Method for laser-assisted silicon reaction infiltration connection of silicon carbide ceramic and composite material thereof

Abstract

The invention relates to a method for laser-assisted silicon reaction infiltration connection of silicon carbide ceramic and a composite material thereof. The method for connecting the silicon carbide ceramic and the composite material thereof through laser-assisted silicon reaction infiltration comprises the following steps: (1) coating a carbon-containing suspension on the surface of a silicon carbide part, drying, and then carrying out laser cladding treatment on the surface of the silicon carbide part to obtain a to-be-connected silicon carbide part with a laser-cladded porous carbon layer on the surface; and (2) butting the two to-be-connected silicon carbide parts with the laser-clad porous carbon layers on the surfaces, placing silicon particles at the connection interface, and performing heat treatment to complete laser-assisted silicon reaction infiltration connection of the silicon carbide ceramic and the composite material thereof.

Description

Technical Field

[0001] The present invention belongs to the field of silicon carbide ceramic connection, and in particular relates to a method for connecting silicon carbide ceramic and its composite material by laser-assisted silicon reactive infiltration. Background Art

[0002] Silicon carbide ceramics and their composites have become key materials in high-end manufacturing fields such as aerospace, semiconductor manufacturing, and new energy vehicles due to their high hardness, excellent mechanical and thermophysical properties, and outstanding chemical inertness. However, due to the inherent brittleness of silicon carbide ceramics, their machining faces significant technical bottlenecks. For example, traditional cutting processes are prone to edge chipping defects, and the overall forming of special-shaped or large-sized components faces low yield and high cost. Silicon carbide ceramic connection technology can achieve functional integration from small units to complex / large topological configurations, becoming a key technical path to break through the limitations of single-component forming, reduce the cost of the entire life cycle, and expand applications.

[0003] Numerous silicon carbide ceramic joining technologies have been developed, including direct diffusion bonding, brazing, precursor bonding, glass bonding, and reaction bonding. Reaction bonding involves preparing a porous carbon layer on the bonding surface, which then reacts with silicon at high temperatures to form silicon carbide. This method offers advantages such as consistent composition between the bonding layer and the substrate, no mismatch in thermal expansion coefficients, and a high operating temperature, making it an ideal joining method for silicon carbide ceramics and their composites.

[0004] However, currently used reactive joining methods suffer from issues such as high levels of free silicon, long joining cycles, and difficulty controlling the composition and thickness of the joining layer, all of which affect the performance and precision of the connected components. Furthermore, in joining large components, due to the small weld seams, capillary forces prevent the silicon melt from fully infiltrating and filling the microchannels, resulting in incomplete reactions and a reduction in strength and performance. Therefore, developing a new reactive infiltration joining process for silicon carbide ceramics has become a research hotspot. Summary of the Invention

[0005] In order to solve the problems of traditional silicon carbide ceramic reaction joining technology, such as the presence of excessive free silicon in the joining part (joining layer), long joining period, difficulty in controlling the composition and thickness of the joining layer, and incomplete reaction, the present invention provides a method for laser-assisted silicon reactive infiltration joining of silicon carbide ceramics and their composite materials.

[0006] Specifically, the present invention provides a method for laser-assisted silicon reactive infiltration bonding of silicon carbide ceramics and their composite materials, the bonding method comprising the following steps: (1) coating a carbon-containing suspension on the surface of a silicon carbide component and drying the suspension, and then performing a laser cladding treatment on the surface to obtain a silicon carbide component to be connected having a laser-clad porous carbon layer on the surface; (2) Two silicon carbide components to be connected with a laser-clad porous carbon layer on their surfaces are butt-jointed and silicon particles are placed at the connection interface. After heat treatment, the laser-assisted silicon reactive infiltration connection of silicon carbide ceramics and their composite materials is completed.

[0007] Preferably, in step (1), the silicon carbide component is a silicon carbide ceramic or silicon carbide composite material with a pure surface, or a silicon carbide ceramic or silicon carbide composite material with a laser-clad silicon layer on the surface.

