A method for brazing dissimilar materials based on hollow glass microsphere composite brazing filler metal
The preparation and application of hollow glass microsphere composite brazing filler metal have solved the problems of low joint strength and agglomeration of reinforcing phase caused by the difference in thermal expansion coefficients in the brazing of dissimilar materials, and have achieved the improvement of high-temperature mechanical properties and a significant increase in joint strength.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- HARBIN INST OF TECH
- Filing Date
- 2024-11-12
- Publication Date
- 2026-07-31
AI Technical Summary
During the brazing of dissimilar materials, the large difference in thermal expansion coefficients leads to low joint strength, and the agglomeration of reinforcing phase particles easily affects the stability of the joint's mechanical properties.
Hollow glass microsphere composite brazing filler metal is prepared by mixing hollow glass microspheres with brazing filler metal powder and then brazing it under vacuum conditions. The low thermal expansion coefficient and spherical structure of the hollow glass microspheres are used to alleviate residual stress and inhibit the formation of brittle compounds.
It significantly improves the high-temperature mechanical properties and shear strength of brazed joints, reduces the coefficient of thermal expansion, avoids agglomeration of reinforcing phase, and enhances the stability and strength of the joint.
Smart Images
Figure CN119260244B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of brazing technology for dissimilar materials, and specifically to a method for brazing dissimilar materials based on hollow glass microsphere composite brazing filler metal. Background Technology
[0002] Joining dissimilar materials to form composite components can maximize the superior properties of each material, meeting the functional and performance requirements of modern engineering structures. Compared to other welding methods, brazing is one of the most effective methods for joining dissimilar materials such as metals, ceramics, composite materials, and glass. However, the significant difference in the coefficients of thermal expansion between dissimilar materials and between the base material and the filler metal makes the joint prone to generating large residual stresses, severely weakening the strength of the brazed joint and even directly leading to post-weld cracking. Furthermore, the brazing seam easily generates a large number of brittle compounds, which also affect the mechanical properties of the joint.
[0003] Currently, the most common method for alleviating residual stress is to use composite brazing filler metals. Composite brazing filler metals refer to the addition of reinforcing phases with low coefficients of thermal expansion to traditional metal brazing filler metals, thereby reducing the coefficient of thermal expansion of the filler metal and alleviating residual stress caused by the mismatch in coefficients of thermal expansion. Adding nano-Al2O3, TiO2, CNTs, and other low-coefficient reinforcing phase particles to the filler metal can alleviate residual stress at the joint to some extent. However, when the amount of reinforcing phase added is large, its high surface energy makes it prone to agglomeration, which can actually reduce the mechanical properties of the joint. Therefore, the range of nano-reinforcing phases that can be added is relatively small, and the coefficient of thermal expansion of the composite brazing filler metal still differs significantly from that of the base metal. Thus, the effect of using nano-reinforcing phase composite brazing filler metals to alleviate residual stress at the joint is extremely limited. Summary of the Invention
[0004] The purpose of this invention is to solve the problems of low joint strength due to large differences in thermal expansion coefficients during traditional brazing processes between dissimilar materials and between base material and brazing filler metal, and the problem that adding reinforcing phase particles to the brazing seam to alleviate residual stress can lead to the agglomeration of reinforcing phase particles, which in turn affects the stability of the joint's mechanical properties. The invention provides a method for brazing dissimilar materials based on hollow glass microsphere composite brazing filler metal.
[0005] A method for preparing a hollow glass microsphere composite solder comprises the following steps:
[0006] Step S1:
[0007] Hollow glass microspheres were dispersed in deionized water and ultrasonically cleaned at 20–30°C. After ultrasonic cleaning, the precipitate was removed by standing, and the upper floating matter was taken to obtain hollow glass microspheres with complete structure.
[0008] Step S2:
[0009] The hollow glass microspheres with intact structure obtained in step S1 are placed in a vacuum drying oven for drying to obtain dried hollow glass microspheres.
