A connection method for silicon nitride ceramic / nickel-based high-temperature alloy joints with surface micro-texture

Abstract

A connection method for silicon nitride ceramic / nickel-based high-temperature alloy joints with surface micro-structures relates to a connection method for silicon nitride ceramic / nickel-based high-temperature alloy joints. The present invention aims to solve the technical problem that the current silicon nitride ceramic / nickel-based high-temperature alloy joints will generate residual stress, resulting in microcracks in the connection joints and poor mechanical properties. The present invention processes the silicon nitride surface by laser to construct a microstructure, designs microstructures with different morphologies, can effectively increase the final joint surface area and improve the distribution of residual stress in the joint, and can achieve an increase in joint strength. Laser treatment does not introduce impurity elements, especially oxygen elements, and the Si element directly reacts with the active element Ti to generate sufficient interface reactants, ensuring good bonding between the silicon nitride and the weld. The process of the present invention is simple, and laser treatment of the silicon nitride ceramic surface can effectively improve the connection strength of the joint, thereby achieving a high-strength connection between ceramics and metals.

Description

Technical Field

[0001] The invention relates to a connection method for a silicon nitride ceramic / nickel-based high-temperature alloy joint. Background Art

[0002] Silicon nitride ceramics have the excellent properties of low density and high strength and are widely used in the aerospace field. However, due to the brittleness of the ceramic material itself, it is difficult to process it into complex large components. The preparation of ceramic-metal dissimilar material joints can help to fully utilize its excellent properties. Nickel-based high-temperature alloys (GH4169) are regarded as excellent structural materials in high-temperature fields due to their high high-temperature performance and easy processing and forming advantages. However, the biggest difficulty in obtaining high-performance dissimilar material joints is the residual stress problem caused by the large difference in the thermophysical properties of the parent materials, which leads to microcracks in the joints and poor mechanical properties. Summary of the Invention

[0003] The present invention aims to solve the technical problem that the current silicon nitride ceramic / nickel-based high-temperature alloy joints will generate residual stress, resulting in microcracks in the connected joints and poor mechanical properties, and provide a connection method for silicon nitride ceramic / nickel-based high-temperature alloy joints with surface micro-structures.

[0004] The connection method for a silicon nitride ceramic / nickel-based high-temperature alloy joint with a surface microstructure of the present invention is carried out according to the following steps:

[0005] 1. Preparation of silicon nitride surface microstructure:

[0006] 1. Grind the surface of the silicon nitride ceramic block to be welded on a 400# diamond grinding disc until the surface of the sample is flat. Then use W3.5 diamond grinding paste to grind on a flat piece of glass until there is no obvious wire cutting mark on the surface of the silicon nitride ceramic block to be welded. Then use W1 grinding paste to grind until the surface of the silicon nitride ceramic block to be welded is bright.

[0007] 2. Placing the bright silicon nitride under a laser, and obtaining a microstructure on the surface of the silicon nitride under the action of high-energy laser, namely the silicon nitride mother material; the microstructure is a cone array structure or a cylinder array structure;

[0008] 2. Placing the intermediate layer metal and the silicon nitride base material obtained in step 1 on the surface to be welded of the nickel-based high-temperature alloy in sequence, applying adhesive between the layers to form a tight fit, and obtaining a workpiece to be welded;

[0009] The structure of the intermediate metal layer is: Ti foil / Cu foil / Ni foil / MoCu foil / Ni foil / Cu foil, wherein the Ti foil is located close to the silicon nitride base material, and adhesive is applied between each layer to form a tight fit;

[0010] 3. Place the workpiece to be welded assembled in step 2 into a vacuum heating furnace, raise the temperature from room temperature to 300℃~310℃ and keep it warm for 30min~35min to ensure that the adhesive is completely volatilized; then raise the temperature from 300℃~310℃ to 1080~1160℃ and keep it warm for 5min~20min, then slowly cool it down to 300℃~310℃, and finally cool it to room temperature with the furnace to complete the brazing of ceramic and metal. The whole process is carried out under vacuum.