[0008] Preferably, the preparation process of the silicon carbide component with a laser-clad silicon layer on the surface includes the following steps: coating a silicon powder suspension on the surface of a pure silicon carbide component and drying it, and then performing laser cladding treatment on the surface to obtain a silicon carbide component with a laser-clad silicon layer on the surface.

[0009] Preferably, the silicon powder content in the silicon powder suspension is 10-50 wt%, preferably 20 wt%; the average particle size of the silicon powder is 1-10 μm, preferably 1-5 μm.

[0010] Preferably, the laser for laser cladding treatment after coating with silicon powder suspension includes one of solid laser, gas laser, semiconductor laser, and fiber laser; the laser power is 30 to 180 W, the scanning speed is 10 to 30 mm / s, the spot spacing is 0.05 to 0.20 mm, and the laser cladding atmosphere is one of vacuum, argon, and nitrogen.

[0011] Preferably, in step (1), the raw materials of the carbon-containing suspension include: 40-85 wt% of phenolic resin solution, 5-40 wt% of carbon black, 5-40 wt% of SiC powder, and 1-5 wt% of dispersant.

[0012] Preferably, the phenolic resin solution is a mixed solution of phenolic resin and anhydrous ethanol, the content of anhydrous ethanol is 40-70wt%; the particle size of the carbon black is 1-500nm; the particle size of the SiC powder is 0.2-10μm; and the dispersant is castor oil phosphate or castor oil.

[0013] Preferably, in step (1), the laser for the laser cladding treatment includes one of a solid laser, a gas laser, a semiconductor laser, and a fiber laser; the laser power is 15 to 75 W and is not 75 W, the scanning speed is 10 to 30 mm / s, the spot spacing is 0.10 to 0.30 mm, and the laser cladding atmosphere is one of vacuum, argon, and nitrogen.

[0014] Preferably, in step (2), the particle size of the silicon particles is 1 to 10 mm.

[0015] Preferably, in step (2), the heat treatment temperature is 1500-1650° C., the holding time is 30-180 min, and the protective atmosphere is vacuum.

[0016] Beneficial effects (1) The present invention utilizes laser cladding technology to laser crack a carbon-containing slurry to rapidly prepare a porous carbon layer. The structure and thickness of the laser-clad carbon layer are easily controlled, providing a good reaction layer for subsequent silicon reaction infiltration and reducing the content of free silicon in the connecting layer. Compared with the traditional reaction connecting method (coating a carbon slurry containing a pore-forming agent and then performing high-temperature vacuum cracking), the connecting cycle is shorter and the connecting cost is lower. (2) The present invention can add a laser-clad silicon layer between the laser-clad carbon layer and the substrate, so that the porous carbon layer can react with the laser-clad silicon layer first, reducing the silicon content required for the complete reaction of carbon in the subsequent silicon reaction infiltration process, and can solve the problems of difficult silicon infiltration and incomplete carbon reaction in welds of large components. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is the surface SEM image of the porous carbon layer after laser cladding in Example 1; Figure 2 This is a SEM image of the interface morphology between the connecting layer and the silicon carbide substrate in the test bar of Example 1; Figure 3 This is a SEM image of the interface morphology between the connecting layer and the silicon carbide substrate in the test bar of Example 3; Figure 4 This is a SEM image of the interface morphology between the connecting layer and the silicon carbide substrate in the test bar of Example 5; Figure 5 This is an SEM image of the interface morphology structure between the connecting layer and the silicon carbide substrate of Comparative Example 1. DETAILED DESCRIPTION

[0018] The present invention will be further described below by the following embodiments. It should be understood that the following embodiments are only used to illustrate the present invention, not to limit the present invention. The percentages below are all by mass unless otherwise specified.

[0019] The following is an exemplary description of the laser-assisted silicon reactive infiltration method for bonding silicon carbide ceramics and their composite materials provided by the present invention. The bonding method may include the following steps: (1) coating a carbon-containing suspension on the surface of a silicon carbide component and drying the suspension, and then performing a laser cladding treatment on the surface to obtain a silicon carbide component to be connected having a laser-clad porous carbon layer on the surface; (2) Two silicon carbide components to be connected with a laser-clad porous carbon layer on their surfaces are butt-jointed and silicon particles are placed at the connection interface. After heat treatment, the laser-assisted silicon reactive infiltration connection of silicon carbide ceramics and their composite materials is completed.