[0010] Step S3:
[0011] The dried hollow glass microspheres obtained in step S2 are mixed with the brazing filler powder, and then a dispersant is added. After mixing evenly, a hollow glass microsphere composite brazing filler is obtained; the mass ratio of the dried hollow glass microspheres to the brazing filler powder is (0.001~0.05):1.
[0012] The method for brazing dissimilar materials based on hollow glass microsphere composite brazing filler metal is carried out according to the following steps:
[0013] Hollow glass microsphere composite brazing filler metal is assembled between the surfaces of two dissimilar base materials to be joined, and then placed in a brazing furnace at a vacuum degree of 1×10⁻⁶. -4 ~5×10 -3 Under the condition of Pa, the temperature is raised to 20-150°C above the melting point of the brazing filler metal, and the connection is brazed for 1-60 minutes. After the brazing is completed, the temperature is first cooled to 200-450°C, and then cooled to room temperature to complete the brazing of dissimilar materials based on hollow glass microsphere composite brazing filler metal.
[0014] The dissimilar base materials to be welded are C / C composite materials and SiO2. 2f Two of the following: SiO2 composite material, C / SiC composite material, multiphase ceramics, oxide ceramics, microcrystalline glass, sapphire, Ni-based alloys, Ti alloys, Zr alloys, Nb alloys, and Fe-based alloys.
[0015] The beneficial effects of this invention are:
[0016] 1. The hollow glass microspheres in the composite brazing filler metal of the present invention have a low specific surface area, which effectively avoids the agglomeration of the reinforcing phase during brazing; at the same time, the hollow glass microspheres are well bonded to the brazing filler metal, without defects such as pores, and the spherical structure of the glass microspheres is well preserved, which significantly reduces the thermal expansion coefficient of the brazing joint, which helps to alleviate the residual stress generated at the joint during brazing and obtain a brazed joint with excellent performance.
[0017] 2. In the hollow glass microsphere composite brazing filler metal of the present invention, the hollow glass microspheres are dispersed in the brazing seam, which not only has a certain supporting effect, but also can resist the high temperature softening phenomenon of the brazing filler metal, thereby significantly improving the high temperature mechanical properties of the joint.
[0018] 3. The hollow glass microspheres in the composite brazing filler metal of the present invention readily react with active elements such as Ti, Zr, and Cr present in the brazing filler metal and dissolved from the base material into the brazing seam during the brazing process, which significantly inhibits the formation and agglomeration of brittle intermetallic compounds and ensures the mechanical properties of the brazed joint.
[0019] 4. The present invention uses hollow glass microsphere composite brazing filler metal. Compared with microcrystalline glass and C / C material brazed with AgCuInTi, the Ti-Cu brittle phase in the joint interface is significantly reduced, and the shear strength of the welded joint reaches 23MPa, which is 400% higher than that without glass microspheres.
[0020] 5. The method for preparing the hollow glass microsphere composite brazing filler metal of this invention is simple and low in cost. The hollow glass microspheres have the characteristics of low thermal expansion coefficient and non-agglomeration, which are beneficial for controlling the interface structure and alleviating residual stress in the joint. In addition, using the hollow glass microsphere composite brazing filler metal to connect dissimilar materials will result in a porous brazing joint. This porous structure can improve the stress distribution of the joint and consume fracture energy during crack propagation, thereby enhancing the brazing performance and improving the joint strength.
[0021] This invention provides a method for brazing dissimilar materials based on hollow glass microsphere composite brazing filler metal. Attached Figure Description
[0022] Figure 1 This diagram illustrates the process flow of the present invention for brazing dissimilar materials based on hollow glass microsphere composite brazing filler metal;
[0023] Figure 2 This image shows the interfacial structure of the brazed joint of the hollow glass microsphere composite brazing filler metal in Example 1.
