A high-temperature brazing filler metal for silicon carbide-based ceramics and a preparation method and application thereof

Abstract

The application provides a high-temperature brazing filler metal for silicon carbide-based ceramic connection and a preparation method and application thereof, and belongs to the technical field of silicon carbide ceramic materials. The high-temperature brazing filler metal for silicon carbide-based ceramic connection provided by the application comprises 2-15% of metal powder and the balance of Ti-Si powder in percentage by mass, wherein the metal powder comprises Fe powder, Al powder, Ni powder, Cr powder or Co powder. A small amount of metal elements is added in the Ti-Si brazing filler metal, so that the melting point of the brazing filler metal is reduced, the connection time is shortened, and the liquid brazing filler metal is promoted to generate the Ti3SiC2 MAX phase with high strength by in-situ reaction with the silicon carbide-based ceramic to connect the base material; meanwhile, the brazing filler metal is in a liquid state at high temperature, so that the densification of the weld is achieved without using pressure, and the mechanical properties of the connected parts at room temperature and high temperature are improved.

Description

Technical Field

[0001] This invention relates to the field of silicon carbide ceramic materials technology, and in particular to a high-temperature brazing filler metal for silicon carbide-based ceramic bonding, its preparation method, and its application. Background Technology

[0002] Silicon carbide (SiC) ceramics and their composites (such as SiC) f SiC (SiC-based ceramics) is a crucial class of high-temperature structural materials, possessing excellent thermal, mechanical, and chemical properties, making it suitable for high-temperature applications such as nuclear reactors and aerospace. However, due to its high covalent nature and extremely low self-diffusion, SiC-based ceramics require high-temperature and high-pressure conditions to achieve densification during fabrication, making the processing of components with complex shapes difficult. Therefore, developing reliable SiC-based ceramic joining technologies and ensuring the high-temperature performance of the joints is of paramount importance.

[0003] Among the various methods for joining silicon carbide-based ceramics, such as diffusion welding, spark plasma sintering (SPS) joining, and C-Si reactive joining, high joining temperatures (≥1500℃) and certain pressures (≥10MPa) are required, thus limiting their ability to join silicon carbide-based ceramics with complex shapes. In contrast, brazing, as a pressureless joining method, has advantages such as simple process and reliable connection. However, the low melting point of the brazing filler metal may limit the application of the joined components at high temperatures (≥1000℃). Therefore, selecting a suitable brazing filler metal plays a decisive role in the high-temperature performance of silicon carbide-based ceramic brazed joints.

[0004] Ti3SiC2MAX phase, as a special ternary compound, not only possesses the high-temperature performance of ceramics but also exhibits certain metal-like plasticity. Therefore, Ti3SiC2 is considered one of the most promising bonding materials for silicon carbide-based ceramics. Currently, the direct bonding of SiC-based ceramics using Ti3SiC2 mainly employs diffusion bonding or SPS bonding, both of which require high bonding temperatures (≥1500℃) and pressures (≥10MPa). For example, Chinese patent application CN202311401048.9 discloses a method for in-situ synthesis of MAX phase brazing of silicon carbide-based ceramics. This method uses a TiSi+SiC composite brazing filler metal to connect SiC-based ceramics, and the resulting joint phase is Ti3SiC2 phase. The joint still maintains a high level of shear strength (83MPa) at 1200℃. However, when connecting at low temperatures, this method requires a long holding time (200 min at 1500℃) because the TiSi+SiC brazing filler metal is difficult to completely melt. Meanwhile, Dong et al., in their paper "Microstructure and mechanical properties of SiC-SiC joints joined by...", ... In the paper "spark plasmas interning" (doi: http: / / dx.doi.org / 10.1016 / j.ceramint.2016.06.049), a method for bonding SiC ceramics using Ti / Si / C / Al powder was successfully proposed. However, this bonding method requires a high temperature of 1600℃ and a high pressure of 30MPa, which places extremely high demands on the equipment. In addition, Wang et al. proposed a method for bonding SiC ceramics using Ti3SiC2+B4C powder in the paper "Beneficial effects of B4C addition on the microstructure and mechanical properties of SiC ceramic joints diffusion bonded with Ti3SiC2" (doi: https: / / doi.org / 10.1016 / j.msea.2018.11.021). The obtained joint has a room temperature shear strength of 112MPa. However, there is a Ti3SiC2 phase decomposition phenomenon in this process, and the bonding needs to be carried out under high pressure (50MPa). In the aforementioned joining methods, excessively high joining temperatures and prolonged heat and pressure holding not only risk damaging the base material but also limit the joining of complex-shaped silicon carbide-based ceramics. Furthermore, they increase energy consumption during production, severely restricting the widespread application of silicon carbide ceramics and their composites. Therefore, reducing the temperature, time, and pressure during the preparation of silicon carbide-based ceramics has become a pressing technical problem in this field. Summary of the Invention

[0005] The purpose of this invention is to provide a high-temperature brazing filler metal for silicon carbide-based ceramic connections, its preparation method, and its application. The high-temperature brazing filler metal provided by this invention requires low temperature and short time in the process of preparing silicon carbide-based ceramic connectors, and does not require the application of additional pressure.

[0006] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0007] This invention provides a high-temperature brazing filler metal for silicon carbide-based ceramic bonding, comprising, by mass percentage, 2-15% metal powder and the balance Ti-Si powder, wherein the metal powder includes Fe powder, Al powder, Ni powder, Cr powder or Co powder.

