Method for brazing SiCf / SiC composite material by using Si-Zr + xCf high-temperature brazing filler metal

Abstract

The invention discloses a method for brazing a SiCf / SiC composite material by using Si-Zr + xCf high-temperature brazing filler metal, and relates to a method for brazing the SiCf / SiC composite material. The invention aims to solve the technical problem that the high-temperature brazing strength of the current SiCf / SiC composite material is not high. The high-temperature low-cost Si-Zr + xCf high-temperature brazing filler metal is designed on the basis of the Si-10Zr eutectic brazing filler metal, and the high-temperature reliable connection of the SiCf / SiC composite material is realized by adopting the brazing filler metal; the Si-Zr + xCf high-temperature brazing filler metal and a SiCf / SiC composite material have the excellent characteristic of good wettability, the bonding strength of an obtained joint is reliable, the room-temperature shear strength of the joint reaches 57 MPa, the high-temperature shear strength at the temperature of 1200 DEG C reaches 60 MPa, and the joint reliability is high.

Description

Technical Field

[0001] The present invention relates to a brazing SiC f / SiC composite material method. Background Art

[0002] SiC f / SiC composite material is a commonly used continuous fiber reinforced composite material, that is, continuous textured SiC fibers are used to reinforce and toughen the SiC ceramic matrix, thereby forming a composite material with SiC fibers as the reinforcement phase and SiC ceramics as the matrix phase and continuous phase. f / SiC ceramic matrix composites retain the excellent properties of silicon carbide ceramics such as high temperature resistance, high thermal conductivity, and low density. Through fiber reinforcement and toughening, they effectively overcome the shortcomings of SiC ceramics such as high brittleness, sensitivity to cracks, and susceptibility to catastrophic damage, thus achieving safe and reliable performance. They have been gradually applied to high-temperature resistant parts in aerospace engines. f / SiC composite materials are complex in shape and difficult to form directly. Therefore, from the perspective of practical engineering applications, it is necessary to realize SiC f The connection of SiC composite materials is of great significance for widening the f The use of SiC composite materials in aerospace engines is of great significance and has broad application prospects.

[0003] Current information about SiC f The research on the connection of SiC composite materials has attracted more and more attention from scholars. f / SiC composite materials, because the general high-activity metal brazing filler metals such as Ag-Cu-Ti and Ti-Zr-Cu-Ni are easy to oxidize, have harsh connection conditions, and have low connection temperatures, and usually have higher f / SiC composites have a higher thermal expansion coefficient and are therefore not suitable for SiC f / SiC composite materials with high temperature and high strength. Therefore, it is necessary to find f / SiC composite materials have a better matching thermal expansion coefficient and a solder with an appropriate connection temperature. For Si-based solder, its thermal expansion coefficient is greatly affected by the Si element, which makes it f / SiC composite materials have little difference in thermal expansion coefficient, which can better control the residual stress of the joint, and Si-based brazing filler metal has little difference in thermal expansion coefficient. f / SiC composite materials have good wettability and adhesion, high melting point, generally above 1200℃ and high temperature oxidation resistance. fSi-based high-temperature brazing filler metals for connecting SiC / SiC composite materials are very important for obtaining reliable and high-temperature resistant SiC f / SiC composite material joint components are of great significance. f There are relatively few literatures on SiC composites themselves. B. Riccardi successfully brazed SiC at 1380℃ by using 78Si-22Ti low-activity brazing filler metal. f / SiC composite material (Journal of Nuclear Materials, 307–311 (2002) 1237–1241), the joint has a good shear strength of 70MPa at 600°C. Z.He brazed SiC in an argon atmosphere at 1460°C using Si-10Zr eutectic brazing filler metal. f / SiC and C f / C composite material (Journal of the European Ceramic Society, 41 (2021) 1142-1150), the joint shear strength reached 38MPa. This shows that Si-10Zr eutectic solder can not only f / SiC composite materials also have the potential to withstand high temperatures. Adding C to the Si-10Zr eutectic solder f Formation of Si-Zr-xC f Composite brazing alloy is expected to achieve high-strength brazing of SiC f / SiC composite material and achieve high temperature resistance of 1000℃ for the joint. Summary of the invention

[0004] The present invention is to solve the current SiC f / SiC composite material high temperature brazing strength is not high technical problem, and provide a Si-Zr + xC f High temperature brazing SiC f / SiC composite material method.