[0024] Figure 3 This diagram shows the interfacial microstructure of the brazed joint without the use of glass microspheres in Comparative Example 1.
[0025] Figure 4 This diagram shows the interfacial structure of the brazed joint of the hollow glass microsphere composite brazing filler metal in Example 2. Detailed Implementation
[0026] Specific Implementation Method 1: This implementation method describes a method for preparing hollow glass microsphere composite solder, which is carried out according to the following steps:
[0027] Step S1:
[0028] Hollow glass microspheres were dispersed in deionized water and ultrasonically cleaned at 20–30°C. After ultrasonic cleaning, the precipitate was removed by standing, and the upper floating matter was taken to obtain hollow glass microspheres with complete structure.
[0029] Step S2:
[0030] The hollow glass microspheres with intact structure obtained in step S1 are placed in a vacuum drying oven for drying to obtain dried hollow glass microspheres.
[0031] Step S3:
[0032] The dried hollow glass microspheres obtained in step S2 are mixed with the brazing filler powder, and then a dispersant is added. After mixing evenly, a hollow glass microsphere composite brazing filler is obtained; the mass ratio of the dried hollow glass microspheres to the brazing filler powder is (0.001~0.05):1.
[0033] Specific Implementation Method Two: The difference between this implementation method and Specific Implementation Method One is that the ratio of the mass of hollow glass microspheres to the volume of deionized water in step S1 is (5-15) g: (600-1000) mL, and the diameter of the hollow glass microspheres is 2 μm to 100 μm.
[0034] The other steps are the same as in Specific Implementation Method 1.
[0035] Specific Implementation Method 3: The difference between this implementation method and Specific Implementation Method 1 or 2 is that the ultrasonic cleaning time in step S1 is 0.5 to 12 hours, and the settling time is 1 to 3 hours.
[0036] The other steps are the same as in Specific Implementation Method 1 or 2.
[0037] Specific Implementation Method Four: The difference between this implementation method and Specific Implementation Methods One to Three is that: in step S2, the vacuum degree in the vacuum drying oven is 1 Pa to 100 Pa, the drying temperature is 60 to 100°C, and the drying time is 5 to 12 hours.
[0038] The other steps are the same as those in Specific Implementation Methods One to Three.
[0039] Specific Implementation Method 5: The difference between this implementation method and Specific Implementation Methods 1 to 4 is that the solder powder mentioned in step S3 is Cu-based solder, Ag-based solder, Ni-based solder, Sn-based solder, Ti-based solder, or Zr-based solder.
[0040] The other steps are the same as those in Specific Implementation Methods One through Four.
[0041] Specific Implementation Method Six: The difference between this implementation method and Specific Implementation Methods One to Five is that the dispersant mentioned in step S3 is anhydrous ethanol, acetone, ethylene glycol, cellulose solution or isopropanol.
[0042] The other steps are the same as those in Specific Implementation Methods 1 to 5.
[0043] Specific Implementation Method Seven: The difference between this implementation method and Specific Implementation Methods One to Six is that mechanical stirring is used in step S3, with a stirring speed of 10 to 500 r / min and a stirring time of 1 to 30 min.
[0044] The other steps are the same as those in Specific Implementation Methods 1 to 6.
[0045] Specific Implementation Method Eight: This implementation method for brazing dissimilar materials based on hollow glass microsphere composite brazing filler metal is carried out according to the following steps:
[0046] Hollow glass microsphere composite brazing filler metal is assembled between the surfaces of two dissimilar base materials to be joined, and then placed in a brazing furnace at a vacuum degree of 1×10⁻⁶. -4 ~5×10 -3 Under the condition of Pa, the temperature is raised to 20-150°C above the melting point of the brazing filler metal, and the connection is brazed for 1-60 minutes. After the brazing is completed, the temperature is first cooled to 200-450°C, and then cooled to room temperature to complete the brazing of dissimilar materials based on hollow glass microsphere composite brazing filler metal.