[0020] In some embodiments, in step (1), the silicon carbide component can be a pure surface silicon carbide ceramic, a silicon carbide composite material, or a silicon carbide ceramic or silicon carbide composite material with a laser-clad silicon layer on the surface. The silicon carbide composite material can include carbon fiber reinforced silicon carbide and silicon carbide fiber reinforced silicon carbide; wherein, the preparation process of the silicon carbide component with a laser-clad silicon layer on the surface can include the following steps: coating a silicon powder suspension on the surface of the pure surface silicon carbide component and drying it, and then performing laser cladding treatment on the surface to obtain a silicon carbide component with a laser-clad silicon layer on the surface.

[0021] Furthermore, the silicon powder suspension includes silicon powder and a solvent, the solvent is selected from deionized water / organic solvent, the organic solvent is preferably at least one of ethanol, acetone and methanol, more preferably ethanol (ethanol is volatile and can prevent organic matter from cracking during the laser cladding process and affecting the formation of the cladding layer); the average particle size of the silicon powder can be 1 to 10 μm, preferably 1 to 5 μm, which is conducive to obtaining a coating with appropriate thickness and good bulk density; the silicon powder content in the silicon powder suspension is 10 to 50 wt%, preferably 20 wt%.

[0022] Furthermore, the method of coating the silicon powder suspension includes a spin coating method, a spray coating method and a screen printing coating method.

[0023] Furthermore, the silicon powder suspension is coated on the surface of the pure surface silicon carbide component and dried in a vacuum oven, an electric blast drying oven or a hot air circulation oven; the temperature can be 80-100°C, preferably 90°C; the holding time can be 15-45 minutes, preferably 30 minutes.

[0024] Furthermore, the laser for laser cladding treatment after coating and drying the silicon powder suspension can include one of a solid laser, a gas laser, a semiconductor laser, and a fiber laser. Preferably, it is a laser source with a high absorption coefficient for silicon powder to improve the energy utilization rate of the laser, such as a carbon dioxide gas laser. The laser power can be 30 to 180 W, the scanning speed can be 10 to 30 mm / s, and the spot spacing can be 0.05 to 0.20 mm. These parameters are conducive to obtaining a suitable laser energy density. Too high a laser energy density will cause the silicon powder to vaporize, while too low a laser energy density will cause it to fail to melt and have poor bonding with the substrate. The laser cladding atmosphere can be one of vacuum, argon, and nitrogen, preferably a protective atmosphere such as argon and vacuum, which can prevent the silicon powder from oxidizing under the action of the laser and protect the silicon carbide substrate.

[0025] In some embodiments, in step (1), the raw materials of the carbon-containing suspension may include: 40-85wt% of phenolic resin solution, 5-40wt% of carbon black, 5-40wt% of SiC powder, and 1-5wt% of dispersant; wherein the phenolic resin solution is a mixed solution of phenolic resin and anhydrous ethanol, and the content of anhydrous ethanol is 40-70wt%, which is conducive to preparing a suspension with a viscosity that is conducive to dispersion and coating; the particle size of the carbon black is 1-500nm, which is conducive to maintaining good reaction activity and good dispersibility; the particle size of the SiC powder is 0.2-10μm; and the dispersant may be castor oil phosphate or castor oil.

[0026] The above-mentioned materials can be weighed according to the proportions and then ball-milled to obtain a carbon-containing suspension. Under the action of laser, the phenolic resin undergoes a rapid cracking reaction and forms porous carbon with good pore distribution, providing a good reaction layer for subsequent siliconization treatment. The presence of carbon black can increase the carbon content and reduce the content of free silicon in the connecting layer. SiC powder can serve as a precipitation node for newly generated SiC in the siliconization reaction, promote the siliconization reaction, and increase the SiC content in the connecting layer. The dispersant has a good dispersing effect on SiC powder and carbon black, can reduce powder accumulation, and promote uniform distribution.

