A brazing method for simultaneously achieving a porous structure of a weld when welding a porous material

Abstract

A brazing method for synchronously realizing a porous structure of a welding seam when welding a porous material, and belongs to the field of welding of porous materials. The present application solves the problem that it is difficult to ensure that the welding seam is in a porous structure when welding a porous material. Method: the filler metal, pore forming agent and resin powder are determined by the base material to prepare the filler metal slurry; the base material and the filler metal slurry are assembled, then heated and sintered, and ultrasonic vibration is applied at the sintering temperature. The welding seam in the joint obtained by the present application is in a porous structure, and the pore diameter or porosity in the welding seam can be adjusted according to the relevant parameters of the base material by adjusting the ratio of the filler metal, which can ensure the continuity of the porosity of the base material; the heating of the filler metal realizes the welding and at the same time completes the preparation of the porous welding seam, which is efficient; the welding of porous metal and porous ceramic can be realized. The method of the present application is used for welding of porous materials.

Description

Technical Field

[0001] This invention relates to the field of welding porous materials. Background Technology

[0002] Porous materials, as an advanced structure-function integrated material, possess advantages such as low density, high specific strength, and high specific surface area. They also exhibit excellent thermal properties, good acoustic characteristics, and biocompatibility, making them widely used in chemical product filtration, wastewater treatment, and noise reduction in industrial equipment. However, in practical applications, single, simple porous material components are insufficient to meet the demands of complex, large-scale, and multifunctional integrated modern industrial applications. Therefore, techniques such as welding are necessary to connect similar or dissimilar porous materials.

[0003] Commonly used welding techniques for porous materials are brazing or diffusion welding. However, these methods have significant drawbacks in practical applications: the welding process easily leads to pore blockage, meaning the presence of the filler metal disrupts the continuity of the pores in the porous material. This causes the porous material to lose its core functions as a catalyst carrier or filter material, making the weld area a performance bottleneck in the entire component and severely limiting its application in industrial settings. Summary of the Invention

[0004] This invention addresses the challenge of ensuring a porous weld structure when welding porous materials, proposing a brazing method that simultaneously achieves this structure. This method involves introducing a pore-forming agent into the brazing filler metal and utilizing an ultrasonic-assisted process. This allows for reliable material bonding while simultaneously forming a porous weld. The entire process is simple to operate, requires no complex equipment, and significantly reduces the welding costs of porous material components.

[0005] The method of this invention includes the following steps. First, the base material is determined. After selecting the base material, parameters such as pore size and porosity need to be measured. The brazing filler metal is selected based on the properties of the base material. If welding porous ceramics, AgCu or AgCuTi brazing filler metals with active elements and strong wettability are selected. If welding porous metals, there are more choices of brazing filler metals, such as Zn-based or Al-based brazing filler metals. Second, based on the pore size and porosity of the base material, the required ratio of pore-forming material and resin powder in the brazing filler metal is determined, and the brazing filler metal powder, pore-forming material, and resin powder are mixed. Then, the base material and brazing filler metal are assembled using a suitable graphite jig. After assembly, they are placed in a heating furnace, heated to a certain temperature, subjected to ultrasonic vibration, and held at that temperature for a period of time to complete the welding. Specific operations are as follows:

[0006] A brazing method for simultaneously achieving a porous weld structure when welding porous materials, specifically comprising the following steps:

[0007] 1. Ball mill and mix brazing filler metal powder, hole-forming material and resin powder to obtain brazing filler metal slurry;

[0008] 2. The brazing slurry obtained in step 1 is laid between two porous materials to be welded to form a workpiece. The workpiece is clamped and assembled using an upper and lower pressure head and placed in a muffle furnace. It is heated and sintered in an air atmosphere. When the temperature reaches the sintering temperature, ultrasonic vibration is applied. After the ultrasonic vibration ends, the sintering temperature is maintained for a period of time, and then the furnace is cooled to complete the brazing.

