JPH08239278A - Brazing between silicon carbide material and metallic material - Google Patents

Abstract

PURPOSE: To lower the stress occurring on the boundary face of silicon carbide to inhibit the silicon carbide material from being cracked by inserting a specific metal of low thermal expansion between the silicon carbide material and the metallic material and brazing them. CONSTITUTION: Between a silicon carbide 1 and a metallic material 2, are placed a metal plate 7 which has low thermal expansion close to the linear thermal expansion of the silicon nitride and another soft metal 8, and additionally a brazing filler metal foil 6 30-80μm thick are placed between individual materials 1, 8, 7 and 2, and then they are brazed by heating.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a brazing method for a silicon carbide (SiC) member and a metal member, and more particularly to a SiC brazing method which can be advantageously applied to the production of acceleration tubes, gas turbine parts and nuclear parts.

[0002]

2. Description of the Related Art Conventionally, there are the following three types of methods for joining SiC and metal. The first is Si
This is a method in which C is metallized and then brazed with silver brazing, the second is a method in which SiC is directly joined by silver brazing containing an active metal without performing metallization, and the third is metallized in SiC. Sn-
This is a method of brazing with a low melting point brazing material such as Au type brazing material.

A method of brazing with silver brazing after metallizing the first SiC is performed by using Ti, M for SiC.
After performing the metallization treatment of three layers of o and Ni, BAg-
8 Brazing material (composition: Ag-28Cu, melting point: about 780 ° C)
Is used to braze SiC and metal at about 800 ° C., and a method of directly joining SiC with a second active-metal-containing silver braze is a Ti-containing BAg-8 brazing material (composition: A
g-28Cu-2Ti, melting point: about 790 ° C.)
iC and a metal are brazed at about 820 ° C., and the third SiC is subjected to a metallizing treatment to Sn-A.
The method of brazing with a u-based brazing material is
After performing the metallization treatment of three layers of i, Mo and Ni, S
Si using n-10Au brazing material (melting point: about 250 ° C.)
C and metal are brazed at about 325 ° C.

[0004]

In the first and second conventional methods, since the brazing temperature is as high as about 800 ° C.,
The difference between the coefficient of thermal expansion of SiC (5 × 10 ⁻⁶ / K) and the coefficient of thermal expansion of the metal bonded to it (for example, Cu is 18 × 10 ⁻⁶ / K), and the temperature difference between the brazing temperature and room temperature. Excessive thermal stress due to occurs at the joint interface during cooling from the brazing temperature,
There are problems that peeling occurs at the bonding interface and cracks are likely to occur in SiC that is relatively brittle. Moreover, in the third conventional method, the brazing temperature is about 325 ° C.
Since the difference is lower than that of the second method, the difference in thermal expansion between the SiC member and the metal member is relatively small, so that cracks and the like do not occur in the SiC member, but the brazing material of this method has the strength of the brazing material itself. Is low and the heat resistance is poor (melting at about 250 ° C.). Further, there is a problem that the metallization treatment is indispensable for SiC and the cost becomes high.

In view of the above-mentioned state of the art, the present invention aims to provide a brazing method for a SiC member and a metal member, which is free from the problems of the conventional method.

[0006]

According to the present invention, when a silicon carbide member is brazed to a metal member, a low thermal expansion metal having a linear expansion coefficient close to that of the silicon carbide member is inserted between both members for brazing. A method of brazing a silicon carbide member and a metal member, characterized in that a softer metal plate is inserted between the silicon carbide member and a low thermal expansion metal having a linear expansion coefficient close to that of the member. This is a brazing method for a silicon carbide member and a metal member.

That is, according to the brazing method for the SiC member and the metal member of the present invention, a low thermal expansion metal is inserted between the SiC member and the metal member to buffer the stress generated in the SiC member and the SiC member and the metal member. A member is brazed, and more preferably, a soft metal is also inserted between the low thermal expansion metal to be inserted and the SiC member for brazing.

In the present invention, the mating metal for brazing the SiC member may be any metallic material,
For example, in addition to oxygen-free copper given in the examples below, stainless steel {SUS304: coefficient of thermal expansion (α) = 18.7 × 10 ^-6
/ K, SUS430: α = 11.3 × 10 ⁻⁶ / K}, superalloy {Inconel: α = 13.0 × 10 ⁻⁶ / K, Hastelloy X: α = 13.9 × 10 ⁻⁶ / K} , Titanium alloy {T
i-6Al-4V: α = 10.3 × 10 ⁻⁶ / K, pure T
i: α = 10.4 × 10 ⁻⁶ / K} and the like.

The low thermal expansion used in the present invention
The metal selected should be close to the coefficient of thermal expansion (α) of the SiC member.
Be done. For example, pure W and its alloy (α = 5 × 10^-6/
K), pure Mo and its alloys (α = 6 × 10^-6/ K), pure
Ta and its alloys (α = 7 × 10 ^-6/ K), pure Re and
The alloy (α = 7 × 10^-6/ K), pure Nb and its alloys
(Α = 8 × 10^-6/ K) and the like.