[0027] In some embodiments, in step (1), the drying temperature may be 120-180° C., preferably 160° C.; and the holding time may be 2-4 h, preferably 3 h.

[0028] In some embodiments, in step (1), the laser for the laser cladding process may include one of a solid laser, a gas laser, a semiconductor laser, and a fiber laser, preferably a carbon dioxide gas laser; the laser power may be 15 to 75 W and not 75 W. Too much power may lead to excessive cracking or gasification of the phenolic resin, while too little power may lead to incomplete cracking of the phenolic resin and poor pore structure; the scanning speed is 10 to 30 mm / s. Too high a speed may lead to a short laser dwell time, insufficient heat transfer, and a low degree of cracking; too low a speed may lead to excessive laser energy density and excessive cracking of the resin; the spot spacing is 0.10 to 0.30 mm. Too little spacing may lead to excessive overlap between the lasers and repeated cracking; too much spacing may lead to failure to irradiate the partial area between the two laser beams; the laser cladding atmosphere may be one of vacuum, argon, and nitrogen, preferably vacuum.

[0029] In some embodiments, in step (2), the docking can be completed using a graphite mold. For example, a small pressure can be applied using bolts provided with the graphite mold to ensure good contact between the two silicon carbide components to be connected.

[0030] In some embodiments, in step (2), the particle size of the silicon particles may be 1 to 10 mm.

[0031] In some embodiments, in step (2), the heat treatment can be performed in a sintering furnace or a welding furnace; the temperature can be 1500-1650° C., the holding time can be 30-180 min, and the protective atmosphere is vacuum.

[0032] This invention uses laser cladding technology to rapidly decompose phenolic resin to form porous carbon with a well-defined pore structure. Appropriate amounts of carbon powder and silicon carbide powder are added to the suspension to ensure a low free silicon content and a high silicon carbide content in the connecting layer. This allows for a connecting layer with a free silicon content below 20%, a four-point bending strength exceeding 205 MPa, and a precisely controlled thickness of 20 to 50 μm.

[0033] It should also be noted that before applying the suspension, the surface of the silicon carbide parts to be connected can be pretreated to remove impurities such as silicon dioxide, carbon, and oil on the surface; the pretreatment may include: surface grinding and ultrasonic cleaning; preferably, the silicon carbide surface layer is first ground off using a grinder, and then ultrasonic cleaning is performed with ethanol and deionized water in sequence.

[0034] The following examples are further given to illustrate the present invention in detail. It should be understood that the following examples are only used to further illustrate the present invention and cannot be interpreted as limiting the scope of protection of the present invention. Some non-essential improvements and adjustments made by those skilled in the art based on the above content of the present invention all fall within the scope of protection of the present invention. The specific process parameters and the like in the following examples are only examples within a suitable range, and those skilled in the art can make selections within a suitable range through the description herein, and are not limited to the specific numerical values exemplified below. Unless otherwise specified, the technical means used in the examples are conventional means well known to those skilled in the art.

[0035] Example 1

[0036] The method for laser-assisted silicon reactive infiltration bonding of silicon carbide ceramics and their composite materials provided in this embodiment includes the following steps: (1) Weigh 100 g of phenolic resin solution (the mass ratio of phenolic resin to anhydrous ethanol is 1:1), 10 g of SiC powder, 20 g of carbon black, and 2.5 g of castor oil phosphate dispersant, place them in a ball mill and mill them for 24 h to prepare a carbon-containing suspension; evenly apply the carbon-containing suspension on the surface of the silicon carbide component to be connected after grinding and ultrasonic cleaning, and dry it in an oven at 160°C for 3 h to obtain a silicon carbide component with a surface coated with a carbon layer; Laser cladding of silicon carbide components coated with a carbon layer on their surface was performed using a carbon dioxide laser in a vacuum atmosphere. The specific laser parameters were: laser power 21W, scanning speed 15mm / s, spot spacing 0.15mm, and repeated scanning twice to obtain a laser-clad porous carbon layer. (2) The connection surfaces of two silicon carbide parts to be connected with a laser-clad porous carbon layer on their surfaces are aligned and clamped by a graphite clamp with a pressure of 1 to 20 MPa, and silicon particles with a particle size of 1 to 5 mm are placed on the connection interface. Then, the connection is carried out in a sintering furnace with a connection temperature of 1550°C and a holding time of 60 minutes in a vacuum environment to obtain a connection test bar.

