Silicon-based brazing filler metal, SiC and SiCf / SiC connecting method
By using a specific ratio of silicon-based solder and controlling the solder in the Si-rich near-eutectic region to form a mutually soluble solid solution lamellar structure, the low-strength welding problem of silicon carbide and silicon carbide fiber-reinforced ceramic matrix composites was solved, and a high-strength welded joint was obtained.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-30
- Publication Date
- 2026-03-24
AI Technical Summary
In the existing technology, it is difficult to obtain high-strength welded joints when joining silicon carbide with silicon carbide fiber-reinforced silicon carbide ceramic matrix composites. Commonly used brazing filler metals react with silicon carbide fibers at high temperatures to form brittle metal carbides, resulting in low joint strength.
A silicon-based solder with a specific ratio, including Ti: 2.3% to 8.3%, Zr: 2.3% to 8.3%, Hf: 2.3% to 8.3%, with the balance being Si, is used to form a ternary eutectic structure. This controls the solder in the Si-rich near-eutectic range, reduces metal activity, avoids the formation of brittle metal carbides, and improves welding strength by forming a mutually soluble solid solution lamellar structure with Ti, Zr, Hf and Si.
Under high-temperature brazing conditions, the brazing filler metal has good spreading ability, avoids the formation of brittle metal carbides, improves the strength of the weld joint, has strong stress absorption and crack propagation resistance, and obtains a high-strength weld joint.
Smart Images
Figure CN121715741A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of welding technology, and more specifically, to a silicon-based solder, SiC and SiC f / SiC connection method. Background Technology
[0002] Silicon carbide and silicon carbide fiber-reinforced silicon carbide ceramic matrix composites (SiC f Silicon carbide (SiC) is widely used in aerospace and advanced nuclear energy equipment due to its ultra-high thermal conductivity, low coefficient of thermal expansion, high strength, and excellent radiation resistance. However, its inherent brittleness and difficulty in machining make its joining a major bottleneck in engineering applications. Welding has become an effective method to solve this technical problem. Compared with other welding methods such as diffusion welding, brazing has advantages such as simple process, high production efficiency, and the ability to perform welding at relatively low temperatures. Currently, for joining silicon carbide to silicon carbide fiber-reinforced silicon carbide ceramic matrix composites, commonly used brazing filler metals include Ag-Cu-Ti and Ti-Zr-Ni-Cu. Although they have good wettability, the active metals in these filler metals react strongly with the carbon in the silicon carbide fibers under high-temperature conditions, forming a thick and brittle metal carbide layer, resulting in low weld joint strength. Summary of the Invention
[0003] The problem solved by this invention is: how to obtain a high-strength weld joint for the connection of silicon carbide and silicon carbide fiber-reinforced silicon carbide ceramic matrix composites.
[0004] To address the above problems, the present invention provides a silicon-based solder, which, by molar percentage, comprises: Ti: 2.3% to 8.3%, Zr: 2.3% to 8.3%, Hf: 2.3% to 8.3%, with the balance being Si.
[0005] Optionally, the molar ratio of Ti, Zr, and Hf is 1:1:1.
[0006] The present invention also provides a SiC and SiC f / SiC connection methods include: Step S1: Place the silicon-based solder as described above between the SiC substrate and the SiC substrate. f Between / SiC parent materials, a sandwich structure is formed for the components to be connected; Step S2: Vacuum brazing is performed on the components to be connected to obtain a welded joint.
[0007] Optionally, in step S2, the vacuum brazing of the components to be connected includes: heating the components to be connected to 300°C to 350°C at a first heating rate, holding at that temperature for 15 min to 25 min, then heating at a second heating rate to 1360°C to 1390°C, holding at that temperature for 5 min to 20 min, then heating at a first cooling rate to 750°C to 850°C, and finally cooling at a second cooling rate to room temperature.
[0008] Optionally, the first heating rate is 4°C / min to 6°C / min.
[0009] Optionally, the second heating rate is from 5°C / min to 10°C / min.
[0010] Optionally, the first cooling rate is 3°C / min to 5°C / min.
[0011] Optionally, the second cooling rate is 8°C / min to 10°C / min.
[0012] Optionally, in step S1, the silicon-based solder is in sheet form.
[0013] Optionally, in step S1, the thickness of the silicon-based solder is 0.3 mm to 0.6 mm.