[0011] In step one, the present invention uses a laser to treat the silicon nitride surface to construct microstructures. Designing microstructures with varying morphologies effectively increases the surface area of ​​the final joint and improves the distribution of residual stress in the joint, thereby increasing joint strength. Under the action of high-energy laser light, the Si-N bond in the silicon nitride breaks, and the nitrogen escapes as N2. The molten Si cools and solidifies on the surface of the microstructures. The laser treatment does not introduce impurity elements, particularly oxygen, and no SiO2 layer forms on the surface after laser treatment. The Si element directly reacts with the active element Ti to produce sufficient interfacial reactants, ensuring a good bond between the silicon nitride and the weld.

[0012] This invention aims to achieve a ceramic-high-temperature alloy joint with a well-defined interface. This joint is resistant to high temperatures and is achieved by surface-treating silicon nitride with GH4169 through a partial transient liquid phase bonding process. This approach utilizes a simple process and laser treatment of the silicon nitride ceramic surface to effectively enhance the joint strength, achieving a high-strength ceramic-metal connection. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 This is the SEM image of the silicon nitride base material obtained in step 1 of experiment 1;

[0014] Figure 2 The XRD pattern of the silicon nitride base material obtained in step 1 of experiment 1;

[0015] Figure 3 The Raman spectrum of the silicon nitride base material obtained in step 1 of experiment 1;

[0016] Figure 4 This is the SEM photo of the joint structure obtained in Experiment 1;

[0017] Figure 5 for Figure 4 EDS analysis results of the corresponding positions in;

[0018] Figure 6 This is a photo of the element distribution on the silicon nitride side of the joint obtained in Experiment 1;

[0019] Figure 7 This is the SEM image of the silicon nitride base material obtained in step 1 of experiment 4. DETAILED DESCRIPTION

[0020] Specific embodiment 1: This embodiment is a connection method for silicon nitride ceramic / nickel-based high-temperature alloy joints with surface micro-structures, which is specifically carried out in the following steps:

[0021] 1. Preparation of silicon nitride surface microstructure:

[0022] 1. Grind the surface of the silicon nitride ceramic block to be welded on a 400# diamond grinding disc until the surface of the sample is flat. Then use W3.5 diamond grinding paste to grind on a flat piece of glass until there is no obvious wire cutting mark on the surface of the silicon nitride ceramic block to be welded. Then use W1 grinding paste to grind until the surface of the silicon nitride ceramic block to be welded is bright.

[0023] 2. Placing the bright silicon nitride under a laser, obtaining a microstructure on the surface of the silicon nitride under the action of a high-energy laser, and then performing ultrasonic cleaning to obtain a silicon nitride mother material; the microstructure is a conical array structure or a cylindrical array structure;

[0024] 2. Placing the intermediate layer metal and the silicon nitride base material obtained in step 1 on the surface to be welded of the nickel-based high-temperature alloy in sequence, applying adhesive between the layers to form a tight fit, and obtaining a workpiece to be welded;

[0025] The structure of the intermediate metal layer is: Ti foil / Cu foil / Ni foil / MoCu foil / Ni foil / Cu foil, wherein the Ti foil is located close to the silicon nitride base material, and adhesive is applied between each layer to form a tight fit;

[0026] 3. Place the workpiece to be welded assembled in step 2 into a vacuum heating furnace, raise the temperature from room temperature to 300℃~310℃ and keep it warm for 30min~35min to ensure that the adhesive is completely volatilized; then raise the temperature from 300℃~310℃ to 1080~1160℃ and keep it warm for 5min~20min, then slowly cool it down to 300℃~310℃, and finally cool it to room temperature with the furnace to complete the brazing of ceramic and metal. The whole process is carried out under vacuum.

[0027] Specific embodiment 2: This embodiment differs from specific embodiment 1 in that the laser in step 1-2 is a femtosecond laser. Other aspects are the same as specific embodiment 1.

[0028] Specific embodiment 3: This embodiment differs from specific embodiment 2 in that the parameters of the high-energy laser in step 1-2 are: laser frequency of 200kHz-250kHz, scanning speed of 500mm / s-600mm / s, laser beam size of 30μm-40μm, laser power of 12W-15W, and wavelength of 355nm-455nm. Other parameters are the same as specific embodiment 2.

[0029] Specific embodiment 4: This embodiment differs from specific embodiments 1 to 3 in that the nickel-based high-temperature alloy is surface cleaned before step 2. Other aspects are the same as specific embodiments 1 to 3.