[0047] The dissimilar base materials to be welded are C / C composite materials and SiO2. 2f Two of the following: SiO2 composite material, C / SiC composite material, multiphase ceramics, oxide ceramics, microcrystalline glass, sapphire, Ni-based alloys, Ti alloys, Zr alloys, Nb alloys, and Fe-based alloys.
[0048] The beneficial effects of this implementation method are:
[0049] 1. In this embodiment, the hollow glass microspheres in the composite brazing filler metal have a low specific surface area, which effectively avoids the agglomeration of the reinforcing phase during brazing. At the same time, the hollow glass microspheres are well bonded to the brazing filler metal, with no defects such as pores, and the spherical structure of the glass microspheres is well preserved, which significantly reduces the thermal expansion coefficient of the brazing joint, which helps to alleviate the residual stress generated at the joint during brazing and obtain a brazed joint with excellent performance.
[0050] 2. In this embodiment, the hollow glass microspheres in the hollow glass microsphere composite brazing filler metal are dispersed in the brazing seam, which not only has a certain supporting effect, but also can resist the high-temperature softening phenomenon of the brazing filler metal, thereby significantly improving the high-temperature mechanical properties of the joint.
[0051] 3. In this embodiment, the hollow glass microspheres in the composite brazing filler metal readily react with active elements such as Ti, Zr, and Cr present in the brazing filler metal and dissolved from the base material into the brazing seam during the brazing process. This significantly inhibits the formation and agglomeration of brittle intermetallic compounds, thus ensuring the mechanical properties of the brazed joint.
[0052] 4. In this embodiment, hollow glass microspheres are used as the composite brazing filler metal. Compared with microcrystalline glass and C / C material brazed with AgCuInTi, the Ti-Cu brittle phase in the joint interface is significantly reduced, and the shear strength of the welded joint reaches 23MPa, which is 400% higher than that without glass microspheres.
[0053] 5. The hollow glass microsphere composite brazing filler metal preparation method described in this embodiment is simple and low-cost. Hollow glass microspheres possess characteristics such as a low coefficient of thermal expansion and resistance to agglomeration, which are beneficial for controlling the interfacial structure and alleviating residual stress at the joint. Furthermore, using hollow glass microsphere composite brazing filler metal to connect dissimilar materials will result in a porous brazing joint. This porous structure can improve the stress distribution at the joint and consume fracture energy during crack propagation, thereby enhancing brazing performance and increasing joint strength.
[0054] Specific Implementation Method Nine: The difference between this implementation method and Specific Implementation Method Eight is that the dissimilar base materials to be welded are microcrystalline glass and C / C composite material.
[0055] The other steps are the same as in Specific Implementation Method 8.
[0056] Specific Implementation Method 10: The difference between this implementation method and Specific Implementation Method 8 or 9 is that the heating rate is 1-30℃ / min and the cooling rate is 1-50℃ / min.
[0057] The other steps are the same as in specific implementation method eight or nine.
[0058] The beneficial effects of the present invention are verified using the following embodiments:
[0059] Example 1: A method for brazing dissimilar materials based on hollow glass microsphere composite brazing filler metal, comprising the following steps:
[0060] Step S1:
[0061] 5g of hollow glass microspheres were dispersed in 1000mL of deionized water and ultrasonically cleaned at 25℃ for 1h. After ultrasonic cleaning, the mixture was allowed to stand for 3h to remove the broken glass microsphere precipitate. The upper floating matter was taken to obtain hollow glass microspheres with complete structure.
[0062] The hollow glass microspheres have a diameter of 30 μm;
[0063] Step S2:
[0064] The structurally intact hollow glass microspheres obtained in step S1 were placed in a vacuum drying oven and dried for 10 hours under a vacuum of 10 Pa and a temperature of 80 °C to obtain dried hollow glass microspheres.
