JPH06321648A - Method for joining ceramic to nickel - Google Patents

Abstract

PURPOSE:To join ceramic to nickel with high joining strength. CONSTITUTION:When silicon nitride ceramic 1 is joined to nickel 5, a carbon layer 4 is formed on the surface of the nickel 5 to be joined and joining is carried out with an Ag-Cu-Ti brazing filler metal 2 by heating in vacuum. Since the carbon layer prevents the diffusion of Ni into the brazing filler metal and the amt. of Ti reacting with Ni is reduced, the amt. of Ti reacting with the ceramic is relatively increased and a reacted layer consisting of TiN and Ti5Si3 is sufficiently formed at the interface between the silicon nitride ceramic and the brazing filler metal.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for joining ceramics and nickel or an alloy containing a large amount of nickel.

[0002]

2. Description of the Related Art Conventionally, in order to bond a powder compact such as ceramics to a metal, first, the surface of the ceramic is Mo.
-Mn method (telefken method) is used for metallization, then nickel (Ni) plating is applied, and if necessary, an intermediate material for buffering stress is used, and silver (Ag) brazing or the like is used to braze the metal. . In the above-mentioned metallization method, since the joining is performed in two steps, the joining is performed without metallization, so Ag-C
u-Ti system, Cu-Al-Si-Ti system, Ag-Cu-
A brazing material containing an active metal such as Ti-In is used to directly react with the ceramics for bonding. In the Ag-Cu-Ti-based brazing material, the content of Ti, which is an active metal, is usually 1 to 2 wt%.

Japanese Unexamined Patent Publication No. 59-232692 describes a Ti-Ag-Cu based brazing material having a Ti content of 3 to 80 wt% as a brazing material for joining ceramics and metal.

When ceramics and metal are joined by heating,
Due to the difference in thermal expansion between the two, residual stress acts in the vicinity of the joint during the cooling process, causing a decrease in the joint strength of the joint and cracks in the ceramics. In order to reduce this residual stress, a low thermal expansion metal such as Mo, W, Kovar alloy, etc. is inserted between the two for joining, or a soft metal plate such as nickel, copper, aluminum or the like is interposed between the ceramic and the metal. I try to join. Among these soft metals, since Cu has a low yield strength, the Cu portion will be deformed if it is used in a bonded body to which stress is applied. Al is also the same and has a low melting point, so it cannot be used for a bonded body used at high temperature. Ni is suitable as a cushioning material for joining ceramics and metals, since Ni has a proof stress and has excellent properties in terms of oxidation resistance and heat resistance.

An Ag-Cu-Ti based brazing filler metal (Ti content: 1 to 2 wt%) is usually used for joining the ceramics and the metal or the ceramics together. With this brazing material,
When the ceramics and the metal are joined using the buffer material of the Ni plate, the joining is not sufficiently performed. The reason is estimated as follows. As shown in FIG. 2, the joining of the ceramic and the Ni using the Ag—Cu—Ti based brazing filler metal 2 is performed.
At the interface X of silicon nitride ceramics, TiN and Ti5S
It is considered that the reaction layer of i3 is generated and the bonding is performed by the formation of this layer. On the other hand, from the interface Y with Ni, Ni is dissolved in the brazing filler metal 2 and reacts preferentially with Ti, so that N
An i-Ti based alloy is formed. Therefore, Ti is insufficient at the interface X of the silicon nitride ceramics, and TiN and Ti5S
i3 is formed only on a part of the interface, and sufficient bonding cannot be obtained. The cross-sectional structure of the bonded portion of this bonded body was observed with a scanning electron microscope (SEM), and the element distribution was measured with an electron beam microanalyzer (EPMA).

As shown in FIG. 5, which is a schematic view showing the distribution state of the Ti element performed by the microanalyzer (EPMA) at the joint portion of the above-mentioned joined body, the Ti element is sparsely distributed in the brazing material. There is. Further, as shown in FIG. 6 which is a schematic diagram showing the distribution state of the Ni element, the Ni element is diffused in the brazing material in the same distribution as the Ti element. From this, Ti in the brazing material is preferentially combined with Ni melted in the brazing material to form a Ni—Ti based alloy, and Ti is insufficient at the interface X of the silicon nitride ceramics.
It can be seen that the reaction layers of Ti5Si3 and Ti5Si3 were formed only at some interfaces.

[0007]

As described above, nickel has excellent characteristics as a cushioning material used for joining ceramics and metal, but when joined using a normal Ag-Cu-Ti based brazing material. However, the bonding strength is low and the variation is large. An object of the present invention is to provide a method of joining ceramics and nickel, which is capable of joining ceramics and nickel with high joining strength.