[0008] Preferably, the mass ratio of Ti to Si in the Ti-Si powder is 1:(0.35~1.5).

[0009] Preferably, the particle size of the metal powder is 5–15 μm.

[0010] Preferably, the particle size of the Ti-Si powder is 5–15 μm.

[0011] The present invention provides a method for preparing the high-temperature brazing filler metal for silicon carbide-based ceramic bonding as described in the above technical solution, comprising: mixing metal powder and Ti-Si powder and then sequentially ball milling and drying to obtain the high-temperature brazing filler metal.

[0012] Preferably, the grinding balls used in the ball mill are agate grinding balls, the grinding medium used in the ball mill is ethanol, the rotation speed of the ball mill is 200-300 r / min, and the grinding time is 3-5 h.

[0013] This invention provides the application of the high-temperature brazing filler metal for silicon carbide-based ceramic connections described in the above-described technical solution or the high-temperature brazing filler metal for silicon carbide-based ceramic connections prepared by the preparation method described in the above-described technical solution in the brazing of silicon carbide-based ceramics.

[0014] Preferably, the application includes the following steps:

[0015] (1) Mix the high-temperature brazing filler metal and binder for connecting silicon carbide-based ceramics to obtain a paste-like high-temperature brazing filler metal;

[0016] (2) Apply the paste-like high-temperature solder obtained in step (1) to the surface of the silicon carbide-based ceramic component to be soldered, and then assemble the silicon carbide-based ceramic component to obtain the component to be soldered; or, first assemble the silicon carbide-based ceramic component, and then apply the paste-like high-temperature solder to the overlap of the silicon carbide-based ceramic component to obtain the component to be soldered.

[0017] (3) Vacuum brazing is performed on the components to be welded obtained in step (2) to obtain silicon carbide-based ceramic connectors.

[0018] Preferably, in step (1), the mass ratio of high-temperature brazing filler metal and adhesive for silicon carbide-based ceramic bonding is (3-5):1.

[0019] Preferably, the process parameters for vacuum brazing in step (3) include: at 1×10 -4 ~1×10 -1 In a vacuum atmosphere of Pa, the temperature is first increased to 300–500℃ at a rate of 8–12℃ / min and held for 5–15 min; then increased to 1000–1050℃ at a rate of 15–25℃ / min and held for 5–15 min; then increased to 1200–1500℃ at a rate of 8–12℃ / min and held for 5–40 min; finally, the furnace is cooled.

[0020] This invention provides a high-temperature brazing filler metal for joining silicon carbide-based ceramics. By mass percentage, it comprises 2-15% metal powder and the balance Ti-Si powder, wherein the metal powder includes Fe powder, Al powder, Ni powder, Cr powder, or Co powder. The high-temperature brazing filler metal provided by this invention, by adding a small amount of metal elements to the Ti-Si filler metal, can lower the melting point of the filler metal, shorten the joining time, and promote in-situ reaction between the liquid filler metal and the silicon carbide-based ceramic to generate a high-strength Ti3SiC2MAX phase for joining the base material. Simultaneously, because the filler metal is liquid at high temperatures, pressure is not required to achieve weld densification, thereby improving the mechanical properties of the joint at room temperature and high temperature (1300℃). The results of the embodiments show that the weld of the silicon carbide-based ceramic connector obtained by vacuum brazing with the high-temperature brazing filler metal provided by the present invention is composed of TiSi2 phase, Ti3SiC2MAX phase and metal silicide. The room temperature shear strength of the silicon carbide-based ceramic connector is 90-120 MPa, and the shear strength at 1300℃ is 39-55 MPa. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the present invention, which involves first coating a paste-like high-temperature solder and then assembling a silicon carbide-based ceramic component.

[0022] Figure 2 This is a schematic diagram of the present invention, which first assembles a silicon carbide-based ceramic component and then coats it with a paste-like high-temperature brazing filler metal;

[0023] Figure 3 This is a SEM image of the brazed joint of the silicon carbide-based ceramic connector obtained in Application Example 1 of the present invention;

[0024] Figure 4 The image shows the XRD pattern of the brazed joint of the silicon carbide-based ceramic connector obtained in Application Example 1 of the present invention. Detailed Implementation

[0025] This invention provides a high-temperature brazing filler metal for silicon carbide-based ceramic bonding, comprising, by mass percentage, 2-15% metal powder and the balance Ti-Si powder, wherein the metal powder includes Fe powder, Al powder, Ni powder, Cr powder or Co powder.

[0026] The high-temperature brazing filler metal for silicon carbide-based ceramic bonding provided by this invention comprises 2-15% metal powder, preferably 5-10%, and more preferably 6-8%, by weight percentage. In this invention, the metal powder includes Fe powder, Al powder, Ni powder, Cr powder, or Co powder; the particle size of the metal powder is preferably 5-15 μm; and the purity of the metal powder is preferably ≥99.9 wt.%. This invention does not impose any specific limitations on the source of the metal powder; commercially available products well-known to those skilled in the art can be used. This invention reduces the brazing temperature (≤1500℃) and prevents silicon carbide fibers from being damaged at high temperatures by adding a small amount of metal elements (Fe, Al, Ni, Cr, or Co) to Ti-Si high-temperature brazing filler metal (the operating temperature of third-generation SiC fibers is ≤1450℃). At the same time, the high-temperature liquid phase formed by the metal powder can promote the in-situ generation of the MAX phase reaction, shortening the connection time required for high-temperature brazing (≤40min). By controlling the amount of metal powder in the high-temperature brazing filler metal, it is possible to avoid both insufficient metal powder, which would result in an insignificant improvement effect, and excessive metal powder, which would affect the welding performance.