[0065] Step S3:
[0066] The dried hollow glass microspheres obtained in step S2 are mixed with the brazing filler metal powder, and then anhydrous ethanol is added as a dispersant. The mixture is mechanically stirred at a stirring speed of 100 r / min for 20 min to obtain the hollow glass microsphere composite brazing filler metal (e.g., ...). Figure 1 (as shown);
[0067] The mass ratio of the dried hollow glass microspheres to the brazing filler powder is 0.005:1, and the brazing filler powder is AgCuInTi brazing filler.
[0068] Step S4:
[0069] Hollow glass microsphere composite brazing filler metal is placed between the microcrystalline glass substrate and the C / C composite material surfaces to be joined for assembly, and then placed in a brazing furnace at a vacuum degree of 5×10⁻⁶. -3 Under the condition of Pa, the temperature is increased to 770℃ at a rate of 10℃ / min, and the connection is brazed at 770℃ for 10min. After the brazing is completed, the temperature is first cooled to 200℃ at a rate of 5℃ / min, and finally the heating is turned off and the furnace is cooled to room temperature.
[0070] The microcrystalline glass has a size of 7mm×7mm×7mm, and the C / C composite material has a size of 7mm×7mm×7mm. Before brazing, the surfaces of the microcrystalline glass and the C / C composite material to be brazed are polished with 240#, 400#, 600# and 1000# sandpaper in sequence, and then ultrasonically cleaned in acetone for 10 minutes, and then taken out and dried.
[0071] Comparative Example 1: The method for brazing dissimilar materials is carried out according to the following steps:
[0072] AgCuInTi solder powder was mixed with anhydrous ethanol to form a solder paste, which was then applied between the C / C composite material and the microcrystalline glass for brazing.
[0073] Before brazing, the surfaces of the microcrystalline glass and C / C composite material to be brazed are successively polished with 240#, 400#, 600# and 1000# sandpaper, then ultrasonically cleaned in acetone for 10 minutes, and then taken out and dried.
[0074] The brazing process parameters are as follows: the vacuum brazing furnace is evacuated to a vacuum level of 5×10⁻⁶. -3 Pa, then the temperature was increased to 770°C at a rate of 10°C / min, and brazed at 770°C for 10 min. After brazing, the temperature was cooled to 200°C at a rate of 5°C / min, and finally the heating was turned off and the furnace was cooled to room temperature.
[0075] Figure 2 This diagram shows the interfacial microstructure of the brazed joint of the hollow glass microsphere composite brazing filler metal in Example 1. Figure 3 This diagram shows the interfacial microstructure of the brazed joint without glass beads in Comparative Example 1; for example... Figure 2-3 As shown, after adding hollow glass microspheres in Example 1, the Ti-Cu phase in the joint interface was significantly reduced, and the joint shear strength reached 10 MPa, which was 150% higher than that without glass microspheres.
[0076] Example 2: A method for brazing dissimilar materials based on hollow glass microsphere composite brazing filler metal, comprising the following steps:
[0077] Step S1:
[0078] 5g of hollow glass microspheres were dispersed in 1000mL of deionized water and ultrasonically cleaned at 25℃ for 1h. After ultrasonic cleaning, the mixture was allowed to stand for 3h to remove the broken glass microsphere precipitate. The upper floating matter was taken to obtain hollow glass microspheres with complete structure.
[0079] The hollow glass microspheres have a diameter of 30 μm;
[0080] Step S2:
[0081] The structurally intact hollow glass microspheres obtained in step S1 were placed in a vacuum drying oven and dried for 10 hours under a vacuum of 10 Pa and a temperature of 80 °C to obtain dried hollow glass microspheres.
[0082] Step S3:
[0083] The dried hollow glass microspheres obtained in step S2 are mixed with the brazing filler powder, and then anhydrous ethanol is added as a dispersant. The mixture is mechanically stirred at a stirring speed of 100 r / min for 20 min to obtain the hollow glass microsphere composite brazing filler.