[0030] Specific embodiment 5: This embodiment differs from specific embodiment 4 in that the surface cleaning process of the nickel-based high-temperature alloy is as follows:

[0031] The surface of the nickel-based alloy to be welded is treated with water sandpaper to remove any visible scratches and oxide layer. The surface is then polished with 600, 800, and 1000 grit metallographic sandpaper until no visible scratches remain. Finally, the surface is polished with 0.5 μm diamond particles to a bright finish, followed by ultrasonic cleaning. The remainder of the process is the same as in the fourth embodiment.

[0032] Specific embodiment 6: This embodiment differs from specific embodiment 5 in that the adhesives mentioned in both places in step 2 are 502 glue. Other aspects are the same as specific embodiment 5.

[0033] Specific embodiment seven: This embodiment differs from specific embodiment six in that in step three, when the temperature reaches above 750°C, the vacuum degree must be ensured to be within 1×10 -2 Pa or less. Other aspects are the same as those in the sixth embodiment.

[0034] Specific embodiment eight: This embodiment differs from specific embodiment seven in that in step three, the temperature is raised from room temperature to 300°C to 310°C at a heating rate of 10°C / min and kept at that temperature for 30min to 35min to ensure complete volatilization of the adhesive. Other aspects are the same as specific embodiment seven.

[0035] Specific embodiment 9: This embodiment differs from specific embodiment 8 in that in step 3, the temperature is subsequently raised from 300°C to 310°C to 1080°C to 1160°C at a heating rate of 10°C / min and kept at that temperature for 5min to 20min. Other aspects are the same as specific embodiment 8.

[0036] Specific embodiment 10: This embodiment differs from specific embodiment 9 in that in step 3, the temperature is slowly lowered to 300°C to 310°C at 5°C / min, and finally cooled to room temperature in the furnace to complete the brazing of the ceramic and metal. The entire process is carried out under vacuum. Other aspects are the same as specific embodiment 9.

[0037] The present invention is verified by the following test:

[0038] Test 1: This test is a method for connecting silicon nitride ceramic / nickel-based high-temperature alloy joints with surface micro-textures. The specific steps are as follows:

[0039] 1. Preparation of silicon nitride surface microstructure:

[0040] 1. Grind the surface of the silicon nitride ceramic block to be welded on a 400# diamond grinding disc until the surface of the sample is flat. Then use W3.5 diamond grinding paste to grind on a flat piece of glass until there is no obvious wire cutting mark on the surface of the silicon nitride ceramic block to be welded. Then use W1 grinding paste to grind until the surface of the silicon nitride ceramic block to be welded is bright.

[0041] 2. The bright silicon nitride surface is placed under a femtosecond laser, and a microstructure is obtained on the silicon nitride surface under the action of a high-energy laser, and then ultrasonic cleaning is performed with anhydrous ethanol for 10 minutes to obtain a silicon nitride base material; the microstructure is a conical array structure, wherein the radius of the unit structure is 40 μm, the height is 15 μm, and the array unit spacing is 100 μm (such as Figure 1 shown);

[0042] The parameters of the high-energy laser are: laser frequency of 200 kHz, scanning speed of 500 mm / s, laser beam size of 30 μm, laser power of 12 W, and wavelength of 355 nm;

[0043] 2. Treat the oxide layer and visible coarse scratches on the surface of the nickel-based alloy GH4169 to be welded, using water sandpaper, and then polish it with 600, 800, and 1000 grit metallographic sandpaper in sequence until there are no obvious scratches on the surface to be welded. Finally, polish it with diamond particles with a particle size of 0.5 μm to make the surface to be welded bright, and then perform ultrasonic cleaning with anhydrous ethanol for 10 minutes. Place the intermediate layer metal and the silicon nitride base material obtained in step 1 on the surface to be welded of the nickel-based high-temperature alloy GH4169 in sequence, and apply adhesive between the layers to form a tight fit to obtain a workpiece to be welded;

[0044] The structure of the intermediate metal layer is: Ti foil / Cu foil / Ni foil / MoCu foil / Ni foil / Cu foil, wherein the Ti foil is located close to the silicon nitride base material, and adhesive is applied between each layer to form a tight fit;

[0045] The adhesives mentioned in both places in step 2 are 502 glue;

[0046] 3. Place the workpiece to be welded assembled in step 2 into a vacuum heating furnace, heat it from room temperature to 300°C at a heating rate of 10°C / min and keep it warm for 30 minutes to ensure that the adhesive is completely volatilized; then heat it from 300°C to 1100°C at a heating rate of 10°C / min and keep it warm for 10 minutes, then slowly cool it down to 300°C at a rate of 5°C / min, and finally cool it to room temperature with the furnace to complete the brazing of silicon nitride ceramics and nickel-based high-temperature alloy GH4169. The whole process is carried out under vacuum. When the temperature reaches above 750°C, the vacuum degree must be ensured to be 1×10 -2Below Pa.