[0027] The high-temperature solder for silicon carbide-based ceramic bonding provided by this invention comprises, by weight percentage, the balance being Ti-Si powder. In this invention, the mass ratio of Ti to Si in the Ti-Si powder is preferably 1:(0.35–1.5), more preferably 1:(0.5–1.3), and even more preferably 1:(0.6–1.2); the particle size of the Ti-Si powder is preferably 5–15 μm; and the purity of the Ti-Si powder is preferably ≥99.9 wt.%. This invention does not specifically limit the source of the Ti-Si powder; commercially available products well known to those skilled in the art or Ti-Si powder prepared using preparation processes well known to those skilled in the art that meet the above requirements are acceptable. In this invention, the Ti-Si powder serves as the matrix material for the high-temperature solder.

[0028] The high-temperature brazing filler metal for silicon carbide-based ceramic bonding provided by this invention is a high-temperature brazing filler metal configured by adding a small amount of metal elements to Ti-Si filler metal. This can lower the melting point of the filler metal, shorten the bonding time, and promote the in-situ reaction between the liquid filler metal and silicon carbide-based ceramic to generate a high-strength Ti3SiC2MAX phase to bond the base material. At the same time, since the filler metal is liquid at high temperature, the weld densification can be achieved without the use of pressure, thereby improving the mechanical properties of the connector at room temperature and high temperature (1300℃).

[0029] The present invention provides a method for preparing the high-temperature brazing filler metal for silicon carbide-based ceramic bonding as described in the above technical solution, comprising: mixing metal powder and Ti-Si powder and then sequentially ball milling and drying to obtain the high-temperature brazing filler metal.

[0030] In this invention, the grinding balls used in the ball milling are preferably agate grinding balls; the grinding media used in the ball milling are preferably ethanol; the ball milling speed is preferably 200-300 r / min, more preferably 220-280 r / min, and even more preferably 250 r / min; the ball milling time is preferably 3-5 h, more preferably 4 h. This invention does not impose any special limitations on the ball-to-material ratio and the amount of grinding media used in the ball milling process; these can be determined based on the technical knowledge of those skilled in the art. By controlling the ball milling parameters, this invention enables the metal powder and Ti-Si powder to be thoroughly and uniformly mixed.

[0031] In this invention, the drying temperature is preferably 60–80°C, more preferably 70°C; the drying time is preferably 30–120 min, more preferably 60 min; and the drying is preferably carried out in a forced-air drying oven. This invention removes the ball milling media through drying, obtaining a dry, high-temperature brazing filler metal.

[0032] The method for preparing high-temperature brazing filler metal for silicon carbide-based ceramic connections provided by this invention is simple, requires little equipment, has a short preparation time, and is suitable for large-scale promotion.

[0033] The present invention also provides the application of the high-temperature brazing filler metal for silicon carbide-based ceramic connections described in the above technical solution or the high-temperature brazing filler metal for silicon carbide-based ceramic connections prepared by the preparation method described in the above technical solution in the brazing of silicon carbide-based ceramics.

[0034] In this invention, the application of the high-temperature brazing filler metal for silicon carbide-based ceramic bonding in silicon carbide-based ceramic brazing preferably includes the following steps:

[0035] (1) The silicon carbide-based ceramic bonding high-temperature solder and binder are mixed to obtain a paste-like high-temperature solder;

[0036] (2) Apply the paste-like high-temperature solder obtained in step (1) to the surface of the silicon carbide-based ceramic component to be soldered, and then assemble the silicon carbide-based ceramic component to obtain the component to be soldered; or, first assemble the silicon carbide-based ceramic component, and then apply the paste-like high-temperature solder to the overlap of the silicon carbide-based ceramic component to obtain the component to be soldered.

[0037] (3) Vacuum brazing is performed on the components to be welded obtained in step (2) to obtain silicon carbide-based ceramic connectors.

[0038] The present invention preferably mixes the silicon carbide-based ceramic bonding high-temperature solder and binder to obtain a paste-like high-temperature solder.

[0039] In this invention, the binder is preferably polyvinyl butyral; the mass ratio of the high-temperature solder for connecting silicon carbide-based ceramics to the binder is preferably (3-5):1, more preferably 4:1. This invention does not impose any particular limitation on the specific method of mixing the high-temperature solder and binder for connecting silicon carbide-based ceramics; any method well-known to those skilled in the art that ensures uniform mixing is acceptable. By mixing the high-temperature solder and binder, this invention ensures that the high-temperature solder bonds well to the silicon carbide-based ceramic component, thereby facilitating subsequent vacuum brazing.

[0040] In one technical solution of the present invention, after obtaining the paste-like high-temperature solder, it is preferable to coat the paste-like high-temperature solder onto the surface of the silicon carbide-based ceramic component to be soldered, and then assemble the silicon carbide-based ceramic component to obtain the component to be soldered. A schematic diagram of the present invention, showing the process of first coating the paste-like high-temperature solder and then assembling the silicon carbide-based ceramic component, is shown below. Figure 1 As shown.