[0009] Furthermore, if the porous material to be soldered is a porous ceramic, then the solder powder mentioned in step one is AgCu solder or AgCuTi solder; if the porous material to be soldered is a porous metal, then the solder powder mentioned in step one is Zn-based solder or Al-based solder.

[0010] Furthermore, the porous ceramic is one or a mixture of several of the following ceramics: porous Si3N4 ceramic, porous Si2N2O ceramic, porous SiC ceramic, porous SiBCN ceramic, porous ZrO2 ceramic, porous Al2O3 ceramic, porous TiB2 ceramic, porous B4C ceramic, porous ZrB2 ceramic, porous TaB2 ceramic, and porous ZrC ceramic. The thickness of the porous ceramic is 0.5~10 mm, and the porosity is 10%~60%.

[0011] The porous metal is porous aluminum, porous aluminum alloy, porous copper, porous copper alloy, porous titanium, or porous titanium alloy. The thickness of the porous metal is 0.5~10 mm, and the porosity is 10%~60%.

[0012] Furthermore, in step one, the ball milling process, the pore-forming material is 15 to 35 parts by mass, the brazing filler powder is 60 to 80 parts, and the resin powder is 5 to 10 parts; the diameter of the pore-forming material is 1 to 50 μm, the diameter of the brazing filler powder is 10 to 50 μm, and the diameter of the resin powder is 1 to 50 μm.

[0013] Furthermore, in step one, the ball milling process is carried out with a rotation speed of 100-500 r / min and a milling time of 1-10 h.

[0014] Furthermore, in step two, the thickness of the brazing filler slurry is 0.05~0.3mm.

[0015] Furthermore, in step two, the pressure applied by the upper and lower pressure heads to the workpiece to be welded is 0.05~0.3MPa; when the porosity of the porous material to be welded is 30%~40%, the pressure applied is controlled at 0.05~0.15MPa, and when the porosity of the porous material to be welded is 20%~30%, the pressure applied is controlled at 0.15~0.3MPa.

[0016] Furthermore, in step two, after clamping and assembling the workpiece to be welded, it is fixed in a graphite mold and then placed into a muffle furnace.

[0017] Furthermore, in step two, the ultrasonic frequency is controlled to be 15~60 kHz, the amplitude to be 1~50 μm, the ultrasonic time to be 1~1000 s, and the pressure of the ultrasonic head to be 0.05~1 MPa.

[0018] Furthermore, in step two, the heating rate is controlled at 1~10℃ / min to reach the sintering temperature. After ultrasonication, the sintering temperature is maintained for 1~10h.

[0019] This invention, by adding a pore-forming material and resin powder to the brazing filler metal, achieves effective connection of porous materials while ensuring the porous structure of the brazed weld. The joint obtained by this invention guarantees the continuity of the properties of the base material. During the welding process, a certain amount of pore-forming material and resin powder are added to the brazing filler metal. While the brazing filler metal is heated to achieve welding, the resin powder volatilizes, directly forming a porous structure in the weld. The pore-forming material itself has a porous structure, which also ensures the continuity of the porous structure of the weld.

[0020] The method of this invention has the following advantages: 1. It achieves a true "structure-function integration" connection, maintaining the porous characteristics of the weld and enabling the weld and base material to have the same sound absorption and heat insulation functions; 2. It can directly use ultrasonic-assisted brazing equipment without requiring equipment modification or increasing costs; 3. The added pore-forming agent is low-cost, easy to prepare, and readily available; 4. It can achieve the preparation of composite brazing filler metal and the formation of the weld in one step, improving welding efficiency; 5. The porosity and pore size of the weld can be adjusted or changed according to the porosity and pore size of the base material, providing high flexibility; 6. Ultrasonic waves can promote the penetration of brazing filler metal into the base material during the welding process, improving the mechanical properties of the joint; 7. It does not use flux, making it green and environmentally friendly.

[0021] Beneficial effects of this invention:

[0022] 1. The weld seam in the joint obtained by the present invention has a porous structure, and the pore size or porosity in the weld seam can be adjusted by adjusting the brazing filler metal ratio according to the relevant parameters of the base material, which can ensure the continuity of the porous properties of the base material.