[0005] The present invention uses Si-Zr+xC f High temperature brazing SiC f The method of the SiC composite material is carried out in the following steps:

[0006] 1. Preparation of Si-Zr eutectic solder ingot by vacuum arc melting;

[0007] 2. Use a crusher to crush the Si-Zr eutectic solder ingot, then grind it into Si-Zr solder powder at a low speed under argon protection, and then add short C f Powder (carbon fiber powder), mixed with a planetary ball mill at a low speed under argon protection, and then dried to obtain powdered Si-Zr+xC fBrazing filler metal;

[0008] The Si-Zr+xC f C in solder f The mass fraction of powder is 0.5% to 5%;

[0009] 3. Use wire cutting to cut two base materials SiC f / SiC composite material is cut into required size, and then the base material is cleaned;

[0010] 4. The powdered Si-Zr+xC prepared in step 2 f The brazing material is pressed into a green body, and then pressure is applied, and then Si-Zr+xC f The brazing filler metal is placed between two SiC f / SiC composite materials, and each layer is fixed with an organic binder to obtain an assembly;

[0011] 5. Place the assembly prepared in step 4 into a graphite mold and place it in a vacuum or atmosphere furnace. The entire process is carried out under vacuum or protective atmosphere. First, heat the temperature to 300°C to 310°C at 10°C / min to 15°C / min and keep it warm for 30 minutes to remove the organic binder, then heat it to 1000°C to 1100°C at 10°C / min to 15°C / min, then heat it to the brazing temperature of 1460°C to 1500°C at 5°C / min to 10°C / min and keep it warm for 5 minutes to 20 minutes; then cool it to 300°C to 310°C at 5°C / min to 10°C / min, and then cool it to room temperature with the furnace to complete the brazing of SiC f / SiC composite material.

[0012] The present invention designs a high-temperature and low-cost Si-Zr+xC based on Si-10Zr (at.%) eutectic solder. f (x = 0.5 ~ 5wt.%) high temperature brazing material, and use the brazing material to achieve SiC f / SiC composite material high temperature reliable connection; the Si-Zr+xC f High temperature brazing material and SiC f / SiC composite materials have the excellent characteristic of good wettability, and the obtained joint bonding strength is reliable.

[0013] The Si-Zr+xC f The high temperature solder is composed of three elements: Si, Zr and C; wherein the mass fraction of Si is 70% to 75%, the mass fraction of Zr is 25% to 30%, and the mass fraction of C is 0.5% to 5%; the connection method adopts the Si-Zr+xC f High temperature brazing filler metals are used to connect SiC in protective atmosphere or vacuum conditions above 1460℃.f / SiC composite materials.

[0014] The process of the present invention is simple and successfully realizes SiC f / SiC composite material has high strength connection, the room temperature shear strength of the joint reaches 57MPa, and the high temperature shear strength of 1000℃ reaches 87MPa, and the joint has strong reliability; the present invention uses SiC f / SiC composite material itself is connected, which solves the problem that complex components of the composite material are difficult to form, and can realize the application of the composite material components in the fields of aerospace and nuclear power.

[0015] Compared with the prior art, the present invention provides a high melting point, low cost Si-Zr+xC f High temperature brazing material, and SiC f The connection of / SiC composite materials has the following beneficial effects:

[0016] 1. Si-Zr+xC provided by the present invention f High temperature brazing filler metal for SiC f / SiC composite material connection method, Si-Zr+xC f High temperature brazing filler metal as the intermediate layer, direct brazing to achieve SiC f / SiC composite materials, where Si-Zr+xC f High temperature solder has high melting point and excellent wetting properties with the base material, and few defects in the connection layer, which is conducive to achieving high temperature reliability of the joint;

[0017] 2. At 30℃~1000℃, the thermal expansion coefficient of Si-Zr high temperature solder is 6.4×10 -6 / K, compared with SiC f / SiC composite material (4.4×10 -6 / K) is relatively close; after adding carbon fiber to the brazing material, the thermal expansion coefficient is lower and closer to SiC f / SiC composite materials;