[0014] Compared with related technologies, the silicon-based brazing filler metal provided by this invention is a ternary eutectic silicon-based brazing filler metal composed of titanium (Ti), zirconium (Zr), hafnium (Hf), and silicon (Si) in a specific ratio. By controlling the total molar fraction of metal elements in the silicon-based brazing filler metal, the silicon-based brazing filler metal is placed in the Si-rich near-eutectic range. Under high-temperature brazing conditions, the brazing filler metal melt has good spreading ability. The metal elements are less active due to the high-silicon environment, thereby reducing the possibility of strong reactions between the metal elements and carbon in silicon carbide fibers and avoiding the formation of brittle metal carbides, which is beneficial to improving the strength of the weld joint. In addition, since Ti, Zr, and Hf all belong to group IVB, their outer electron structures are similar and their crystal chemical behaviors are consistent. During the brazing of silicon carbide and silicon carbide fiber-reinforced silicon carbide ceramic matrix composites, these three elements can form a highly miscible solid solution lamellar structure with Si, which together with the Si-rich phase constitutes a fine and uniform eutectic structure. This gives the weld a strong ability to absorb stress and inhibit crack propagation during cooling, which is beneficial to improving the strength of the weld joint. In summary, the silicon-based solder provided by this invention can be used in silicon carbide (SiC) and silicon carbide fiber-reinforced silicon carbide ceramic matrix composites (SiC). f The connection of / SiC can produce a welded joint with high strength. Attached Figure Description
[0015] Figure 1Scanning electron microscope (SEM) images of the silicon-based solder in Example 1; Figure 2 The image shown is a scanning electron microscope (SEM) image of the welded joint obtained in Example 1. Detailed Implementation
[0016] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Although some embodiments of the present invention are shown in the drawings, it should be understood that the present invention can be implemented in various forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided to provide a more thorough and complete understanding of the present invention. It should be understood that the accompanying drawings and embodiments of the present invention are for illustrative purposes only and are not intended to limit the scope of protection of the present invention.
[0017] Unless otherwise defined, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.
[0018] The term "comprising" and its variations as used herein are open-ended, meaning "including but not limited to"; the term "based on" means "at least partially based on"; the term "one embodiment" means "at least one embodiment"; the term "another embodiment" means "at least one additional embodiment"; the term "some embodiments" means "at least some embodiments"; and the term "optionally" means "optional embodiments". Definitions of other terms will be given in the following description. It should be noted that the concepts of "first," "second," etc., mentioned in this invention are used to distinguish different objects, not to describe a specific order or hierarchy. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined with "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.
[0019] In this invention, silicon carbide fiber-reinforced silicon carbide ceramic matrix composite material (SiC) f SiC composites are a commonly used type of continuous fiber reinforced composite material. They are made by using continuously textured SiC fibers to reinforce and toughen the SiC ceramic matrix, thus forming a composite material with SiC fibers as the reinforcing phase, SiC ceramic as the matrix phase and continuous phase.
[0020] The silicon-based solder provided in this embodiment of the invention comprises, by molar percentage: Ti: 2.3% to 8.3%, Zr: 2.3% to 8.3%, Hf: 2.3% to 8.3%, with the balance being Si.
[0021] The silicon-based brazing filler metal provided in this invention is a ternary eutectic silicon-based brazing filler metal composed of titanium (Ti), zirconium (Zr), hafnium (Hf), and silicon (Si) in a specific ratio. By controlling the total molar fraction of the metal elements in the silicon-based brazing filler metal, the filler metal is placed in the Si-rich near-eutectic range. Under high-temperature brazing conditions, the filler metal melt has good spreading ability. The metal elements are less reactive due to the high-silicon environment, which reduces the possibility of strong reactions between the metal elements and carbon in the silicon carbide fibers, avoiding the formation of brittle metal carbides, thus improving the strength of the weld joint. In addition, since Ti, Zr, and Hf belong to the IVB group, their outer electron structures are similar and their crystal chemical behaviors are consistent. During the brazing of silicon carbide and silicon carbide fiber-reinforced silicon carbide ceramic matrix composites, these three elements can form a highly miscible solid solution lamellar structure with Si, which together with the Si-rich phase constitutes a fine and uniform eutectic structure. This gives the weld a strong ability to absorb stress and inhibit crack propagation during cooling, which is beneficial to improving the strength of the weld joint. In summary, using the silicon-based brazing filler metal provided in the embodiments of the present invention for joining silicon carbide and silicon carbide fiber-reinforced silicon carbide ceramic matrix composites can yield welded joints with high strength.