[0041] In this invention, the silicon carbide-based ceramic component preferably undergoes surface pretreatment before use; the surface pretreatment preferably involves first grinding with a diamond grinding wheel to 1500 grit, followed by ultrasonic cleaning with ethanol for 10 minutes. This invention does not impose any specific limitations on the power used in the ultrasonic cleaning; it can be determined based on the technical knowledge of those skilled in the art. By pretreating the silicon carbide-based ceramic component, this invention can remove stains and oxides from its surface.

[0042] In this invention, the coating thickness of the paste-like high-temperature solder on the surface of the silicon carbide-based ceramic component to be soldered is preferably 50-100 μm.

[0043] In another technical solution of the present invention, after obtaining the paste-like high-temperature solder, it is preferable to first assemble the silicon carbide-based ceramic component, and then apply the paste-like high-temperature solder to the overlap of the silicon carbide-based ceramic component to obtain the component to be soldered. A schematic diagram of the present invention, showing the assembly of the silicon carbide-based ceramic component followed by the application of the paste-like high-temperature solder, is shown below. Figure 2 As shown.

[0044] In this invention, the silicon carbide-based ceramic component is preferably subjected to surface pretreatment before use; the operation of the surface pretreatment is preferably the same as the aforementioned surface pretreatment operation, and will not be repeated here.

[0045] In this invention, the coating thickness of the paste-like high-temperature solder at the overlap of the silicon carbide-based ceramic component is preferably 2 to 3 mm.

[0046] After obtaining the component to be welded, the present invention preferably performs vacuum brazing on the component to be welded to obtain a silicon carbide-based ceramic connector.

[0047] In this invention, the vacuum brazing is preferably performed in a vacuum brazing furnace. This invention does not impose any specific limitations on the model or source of the vacuum brazing furnace; any commercially available product well-known to those skilled in the art can be used.

[0048] In this invention, the preferred process parameters for vacuum brazing include: at 1×10 -4 ~1×10 -1 In a vacuum atmosphere of Pa, the temperature is first increased to 300–500°C at a rate of 8–12°C / min and held for 5–15 min, then increased to 1000–1050°C at a rate of 15–25°C / min and held for 5–15 min, then increased to 1200–1500°C at a rate of 8–12°C / min and held for 5–40 min, and finally cooled in the furnace; more preferably, in a vacuum atmosphere of 1×10 Pa, the temperature is increased to 300–500°C and held for 5–40 min, then increased to 1200–1500°C and held for 5–40 min, and finally cooled in the furnace; -3 ~1×10 -2 In a vacuum atmosphere of Pa, the temperature is first increased to 300–500°C at a rate of 10°C / min and held for 10 min, then increased to 1000°C at a rate of 20°C / min and held for 10 min, then increased to 1200–1400°C at a rate of 10°C / min and held for 10–30 min, and finally cooled with the furnace; a further preferred method is to use a vacuum atmosphere of 1×10 Pa. -3 ~1×10 -2 In a vacuum atmosphere of Pa, the temperature is first increased to 350–450°C at a rate of 10°C / min and held for 10 min, then increased to 1000°C at a rate of 20°C / min and held for 10 min, then increased to 1200–1300°C at a rate of 10°C / min and held for 10–30 min, and finally cooled with the furnace. This invention controls the process parameters of vacuum brazing. Holding at a lower temperature allows the organic binder in the brazing filler metal to volatilize and purifies the furnace atmosphere. The subsequent increase to approximately 1000°C ensures uniform heating of the workpiece. Finally, heating at approximately 1200°C causes an in-situ reaction between the high-temperature brazing filler metal and the silicon carbide-based ceramic, generating MAX-linked silicon carbide-based ceramic. This allows for brazing of silicon carbide-based ceramics at a relatively low temperature.

[0049] The high-temperature brazing filler metal provided by this invention requires low temperature and short holding time during the preparation of silicon carbide-based ceramic connectors, and does not require the application of additional pressure.

[0050] The technical solutions of this invention will be clearly and completely described below with reference to the embodiments thereof. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0051] Example 1

[0052] A high-temperature brazing filler metal for silicon carbide-based ceramic bonding, comprising, by mass percentage: 8% metal powder and the balance Ti-Si powder, wherein the mass ratio of Ti to Si in the Ti-Si powder is 1:1.2;

[0053] The metal powder is Fe powder with a particle size of 5-15 μm and a purity of ≥99.9 wt.%; the Ti-Si powder has a particle size of 5-15 μm and a purity of ≥99.9 wt.%.

[0054] The preparation method of the high-temperature brazing filler metal for silicon carbide-based ceramic bonding is as follows: metal powder and Ti-Si powder are mixed and then ball-milled and dried sequentially to obtain the high-temperature brazing filler metal; the grinding balls used for ball milling are agate grinding balls; the grinding medium used for ball milling is ethanol; the ball milling speed is 300 r / min and the ball milling time is 4 h; the drying temperature is 70 ℃ and the drying time is 60 min.