[0018] 3. During the connection process, the solder and the base material interact with each other, SiC f / SiC composite material surface and liquid Si-Zr+xC f After high temperature solder contact, Si-Zr+xC f High temperature brazing filler metal infiltrates SiC fThe pores between the fiber / fiber or fiber / matrix of the SiC composite material play a role of filling the pores, and the brazing material reacts with the SiC matrix and the SiC fiber to generate a new SiC reaction layer; the maximum shear strength of the joint obtained by heat preservation at 1480℃ for 10min is about 57MPa at room temperature, the shear strength at 1000℃ reaches 87MPa, and the shear strength at 1200℃ reaches 60MPa. Therefore, the present invention adopts high melting point and low cost Si-Zr+xC f High temperature brazing filler metal as intermediate layer for SiC f The connection of SiC / SiC composite materials can achieve good wetting and interface bonding of the base material, thereby realizing the forming and manufacturing of complex-shaped structural parts. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 SiC obtained in Experiment 3 f SEM image of / SiC composite joint;

[0020] Figure 2 SiC obtained in Experiment 3 f Interface microstructure diagram of / SiC composite material joint and energy spectrum point analysis diagram of the phase. DETAILED DESCRIPTION

[0021] Specific implementation method 1: This implementation method is a method using Si-Zr+xC f High temperature brazing SiC f The method of the SiC composite material is specifically carried out according to the following steps:

[0022] 1. Preparation of Si-Zr eutectic solder ingot by vacuum arc melting;

[0023] 2. Use a crusher to crush the Si-Zr eutectic solder ingot, then grind it into Si-Zr solder powder at a low speed under argon protection, and then add short C f The powder was mixed by low-speed ball milling in a planetary ball mill under argon protection, and then dried to obtain powdered Si-Zr+xC f Brazing filler metal;

[0024] The Si-Zr+xC f C in solder f The mass fraction of powder is 0.5% to 5%;

[0025] 3. Use wire cutting to cut two base materials SiC f / SiC composite material is cut into required size, and then the base material is cleaned;

[0026] 4. The powdered Si-Zr+xC prepared in step 2 fThe brazing material is pressed into a green body, and then pressure is applied, and then Si-Zr+xC f The brazing filler metal is placed between two SiC f / SiC composite materials, and each layer is fixed with an organic binder to obtain an assembly;

[0027] 5. Place the assembly prepared in step 4 into a graphite mold and place it in a vacuum or atmosphere furnace. The entire process is carried out under vacuum or protective atmosphere. First, heat the temperature to 300°C to 310°C at 10°C / min to 15°C / min and keep it warm for 30 minutes to remove the organic binder, then heat it to 1000°C to 1100°C at 10°C / min to 15°C / min, then heat it to the brazing temperature of 1460°C to 1500°C at 5°C / min to 10°C / min and keep it warm for 5 minutes to 20 minutes; then cool it to 300°C to 310°C at 5°C / min to 10°C / min, and then cool it to room temperature with the furnace to complete the brazing of SiC f / SiC composite material.

[0028] Specific embodiment 2: This embodiment is different from specific embodiment 1 in that: the method for preparing Si-Zr eutectic solder ingot by vacuum arc melting in step 1 is: vacuum arc melting of high-purity Zr block and Si block is performed in a water-cooled copper crucible, the current is set to 200A, the voltage is 30V, and the melting time is 15s; the solder is melted 5 to 7 times and the sample is fully turned over during the melting process, and a button-shaped ingot is obtained after the melting is completed. Others are the same as specific embodiment 1.

[0029] Specific implementation method three: This implementation method is different from specific implementation methods one or two in that: the short C f The average length of the powder is 30 μm, the longest is less than 50 μm, and the diameter is 6 μm to 8 μm. The rest is the same as the first or second embodiment.

[0030] Specific embodiment 4: This embodiment differs from the specific embodiments 1 to 3 in that: in step 2, the mixture is milled at a low speed by a planetary ball mill under argon protection for 8 h to 12 h, and then dried to obtain a powdered Si-Zr+xC f The rest is the same as that of the first to third embodiments.

[0031] Specific implementation mode 5: This implementation mode is different from the specific implementation mode 4 in that: the Si-Zr+xC f C in solder f The mass fraction of the powder is 0.5%. Other aspects are the same as those of the fourth embodiment.

[0032] Specific implementation method 6: This implementation method is different from the specific implementation method 5 in that: the Si-Zr+xC f C in solder f The mass fraction of the powder is 1%. The rest is the same as the fifth embodiment.

[0033] Specific implementation method 7: This implementation method is different from specific implementation method 6 in that: the Si-Zr+xC f C in solder f The mass fraction of the powder is 3%. Other aspects are the same as those of the sixth embodiment.

[0034] Specific implementation method 8: This implementation method is different from specific implementation method 7 in that: the Si-Zr+xC f C in solder f The mass fraction of the powder is 5%. Other aspects are the same as those of the seventh embodiment.

