JPS61286273A - Method of joining ceramic to metal - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a method for joining metal and ceramic.

<Prior Art> The most difficult problem in joining metal and ceramic is how to solve the problem of the difference in coefficient of linear expansion between the two.

In particular, the linear expansion coefficients of practical metal materials such as steel and ceramics such as silicon nitride and silicon carbide differ by a factor of 3 to 4, so in such a combination, even if the joint is successful, the joint Large thermal stress occurs during the cooling process,
Cracks and destruction occur in the ceramic parts.

Conventionally, in order to relieve thermal stress in joints, intermediate layers of various shapes are used, such as metals with intermediate coefficients of linear expansion, soft metals such as copper, or intermediate layers of metals with low coefficients of linear expansion. At present, although layers have been inserted and bonded, none of these methods has completely solved this problem.

<Problems to be Solved by the Invention> The present invention has been made in view of the above-mentioned problems, and provides a novel joint that can reduce stress at the joint and prevent destruction of the ceramic part. The purpose is to provide a method.

<Means for Solving the Problems> As a result of intensive research into the above-mentioned problems, the inventors have come to the following new knowledge. That is, it has been found that when joining metal and ceramic, if the ceramic surface is coated with a metal film at least in the surface area where the joining stress spreads, it is possible to prevent the ceramic part from breaking.

Furthermore, we have found that the most suitable metal film is one obtained by a film forming method that applies compressive force to the ceramic surface, such as a fused film.

The present invention has been made based on the above knowledge.

<Function> When ceramic and metal are joined 1. Due to the bonding stress, tensile stress acts on the ceramic surface near the bonding portion.

For this reason, cracks occur in this part, often leading to destruction.

However, in the present invention, since the surface area of the ceramic surface where stress acts is coated with a metal film, the stress acts on this metal film part and the effect on the ceramic is reduced or eliminated. .

Moreover, if this metal film is a surface compressible film such as a fused film, a compressive force is applied to the ceramic surface by the metal film, and the tensile strength of the upper surface appears to be increased.

This compressive stress contributes to reducing or eliminating the tensile stress on the surface.

<Example> Example 1 (Joining of silicon nitride and steel) Silicon nitride = 10≠×100INR round steel bar =
Metallization of 545C round bar silicon nitride with 13≠X50 #l: S 1 on the entire side surface except for the end surface of the joint and the upper end surface.
-Metallize with 50FeNb alloy.

The conditions for metallization were heating to 1400°C under reduced pressure.

A hole (approximately 10 m deep) into which a silicon nitride round rod can be inserted is formed in the joint end surface of the 545C round rod, and the metalized silicon nitride end surface is inserted together with copper powder.

This was heated to 1200° C. in an atmosphere furnace, and both shafts were joined together.

The joint was completely sound and no defects such as cracks were observed.

By the way, if only the parts to be joined are metallized,
Cracks were observed near the boundary between the ceramic and metal shafts.

Example 2 (Joining of silicon carbide and steel) Silicon carbide: 15 x 15 x 5 IIM plate steel: 2
0x20x20am 845C(7) plate ceramic is fully metallized with S 1-50FeNb alloy. The conditions for metallization were the same as in Example 1.

A copper plate of IOO and μ was sandwiched between the bonding surfaces of the ceramic and steel, and the two were bonded by heating to 1200° C. under reduced pressure.

The joint was sound and no cracks were observed in the ceramic part.

Incidentally, when only the joint surface of the ceramic (only one side) was metalized, cracks occurred in the ceramic and the chips fell off.

In the above embodiment, silicon nitride and silicon carbide were selected as the ceramic, and steel was selected as the metal, but the invention is not limited to these. It can also be applied appropriately to ceramics such as other nitrides, carbides, horides, oxides, etc. and other metal materials.

In addition to the methods shown in the examples, metallizing methods include vapor deposition, sputtering, and other methods that form a diffusion layer between the ceramic and firmly adhere to it, and also apply compressive force to the ceramic surface. suitable for those of a nature.

<Effects of the Invention> 1) Even combinations with large differences in linear expansion coefficients can be joined without problems.

2) There is no need to use a complex middle layer.

3) It is inexpensive in terms of cost.

Patent applicant: Miyata Giken Ltd. Representative: Seibu Miyata

Claims (1)

[Claims] 1. A method for joining a ceramic and a metal, which comprises coating at least a surface area of the ceramic surface where stress is applied during joining with a metal film when joining the ceramic and the metal. 2. The method according to claim 1, wherein the metal film is a ceramic surface compressible coating.