[0055] Application Example 1

[0056] The application of the high-temperature brazing filler metal for silicon carbide-based ceramic bonding described in Example 1 in the brazing of silicon carbide-based ceramics specifically includes the following steps:

[0057] (1) The high-temperature solder for connecting silicon carbide-based ceramics and the binder are mixed to obtain a paste-like high-temperature solder; the binder is polyvinyl butyral; the mass ratio of the high-temperature solder for connecting silicon carbide-based ceramics to the binder is 4:1;

[0058] (2) First, the silicon carbide-based ceramic component is pretreated on the surface. Then, the paste-like high-temperature solder obtained in step (1) is coated on the surface of the silicon carbide-based ceramic component to be soldered. Finally, the silicon carbide-based ceramic component is assembled to obtain the component to be soldered. The surface pretreatment is specifically to first grind it to 1500 mesh with a diamond grinding wheel, and then clean it with ethanol ultrasonically for 10 minutes. The coating thickness of the paste-like high-temperature solder on the surface of the silicon carbide-based ceramic component to be soldered is 60 μm.

[0059] (3) The components to be welded obtained in step (2) are vacuum brazed in a vacuum brazing furnace to obtain silicon carbide-based ceramic connectors; the process parameters for the vacuum brazing are: at 2×10 -3 In a vacuum atmosphere of Pa, the temperature is first increased to 500℃ at a rate of 10℃ / min and held for 10 min, then increased to 1000℃ at a rate of 20℃ / min and held for 10 min, then increased to 1400℃ at a rate of 10℃ / min and held for 10 min, and finally cooled with the furnace.

[0060] The brazed joints of the silicon carbide-based ceramic connectors obtained in Example 1 were observed and analyzed using scanning electron microscopy. The SEM morphology images of the brazed joints of the silicon carbide-based ceramic connectors are shown below. Figure 3 As shown, analysis revealed that the weld seam of the silicon carbide-based ceramic connector consists of 10% TiSi2 phase, 85% Ti3SiC2MAX phase, and 5% Fe-Si phase.

[0061] The brazed joints of the silicon carbide-based ceramic connectors obtained in Example 1 were observed using an X-ray diffractometer. The XRD pattern of the brazed joints of the silicon carbide-based ceramic connectors is shown below. Figure 4 As shown. By Figure 3 and Figure 4 It can be seen that the weld phases are mainly composed of TiSi2 phase, Ti3SiC2 phase and Fe-Si phase.

[0062] The shear strength of the silicon carbide-based ceramic connector prepared according to Example 1 was tested using a universal testing machine. The test method was single lap offset shear. The test results showed that the room temperature shear strength of the silicon carbide-based ceramic connector was 115.37 MPa, and the shear strength at 1300℃ was 51.61 MPa.

[0063] Example 2

[0064] A high-temperature brazing filler metal for silicon carbide-based ceramic bonding, comprising, by mass percentage: 2% metal powder and the balance Ti-Si powder, wherein the mass ratio of Ti to Si in the Ti-Si powder is 1:1.2;

[0065] The metal powder is Ni powder with a particle size of 5-15 μm and a purity of ≥99.9 wt.%; the Ti-Si powder has a particle size of 5-15 μm and a purity of ≥99.9 wt.%.

[0066] The preparation method of the high-temperature brazing filler metal for silicon carbide-based ceramic bonding is as follows: metal powder and Ti-Si powder are mixed and then ball-milled and dried sequentially to obtain the high-temperature brazing filler metal; the grinding balls used for ball milling are agate grinding balls; the grinding medium used for ball milling is ethanol; the ball milling speed is 250 r / min, and the ball milling time is 4 h; the drying temperature is 70 ℃, and the drying time is 60 min.

[0067] Application Example 2

[0068] The application of the high-temperature brazing filler metal for silicon carbide-based ceramic bonding described in Example 2 in the brazing of silicon carbide-based ceramics specifically includes the following steps:

[0069] (1) The high-temperature solder for connecting silicon carbide-based ceramics and the binder are mixed to obtain a paste-like high-temperature solder; the binder is polyvinyl butyral; the mass ratio of the high-temperature solder for connecting silicon carbide-based ceramics to the binder is 4:1;

[0070] (2) First, the silicon carbide-based ceramic component is pretreated on the surface. Then, the paste-like high-temperature solder obtained in step (1) is coated on the surface of the silicon carbide-based ceramic component to be soldered. Finally, the silicon carbide-based ceramic component is assembled to obtain the component to be soldered. The surface pretreatment is specifically to first grind it to 1500 mesh with a diamond grinding wheel, and then clean it with ethanol ultrasonically for 10 minutes. The coating thickness of the paste-like high-temperature solder on the surface of the silicon carbide-based ceramic component to be soldered is 80 μm.

[0071] (3) The components to be welded obtained in step (2) are vacuum brazed in a vacuum brazing furnace to obtain silicon carbide-based ceramic connectors; the process parameters for the vacuum brazing are: at 2×10 -3 In a vacuum atmosphere of Pa, the temperature is first increased to 450℃ at a rate of 10℃ / min and held for 10 min, then increased to 1000℃ at a rate of 20℃ / min and held for 10 min, then increased to 1300℃ at a rate of 10℃ / min and held for 30 min, and finally cooled with the furnace.

[0072] The weld microstructure of the silicon carbide-based ceramic connector prepared using scanning electron microscopy corresponding to Example 2 was analyzed. The results showed that the weld of the silicon carbide-based ceramic connector consisted of 27% TiSi2 phase, 70% Ti3SiC2MAX phase and 3% Ni-Si phase.