[0035] Specific embodiment 9: This embodiment is different from specific embodiment 8 in that the process of cleaning the base material in step 3 is as follows: the two surfaces to be welded are ground and polished, and then 600#, 1200# and 1500# water sandpaper are used for grinding in sequence, and then 0.5μm diamond polishing agent is used for surface polishing until there are no obvious scratches, and the polished base material SiC f The / SiC composite material is placed in anhydrous ethanol for ultrasonic oscillation for 10 to 20 minutes, taken out and blown dry for later use. The rest is the same as the eighth embodiment.

[0036] Specific embodiment 10: This embodiment is different from specific embodiment 9 in that the organic binder in step 4 is 502 glue. Other aspects are the same as specific embodiment 9.

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

[0038] Test 1: This test is a Si-Zr+xC f High temperature brazing SiC f The method of the SiC composite material is specifically carried out according to the following steps:

[0039] 1. High-purity Zr blocks and Si blocks were vacuum arc melted together in a water-cooled copper crucible. The current was set to 200A, the voltage was 30V, and the melting time was 15s. The solder was melted 7 times and the sample was fully turned over during the melting process. After the melting was completed, a button-shaped ingot was obtained.

[0040] 2. Use a crusher to crush the Si-Zr eutectic solder ingot, then grind it into Si-Zr solder powder at a low speed under argon protection, and then add short C fThe powder was mixed with a planetary ball mill at a low speed for 10 hours under argon protection, and then dried to obtain powdered Si-Zr+xC f Solder; the short C f The average length of the powder is about 30 μm, the longest does not exceed 50 μm, and the diameter is 7 μm;

[0041] The Si-Zr+xC f C in solder f The mass fraction of powder is 0.5%;

[0042] 3. Use wire cutting to cut two base materials SiC f The SiC composite material is cut into the required size, the two surfaces to be welded are ground and polished, and then 600#, 1200# and 1500# water sandpaper are used for grinding, and then 0.5μm diamond polishing agent is used for surface polishing until there are no obvious scratches. f The / SiC composite material was placed in anhydrous ethanol for ultrasonic oscillation for 10 to 20 minutes, taken out and blown dry for later use;

[0043] 4. The powdered Si-Zr+xC prepared in step 2 f The brazing material is pressed into a green body, and then pressure is applied, and then Si-Zr+xC f The brazing filler metal is placed between two SiC f / SiC composite materials, and each layer is fixed with an organic binder to obtain an assembly; the organic binder described in step 4 is 502 glue;

[0044] 5. Place the assembly prepared in step 4 into a graphite mold and into an atmosphere furnace. The entire process is carried out under argon protection. First, heat the temperature to 300°C at 10°C / min and keep it for 30 minutes to remove the organic binder. Then heat it to 1000°C at 10°C / min, and then heat it to the brazing temperature of 1480°C at 5°C / min and keep it for 10 minutes. Then cool it to 300°C at 5°C / min, and then cool it to room temperature with the furnace to complete the brazing of SiC. f / SiC composite material.

[0045] Experiment 2: This experiment is different from Experiment 1 in that the Si-Zr+xC f C in solder f The mass fraction of the powder is 1%. Other conditions are the same as those in Experiment 1.

[0046] Experiment 3: This experiment is different from Experiment 1 in that the Si-Zr+xC f C in solder f The mass fraction of the powder is 3%. The rest is the same as in Experiment 1.f The shear strength of the SMD / SiC joint at 1000℃ is 87MPa.

[0047] SiC obtained in Experiments 1 to 3 f The room temperature strength of the SiC / SiC joints is shown in Table 1.

[0048] Table 1

[0049]

[0050] Figure 1 SiC obtained in Experiment 3 f SEM images of / SiC composite joints, 1 and 4 are both parent material SiC f / SiC composite material, 2 is Si-Zr-3C f Composite brazing material layer, 3 is SiC generation layer.

[0051] Figure 2 SiC obtained in Experiment 3 f Interface microstructure diagram of / SiC composite material joint and energy spectrum point analysis diagram of the phase.

[0052] Table 2 Figure 2 The element composition of the corresponding points in the weld shows that the weld is composed of the generated phases ZrSi2 (corresponding to spectrum D), Si (corresponding to spectrum A) and SiC (corresponding to spectrum B / C), and there are reaction generated phases SiC (corresponding to spectrum E) and Zr-Si compound phases (corresponding to spectrum F) at the interface.