Further, as the brazing material used in the present invention, Ag-28Cu-2Ti (liquidus temperature: 790 ° C., brazing temperature: 800 to 900 ° C.), Cu-34Ti (liquidus temperature: 875 ° C., brazing) Temperature: 890 to 920 ° C.), C
u-50Ti (liquidus temperature: 975 ° C, brazing temperature: 99)
0 to 1000 ° C., Cu-57Ti (liquidus temperature: 955)
℃, brazing temperature: 970-990 ℃), Ti-25Ni
(Liquid phase temperature: 942 ° C., brazing temperature: 970-990
C), Ti-15Cu-15Ni (liquidus temperature: 920)
C, brazing temperature: 950-990 C), Ti-20Cu
-20Ni-20Zr (liquidus temperature: 800 ° C., brazing temperature: 820 to 900 ° C.) and the like can be mentioned, but Ti-containing BAg-8 brazing material is particularly preferable.

Copper is preferable as the metal to be inserted between the low thermal expansion metal and the SiC member to be inserted.

[0012]

In the method of the present invention, by inserting a low thermal expansion metal between the SiC member and the metal member and brazing,
The thermal stress generated at the SiC interface during brazing between the metal member and the SiC member is reduced, and cracks and the like are prevented from occurring in the SiC member. Further, in the method of the present invention, it is not necessary to perform the metallizing treatment, so that it is possible to shorten the process and reduce the cost.

Further, according to the present invention, by inserting a soft metal such as copper between the low thermal expansion metal to be inserted and the SiC member, it is possible to further prevent the SiC member from cracking.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIGS. The brazing method of the present embodiment is used in the production of the acceleration tube dummy load shown in FIG.
This is applied when the SiC button 1 that exhibits an excellent function as a high-power microwave absorber is bonded to the inner surface of the waveguide 2 made of abbreviated as u).

In the brazing method of this embodiment shown in FIGS. 1 and 2, the OFCu plate 8 and the low thermal expansion metal plate 7 (for example, W: thermal expansion coefficient 5 ×) are provided between the SiC button 1 and the OFCu waveguide 2. 10 ⁻⁶ / K, Mo: Coefficient of thermal expansion 6 × 10 ⁻⁶ / K) is inserted, and a Ti-containing BAg-8 brazing filler metal foil 6 (composition: Ag-28Cu) having a thickness of 30 μm to 80 μm between each member.
-2Ti, melting point: about 790 ° C) and heat to braze. Here, the brazing temperature is about 820 ° C. and is 5 to 30.
It was held for a minute, and cooling was performed slowly enough so as not to cause peeling or cracking.

Here, the OFCu plate 8 is further inserted between the SiC button 1 and the low thermal expansion metal plate 7 because the SiC button 1 and the low thermal expansion metal plate (W or Mo) 7 are inserted.
When the and are directly joined, a crack may occur in the low toughness SiC button 1 due to a slight difference in thermal expansion.
To prevent this, a soft metal plate, namely OFCu
The plate 8 is inserted, and this is preferable in actual operation. That is, in the present invention,
The low thermal expansion metal relaxes stress due to a large thermal expansion difference between the SiC member and the metal, and the soft metal is SiC.
It absorbs a small thermal stress between the member and the low thermal expansion metal.

In the joining by the brazing method of this embodiment, the low thermal expansion metal plate 7 buffers the thermal stress caused by the difference in thermal expansion between the SiC button 1 and the OFCu waveguide 2, and the thermal stress at the joint is increased. To prevent the SiC button 1 from cracking.
As a result, good brazing quality having high strength and heat resistance was obtained, and peeling did not occur at the joint interface.

In the acceleration tube dummy load manufactured by applying the brazing method of this embodiment, the SiC button 1 absorbs the unnecessary high-power microwave 3 generated in the acceleration tube and converts it into heat energy. The thermal energy is transferred to the cooling water 5 flowing in the water cooling jacket 4 via the OFCu waveguide 2 and removed. Therefore, the SiC button 1 above
The temperature of the junction between the and the OFCu waveguide 2 is maintained at about 100 ° C. Although the acceleration tube dummy load was used for a long time in this state, defects such as cracks in the SiC button 1 and peeling of the joint portion did not occur at all in the acceleration tube dummy load.

[0019]

The method for brazing SiC according to the present invention can reduce the stress generated at the SiC interface by inserting a low thermal expansion metal between the SiC member and the metal member and cause cracks or the like in the SiC member. Absent.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a brazing method according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram of an acceleration tube dummy load to which the brazing method according to the embodiment of the present invention is applied.

Front page continuation (72) Inventor Riki Fujiwara 10 Oemachi, Minato-ku, Nagoya, Aichi Mitsubishi Heavy Industries, Ltd. Nagoya Aerospace Systems Works

Claims (2)

[Claims] 1. When a silicon carbide member is brazed to a metal member, a low thermal expansion metal having a linear expansion coefficient close to that of the silicon carbide member is inserted between both members for brazing. And brazing method for metal members. 2. The silicon carbide member and the metal member according to claim 1, wherein a softer metal plate is inserted between the silicon carbide member and the low thermal expansion metal having a linear expansion coefficient close to that of the member. Brazing method.