[0037] like Figure 1 As shown, after laser cladding, Example 1 is composed of porous carbon with a loose structure, which is beneficial to the subsequent siliconization reaction.

[0038] like Figure 2 As shown, the final connection joint formed in Example 1 has a good interface with the substrate, with a dense joint and no obvious defects such as holes or cracks. The connection layer is composed of SiC and a small amount of Si. The substrate surface has a dense layer of newly formed SiC, which ensures the bond between the substrate and the connection layer. The four-point bending strength of the joint is 206.1 MPa.

[0039] Example 2

[0040] The method for laser-assisted silicon reactive infiltration bonding of silicon carbide ceramics and their composite materials provided in this embodiment is similar to that in embodiment 1, except that: In step (2), the connection temperature is 1600°C.

[0041] The interface between the joint formed in Example 2 and the substrate was well bonded, and the four-point bending strength of the joint was 219.6 MPa. This was because as the connection temperature increased, the carbon and silicon in the connection layer reacted more completely, resulting in an increase in strength.

[0042] Example 3

[0043] The method for laser-assisted silicon reactive infiltration bonding of silicon carbide ceramics and their composite materials provided in this embodiment is similar to that in embodiment 1, except that: In step (1), the laser power in the specific laser parameters of laser cladding is 30W.

[0044] like Figure 3As shown, the interface between the joint and the substrate formed in Example 3 is well bonded, with a dense joint and no obvious defects such as holes or cracks. The connecting layer is composed of a large amount of aggregated SiC and a small amount of Si. The substrate surface has a dense layer of newly generated SiC, which ensures the bond between the substrate and the connecting layer. Compared with Example 1, the silicon carbide content in the connecting layer is slightly increased, and aggregation and growth occur. This may be because the degree of cracking of the phenolic resin is higher with the increase of laser power. The four-point bending strength of the joint is 234.3MPa.

[0045] Example 4

[0046] The method for laser-assisted silicon reactive infiltration bonding of silicon carbide ceramics and their composite materials provided in this embodiment is similar to that in embodiment 1, except that: In step (1), the laser power in the specific laser parameters of laser cladding is 30 W; In step (2), the connection temperature is 1600°C.

[0047] As the connection temperature increases, the carbon in the connection layer reacts more completely with the silicon. The connection joint formed in Example 4 is tightly bonded to the interface of the substrate, and the four-point bending strength of the joint reaches 265.8 MPa.

[0048] Example 5

[0049] The method for laser-assisted silicon reactive infiltration bonding of silicon carbide ceramics and their composite materials provided in this embodiment includes the following steps: (1) Weighing 10 g of silicon powder, 40 g of ethanol, and 25 g of agate balls, placing them in a ball mill and ball milling for 6 h to prepare a suspension with a silicon powder content of 20%; evenly coating the silicon powder suspension on the surface of a silicon carbide component that has been processed by a grinder and ultrasonically cleaned, and drying it in an oven at 90°C for 30 min to obtain a silicon carbide component with a surface coated with silicon powder; laser cladding the silicon carbide component with a surface coated with silicon powder using a carbon dioxide laser in a vacuum atmosphere, with the specific laser parameters being: laser power 60 W, scanning speed 15 mm / s, spot spacing 0.1 mm, and repeating the scan twice to obtain a laser cladding silicon layer; (2) Weigh 100 g of phenolic resin solution (the mass ratio of phenolic resin to anhydrous ethanol is 1:1), 10 g of SiC powder, 20 g of carbon black and 2.5 g of castor oil phosphate dispersant, place them in a ball mill and mill them for 24 h to prepare a carbon-containing suspension; evenly apply the carbon-containing suspension on the silicon carbide parts to be connected with a laser-clad silicon layer on the surface, and dry them in an oven at 160°C for 3 h to obtain silicon carbide parts with a surface coated with a carbon layer; The surface-coated carbon layer was laser clad using a carbon dioxide laser in a vacuum atmosphere. The specific laser parameters were: laser power 30W, scanning speed 15mm / s, spot spacing 0.15mm, and repeated scanning twice to obtain a laser-clad porous carbon layer. (3) The connection surfaces of two silicon carbide parts to be connected, which have a laser-clad silicon layer and a laser-clad porous carbon layer on their surfaces, are aligned and clamped by a graphite clamp with a pressure of 1 to 20 MPa, and 1 to 5 mm silicon particles are placed on the connection interface. Then, the connection is carried out in a sintering furnace with a connection temperature of 1600 ° C and a holding time of 60 min in a vacuum environment to obtain a connection test bar.