[0023] 2. This invention achieves welding by heating the brazing filler metal while simultaneously preparing the porous weld seam, resulting in high efficiency.

[0024] 3. The present invention has a wide range of applications, namely, it can realize the welding of porous metals and porous ceramics.

[0025] The method of this invention is used for welding porous materials. Attached Figure Description

[0026] Figure 1This is a schematic diagram of the workpiece to be welded being placed in a muffle furnace as described in Example 1;

[0027] Figure 2 This is a cross-sectional topographic image of the joint obtained by brazing in Example 1;

[0028] Figure 3 The figure shows the shear strength test results of the joint obtained by brazing in Example 1. Detailed Implementation

[0029] Specific Implementation Method 1: This implementation method provides a brazing method for simultaneously achieving a porous weld structure when welding porous materials. The method is specifically carried out according to the following steps:

[0030] 1. Ball mill and mix brazing filler metal powder, hole-forming material and resin powder to obtain brazing filler metal slurry;

[0031] 2. The brazing slurry obtained in step 1 is laid between two porous materials to be welded to form a workpiece. The workpiece is clamped and assembled using an upper and lower pressure head and placed in a muffle furnace. It is heated and sintered in an air atmosphere. When the temperature reaches the sintering temperature, ultrasonic vibration is applied. After the ultrasonic vibration ends, the sintering temperature is maintained for a period of time, and then the furnace is cooled to complete the brazing.

[0032] Specific Implementation Method Two: This implementation method differs from Specific Implementation Method One in that: if the porous material to be welded is porous ceramic, then the brazing filler powder mentioned in step one is AgCu brazing filler or AgCuTi brazing filler; if the porous material to be welded is porous metal, then the brazing filler powder mentioned in step one is Zn-based brazing filler or Al-based brazing filler. Everything else is the same as in Specific Implementation Method One.

[0033] Specific Implementation Method Three: This implementation method differs from Specific Implementation Method One or Two in that the porous ceramic is one or a mixture of several of the following ceramics: porous Si3N4 ceramic, porous Si2N2O ceramic, porous SiC ceramic, porous SiBCN ceramic, porous ZrO2 ceramic, porous Al2O3 ceramic, porous TiB2 ceramic, porous B4C ceramic, porous ZrB2 ceramic, porous TaB2 ceramic, and porous ZrC ceramic. The thickness of the porous ceramic is 0.5~10 mm, and the porosity is 10%~60%.

[0034] The porous metal is porous aluminum, porous aluminum alloy, porous copper, porous copper alloy, porous titanium, or porous titanium alloy. The thickness of the porous metal is 0.5~10 mm, and the porosity is 10%~60%. Other aspects are the same as in specific embodiments one or two.

[0035] Specific Implementation Method Four: This implementation method differs from Specific Implementation Methods One to Three in that: in step one, during the ball milling process, the mass fractions of the hole-forming material are 15 to 35 parts, the brazing filler metal powder is 60 to 80 parts, and the resin powder is 5 to 10 parts; the diameter of the hole-forming material is 1 to 50 μm, the diameter of the brazing filler metal powder is 10 to 50 μm, and the diameter of the resin powder is 1 to 50 μm. Everything else is the same as in Specific Implementation Methods One to Three.

[0036] Specific Implementation Method Five: This implementation method differs from Specific Implementation Methods One to Four in that: the ball milling mixture in step one is controlled at a rotation speed of 100~500 r / min, and the ball milling time is 1~10 h. Everything else is the same as in Specific Implementation Methods One to Four.

[0037] Specific Implementation Method Six: This implementation method differs from Specific Implementation Methods One to Five in that the thickness of the brazing filler slurry laid in step two is 0.05~0.3mm. Everything else is the same as in Specific Implementation Methods One to Five.