[0047] After the connection is completed, there are no obvious microcracks in the silicon nitride ceramic / GH4169 alloy joint, and the room temperature shear strength of the joint is 142 MPa.

[0048] Figure 1 This is an SEM image of the silicon nitride base material obtained in step 1 of experiment 1, indicating that the laser treatment obtains a uniform conical array structure, in which the radius of the unit structure is 40 μm, the height is 15 μm, and the array unit spacing is 100 μm.

[0049] Figure 2 The XRD image of the silicon nitride parent material was obtained in step 1 of experiment 1. Since the residual silicon layer is thin, XRD will penetrate it, and the strongest signal of the parent material silicon nitride will cover the signal of Si, so the peaks shown in the figure are all silicon nitride peaks. Therefore, Raman is used for micro-area characterization. Figure 3 The Raman spectrum of the silicon nitride base material was obtained in step 1 of experiment 1. The Raman results showed that no impurities were introduced by the laser treatment. Only the Si peak was detected after the laser treatment, verifying that the molten Si element cooled and solidified on the modified surface.

[0050] Figure 4 This is the SEM photo of the joint structure obtained in Experiment 1. The picture shows that the joint is well bonded and no obvious defects are found.

[0051] Figure 5 for Figure 4 From the EDS analysis results of the corresponding position in the joint, it can be seen that the microstructure of the joint is a copper-based solid solution containing a small amount of Ni element and a dispersed Ti-Cu intermetallic compound phase.

[0052] Figure 6 This is a photo of the element surface distribution on the silicon nitride side of the joint obtained in Experiment 1. It can be seen that the Ti element is enriched in the interface reaction layer, with only a small amount of copper-based solid solution dispersed, and Cu and Ni elements are enriched in the weld.

[0053] Experiment 2: This experiment differs from Experiment 1 in that:

[0054] The parameters of the high-energy laser in step 1-2 are different. The microstructure obtained in step 1 is a conical array structure, wherein the radius of the unit structure is 30 μm, the height is 20 μm, and the array unit spacing is 120 μm;

[0055] In step three, the temperature was then increased from 300°C to 1120°C at a rate of 10°C / min and held for 5 minutes. All other conditions were the same as in experiment one. After the connection was completed, the silicon nitride ceramic / GH4169 alloy joint showed no visible microcracks, and the room temperature shear strength of the joint was 54 MPa.

[0056] Experiment 3: This experiment differs from Experiment 1 in that:

[0057] The high-energy laser parameters in step 1-2 were different. The resulting microstructure in step 1 was a conical array structure, with a unit cell radius of 20 μm, a height of 10 μm, and a spacing of 100 μm. All other parameters were the same as in experiment 1. After the connection was completed, the silicon nitride ceramic / GH4169 alloy joint showed no visible microcracks, and the room-temperature shear strength of the joint was 96 MPa.

[0058] Test 4: This test differs from Test 1 in that:

[0059] The parameters of the high-energy laser in step 1-2 are different. The specific parameters of the laser are as follows: frequency of 200 kHz, scanning speed of 400 mm / s, laser beam size of 30 μm, laser power of 14 W, wavelength of 350 nm; the microstructure obtained in step 1 is a cylindrical array structure, wherein the radius of the unit structure is 35 μm, the height is 40 μm, and the array unit spacing is 80 μm (such as Figure 7 (as shown); other aspects were the same as in Test 1. After the connection was completed, the silicon nitride ceramic / GH4169 alloy joint had no obvious microcracks, and the room temperature shear strength of the joint was 94 MPa.