[0084] The mass ratio of the dried hollow glass microspheres to the brazing filler powder is 0.01:1, and the brazing filler powder is AgCuInTi brazing filler.
[0085] Step S4:
[0086] Hollow glass microsphere composite brazing filler metal is placed between the microcrystalline glass substrate and the C / C composite material surfaces to be joined for assembly, and then placed in a brazing furnace at a vacuum degree of 5×10⁻⁶. -3 Under the condition of Pa, the temperature is increased to 770℃ at a rate of 10℃ / min, and the connection is brazed at 770℃ for 10min. After the brazing is completed, the temperature is first cooled to 200℃ at a rate of 5℃ / min, and finally the heating is turned off and the furnace is cooled to room temperature.
[0087] The microcrystalline glass has a size of 7mm×7mm×7mm, and the C / C composite material has a size of 7mm×7mm×7mm. Before brazing, the surfaces of the microcrystalline glass and the C / C composite material to be brazed are polished with 240#, 400#, 600# and 1000# sandpaper in sequence, and then ultrasonically cleaned in acetone for 10 minutes, and then taken out and dried.
[0088] Figure 4 This image shows the interfacial microstructure of the brazed joint of the hollow glass microsphere composite brazing filler metal in Example 2; from... Figure 2 , Figure 3and Figure 4 The comparison shows that as the content of hollow glass microspheres in the composite brazing filler metal increases, the Ti-Cu phase in the joint interface is significantly reduced, and there is almost no agglomeration of brittle compounds. The final shear strength of the joint reaches 23 MPa, which is 400% higher than that without glass microspheres.
Claims
1. A method for preparing a hollow glass microsphere composite solder, characterized in that... The preparation method is carried out according to the following steps: Step S1: 5g of hollow glass microspheres were dispersed in 1000mL of deionized water and ultrasonically cleaned at 25℃ for 1h. After ultrasonic cleaning, the mixture was allowed to stand for 3h to remove the broken glass microsphere precipitate. The upper floating matter was taken to obtain hollow glass microspheres with complete structure. The hollow glass microspheres have a diameter of 30 μm; Step S2: The structurally intact hollow glass microspheres obtained in step S1 were placed in a vacuum drying oven and dried for 10 hours under a vacuum of 10 Pa and a temperature of 80 °C to obtain dried hollow glass microspheres. Step S3: The dried hollow glass microspheres obtained in step S2 are mixed with the brazing filler powder, and then anhydrous ethanol is added as a dispersant. The mixture is mechanically stirred at a stirring speed of 100 r / min for 20 min to obtain the hollow glass microsphere composite brazing filler. The mass ratio of the dried hollow glass microspheres to the solder powder is 0.005:1 or 0.01:1, and the solder powder is AgCuInTi solder.
2. A method for brazing dissimilar materials using hollow glass microsphere composite brazing filler metal prepared according to claim 1, characterized in that... This method is performed in the following steps: Step S4: Hollow glass microsphere composite brazing filler metal is placed between the microcrystalline glass substrate and the C / C composite material surfaces to be joined for assembly, and then placed in a brazing furnace at a vacuum degree of 5×10⁻⁶. -3 Under the condition of Pa, the temperature is increased to 770℃ at a rate of 10℃ / min, and the connection is brazed at 770℃ for 10min. After the brazing is completed, the temperature is first cooled to 200℃ at a rate of 5℃ / min, and finally the heating is turned off and the furnace is cooled to room temperature. The microcrystalline glass has a size of 7mm×7mm×7mm, and the C / C composite material has a size of 7mm×7mm×7mm. Before brazing, the surfaces of the microcrystalline glass and the C / C composite material to be brazed are polished with 240#, 400#, 600# and 1000# sandpaper in sequence, and then ultrasonically cleaned in acetone for 10 minutes, and then taken out and dried.