JPH0448754B2 - - Google Patents

Description

[Detailed description of the invention]

(Field of Industrial Application) The present invention relates to a joined body that requires the joining of ceramics and metal with high strength in turbochargers, heat exchangers, first walls of nuclear fusion reactors, electromagnetic parts, etc., and a method for manufacturing the same. It is something. (Prior Art) Ceramics generally have a smaller coefficient of thermal expansion than metals, and parts bonded to metals will break due to thermal stress generated from the difference in thermal expansion between the two. This effect is particularly significant for parts that are used under thermal cycles. Therefore, in order to reduce such stress, an intermediate layer whose thermal expansion coefficient is between that of the ceramics and the metal to be bonded is often inserted, or a soft intermediate layer with large deformability is inserted for bonding. Recently, in Japanese Unexamined Patent Publication No. 60-231471, the intermediate layer is composed of layers, and the intermediate layer in contact with the ceramic is made of a metal or alloy whose thermal expansion coefficient is close to that of the ceramic, and the intermediate layer in contact with the metal has a thermal expansion coefficient similar to that of the ceramic. Metal-ceramic bonded bodies characterized by smaller metals or alloys have been announced. This method breaks away from the usual concept of making the order of the coefficients of thermal expansion of the intermediate layer monotonically increasing or decreasing.
That is, it is proposed that the relationship of the thermal expansion coefficient α is as follows. α (ceramics) ≒ α (intermediate layer 1) > α (intermediate layer 2) < α (metal) In the embodiment of this invention, Nb and _Mo are selected to join Al ₂ O ₃ and stainless steel _. ／Nb／
The Mo/stainless steel arrangement provides a bonded body with high bonding strength. (Problem to be solved by the invention) However, as this example shows, the middle class
Selection of Nb and Mo requires complex considerations;
Furthermore, since the ceramics and metals to be bonded are different, it is possible that the intermediate layer Nb and Mo may affect the performance of the bonded body. For example, since Nb and Mo are used, there are drawbacks such as the inability to use it in high-temperature air. (Means for Solving the Problems) The present invention uses an intermediate layer as a means for alleviating the thermal stress as described above, but unlike the conventional method, the thermal expansion coefficient of the intermediate layer is sequentially increased or decreased sequentially. In addition, in view of the fact that no special solution can be obtained even if the intermediate layer material is a complex combination of high-melting point metals as in JP-A No. 60-231471, it is decided to use at least two intermediate layers, This method attempts to bond the ceramic base material and the metal base material by using the same material for the intermediate layer as the ceramic base material and the metal base material, respectively. The gist of the invention is as follows. First Invention Consisting of a ceramic base material and a metal base material, and a ceramic intermediate layer and a metal intermediate layer made of the same material and having the same or similar coefficient of thermal expansion, respectively, are interposed between the ceramic base material and the metal base material, and the ceramic intermediate layer is made of metal. The intermediate layers are sandwiched between each other or between the metal intermediate layer and the metal base material, and the metal intermediate layer is arranged and bonded so as to be sandwiched between the ceramic intermediate layers or between the ceramic intermediate layer and the ceramic base material. A bonded body of ceramics and metal characterized by the following. 2nd invention In a method of bonding by inserting at least two or more intermediate layers between a ceramic base material and a metal base material, the ceramic base material and the metal base material to be bonded have at least a material and a coefficient of thermal expansion. A ceramic intermediate layer and a metal intermediate layer, which are the same or similar to each other, are inserted between the ceramic base material and the metal base material, and both bonding interfaces of the ceramic intermediate layer are bonded to each other or to the metal intermediate layer and the metal intermediate layer. and a base material, and both bonding interfaces of the metal intermediate layer are arranged and bonded so as to be sandwiched between the ceramic intermediate layers or between the ceramic intermediate layer and the ceramic base material. joining method. (Function) The present inventors selected Ti and Mo as the intermediate layer to join SiC and stainless steel, and
An experiment was conducted to obtain a bonded body with high strength by sandwiching a silver solder foil at each interface of a Mo/stainless steel array and brazing it. In this case, in the SiC/Mo/Ti/stainless steel arrangement, the bonding strength is high when measured immediately after bonding, but if left for about a day, the bonded structure will spontaneously break and the arrangement order of the intermediate layer will change. I learned something important. The relationship between the coefficient of thermal expansion α at this time is α (SiC) < α (Ti) > α (Mo) < α (stainless steel). Here, the present inventor has developed an intermediate layer of refractory metals such as Ti and Mo.
Even if an intermediate layer made of the same material as SiC and stainless steel, which are the base materials to be bonded, is used instead, from the point of view of thermal expansion coefficient only, α (SiC) < α (stainless steel) > α (SiC) < α (stainless steel), so if stainless steel and SiC itself are used as the intermediate layer, the intermediate layer stainless steel will be sandwiched between the base material SiC and the intermediate layer SiC, and the intermediate layer SiC will be sandwiched between the intermediate layer stainless steel and the intermediate layer SiC. The coefficient of thermal expansion is exactly the same on both sides of the intermediate layer sandwiched between the stainless steel base material, and the deformation of the stainless steel intermediate layer is restrained by the SiC on both sides, and conversely, the deformation of the SiC intermediate layer is restrained. It will be restrained by stainless steel on both sides. For example, if one side of a metal plate is coated with ceramics, the plate will warp due to the difference in coefficient of thermal expansion, but if the same ceramic is coated on the back side of the metal plate, no deformation will occur. Furthermore, although SiC and stainless steel were joined by brazing, SiC and