[0008]

According to the present invention, a carbon layer is formed on the joint surface on the nickel side in the joining of semix and nickel or an alloy containing a large amount of nickel.
It is a method of joining ceramics and nickel, characterized by heating and joining in a vacuum atmosphere using a Cu-Ti based brazing material.

[0009]

[Function] The carbon layer formed on the nickel-side bonding surface
Prevents Ni from diffusing into the brazing material. Therefore, the amount of Ti in the brazing material that reacts with Ni decreases, and the amount of Ti that reacts with the ceramics relatively increases, so that the reaction layer necessary for bonding is sufficiently formed at the interface of the ceramics.

[0010]

Embodiments of the present invention will be described with reference to the drawings.
As shown in FIG. 1, a cylindrical silicon nitride ceramic (S
This is the case where i3N4) 1 is bonded to the nickel 5 surface of the bonded body of nickel (Ni) 5 and Kovar alloy 6. On the side of ceramics 1 (φ10 mm, L20 mm), Ti foil 3 (φ
10 mm, thickness 2 μm), Ag-Cu-Ti based brazing filler metal 2 (Ag: 63 wt%, Cu: 35.25 wt%,
Ti: 1.75 wt%) with a thickness of 50 μm interposed, and a carbon (C) layer 4 with a thickness of about 5 μm is formed on the surface of nickel 5 by vapor deposition.
Heated to 0 ° C and held for 10 minutes.

The breaking strength of the joint portion of this joined body was as high as 420 MPa in the four-point bending test strength (Example 1 in Table 1), and the breaking occurred in the ceramics. For comparison, a case where the carbon layer 4 was joined without being provided (Table 1
Comparative Example 1), the breaking strength of the joined body was 275 MPa in the four-point bending test strength, and the breaking occurred in the ceramic including a part of the interface.

The cross section of the joint portion of the joint body of the above-mentioned example was subjected to surface analysis of component elements by a microanalyzer (EPMA). The result of the Ti elemental analysis is shown in FIG. 3 and the result of the Ni elemental analysis is shown in a schematic diagram in FIG. As shown in FIG. 3, Ti is densely distributed at the interface of the silicon nitride ceramics,
On the other hand, Ni does not exist on the interface side of the silicon nitride ceramics as shown in FIG. As shown in FIG. 3, the carbon layer formed on the joint surface on the nickel side reacts with Ni to form a Ti—C compound, which prevents the diffusion of Ni into the brazing material. Presumed. Therefore, pure TiN and Ti5Si3 layers are sufficiently formed at the interface of the silicon nitride ceramics, and the bonding strength is improved.

Cobalt (Ni 29%, Co 17%, M) which is a low thermal expansion alloy containing a large amount of nickel instead of Ni
n, Si, Mg, Zr, C, Al, Ti all less than 1%, balance F
Even if e) is bonded to ceramics, it is also strongly bonded. Table 1 below shows the joining conditions and the four-point bending test strength of the examples and comparative examples.

[0014] Note 1: The bonding metal of Example 1 and Comparative Examples 1 to 3 is Ni-
A joint of Kovar. Note 2: The joining metal of Example 2 and Comparative Examples 4 to 5 is Ni. Note 3: The circles in the Ti foil and C layer columns indicate that they are used, and the blank columns indicate that they are not used.

[0015]

According to the present invention, ceramics and nickel can be bonded with high bonding strength in bonding ceramics and nickel or an alloy containing a large amount of nickel.

[Brief description of drawings]

FIG. 1 is an explanatory view of an embodiment of the method of the present invention.

FIG. 2 is an explanatory view of a reaction layer in a joint part.

FIG. 3 is a schematic diagram showing the Ti distribution of the surface analysis of the joint portion of the example.

FIG. 4 is a schematic diagram showing the Ni distribution of the surface analysis of the joint portion of the example.

FIG. 5 is a schematic diagram showing a Ti distribution in a surface analysis of a bonded portion by a conventional method.

FIG. 6 is a schematic diagram showing a Ni distribution in a surface analysis of a bonded portion by a conventional method.

[Explanation of symbols]

1 Silicon Nitride Ceramics 2 Ag-Cu-Ti Based Brazing Material 3 Ti Foil 4 Carbon 5 Nickel 6 Kovar Alloy

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Toshiyuki Takashima 7-15-15 Maeda Maeda, Teine-ku, Sapporo, Hokkaido Hokkaido Institute of Technology

Claims (1)

[Claims] 1. When bonding semix and nickel or an alloy containing a large amount of nickel, a carbon layer is formed on the nickel-side bonding surface and heated in a vacuum atmosphere using an Ag—Cu—Ti based brazing material. A method of joining ceramics and nickel, which is characterized by joining.