[0053] Table 2

[0054]

Claims

1. A method using Si-Zr+xC f High temperature brazing SiC f / SiC composite material method, characterized in that Using Si-Zr+xC f High temperature brazing SiC f The method of the SiC composite material is carried out in the following steps:

1. Preparation of Si-Zr eutectic solder ingot by vacuum arc melting; 2. Use a crusher to crush the Si-Zr eutectic solder ingot, then grind it into Si-Zr solder powder at a low speed under argon protection, and then add short C f The powder was mixed by low-speed ball milling in a planetary ball mill under argon protection, and then dried to obtain powdered Si-Zr+xC f Brazing filler metal; The Si-Zr+xC f C in solder f The mass fraction of powder is 0.5% to 5%; 3. Use wire cutting to cut two base materials SiC f / SiC composite material is cut into required size, and then the base material is cleaned; 4. The powdered Si-Zr+xC prepared in step 2 f The brazing material is pressed into a green body, and then pressure is applied, and then Si-Zr+xC f The brazing filler metal is placed between two SiC f / SiC composite materials, and each layer is fixed with an organic binder to obtain an assembly; 5. Place the assembly prepared in step 4 into a graphite mold and place it in a vacuum or atmosphere furnace. The entire process is carried out under vacuum or protective atmosphere. First, heat the temperature to 300°C to 310°C at 10°C / min to 15°C / min and keep it warm for 30 minutes to remove the organic binder, then heat it to 1000°C to 1100°C at 10°C / min to 15°C / min, then heat it to the brazing temperature of 1460°C to 1500°C at 5°C / min to 10°C / min and keep it warm for 5 minutes to 20 minutes; then cool it to 300°C to 310°C at 5°C / min to 10°C / min, and then cool it to room temperature with the furnace to complete the brazing of SiC f / SiC composite material.

2. A method according to claim 1 using Si-Zr+xC f High temperature brazing SiC f / SiC composite material method, characterized in that The method for preparing Si-Zr eutectic solder ingot by vacuum arc melting in step one is: vacuum arc melting of high-purity Zr block and Si block is carried out in a water-cooled copper crucible, the current is set to 200A, the voltage is 30V, and the melting time is 15s; the solder is melted 5 to 7 times and the sample is fully turned over during the melting process, and a button-shaped ingot is obtained after the melting is completed.

3. A method according to claim 1 using Si-Zr+xC f High temperature brazing SiC f / SiC composite material method, characterized in that The short C described in step 2 f The average length of the powder is 30μm, the longest is less than 50μm, and the diameter is 6μm to 8μm.

4. The method according to claim 1 using Si-Zr+xC f High temperature brazing SiC f / SiC composite material method, characterized in that In step 2, the mixture is milled at a low speed in a planetary ball mill under argon protection for 8 h to 12 h, and then dried to obtain powdered Si-Zr+xC f Solder.

5. The method according to claim 1 using Si-Zr+xC f High temperature brazing SiC f / SiC composite material method, characterized in that Si-Zr+xC described in step 2 f C in solder f The mass fraction of powder is 0.5%.

6. The method according to claim 1 using Si-Zr+xC f High temperature brazing SiC f / SiC composite material method, characterized in that Si-Zr+xC described in step 2 f C in solder f The mass fraction of powder is 1%.

7. The method according to claim 1 using Si-Zr+xC f High temperature brazing SiC f / SiC composite material, characterized in that Si-Zr+xC described in step 2 f C in solder f The mass fraction of powder is 3%.

8. The method according to claim 1 using Si-Zr+xC f High temperature brazing SiC f / SiC composite material method, characterized in that Si-Zr+xC described in step 2 f C in solder f The mass fraction of powder is 5%.

9. The method according to claim 1 using Si-Zr+xC f High temperature brazing SiC f / SiC composite material, characterized in that The process of cleaning the base material in step 3 is as follows: the two surfaces to be welded are ground and polished, and then 600#, 1200# and 1500# water sandpaper are used for grinding, and then 0.5μm diamond polishing agent is used for surface polishing until there are no obvious scratches. f The / SiC composite material was placed in anhydrous ethanol for ultrasonic oscillation for 10 min to 20 min, taken out and blown dry for later use.

10. The method according to claim 1 using Si-Zr+xC f High temperature brazing SiC f / SiC composite material, characterized in that The organic binder described in step 4 is 502 glue.

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