[0073] The shear strength of the silicon carbide-based ceramic connector prepared using a universal testing machine in accordance with Example 2 was tested using a single lap offset shear test. The results showed that the room temperature shear strength of the silicon carbide-based ceramic connector was 90.55 MPa, and the shear strength at 1300℃ was 43.25 MPa.

[0074] Example 3

[0075] A high-temperature brazing filler metal for silicon carbide-based ceramic bonding, comprising, by mass percentage: 15% metal powder and the balance Ti-Si powder, wherein the mass ratio of Ti to Si in the Ti-Si powder is 1:1.5;

[0076] The metal powder is Al powder with a particle size of 5-15 μm and a purity of ≥99.9 wt.%; the Ti-Si powder has a particle size of 5-15 μm and a purity of ≥99.9 wt.%.

[0077] The preparation method of the high-temperature brazing filler metal for silicon carbide-based ceramic bonding is as follows: metal powder and Ti-Si powder are mixed and then ball-milled and dried sequentially to obtain the high-temperature brazing filler metal; the grinding balls used for ball milling are agate grinding balls; the grinding medium used for ball milling is ethanol; the ball milling speed is 250 r / min, and the ball milling time is 4 h; the drying temperature is 70 ℃, and the drying time is 60 min.

[0078] Application Example 3

[0079] The application of the high-temperature brazing filler metal for silicon carbide-based ceramic bonding described in Example 3 in the brazing of silicon carbide-based ceramics specifically includes the following steps:

[0080] (1) The high-temperature solder for connecting silicon carbide-based ceramics and the binder are mixed to obtain a paste-like high-temperature solder; the binder is polyvinyl butyral; the mass ratio of the high-temperature solder for connecting silicon carbide-based ceramics to the binder is 4:1;

[0081] (2) First, the silicon carbide-based ceramic component is pretreated on the surface, then the silicon carbide-based ceramic component is assembled, and finally the paste-like high-temperature solder obtained in step (1) is coated on the overlap of the silicon carbide-based ceramic component to obtain the component to be soldered; the surface pretreatment is to first grind to 1500 mesh with a diamond grinding wheel, and then clean with ethanol ultrasonically for 10 minutes; the coating thickness of the paste-like high-temperature solder on the surface of the silicon carbide-based ceramic component to be soldered is 3 mm;

[0082] (3) The components to be welded obtained in step (2) are vacuum brazed in a vacuum brazing furnace to obtain silicon carbide-based ceramic connectors; the process parameters for the vacuum brazing are: at 2×10 -3 In a vacuum atmosphere of Pa, the temperature is first increased to 300℃ at a rate of 10℃ / min and held for 10 min, then increased to 1000℃ at a rate of 20℃ / min and held for 10 min, then increased to 1200℃ at a rate of 10℃ / min and held for 40 min, and finally cooled with the furnace.

[0083] The weld microstructure of the silicon carbide-based ceramic connector prepared in Example 3 was analyzed using scanning electron microscopy. The results showed that the weld of the silicon carbide-based ceramic connector consisted of 40% TiSi2 phase, 52% Ti3SiC2MAX phase and 8% Al-Si phase.

[0084] The shear strength of the silicon carbide-based ceramic connector prepared using a universal testing machine in accordance with Example 3 was tested using a single lap offset shear test. The results showed that the room temperature shear strength of the silicon carbide-based ceramic connector was 96.35 MPa, and the shear strength at 1300℃ was 30.87 MPa.

[0085] Example 4

[0086] A high-temperature brazing filler metal for silicon carbide-based ceramic bonding, comprising, by mass percentage: 10% metal powder and the balance Ti-Si powder, wherein the mass ratio of Ti to Si in the Ti-Si powder is 1:1.5;

[0087] The metal powder is Co powder with a particle size of 5-15 μm and a purity of ≥99.9 wt.%; the Ti-Si powder has a particle size of 5-15 μm and a purity of ≥99.9 wt.%.

[0088] The preparation method of the high-temperature brazing filler metal for silicon carbide-based ceramic bonding is as follows: metal powder and Ti-Si powder are mixed and then ball-milled and dried sequentially to obtain the high-temperature brazing filler metal; the grinding balls used for ball milling are agate grinding balls; the grinding medium used for ball milling is ethanol; the ball milling speed is 250 r / min, and the ball milling time is 4 h; the drying temperature is 70 ℃, and the drying time is 60 min.

[0089] Application Example 4

[0090] The application of the high-temperature brazing filler metal for silicon carbide-based ceramic bonding described in Example 4 in the brazing of silicon carbide-based ceramics specifically includes the following steps:

[0091] (1) The high-temperature solder for connecting silicon carbide-based ceramics and the binder are mixed to obtain a paste-like high-temperature solder; the binder is polyvinyl butyral; the mass ratio of the high-temperature solder for connecting silicon carbide-based ceramics to the binder is 4:1;

[0092] (2) First, the silicon carbide-based ceramic component is pretreated on the surface. Then, the paste-like high-temperature solder obtained in step (1) is coated on the surface of the silicon carbide-based ceramic component to be soldered. Finally, the silicon carbide-based ceramic component is assembled to obtain the component to be soldered. The surface pretreatment is specifically to first grind it to 1500 mesh with a diamond grinding wheel, and then clean it with ethanol ultrasonically for 10 minutes. The coating thickness of the paste-like high-temperature solder on the surface of the silicon carbide-based ceramic component to be soldered is 90 μm.