stainless steel can be directly joined by solid phase diffusion bonding without using a brazing material. There are many examples in which other metal-ceramic combinations can also be directly bonded. After all, when selecting and bonding ceramics and metal to be bonded as an intermediate layer, bonding using an inorganic adhesive or frit, bonding by a reaction sintering method, etc. can be used in addition to the above two methods. The method of joining ceramics and metal according to the present invention will be illustrated and explained with reference to the drawings. FIG. 1A shows a structure in which a metal intermediate layer 3 and a ceramic intermediate layer 4 are alternately inserted to bond a ceramic base material 1 and a metal base material 2. When bonded in this arrangement, both sides of the metal intermediate layer are sandwiched between ceramics of the same material, so the coefficient of thermal expansion on both sides of the metal intermediate layer is the same. , distortion will not occur on either side and cause the product to warp and break. When a ceramic intermediate layer is also sandwiched between two metals of the same material from both sides, there is no difference in coefficient of thermal expansion on both sides of the intermediate layer, so the metal and ceramics thermally expand in the direction of their respective free surfaces, causing peeling or cracking at the bonding interface. , no destruction etc. will occur.
In the case of joining as shown in Figure 1A, we inserted a brazing filler metal and tested it, but since the thin layer of the brazing filler metal used for bonding is usually ductile, it has deformability, and the coefficient of thermal expansion on both sides of the intermediate layer If they are substantially the same or similar in total, no damage will occur. FIG. 1B shows an example in which two intermediate layers are inserted, and in this case, the metal intermediate layer and the ceramic intermediate layer are each sandwiched between a ceramic base material or a ceramic intermediate layer, and the ceramic intermediate layer are arranged in a sandwiched relationship between the metal substrates or the metal intermediate layer. Therefore, even when these are joined together using brazing filler metal to form a single body, the joining method is exactly the same as the joining method shown in Fig. 1A, and even if there are multiple intermediate layers, the joining is possible without any problem, and the joining is possible. There is no fear of subsequent destruction. Figures 1C and 1D show metal intermediate layers 3A, 3
The case is shown in which the metal intermediate layer 3 in FIG.
1D can be considered to be the same as if the ceramic intermediate layer 4 of FIG. 1A was divided into two parts as shown in 4A and 4B. In FIG. 1C, the two metal intermediate layers 3A and 3B are sandwiched between the ceramic base material 1 and the ceramic intermediate layer 4, so both sides of the metal intermediate layers 3A and 3B are sandwiched between ceramics. Also, in Figure 1D,
The two ceramic intermediate layers 4A and 4B are sandwiched between a metal base material 2 and a metal intermediate layer 3 on both sides. Therefore, just as in the case of Fig. 1A, both sides of the two metal or ceramic laminates are sandwiched between ceramics and metal, respectively. It can be viewed in the same way as layers. In the example shown in Figures 1E and 1F, two metal substrates are used.
It can be divided into two parts like A and 2B, or even if the ceramic base material is divided into two parts like 1A and 1B.
This shows that the bonding principle remains the same; even if a brazing material is inserted between these layers, the bonding will be exactly the same and no damage such as cracking or peeling will occur. The reason for this is that a thin intermediate layer generates less thermal stress than a thick intermediate layer, so it may be preferable to have multiple layers. As described above, according to the present invention, it is easy to select the intermediate layer, and there is no need to change the bonding conditions for each interface when using two or more different intermediate layers different from the materials to be bonded. This enables bonding even when materials with poor oxidation resistance, such as Ti, cannot be used, and is expected to have a significant effect in that the properties of the bonded portion will not be impaired. Example 1 A second plate was placed between a dense Si ₃ N ₄ sintered base material 11 (hot pressed product) measuring 10×10 (mm) in length and width and 4 mm thick and a stainless steel base material 12 (SUS316) having a thickness of 3 mm. As shown in the figure, a stainless steel thin plate 13 with a thickness of 0.4 mm is placed on the side in contact with Si ₃ N ₄ , and a Si ₃ N ₄ plate 14 with a thickness of 1.7 mm is placed as an intermediate layer on the side in contact with the stainless steel, and a graphite type After installation within the temperature 1090℃, pressure
Hot press bonding, that is, diffusion bonding, was performed in a vacuum of 200 Kg/cm ² and an atmosphere of 1×10 ⁻⁴ torr. The temperature was raised at a rate of 25°C/min, and after reaching 1090°C, pressure was applied for 50 minutes, the pressure was lowered, and the temperature was maintained at 1090°C for an additional 10 minutes to remove strain during pressurization. When the temperature is further lowered, the temperature is lowered to 800°C at a cooling rate of 8°C/min, held at this temperature for 1 hour, and then again at a cooling rate of 8°C/min.
The temperature was lowered to 500°C and held at this temperature for 1 hour. One week or more after the bonding, the bonding strength was measured by a shear test. The bonding strength was 4.6Kg/ ^mm2 . Example 2 Between a dense SiC sintered body base material (normal pressure sintered product) 11 with length and width of 10×10 (mm) and a thickness of 4 mm and a stainless steel base material (SUS316) 12, as shown in FIG. To,
On the side in contact with the SiC base material 11, the thickness is 1 or 0.5 mm.
An intermediate layer 13 of a stainless steel thin plate of
A 1.5 mm SiC plate is inserted as the intermediate layer 14, and a silver solder 15 containing Ti2 wt% (composition Ag70.5-
A 70 μm thick foil of Cu27.5−Ti2) was inserted, and brazing was performed in a vacuum of 2×10 ⁻⁵ torr by high-frequency heating. The temperature increase rate during brazing is 50℃/min, 810
℃, and immediately after reaching 810℃, the temperature was lowered at a rate of 10℃/min, and after keeping the temperature constant at 500℃ for 1 hour,
Cooled at 10°C/min. It is effective to perform heat treatment at 500°C to remove strain; if this was not done, cracks could be seen in the SiC intermediate layer at the joint.
After one week or more had passed after the bonding, the bonding strength was measured by a shear test. The results are shown in Table 1.

