JPH0350167A - Structure for joining ceramic parts and metallic parts - Google Patents

Abstract

PURPOSE:To improve the peeling resistant strength at a joint boundary by joining and fixing ceramics parts for buffering thermal stresses on the surface of metallic parts on the side opposite to the surface joined with the ceramic parts. CONSTITUTION:Flange parts 3a, 5a of a piping side appliance 3 and heat exchanger side appliance 5 made of Al, etc., of the metallic members are fixed via intermediate joining rings 2, 4 made of Al-Si, which is a brazing material, to the bottom end surface 1a and top end surface 1b of a ring 1 made of alpha-alumina, etc., which are the ceramics parts. The ceramics rings 7, 9 for buffering thermal stresses made of the same material as the material of the alumina ring 1 are fixed by a pressurized brazing method via intermediate joining rings 6, 8 made of an Al alloy which is a brazing material to the rear surface of the flange part 3a and the upper part of the flange part 5a. The thermal expansion of the metallic parts having the large thermal expansion is suppressed by the ceramics parts for buffering thermal stresses having the small thermal expansion when these parts receive repeated heat cycles.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a bonding structure for ceramic parts and metal parts.

[Prior Art] Generally, ceramics have a smaller coefficient of thermal expansion than metals, so in the joint structure of ceramic parts and metal parts that are used at high temperatures or subjected to thermal cycles, it is necessary to reduce the thermal stress generated at the joint interface between the two. Relaxation is essential. Means for this include interposing a material with an intermediate coefficient of thermal expansion between the two, interposing a soft metal at the bonding interface between the two, or constructing the metal parts from a soft metal such as aluminum. It is known.

In addition, the bonding structure of such ceramic parts and metal parts is
7 of heat exchangers using engine parts and sodium as a heat medium
For example, in this flange part, as shown in FIG. 5, the aluminum pipe fitting 3 and the aluminum heat exchanger side fitting 5 are electrically insulated by the alumina ring 1. The alumina ring 1, the heat exchanger side metal fitting 5, and the piping side metal fitting 3 are connected at A.
They are joined via an intermediate joining ring 2.4 made of JI brazing material. In this case, other parts for the purpose of buffering thermal stress were not joined to the lower side of the pipe-side metal fitting 3 and the upper side of the heat exchanger-side metal fitting 5.

[Problems to be Solved by the Invention] However, in the conventional flange joint structure described above, when subjected to repeated thermal cycles between room temperature and a high temperature of, for example, 350°C, heat exchange with the alumina ring 1 occurs as described above. Due to the difference in coefficient of thermal expansion with the side metal fitting 5, thermal stress is generated near the bonding interface between the two, and this thermal stress causes local separation of the bonding interface, reducing the airtightness of the bonding interface and damaging the heat exchanger. There was a problem in that the durability of the material decreased.

The purpose of this invention is to reduce the thermal stress generated at the bonding interface when a thermal cycle acts on the bonding interface between a ceramic component and a metal component, and to improve the peeling resistance strength of the bonding interface. Our goal is to provide a bonding structure for parts and metal parts.

[Means for Solving the Original Problem] In order to achieve the above object, the present invention joins a ceramic part and a metal part, and a surface of the metal part opposite to at least one of the ceramic parts is coated with the ceramic part. The method is to bond thermal stress-absorbing ceramic parts made of the same material.

In this case, it is preferable that the thickness of the thermal stress buffering ceramic component is equal to or greater than the thickness of the metal component.

[Function] In this invention, a thermal stress buffering ceramic component is bonded and fixed to the surface of the metal component opposite to the bonding surface with the ceramic component, so that when these components are subjected to repeated thermal cycles, thermal expansion will not occur. Thermal expansion of large metal parts is suppressed by using ceramic parts with small thermal expansion and thermal stress. Therefore, the thermal stress generated at the bonding interface between the ceramic component and the metal component is effectively alleviated, and the bonding strength and airtightness of the bonding interface between the ceramic component and the metal component are stably maintained over a long period of time.

[Embodiment] An embodiment embodying the present invention will be described below with reference to FIGS. 1 to 4.

As shown in Fig. 1.2, a lower end surface 1a and an upper end surface 1b of a ring 1 made of α-alumina as a ceramic component.
The flange portions 3a and 5a of the Aj-manufactured tube-side fittings 3 and the A1-made heat exchanger-side fittings 5 as metal members are connected via intermediate joining rings 2 and 4 made of Aj-3t alloy as brazing filler metals. Pressure brazing is fixed in the method detailed below. The alumina ring 1 is formed on the lower surface of the flange portion 3a of the pipe side metal fitting 3 and on the upper surface of the flange portion 5a of the heat exchanger side metal fitting 5 via an intermediate joining ring 6.8 made of AJI alloy, which also serves as a brazing material. Thermal stress [ff ceramic ring 7.9 as a thermal stress buffering ceramic component made of the same material as α-alumina is fixed by pressure brazing, which will be described in detail later.