[0093] (3) The components to be welded obtained in step (2) are vacuum brazed in a vacuum brazing furnace to obtain silicon carbide-based ceramic connectors; the process parameters for the vacuum brazing are: at 2×10 -3 In a vacuum atmosphere of Pa, the temperature is first increased to 450℃ at a rate of 10℃ / min and held for 10 min, then increased to 1000℃ at a rate of 20℃ / min and held for 10 min, then increased to 1500℃ at a rate of 10℃ / min and held for 5 min, and finally cooled with the furnace.

[0094] The weld microstructure of the silicon carbide-based ceramic connector prepared according to Example 4 was analyzed using scanning electron microscopy. The results showed that the weld of the silicon carbide-based ceramic connector was composed of 5% TiSi2 phase, 90% Ti3SiC2MAX phase and 5% Co-Si phase.

[0095] The shear strength of the silicon carbide-based ceramic connector prepared using a universal testing machine in accordance with Example 4 was tested using a single lap offset shear test. The results showed that the room temperature shear strength of the silicon carbide-based ceramic connector was 101.28 MPa, and the shear strength at 1300℃ was 43.27 MPa.

[0096] Example 5

[0097] A high-temperature brazing filler metal for silicon carbide-based ceramic bonding, comprising by mass percentage: 5% metal powder and the balance Ti-Si powder, wherein the mass ratio of Ti to Si in the Ti-Si powder is 1:1;

[0098] The metal powder is Cr powder with a particle size of 5-15 μm and a purity of ≥99.9 wt.%; the Ti-Si powder has a particle size of 5-15 μm and a purity of ≥99.9 wt.%.

[0099] The preparation method of the high-temperature brazing filler metal for silicon carbide-based ceramic bonding is as follows: metal powder and Ti-Si powder are mixed and then ball-milled and dried sequentially to obtain the high-temperature brazing filler metal; the grinding balls used for ball milling are agate grinding balls; the grinding medium used for ball milling is ethanol; the ball milling speed is 250 r / min, and the ball milling time is 4 h; the drying temperature is 70 ℃, and the drying time is 60 min.

[0100] Application Example 5

[0101] The application of the high-temperature brazing filler metal for silicon carbide-based ceramic bonding described in Example 5 in the brazing of silicon carbide-based ceramics specifically includes the following steps:

[0102] (1) The high-temperature solder for connecting silicon carbide-based ceramics and the binder are mixed to obtain a paste-like high-temperature solder; the binder is polyvinyl butyral; the mass ratio of the high-temperature solder for connecting silicon carbide-based ceramics to the binder is 4:1;

[0103] (2) First, the silicon carbide-based ceramic component is pretreated on the surface. Then, the paste-like high-temperature solder obtained in step (1) is coated on the surface of the silicon carbide-based ceramic component to be soldered. Finally, the silicon carbide-based ceramic component is assembled to obtain the component to be soldered. The surface pretreatment is specifically to first grind it to 1500 mesh with a diamond grinding wheel, and then clean it with ethanol ultrasonically for 10 minutes. The coating thickness of the paste-like high-temperature solder on the surface of the silicon carbide-based ceramic component to be soldered is 50 μm.

[0104] (3) The components to be welded obtained in step (2) are vacuum brazed in a vacuum brazing furnace to obtain silicon carbide-based ceramic connectors; the process parameters for the vacuum brazing are: at 2×10 -3 In a vacuum atmosphere of Pa, the temperature is first increased to 450℃ at a rate of 10℃ / min and held for 10min, then increased to 1000℃ at a rate of 20℃ / min and held for 10min, then increased to 1400℃ at a rate of 10℃ / min and held for 10min, and finally cooled with the furnace.

[0105] The weld microstructure of the silicon carbide-based ceramic connector prepared using scanning electron microscopy corresponding to Example 5 was analyzed. The results showed that the weld of the silicon carbide-based ceramic connector consisted of 17% TiSi2 phase, 80% Ti3SiC2MAX phase and 3% Cr-Si phase.

[0106] The shear strength of the silicon carbide-based ceramic connector prepared using a universal testing machine in accordance with Example 5 was tested using a single lap offset shear test. The results showed that the room temperature shear strength of the silicon carbide-based ceramic connector was 97.65 MPa, and the shear strength at 1300℃ was 39.63 MPa.

[0107] Comparative Example 1

[0108] A high-temperature solder is a Ti-Si powder, wherein the mass ratio of Ti to Si in the Ti-Si powder is 1:1.2, the melting point of the Ti-Si powder is about 1530℃, the particle size of the Ti-Si powder is 5-15μm, and the purity of the Ti-Si powder is ≥99.9wt.%.

[0109] The preparation method of the high-temperature solder is as follows: Ti-Si powder is ball-milled and dried sequentially to obtain the high-temperature solder; the grinding balls used for ball milling are agate grinding balls; the grinding medium used for ball milling is ethanol; the ball milling speed is 250 r / min, and the ball milling time is 4 h; the drying temperature is 70 ℃, and the drying time is 60 min.

[0110] Comparative Application Example 1

[0111] The application of the high-temperature brazing filler metal described in Comparative Example 1 in the brazing of silicon carbide-based ceramics specifically includes the following steps:

[0112] (1) The high-temperature solder and the binder are mixed to obtain a paste-like high-temperature solder; the binder is polyvinyl butyral; the mass ratio of the high-temperature solder to the binder is 4:1.