[0050] like Figure 4 As shown, the interface between the joint and the substrate formed in Example 5 is well bonded, with a dense joint and no obvious defects such as holes or cracks. The connecting layer is composed of SiC and a small amount of Si. The sides close to the substrate are mostly composed of dispersed small particles of silicon carbide, with no obvious silicon layer present. This indicates that the laser-clad silicon layer can react with the porous carbon to form silicon carbide, thereby reducing the residual carbon content. The four-point flexural strength of the joint is 225.7 MPa.

[0051] Example 6

[0052] The method for laser-assisted silicon reactive infiltration bonding of silicon carbide ceramics and their composite materials provided in this embodiment refers to that in embodiment 5, with the main differences being: In step (3), the connection temperature is 1550°C.

[0053] The connection joint formed in Example 6 is tightly bonded to the interface of the substrate, and the four-point bending strength of the joint is 217.4 MPa.

[0054] Comparative Example 1

[0055] The method for bonding silicon carbide ceramics and their composite materials by silicon reactive infiltration provided in this comparative example comprises the following steps: (1) Weigh 100 g of phenolic resin solution (the mass ratio of phenolic resin to anhydrous ethanol is 1:1), 10 g of SiC powder, 20 g of carbon black and 2.5 g of castor oil phosphate dispersant, place them in a ball mill and ball mill for 24 h to prepare a carbon-containing suspension; evenly apply the carbon-containing suspension on the surface of the silicon carbide part to be processed by a grinder and ultrasonically cleaned, and clamp the two parts to be connected with a graphite clamp at a pressure of 1 to 20 MPa, and then dry them in an oven at 160°C for 3 h to obtain a silicon carbide part with a surface coated with a carbon layer; (2) The silicon carbide component with a carbon layer coated on the surface is subjected to high-temperature vacuum cracking in a vacuum sintering furnace at a temperature of 900°C and a holding time of 30 minutes to obtain a porous carbon layer obtained by high-temperature vacuum cracking; 1-5 mm silicon particles are placed on the connection interface, and then the connection is carried out in a sintering furnace at a connection temperature of 1550°C and a holding time of 60 minutes in a vacuum environment to obtain a connection test bar.

[0056] like Figure 5 As shown, due to the lack of a pore-forming agent, the phenolic resin cannot form porous carbon through high-temperature vacuum cracking. The connecting layer formed in Comparative Example 1 is composed of a large amount of free silicon, and the distribution of silicon carbide is very uneven. The four-point bending strength of the joint is only 127.6 MPa. By comparison with Example 1, it can be seen that the structure and thickness of the laser-clad carbon layer can be easily controlled by preparing a porous carbon layer through laser cladding and connecting silicon carbide ceramics through silicon infiltration reaction. This provides a good reaction layer for subsequent silicon reaction infiltration, reduces the content of free silicon in the connecting layer, and shortens the connection cycle and reduces the connection cost.

[0057] Comparative Example 2

[0058] The method for bonding silicon carbide ceramics and their composite materials by silicon reactive infiltration provided in this comparative example comprises the following steps: (1) Weigh 100 g of phenolic resin solution (the mass ratio of phenolic resin to anhydrous ethanol is 1:1), 10 g of SiC powder, 20 g of carbon black, and 2.5 g of castor oil phosphate dispersant, place them in a ball mill and ball mill for 24 h to prepare a carbon-containing suspension; evenly apply the carbon-containing suspension on the surface of the silicon carbide component to be processed by a grinder and ultrasonically cleaned, and dry it in an oven at 160°C for 3 h to obtain a silicon carbide component with a surface coated with a carbon layer; (2) The connecting surfaces of two silicon carbide components to be connected, which are coated with a carbon layer, are directly aligned and clamped by a graphite clamp with a pressure of 1 to 20 MPa, and 1 to 5 mm silicon particles are placed on the connecting interface. Then, the connection is carried out in a sintering furnace with a connection temperature of 1550 ° C and a holding time of 60 min in a vacuum environment to obtain a connection test bar.