[0038] Specific Implementation Method Seven: This implementation method differs from Specific Implementation Methods One to Six in that: in step two, the pressure applied to the workpiece by the upper and lower pressure heads is 0.05~0.3MPa; when the porosity of the porous material to be welded is 30%~40%, the pressure applied is controlled at 0.05~0.15MPa; when the porosity of the porous material to be welded is 20%~30%, the pressure applied is controlled at 0.15~0.3MPa. Everything else is the same as in Specific Implementation Methods One to Six.

[0039] Specific Implementation Method Eight: This implementation method differs from Specific Implementation Methods One to Seven in that: after clamping and assembling the workpiece to be welded in step two, it is fixed in the graphite mold and then placed in the muffle furnace. Everything else is the same as in Specific Implementation Methods One to Seven.

[0040] Specific Implementation Method Nine: This implementation method differs from Specific Implementation Methods One to Eight in that: in step two, the ultrasonic frequency is controlled to be 15~60 kHz, the amplitude to be 1~50 μm, the ultrasonic time to be 1~1000 s, and the pressure of the ultrasonic head to be 0.05~1 MPa. Everything else is the same as in Specific Implementation Methods One to Eight.

[0041] Specific Implementation Method Ten: This implementation method differs from Specific Implementation Methods One to Nine in that: in step two, the heating rate is controlled at 1~10℃ / min to reach the sintering temperature. After ultrasonication, the sintering temperature is maintained for 1~10 hours. Everything else is the same as in Specific Implementation Methods One to Nine.

[0042] The scope of this invention is not limited to the above-described embodiments; a combination of one or more specific embodiments can also achieve the purpose of the invention.

[0043] Example 1:

[0044] 1. Porous Al2O3 ceramic was selected as the porous base material. The porosity of the base material was 40% and the pore size was 50μm. Before the experiment, the base material was cut into small pieces with a size of 10 mm × 10 mm × 5 mm.

[0045] 2. Selection of brazing filler metal: AgCu was selected. When preparing the brazing filler metal, AgCu brazing filler metal powder, acrylic microspheres and pore-forming agent alumina hollow ceramic microspheres were ball-milled in a mass ratio of 7:1:2. During the ball milling process, the acrylic microspheres melted and adhered to the brazing filler metal powder and alumina hollow ceramic microspheres to prepare a slurry. The particle diameter of the three powders was about 20 μm. The ball milling time was controlled at 6 h and the rotation speed was 150 r / min. The brazing filler metal slurry was taken out after ball milling.

[0046] Third, assemble the ceramic base material processed in step one and the brazing filler metal slurry obtained in step two, wherein the thickness of the brazing filler metal slurry is 0.1 mm. Place the assembled part to be welded in a graphite mold, and then place it in a muffle furnace for sintering. Figure 1 As shown, sintering was carried out in an air atmosphere, with a heating rate of 2℃ / min to a sintering temperature of 800℃. After heating, ultrasonic vibration was applied to the sample surface to enhance the wetting of the brazing filler metal on the ceramic and to promote bonding between the filler metal and the ceramic. The ultrasonic parameters were: frequency 20 kHz, amplitude 10 μm, duration 20 s, and pressure of the ultrasonic head 0.2 MPa. After the ultrasonic application, the sample was held at the temperature for another 2 h, and then cooled in the furnace to obtain a joint with a porous weld seam, as shown. Figure 2 As shown; the shear test of the joint yielded a shear strength of 24.7 MPa, as indicated. Figure 3 .

[0047] Depend on Figure 2 As can be seen, the bonding between the upper and lower ceramics and the weld is good, indicating that the method of the present invention can effectively connect ceramics. In addition, there are multiple pores in the weld, which ensure that the weld has the same porous structure as the porous ceramic matrix, thus ensuring the continuity of the porous function of the ceramic matrix.

[0048] Depend on Figure 3 It is evident that the ceramic joint exhibits high strength under these conditions. A joint strength exceeding 20 MPa is comparable to the strength of most porous ceramics themselves. This also means that the present invention achieves both porous welds and high joint strength.