[0113] (2) First, the silicon carbide-based ceramic component is pretreated on the surface. Then, the paste-like high-temperature solder obtained in step (1) is coated on the surface of the silicon carbide-based ceramic component to be soldered. Finally, the silicon carbide-based ceramic component is assembled to obtain the component to be soldered. The surface pretreatment is specifically to first grind it to 1500 mesh with a diamond grinding wheel, and then clean it with ethanol ultrasonically for 10 minutes. The coating thickness of the paste-like high-temperature solder on the surface of the silicon carbide-based ceramic component to be soldered is 100 μm.

[0114] (3) The components to be welded obtained in step (2) are vacuum brazed in a vacuum brazing furnace to obtain silicon carbide-based ceramic connectors; the process parameters for the vacuum brazing are: at 2×10 -3 In a vacuum atmosphere of Pa, the temperature is first increased to 450℃ at a rate of 10℃ / min and held for 10 min, then increased to 1000℃ at a rate of 20℃ / min and held for 10 min, then increased to 1500℃ at a rate of 10℃ / min and held for 40 min, and finally cooled with the furnace.

[0115] The weld microstructure of the silicon carbide-based ceramic connector prepared in Comparative Application Example 1 was analyzed using scanning electron microscopy. The results showed that the high-temperature brazing filler metal in the weld did not melt, and a good connection could not be achieved.

[0116] The shear strength of the silicon carbide-based ceramic connector prepared in Comparative Application Example 1 was tested using a universal testing machine. The test method was single lap offset shear. The room temperature shear strength of the silicon carbide-based ceramic connector was only 2 MPa.

[0117] By comparing Application Examples 1-5 with Comparative Application Example 1, it can be seen that when the addition of metal powder is omitted, even after long-term high-temperature brazing, the high-temperature brazing alloy cannot form a weld with good performance. However, when a small amount of metal powder is added to the high-temperature brazing alloy, not only can the temperature and time during vacuum brazing be reduced, but a weld with good microstructure and excellent mechanical properties can also be formed. This indicates that the high-temperature brazing alloy prepared by adding a small amount of metal elements to Ti-Si brazing alloy can reduce the melting point of the brazing alloy, shorten the connection time, and promote the in-situ reaction between the liquid brazing alloy and silicon carbide-based ceramics to generate a high-strength Ti3SiC2MAX phase to connect the base material.

[0118] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A high-temperature brazing filler metal for silicon carbide-based ceramic bonding, comprising, by weight percentage, 2-15% metal powder and the balance Ti-Si powder, wherein the metal powder is one of Fe powder, Al powder, Ni powder, Cr powder or Co powder; The mass ratio of Ti to Si in the Ti-Si powder is 1:(0.35~1.5). The particle size of the metal powder is 5~15μm; The method for preparing the high-temperature solder for silicon carbide-based ceramic bonding includes: Metal powder and Ti-Si powder are mixed and then ball-milled and dried sequentially to obtain high-temperature brazing filler metal.

2. The high-temperature brazing filler metal for silicon carbide-based ceramic bonding according to claim 1, characterized in that, The Ti-Si powder has a particle size of 5~15μm.

3. A method for preparing the high-temperature solder for silicon carbide-based ceramic bonding as described in any one of claims 1 to 2, comprising: Metal powder and Ti-Si powder are mixed and then ball-milled and dried sequentially to obtain high-temperature brazing filler metal.

4. The preparation method according to claim 3, characterized in that, The grinding balls used in the ball mill are agate grinding balls, the grinding medium used in the ball mill is ethanol, the rotation speed of the ball mill is 200~300 r / min, and the grinding time is 3~5 h.

5. The application of the high-temperature brazing filler metal for silicon carbide-based ceramic bonding as described in any one of claims 1 to 2 or the high-temperature brazing filler metal for silicon carbide-based ceramic bonding prepared by the preparation method described in any one of claims 3 to 4 in the brazing of silicon carbide-based ceramics; The application includes the following steps: (1) Mix the high-temperature solder for connecting silicon carbide-based ceramics with the binder to obtain a paste-like high-temperature solder; (2) Apply the paste-like high-temperature solder obtained in step (1) to the surface of the silicon carbide-based ceramic component to be soldered, and then assemble the silicon carbide-based ceramic component to obtain the component to be soldered; or, first assemble the silicon carbide-based ceramic component, and then apply the paste-like high-temperature solder to the overlap of the silicon carbide-based ceramic component to obtain the component to be soldered. (3) Vacuum brazing is performed on the components to be welded obtained in step (2) to obtain silicon carbide-based ceramic connectors; The process parameters for vacuum brazing in step (3) include: at 1×10 -4 ~1×10 -1 In a vacuum atmosphere of Pa, the temperature is first increased to 300-500℃ at a rate of 8-12℃ / min and held for 5-15 min; then increased to 1000-1050℃ at a rate of 15-25℃ / min and held for 5-15 min; then increased to 1200-1500℃ at a rate of 8-12℃ / min and held for 5-40 min; finally, the furnace is cooled.

6. The application according to claim 5, characterized in that, In step (1), the mass ratio of high-temperature brazing filler metal and adhesive for silicon carbide-based ceramic connection is (3~5):1.

Images