[Table] Example 3 As shown in FIG. 4, Si ₃ N was placed between the dense Si ₃ N ₄ sintered base material 11 and the stainless steel base material 12, each measuring 10×10 (mm in length and width) and 4 mm in thickness. The intermediate layer 13 made of a stainless steel plate with a thickness of 0.5 mm is placed on the side in contact with the intermediate layer ₁ , and the Si ₃ N ₄ plate with a thickness of 1 mm is placed on the side in contact with the stainless steel.
4, and according to Example 2, a brazing material 15 was inserted and brazing was performed. However, in this case, the temperature increase rate up to 810°C was 30°C/min. The shear strength of the resulting joined body was 26.5 Kg/mm ² . Example 4 The same bonding as in Example 3 was performed, but as the intermediate layer, as shown in FIG. 5, 0.5 mm thick Si ₃ N ₄ 14A,
14B and stainless steel plates 13A and 13B are placed alternately, two each for a total of four, to form a Si ₃ N ₄ base material 11 - stainless steel intermediate layer 13A - Si ₃ N ₄ intermediate layer 14A - stainless steel intermediate layer 13B - Si ₃ N ₄ intermediate layer 14B-
Stainless steel base materials 12 were arranged in this order, a Ti-containing brazing filler metal 15 was inserted between them, and they were joined by high frequency heating to obtain a joined body. The shear strength of the resulting joined body was 18.6 Kg/mm ² . Example 5 As shown in FIG. ₆ , _{Si 3}
N ₄ Stainless steel plate 1 with a thickness of 1 mm from the base material 11 side
3. A Si ₃ N ₄ plate 14 with a thickness of 1.5 mm and a stainless steel plate 12B with a thickness of 0.15 mm are arranged as an intermediate layer so as to be in contact with the stainless steel base material 12, and a brazing material 15 is inserted between them. Brazing was performed according to 2. However, the heating rate is 40℃/min, and the maximum heating temperature is
The temperature was 850℃. The shear strength of the resulting joint was 5.4
It was Kg/ ^mm2 . (Effects of the Invention) (1) According to the present invention, when at least two or more intermediate layers are inserted and bonded between a ceramic base material and a metal base material, the material of the intermediate layer is the same as that of the base material. Those having the same or similar composition are used, and the ceramic intermediate layer is sandwiched between the metal base material and the metal intermediate layer or between the metal intermediate layers, and the metal intermediate layer is sandwiched between the ceramic base material and the ceramic intermediate layer or between the ceramic intermediate layers. Since both sides are sandwiched and these are joined directly or by interposing a brazing material, the coefficient of thermal expansion on both sides of the intermediate layer is little or no different, so after joining, the ceramic intermediate layer There is a great industrial advantage in that layer cracking and peeling do not occur. (2) Bonding between the ceramic intermediate layer and the metal intermediate layer or between them and the ceramic base material or the metal base material may be performed by diffusion bonding by heating, bonding by a reactive sintering method, bonding by a brazing material, etc. It has the advantage of being able to freely choose what is legal. Regardless of the bonding method, the intermediate layer is sandwiched between two sides of the same or similar material as the base material, so after bonding, the coefficient of thermal expansion of the material on both sides of the intermediate layer is There is an advantage that there is no risk of damage such as peeling or cracking due to differences. (3) Even if a brazing filler metal is used to bond the intermediate layers to each other or between the intermediate layer and the base material, the bonded brazing filler metal layer is extremely thin compared to the base material or the intermediate layer, and the brazing filler metal itself is Since it is ductile and deformable, thermal stress can be alleviated, and since it is bonded with a brazing filler metal inserted, damage such as peeling and cracking does not occur at the bonding interface. (4) According to the present invention, it is easy to select the intermediate layer, and when using two or more different intermediate layers different from the ceramics and metals to be bonded, as in the conventional method (Japanese Patent Application Laid-Open No. 60-231471). As shown in the figure, there is no need to change the bonding conditions for each interface.
In addition, there is a great industrial advantage in that the properties of the bonded portions do not need to be impaired. The joined body according to the method of the present invention is a hot gas blower,
It is useful for use in turbine blades, turbochargers, crusher linings, heat exchangers, the first wall of nuclear fusion reactors, etc.