[0022] In some embodiments of the present invention, the molar ratio of Ti, Zr and Hf is 1:1:1.
[0023] This invention also provides a SiC and SiC f / SiC connection methods include: Step S1: Place the silicon-based solder as described above between the SiC substrate and the SiC substrate. f Between / SiC parent materials, a sandwich structure is formed for the components to be connected; Step S2: Vacuum brazing is performed on the components to be connected to obtain a welded joint.
[0024] The SiC and SiC provided in the embodiments of the present invention fThe / SiC joining method uses a silicon-based brazing filler metal composed of a specific ratio of titanium (Ti), zirconium (Zr), hafnium (Hf), and silicon (Si). Under high-temperature brazing conditions, the filler metal melt exhibits excellent spreading ability. The metal elements are less reactive due to the high-silicon environment, thus reducing the possibility of strong reactions between the metal elements and the carbon in the silicon carbide fibers, preventing the formation of brittle metal carbides. Furthermore, since Ti, Zr, and Hf belong to the IVB group, their outer electron structures are similar, and their crystal chemical behaviors are consistent. During the brazing of silicon carbide and silicon carbide fiber-reinforced silicon carbide ceramic matrix composites, these three elements can form a highly miscible solid solution lamellar structure with Si, together with the Si-rich phase, constituting a fine and uniform eutectic structure. This results in a weld with strong stress absorption and crack propagation resistance during cooling. Therefore, the method provided in this invention can yield welded joints with high strength.
[0025] In some embodiments of the present invention, step S2, wherein vacuum brazing of the components to be connected includes: heating the components to be connected to 300°C to 350°C at a first heating rate, holding at that temperature for 15 min to 25 min, then heating to 1360°C to 1390°C at a second heating rate, holding at that temperature for 5 min to 20 min, then heating to 750°C to 850°C at a first cooling rate, and finally cooling to room temperature at a second cooling rate; wherein the first heating rate is 4°C / min to 6°C / min, the second heating rate is 5°C / min to 10°C / min, the first cooling rate is 3°C / min to 5°C / min, and the second cooling rate is 8°C / min to 10°C / min.
[0026] In some embodiments of the present invention, in step S1, the silicon-based solder is in sheet form, and the thickness of the silicon-based solder is 0.2 mm to 0.6 mm. Specifically, the preparation method of the sheet-shaped silicon-based solder includes: melting titanium, zirconium, hafnium, and silicon as raw materials to obtain a solder ingot; processing the solder ingot into a sheet form to obtain the sheet-shaped silicon-based solder; wherein the melting is carried out in a vacuum arc melting furnace, the melting temperature is 1400°C to 1550°C, and the melting time is 10 s to 30 s.
[0027] The present invention will be further described below with reference to specific embodiments.
[0028] Example 1 A1. Place silicon-based solder between SiC base material and SiC f Between the SiC base material, a sandwich structure is formed for the components to be connected; the composition of the silicon-based solder, in molar percentage, includes: Ti: 2.3%, Zr: 2.3%, Hf: 2.3%, with the balance being Si; the silicon-based solder is in sheet form.
[0029] A2. Under vacuum conditions, the components to be connected are heated to 310°C at a first heating rate and held for 20 minutes, then heated to 1380°C at a second heating rate and held for 10 minutes, then heated to 800°C at a first cooling rate, and finally cooled to room temperature at a second cooling rate to obtain a welded joint; wherein, the first heating rate is 5°C / min, the second heating rate is 8°C / min, the first cooling rate is 4°C / min, and the second cooling rate is 8°C / min.
[0030] Example 2 The difference from Example 1 is that step A2 is as follows: under vacuum conditions, the components to be connected are heated to 310°C at a first heating rate and held for 20 minutes, then heated to 1390°C at a second heating rate and held for 5 minutes, then heated to 800°C at a first cooling rate, and finally cooled to room temperature at a second cooling rate to obtain a welded joint; wherein, the first heating rate is 6°C / min, the second heating rate is 10°C / min, the first cooling rate is 5°C / min, and the second cooling rate is 10°C / min.