In this example, the alumina ring 1 has a purity of 99.9.
Using α-alumina of wt% or more, the heat exchanger side metal fitting 5
And as the pipe side fitting 3, JI having the composition shown in Table 1.
S-A3003 or JIS-A6061 is used. These Aj gold alloys contain trace amounts of unavoidable impurities.

Further, as the thermal stress buffering ceramic ring 7.9, α-alumina, which is the same material as the alumina ring 1, was used.

(The following is a margin) Table 1 Furthermore, the intermediate bonding rings 2, 4, 6.8 have Aj as a main component, Si: 6-1 3wt%, Mg: 3
．． It is made of an alloy containing 0wt% or less and other unavoidable impurities. This intermediate joining ring 2.4.6.8
Although various commercially available aluminum solders can be used as the material for the
A4004 or BA4004 is used as the skin material, A300
3 as the core material (J I 5-BA
Preference is given to using I8PC).

Next, based on FIGS. 3 and 4, the alumina ring 1, the pipe side fitting 3, the heat exchanger side fitting 5, and the thermal stress
The method for pressure brazing of ceramic rings 7.9, etc. will be explained below.

As shown in FIG. 3, in the heating device (path shown),
A heat exchanger side metal fitting 5 and a piping side metal fitting 3 are brought into contact with both upper and lower end surfaces of the alumina ring 1 via an intermediate joining ring 4.2 made of an Aj-3l-Mg alloy, and furthermore, a bottom surface of the piping side metal fitting 3 is A thermal stress buffering ceramic ring 7 is brought into contact with an intermediate joining ring 6 made of an Aj-3i-Mg alloy, and an intermediate joining ring 8 made of an Aj-31-Mg alloy is placed on the upper surface of the heat exchanger side metal fitting 5. The surface of the thermal stress buffering ceramic ring 7.9 is held between the pressure jigs 10 and 11 with the thermal stress buffering ceramic ring 9 in contact with the ring 7.9.

In this state, the inside of the heating device is evacuated to create a vacuum state, and as shown in Figure 4, it is heated to 600℃, and then held at 600℃ for a predetermined period of time to uniformize the temperature of the entire group. After that, the temperature was lowered at a rate of about 2℃/min, and when the temperature reached 580℃, the temperature was reduced to 0.5kgf/min.
Apply a pressure of "III" using the pressure jig 10.11, maintain the pressurized state until the temperature reaches 520"C, and then when the temperature drops to 400"C, annealing is carried out by holding at 400"C for a predetermined time. After doing this, let it cool. This pressurization begins at a temperature between the liquidus temperature and the common mode temperature of the metal material making up the intermediate bonding ring, and continues to a temperature below the common mode temperature.

The pressing force in this case is 0,05 k (If/i11"
If it is ~2.0kof/nn2, there will be no difference in bonding strength.

Thermal stress buffering ceramic rings 9.7 are joined to the heat exchanger side metal fittings 5 and the piping side metal fittings 3, which are pressure-brazed to the alumina ring 1 in this way. Even after repeated thermal cycles between 100 and 300°F (°C), no peeling occurs at the bonding interface. The thermal stress generated at the bonding interface between ceramic parts and metal parts is
As mentioned above, due to the difference in thermal expansion coefficient between the ceramic material and the metal material that make up both parts, the thermal stress occurs during cooling from the bonding temperature, and the magnitude of the thermal stress varies depending on the shape of the metal part. Change. Therefore, it is only necessary to bond the above-mentioned thermal stress buffering ceramic ring to the bonding interface between the ceramic component and the metal component where thermal stress of a magnitude that would degrade the properties of the bonding interface occurs. For example, in the joint structure shown in Fig. 3, as is clear from the exploded perspective view of the main parts shown in Fig. 2, the heat exchanger side fitting 5 and the pipe n1 fitting 3 have different shapes. The thermal stress generated at the bonding interface between the heat exchange H-side fitting 5 and the alumina ring 1 is greater than the thermal stress generated at the bonding interface between the pipe-side metal fitting 3 and the alumina ring 1. Therefore, in the joint structure shown in FIG. 3, depending on the usage conditions or thermal cycle conditions, the heat exchanger side metal fitting 5
A thermally stressed ceramic ring 9 is bonded only to the surface opposite to the bonding interface with the alumina ring 1, and the pipe side fitting 3 is
It is also possible to adopt a structure in which the thermal stress buffering ceramic ring 7 is not bonded to the surface opposite to the bonding interface between the alumina ring 1 and the alumina ring 1.

Next, another example (Example 2) of this invention will be described.