[Brief explanation of the drawing]

1A, 1B, 1C, 1D, 1E, and 1F are explanatory diagrams showing bonding arrangements of various intermediate layers in the ceramic-metal bonding method of the present invention, and FIG. 6 to 6 are drawings showing a specific arrangement of the ceramic-metal intermediate layer of the present invention and an embodiment in which a brazing material is inserted. 1...Ceramics base material, 2...Metal base material, 3
...Metal intermediate layer, 4...Ceramics intermediate layer, 1
1... SiC or Si ₃ N ₄ ceramic base material, 12
...Stainless steel metal base material, 13A, 13B...
...Stainless steel metal intermediate layer, 14, 14A, 1
4B...Ceramics intermediate layer of Si ₃ N ₄ , 15...
Silver wax foil.

Claims (1)

[Scope of Claims] 1. A ceramic intermediate layer and a metal intermediate layer made of the same material and having the same or similar coefficient of thermal expansion are interposed between a ceramic base material and a metal base material, respectively. The intermediate layer is sandwiched between the metal intermediate layers or between the metal intermediate layer and the metal base material, and the metal intermediate layer is arranged and bonded between the ceramic intermediate layers or between the ceramic intermediate layer and the ceramic base material. A bonded body of ceramics and metal characterized by: 2. The ceramic-metal bonded body according to claim 1, wherein the ceramic intermediate layer and the metal intermediate layer each consist of a plurality of intermediate layers. 3. The ceramic-metal bonded body according to claim 1 or 2, wherein the ceramic base material or the metal base material is bonded in contact with a ceramic intermediate layer or a metal intermediate layer, respectively. 4. In a method of bonding by inserting at least two or more intermediate layers between a ceramic base material and a metal base material, at least the material and the coefficient of thermal expansion are different for the ceramic base material and the metal base material to be bonded, respectively. A ceramic intermediate layer and a metal intermediate layer that are the same or similar are interposed between the ceramic base material and the metal base material, and are sandwiched between the ceramic intermediate layer and the metal base material, and both of the metal intermediate layer A method for bonding ceramics and metal, characterized in that the bonding interface is arranged and bonded so as to be sandwiched between ceramic intermediate layers or between a ceramic intermediate layer and a ceramic base material. 5. The method of joining ceramics and metal according to claim 4, wherein the ceramic intermediate layer and the metal intermediate layer each include a plurality of intermediate layers. 6. The method of joining ceramics and metal according to claim 4 or 5, wherein the ceramic base material or the metal base material is in contact with a ceramic intermediate layer or a metal intermediate layer, respectively. 7. Ceramics and metal according to any one of claims 4 to 6, which are brazed to each bonding interface between the ceramic base material, the ceramic intermediate layer, the metal intermediate layer, and the metal base material through a brazing material. joining method.