Claims

1. A method for connecting silicon nitride ceramic / nickel-based high-temperature alloy joints with surface microstructures, characterized in that The connection method for silicon nitride ceramic / nickel-based high-temperature alloy joints with surface micro-texture is carried out in the following steps:

1. Preparation of silicon nitride surface microstructure: ①. Grind the surface of the silicon nitride ceramic block to be welded on a 400# diamond grinding wheel until the surface of the sample is flat. Then, grind it on a flat piece of glass with W3.5 diamond grinding paste until there are no obvious wire cutting marks on the surface of the silicon nitride ceramic block to be welded. Then, grind it with W1 grinding paste until the surface of the silicon nitride ceramic block to be welded is bright. ②, placing the bright silicon nitride under a laser, obtaining a microstructure on the surface of the silicon nitride under the action of high-energy laser, and then performing ultrasonic cleaning to obtain a silicon nitride mother material; the microstructure is a conical array structure or a cylindrical array structure; 2. Placing the intermediate layer metal and the silicon nitride base material obtained in step 1 on the surface to be welded of the nickel-based high-temperature alloy in sequence, applying adhesive between the layers to form a tight fit, and obtaining a workpiece to be welded; The structure of the intermediate metal layer is: Ti foil / Cu foil / Ni foil / MoCu foil / Ni foil / Cu foil, wherein the Ti foil is located close to the silicon nitride base material, and adhesive is applied between each layer to form a tight fit; 3. Place the workpiece to be welded assembled in step 2 into a vacuum heating furnace, raise the temperature from room temperature to 300℃~310℃ and keep it warm for 30min~35min to ensure that the adhesive is completely volatilized; then raise the temperature from 300℃~310℃ to 1080~1160℃ and keep it warm for 5min~20min, then slowly cool it down to 300℃~310℃, and finally cool it to room temperature with the furnace to complete the brazing of ceramic and metal. The whole process is carried out under vacuum.

2. A method for connecting a silicon nitride ceramic / nickel-based high-temperature alloy joint with a surface microstructure according to claim 1, characterized in that The laser described in step 1② is a femtosecond laser.

3. A method for connecting a silicon nitride ceramic / nickel-based high-temperature alloy joint with a surface microstructure according to claim 2, characterized in that The parameters of the high-energy laser described in step 1② are: laser frequency of 200kHz to 250kHz, scanning speed of 500mm / s to 600mm / s, laser beam size of 30μm to 40μm, laser power of 12W to 15W, and wavelength of 355nm to 455nm.

4. The method for connecting a silicon nitride ceramic / nickel-based high-temperature alloy joint with a surface microstructure according to claim 1, characterized in that The surface of the nickel-based high-temperature alloy must be cleaned before step 2.

5. A method for connecting a silicon nitride ceramic / nickel-based high-temperature alloy joint with a surface microstructure according to claim 4, characterized in that The process of surface cleaning of the nickel-based high-temperature alloy is as follows: The oxide layer and visible rough scratches on the surface of the nickel-based alloy to be welded of the metal base material are treated with water sandpaper, and then polished with metallographic sandpaper No. 600, 800, and 1000 in sequence until there are no obvious scratches on the surface to be welded. Finally, the surface to be welded is polished with diamond particles with a particle size of 0.5 μm to make it bright, and then ultrasonic cleaning is performed. The rest is the same as the specific implementation method four.

6. The method for connecting a silicon nitride ceramic / nickel-based high-temperature alloy joint with a surface microstructure according to claim 1, characterized in that The adhesives mentioned in both places in step 2 are 502 glue.

7. The method for connecting a silicon nitride ceramic / nickel-based high-temperature alloy joint with a surface microstructure according to claim 1, characterized in that In step 3, when the temperature reaches 750℃ or above, the vacuum degree should be kept at 1×10 -2 Below Pa.

8. A method for connecting a silicon nitride ceramic / nickel-based high-temperature alloy joint with a surface microstructure according to claim 7, characterized in that In step 3, the temperature is raised from room temperature to 300° C. to 310° C. at a heating rate of 10° C. / min and kept at this temperature for 30 min to 35 min to ensure that the adhesive is completely volatilized.

9. A method for connecting a silicon nitride ceramic / nickel-based high-temperature alloy joint with a surface microstructure according to claim 8, characterized in that In step three, the temperature is then raised from 300°C to 310°C to 1080°C to 1160°C at a heating rate of 10°C / min and kept at this temperature for 5min to 20min.

10. A method for connecting a silicon nitride ceramic / nickel-based high-temperature alloy joint with a surface microstructure according to claim 9, characterized in that In step three, the temperature is slowly lowered to 300°C to 310°C at 5°C / min, and finally cooled to room temperature with the furnace to complete the brazing of the ceramic and the metal. The entire process is carried out under vacuum.

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