[0049] In summary, by Figure 2 and Figure 3The results confirm that the method of the present invention can simultaneously achieve the welding of porous materials and the preparation of porous welds. The resulting welds are porous and have high strength. This structure retains the porous structure of the porous ceramic itself at the weld, thus achieving functional continuity while ensuring high strength, making it highly promising for practical applications.

Claims

1. A brazing method for simultaneously achieving a porous weld structure when welding porous materials, characterized in that... This method is specifically carried out in the following steps:

1. Ball mill and mix brazing filler metal powder, hole-forming material and resin powder to obtain brazing filler metal slurry; 2. The brazing slurry obtained in step 1 is laid between two porous materials to be welded to form a workpiece to be welded. The workpiece is clamped and assembled using an upper pressure head and a lower pressure head, and placed in a muffle furnace. It is heated and sintered in an air atmosphere. When the temperature reaches the sintering temperature, ultrasonic vibration is applied. After the ultrasonic vibration ends, the sintering temperature is maintained for a period of time, and then the furnace is cooled to complete the brazing. If the porous material to be soldered is a porous ceramic, then the solder powder mentioned in step one is AgCu solder or AgCuTi solder; if the porous material to be soldered is a porous metal, then the solder powder mentioned in step one is Zn-based solder or Al-based solder. In step one, the ball milling process, the pore-forming material is 15-35 parts by mass, the brazing filler metal powder is 60-80 parts, and the resin powder is 5-10 parts; the diameter of the pore-forming material is 1-50 μm, the diameter of the brazing filler metal powder is 10-50 μm, and the diameter of the resin powder is 1-50 μm; the pore-forming material is alumina hollow ceramic microspheres.

2. The brazing method for simultaneously achieving a porous weld structure when welding porous materials according to claim 1, characterized in that... The porous ceramic is one or a mixture of several of the following: porous Si3N4 ceramic, porous Si2N2O ceramic, porous SiC ceramic, porous SiBCN ceramic, porous ZrO2 ceramic, porous Al2O3 ceramic, porous TiB2 ceramic, porous B4C ceramic, porous ZrB2 ceramic, porous TaB2 ceramic, and porous ZrC ceramic. The thickness of the porous ceramic is 0.5~10 mm, and the porosity is 10%~60%. The porous metal is porous aluminum, porous aluminum alloy, porous copper, porous copper alloy, porous titanium, or porous titanium alloy. The thickness of the porous metal is 0.5~10 mm, and the porosity is 10%~60%.

3. The brazing method for simultaneously achieving a porous weld structure when welding porous materials according to claim 1, characterized in that... The ball milling process described in step one is carried out at a speed of 100-500 r / min for 1-10 h.

4. The brazing method for simultaneously achieving a porous weld structure when welding porous materials according to claim 1, characterized in that... Step 2: The thickness of the brazing filler slurry should be 0.05~0.3mm.

5. The brazing method for simultaneously achieving a porous weld structure when welding porous materials according to claim 1, characterized in that... In step two, the pressure applied by the upper and lower pressure heads to the workpiece to be welded is 0.05~0.3MPa; when the porosity of the porous material to be welded is 30%~40%, the pressure is controlled to be 0.05~0.15MPa; when the porosity of the porous material to be welded is 20%~30%, the pressure is controlled to be 0.15~0.3MPa.

6. The brazing method for simultaneously achieving a porous weld structure when welding porous materials according to claim 1, characterized in that... Step two involves clamping and assembling the workpiece to be welded, fixing it in a graphite mold, and then placing it into a muffle furnace.

7. The brazing method for simultaneously achieving a porous weld structure when welding porous materials according to claim 1, characterized in that... Step 2: Control the ultrasonic frequency to 15~60 kHz, the amplitude to 1~50 μm, the ultrasonic time to 1~1000 s, and the pressure of the ultrasonic head to 0.05~1 MPa.

8. The brazing method for simultaneously achieving a porous weld structure when welding porous materials according to claim 1, characterized in that... Step 2: Control the heating rate to 1~10℃ / min to reach the sintering temperature. After ultrasonication, maintain the sintering temperature for 1~10h.

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