[0059] In Comparative Example 2, after coating the carbon-containing suspension, silicon reaction infiltration connection was directly performed without high-temperature vacuum cracking. The resulting connection joint had poor interface bonding with the substrate, and the four-point bending strength of the joint was 107.9 MPa.

[0060] Comparative Example 3

[0061] The method for bonding silicon carbide ceramics and their composite materials by silicon reactive infiltration provided in this comparative example comprises the following steps: (1) Weigh 10 g of silicon powder, 40 g of ethanol, and 25 g of agate balls, place them in a ball mill and mill for 6 h to prepare a suspension with a silicon powder content of 20%; evenly apply the silicon powder suspension on the surface of the silicon carbide component to be processed by a grinder and ultrasonically cleaned, and dry it in an oven at 90°C for 30 min to obtain a silicon carbide component with a surface coated with silicon powder; laser cladding the surface to be connected using a carbon dioxide laser in a vacuum atmosphere, with the specific laser parameters being: laser power 60 W, scanning speed 15 mm / s, spot spacing 0.1 mm, and repeating the scan twice to obtain a laser cladding silicon layer; (2) Weigh 100 g of phenolic resin solution (the mass ratio of phenolic resin to anhydrous ethanol is 1:1), 10 g of SiC powder, 20 g of carbon black and 2.5 g of castor oil phosphate dispersant, place them in a ball mill and ball mill for 24 h to prepare a carbon-containing suspension; evenly apply the carbon-containing suspension on the silicon carbide parts to be connected with a laser-clad silicon layer on the surface, and clamp the two parts to be connected with a graphite clamp at a pressure of 1 to 20 MPa, and then dry them in an oven at 160°C for 3 h to obtain silicon carbide parts with a surface coated with a carbon layer; (3) The silicon carbide component with a carbon layer coated on its surface is subjected to high-temperature vacuum cracking in a vacuum sintering furnace at a temperature of 900°C and a holding time of 30 minutes to obtain a porous carbon layer cracked at high temperature; then, the connection surfaces of the two silicon carbide components to be connected, with the porous carbon layer cracked at high temperature and the laser-clad silicon layer on their surfaces, are aligned and clamped by a graphite clamp at a pressure of 1 to 20 MPa, and 1 to 5 mm silicon particles are placed on the connection interface, and then the connection is carried out in a sintering furnace at a connection temperature of 1550°C and a holding time of 60 minutes in a vacuum environment to obtain a connection test bar.

[0062] The interface bonding between the joint and the substrate formed in Comparative Example 3 was average, with a four-point flexural strength of 138.6 MPa. In this comparative example, a laser-clad silicon layer was added between the substrate and the connecting layer to promote interfacial bonding while reducing the silicon content required for complete carbon reaction during the subsequent silicon reaction infiltration process. This resulted in a slight improvement in strength compared to Comparative Example 1.

