooled, strain occurs at the interface, so it is important to alleviate that stress.

Conventionally, a method for achieving the second zero element described above, that is,
As a way to relieve stress, +11 materials with a coefficient of thermal expansion intermediate between their respective coefficients of thermal expansion (e.g., rt gold alloy I nva
(2) A method of joining metal and ceramics by interposing a material (such as Cu, A1, Ni5T, etc.) that plastically deforms during the joining operation of the two.
There is a method of joining the two by intervening (such as i).

[Problem to be solved by the invention]

However, all of the above conventional methods require a step of inserting a third metal between the metal and the ceramic, and a reaction layer of the third metal material and a binder such as a brazing material or an active metal. The problem is that it has difficulties that must be controlled.

The present invention solves the problems of the conventional bonding method described above, and allows metal and ceramics to be bonded together without the need for the complicated process of inserting a third metal between the metal and ceramics to relieve stress. A metal/ceramic bonded body that can significantly alleviate the stress that occurs between the two during bonding, resulting in a metal/ceramic bonded body with excellent properties such as strength.
The purpose is to provide a ceramic bonding method.

[Means to solve the problem]

In order to achieve the above object, the present invention provides a metal-ceramic bonding method in which a metal and a ceramic are bonded by brazing, diffusion bonding, active metal, etc. In this case, a member is arranged to suppress thermal expansion of the metal in a direction parallel to the joint surface, and the thermal expansion coefficient of the member is made smaller than that of the metal.

[Effect]

By adopting the above means, the present invention disposes a member that suppresses the thermal expansion of the metal in the direction parallel to the bonding surface at least near the bonding surface of the metal to be bonded to the ceramic. is suppressed in accordance with the coefficient of thermal expansion of the member.

The coefficient of thermal expansion of this member, 5, is smaller than the coefficient of thermal expansion of the metal bonded to the ceramic, so it can be made smaller than the coefficient of thermal expansion of the ceramic.

Therefore, the difference in the amount of thermal expansion between the ceramic and the metal due to heating during the bonding operation is reduced, the shrinkage margin of the metal after the bonding is completed is reduced, and the residual stress near the bonding surface is reduced.

〔Example〕

Embodiments of the present invention shown in the drawings will be described below.

FIG. 1 is an explanatory diagram showing the metal-ceramic bonding method of the present invention.

FIG. 1 shows an example in which a ceramic 1 made of a cylindrical body and a metal 3 made of a cylindrical body having a diameter larger than that of the ceramic 1 are joined by a brazing filler metal 2.

And SiC is used as the ceramic l,
5US304 is used as the metal 3, and Ag-Cu is used as the brazing material 2.

Further, an annular ceramic jig 4 as a member for suppressing thermal expansion of the metal 3 is arranged around the outer periphery of the metal 3 near the joint surface with the ceramic 1.

This ceramic jig 4 is made of a material having a coefficient of thermal expansion smaller than that of the metal 3.

Note that the thermal expansion coefficient α of the ceramic 1 made of SiC is 3×10−′/°C, and the thermal expansion coefficient α of the metal 3 made of 5US304 is 17×IO−′/°C.

In order to join the ceramic 1 and the metal 3 using the brazing filler metal 2 made of Ag-Cu, the temperature is raised to a temperature at which the brazing filler metal 2 reacts, that is, 1000°C.

In this case, the thermal expansion of the metal 3 in the direction parallel to the joint surface is restrained by the ceramic jig 4, and the difference in thermal expansion with the ceramic l becomes small.

Therefore, no distortion occurs at the interface between the ceramic 1 and the metal 3, and the mechanical strength of the metal-ceramic bonded body is improved.

An example of such a method of joining metal and ceramics will be explained in more detail with reference to FIG.

Example 1 5iC as ceramic 1 Ag as brazing material 2
Cu, SUS 304 is used as the metal 3, and SiC, which is the same material as the ceramic l, is used as the annular ceramic jig 4.
was used.

And one diameter of the cylindrical metal 3 and the inner diameter of the annular ceramic jig! , the relationship with 1. = Il.

In this state, when the temperature is raised to a temperature required for the reaction of the brazing filler metal 2, the cylindrical metal 3 thermally expands, but in this case, the thermal expansion of the metal 3 is restrained by the annular ceramic jig 4.

Since the ceramic jig 4 is made of the same material as the ceramic 1, the metal 3 exhibits almost the same thermal expansion as the ceramic 1.

Therefore, there is almost no difference in thermal expansion between the ceramic and the metal 3.

Example 2 The relationship between the diameter 12 of the cylindrical metal 3 and the inner diameter 13 of the annular ceramic jig 4 is as follows. <! The joining operation was performed in the same manner as in Example 1, except that .

In this case, at the same time as the metal 3 thermally expands, the ceramic jig 4
The metal 3 itself also thermally expands, its inner diameter expands, and the metal 3 thermally expands within the expanded range.

Therefore, the thermal expansion of metal 3 when heated to 1000°C is (l, (αn+t)l/1t-11 (however, α4
represents the thermal expansion coefficient of the ceramic jig 4, and the apparent value indicated by ) is suppressed to the above thermal expansion coefficient α.

Therefore, the difference in thermal expansion between the ceramic 1 and the metal 3 is reduced.

Example 3 As the ceramic jig 4, SiC whose thermal expansion coefficient α constitutes the ceramic ■ and SUS 30 which constitutes the metal 3 are used.
ANz with intermediate values of the respective thermal expansion coefficients α of 4
The joining operation was performed in the same manner as in Example 1, except that OsC thermal expansion coefficient α: 8 x 10-'/°C) was used.

In this case, metal 3 is A1. Since it follows the thermal expansion of the ceramic jig 4 made of O, the thermal expansion coefficient α of the metal 3 is suppressed to 8 x 10-"/°C, and the difference in the amount of thermal expansion between the ceramic 1 and the metal 3 is It will become less.

The above method reduces the difference in thermal expansion between the ceramic 1 and the metal 3, so the amount of shrinkage of the metal 3 during the cooling process after the completion of the bonding reaction is smaller than when the ceramic jig 4 is not used. Become.

Therefore, the residual stress near the joint surface between the ceramic 1 and the metal 3 is reduced, and the joint strength is improved.

Note that the bonded body obtained by bonding according to the method of Example 3 had a bonding strength 3 kg/mm" higher than that obtained by the conventional bonding method that did not use the ceramic jig 4.

In the above-mentioned embodiment, an example of ceramics was shown as a jig for restraining the thermal expansion of the metal 3, but in the present invention, the jig is not necessarily limited to ceramics, and the thermal expansion coefficient α of the metal 3 is A metal having a small coefficient of thermal expansion α may also be used.

〔Effect of the invention〕

By having the present invention configured as described above, during the joining operation of metal and ceramics, the thermal expansion of the metal is restrained and becomes close to the amount of thermal expansion of the ceramic, and the amount of shrinkage of the metal after the joining reaction is completed is extremely small. , it has excellent effects such as being able to obtain a bonded body with high strength due to the reduction of residual stress.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing a metal/ceramic bonding method according to the present invention. 1... Ceramics 2... Brazing metal 3... Metal 4... Ceramics jig

Claims (1)

[Claims] (1) In a metal-ceramic bonding method in which metal and ceramics are bonded by brazing, diffusion bonding, active metal, etc., at least near the bonding surface on the metal side to be bonded to the ceramic and parallel to the bonding surface. A metal-ceramic bonding method, characterized in that a member is disposed to suppress thermal expansion of the metal in the direction, and the coefficient of thermal expansion of the member is smaller than the coefficient of thermal expansion of the metal.