[0031] Example 3 The difference from Example 1 is that step A2 is as follows: under vacuum conditions, the components to be connected are heated to 310°C at a first heating rate and held for 20 minutes, then heated to 1360°C at a second heating rate and held for 20 minutes, then heated to 800°C at a first cooling rate, and finally cooled to room temperature at a second cooling rate to obtain a welded joint; wherein, the first heating rate is 4°C / min, the second heating rate is 5°C / min, the first cooling rate is 3°C / min, and the second cooling rate is 9°C / min.
[0032] Comparative Example 1 The difference from Example 1 is that, in step A1, the composition of the silicon-based solder, by molar percentage, includes: Ti: 6.9%, with the balance being Si.
[0033] Comparative Example 2 The difference from Example 1 is that, in step A1, the composition of the silicon-based solder, by molar percentage, includes: Zr: 6.9%, with the balance being Si.
[0034] Comparative Example 3 The difference from Example 1 is that, in step A1, the composition of the silicon-based solder, in molar percentage, includes: Ti: 3.45%, Zr: 3.45%, and the balance being Si.
[0035] Experimental Example The silicon-based solder in Example 1 was characterized by scanning electron microscopy, and the results are shown in the figure. Figure 1 The welded joint obtained in Example 1 was characterized by scanning electron microscopy, and the results are shown in the figure. Figure 2 ,from Figure 2 It can be seen that the active metal elements in the silicon-based solder are distributed in the interface region of the base material in the form of fine solid solution silicides, while the main body of the weld is composed of pure silicon phase, resulting in good interfacial bonding quality of the weld joint. The shear strength of the weld joints prepared in Example 1 and Comparative Examples 1 to 3 was tested, and the results are shown in Table 1. As can be seen from Table 1, the shear strength of the weld joint prepared in Example 1 is higher than that in Comparative Examples 1 to 3. In contrast, the shear strength of the weld joint prepared in Comparative Example 2 is the lowest. This is because the silicon-based solder used in Comparative Example 2 is a Si-Zr binary solder with a high eutectic temperature (about 1360℃). This silicon-based solder cannot completely melt at 1380℃, resulting in poor spreadability, incomplete and uneven interfacial reaction, and the presence of unreacted ZrSi2 brittle phase in the weld, leading to a large number of pores and discontinuous connection defects in local areas.
[0036] Table 1
[0037] While the present invention has been disclosed above, its scope of protection is not limited thereto. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention, and all such changes and modifications will fall within the scope of protection of the present invention.
Claims
1. A silicon-based solder, characterized in that, The composition, by molar percentage, includes: Ti: 2.3% to 8.3%, Zr: 2.3% to 8.3%, Hf: 2.3% to 8.3%, with the balance being Si.
2. The silicon-based solder according to claim 1, characterized in that, The molar ratio of Ti, Zr and Hf is 1:1:
1.
3. A SiC and SiC f The connection method for SiC is characterized by... include: Step S1: Place the silicon-based solder according to claim 1 or 2 between the SiC base material and the SiC substrate. f Between / SiC parent materials, a sandwich structure is formed for the components to be connected; Step S2: Vacuum brazing is performed on the components to be connected to obtain a welded joint.
4. The SiC and SiC according to claim 3 f The connection method for SiC is characterized by... In step S2, the vacuum brazing of the components to be connected includes: heating the components to be connected to 300°C to 350°C at a first heating rate, holding at that temperature for 15 min to 25 min, then heating at a second heating rate to 1360°C to 1390°C, holding at that temperature for 5 min to 20 min, then heating at a first cooling rate to 750°C to 850°C, and finally cooling at a second cooling rate to room temperature.
5. The SiC and SiC according to claim 4 f The connection method for SiC is characterized by... The first heating rate is 4°C / min to 6°C / min.
6. The SiC and SiC according to claim 4 f The connection method for SiC is characterized by... The second heating rate is 5°C / min to 10°C / min.
7. The SiC and SiC according to claim 4 f The connection method for SiC is characterized by... The first cooling rate is 3°C / min to 5°C / min.
8. The SiC and SiC according to claim 4 f The connection method for SiC is characterized by... The second cooling rate is 8°C / min to 10°C / min.
9. The SiC and SiC according to claim 3 f The connection method for SiC is characterized by... In step S1, the silicon-based solder is in sheet form.
10. The SiC and SiC according to claim 9 f The connection method for SiC is characterized by... In step S1, the thickness of the silicon-based solder is 0.3 mm to 0.6 mm.