In this embodiment, the intermediate joint rings 2.4, 6°8 are made of pure aluminum with a purity of 99.9 wt% or more, and the heat exchanger side metal fittings 5 and the piping side metal fittings 3 are made of aluminum alloy (JIS-A3003). After constructing an IG4 board with the same shape as in the above example, it was heated to 600 ° C. and held for a predetermined time using the same heating device as in the above example, and then heated to a pressure of 2.0 kgf/vw2. was applied using a pressing jig 10.11, and then the temperature was lowered to 400°C, and a predetermined annealing was performed at 400°C, followed by cooling. In this example, bonding is achieved at a temperature below the melting point (660° C.) of pure aluminum, which is the intermediate bonding ring, and the intermediate bonding ring and each component are bonded by so-called solid phase bonding.

Next, still another embodiment (Embodiment 3) of the present invention will be described.

In this embodiment, the intermediate joint ring 2, 4.6° 8 is made of the same aluminum alloy as in the first embodiment, the heat exchanger side metal fitting 5 and the piping side metal fitting 3 are made of carbon steel, and
After constructing a structure having the same shape as , it was joined by the same method as in Example 1 above.

On the other hand, as a conventional example, parts made of the same material as in the above embodiment were combined to form a thermally stressed ceramic ring 7.9.
Generated zygotes without.

The joints of these various examples and conventional examples were subjected to thermal cycle tests at temperatures between room temperature and 350°C, and a helium leak test was performed to determine whether there was any deterioration in the airtightness of the joints. The results are shown in Table 2. As is clear from Table 2,
In Example 1 of the present invention, the number of thermal cycles is 30.
Up to 0 times, the frequency of helium leak occurrence was 0.

In addition, in Example 2 of the present invention, the number of thermal cycles was 4.
Up to 00 times, the frequency of helium leak occurrence was 0.

Furthermore, in Example 3 of the present invention, the frequency of occurrence of helium leak was 0 until the number of thermal cycles was repeated 300 times. On the other hand, among the conventional examples 1 to 3, which combine parts made of the same material as the embodiment of the present invention and differ from the embodiment in that there is no ceramic ring due to thermal stress M, conventional examples 1 and 2
In the case of 100 thermal cycles, one 5-width product caused a helium leak. Furthermore, in Conventional Example 3, one 5-striped cloth caused a helium leak after 50 thermal cycles.

Table 2 As is clear from the results in Table 2, it can be seen that the examples of the present invention have better heat cycle resistance than the conventional examples.

Note that the present invention can also be embodied in a joining structure of ceramic parts and metal parts that are subjected to repeated thermal cycles in, for example, electron tube parts, engine parts, etc. other than the above-mentioned heat exchanger.

The metal parts constituting this invention are preferably made of at least one kind of metal material selected from the group consisting of carbon steel, stainless steel, aluminum, aluminum alloy, copper, and mixed metal. It is more preferable to use metal, and the present invention also includes materials whose surfaces are provided with a coating layer in order to impart corrosion resistance or wear resistance to these metal materials.

Additionally, the ceramic parts constituting this invention include alumina,
Preferably, it is a ceramic material from the group consisting of zirconia, silicon nitride and silicon carbide.

Furthermore, in the bonding structure between a ceramic component and a metal component of the present invention, the thermal stress buffering ceramic ring 7.9 does not necessarily have to be made of the same material as the ceramic component, but the materials are similar and the coefficient of thermal expansion is approximately the same. This invention also includes materials made of different materials as long as they are the same.

[Effects of the Invention] As detailed above, the present invention suppresses thermal stress at the joint between a ceramic component and a metal component by using an IR ceramic component to maintain the strength of the joint and improve heat cycle resistance. There are effects that can be improved.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of the main parts showing an embodiment of this invention in which the heat exchanger side metal fitting and the piping side metal fitting are joined by 1 int,
Figure 2 is an exploded perspective view of the main parts, Figure 3 is a sectional view of the main parts to explain the structure of the main parts, Figure 4 is a graph showing the pressure brazing method, and Figure 5 is the conventional example. FIG. 1... Alumina ring as a ceramic component, 2.
4.6.8... Intermediate joining ring, 3... Heat exchanger side metal fitting as a metal component, 7.9... Thermal stress [r Thermal stress buffering ceramic ring as a ceramic component.

Claims (1)

[Claims] 1. A ceramic component and a metal component are bonded, and a thermal stress buffering ceramic component made of substantially the same material as the ceramic component is bonded to at least one surface of the metal component opposite to the ceramic component. Features a joining structure of ceramic and metal parts. 2. The joining structure of a ceramic component and a metal component according to claim 1, wherein the metal component is made of at least one metal selected from the group consisting of carbon steel, stainless steel, aluminum, aluminum alloy, copper, and copper alloy. 3. The joining structure of a ceramic component and a metal component according to claim 1, wherein the metal component is made of aluminum or an aluminum alloy. 4. The joining structure of a ceramic component and a metal component according to claim 1, wherein the thickness of the thermal stress buffering ceramic component is greater than the thickness of the metal component.