[0063] Comparative Example 4

[0064] The method for bonding silicon carbide ceramics and their composite materials by silicon reactive infiltration provided in this comparative example comprises the following steps: (1) Weigh 10 g of silicon powder, 40 g of ethanol, and 25 g of agate balls, place them in a ball mill and mill for 6 h to prepare a suspension with a silicon powder content of 20%; evenly apply the silicon powder suspension on the surface of the silicon carbide component to be processed by a grinder and ultrasonically cleaned, and dry it in an oven at 90°C for 30 min to obtain a silicon carbide component with a surface coated with silicon powder; laser cladding the surface to be connected using a carbon dioxide laser in a vacuum atmosphere, with the specific laser parameters being: laser power 60 W, scanning speed 15 mm / s, spot spacing 0.1 mm, and repeating the scan twice to obtain a laser cladding silicon layer; (2) Weigh 100 g of phenolic resin solution (the mass ratio of phenolic resin to anhydrous ethanol is 1:1), 10 g of SiC powder, 20 g of carbon black and 2.5 g of castor oil phosphate dispersant, place them in a ball mill and mill them for 24 h to prepare a carbon-containing suspension; evenly apply the carbon-containing suspension on the silicon carbide parts to be connected with a laser-clad silicon layer on the surface, and dry them in an oven at 160°C for 3 h to obtain silicon carbide parts with a surface coated with a carbon layer; (3) The connecting surfaces of the two silicon carbide components to be connected, which are coated with a carbon layer, are directly aligned and clamped by a graphite clamp with a pressure of 1 to 20 MPa, and 1 to 5 mm silicon particles are placed on the connecting interface. Then, the connection is carried out in a sintering furnace with a connection temperature of 1550 ° C and a holding time of 60 min in a vacuum environment to obtain a connection test bar.

[0065] The interface bonding between the connection joint formed in Comparative Example 4 and the substrate is general, and the four-point bending strength of the joint is 122.5 MPa.

[0066] Comparative Example 5

[0067] The method for bonding silicon carbide ceramics and their composite materials by silicon reactive infiltration provided in this comparative example comprises the following steps: (1) A phenolic resin solution (the mass ratio of phenolic resin to anhydrous ethanol is 1:1) is evenly coated on the surface of the silicon carbide component to be connected after grinding and ultrasonic cleaning, and then dried in an oven at 160°C for 3 hours to obtain a silicon carbide component with a surface coated with phenolic resin; the silicon carbide component with a surface coated with phenolic resin is laser clad using a carbon dioxide laser in a vacuum atmosphere. The specific laser parameters are: laser power 21W, scanning speed 15mm / s, spot spacing 0.15mm, and repeated scanning twice to obtain a laser clad porous carbon layer; (2) The connection surfaces of two silicon carbide parts to be connected with a laser-clad porous carbon layer on their surfaces are aligned and clamped by a graphite clamp with a pressure of 1 to 20 MPa, and 1 to 5 mm silicon particles are placed on the connection interface. Then, the connection is carried out in a sintering furnace with a connection temperature of 1550 ° C and a holding time of 60 min in a vacuum environment to obtain a connection test bar.

[0068] Compared with Example 1, Comparative Example 5 did not add carbon black and SiC powder to the phenolic resin solution. Instead, the phenolic resin solution was directly coated on the surface of the silicon carbide ceramic and laser cladding was performed, resulting in a small amount of silicon carbide generated in the connecting layer and a significant increase in free silicon. The interface bonding between the formed connecting joint and the substrate was poor, and the four-point bending strength of the joint was 89.9 MPa.

[0069] Comparative Example 6

[0070] The method for bonding silicon carbide ceramics and their composite materials by silicon reactive infiltration provided in this comparative example is similar to that in Example 1, except that: In step (1), among the specific laser parameters of laser cladding, the laser power is 12W.

[0071] Compared with Example 1, the laser power of the laser cladding in Comparative Example 6 is too low, and the phenolic resin cannot be laser-cleaved to form porous carbon, resulting in poor interface bonding between the formed connection joint and the substrate, and the four-point bending strength of the joint is 110.7 MPa.

[0072] Comparative Example 7

[0073] The method for bonding silicon carbide ceramics and their composite materials by silicon reactive infiltration provided in this comparative example is similar to that in Example 1, except that: In step (1), among the specific laser parameters of laser cladding, the laser power is 75W.

[0074] Compared with Example 1, the laser power of the laser cladding in Comparative Example 7 is too high, the phenolic resin and carbon black vaporize and splash at high temperature, the interface bonding between the formed connection joint and the substrate is general, and the four-point bending strength of the joint is 127.2 MPa.

[0075] Although the present invention has been described in detail through the above preferred embodiments, it should be understood that the above description is not intended to limit the present invention. After reading the above description, various modifications and substitutions of the present invention will become apparent to those skilled in the art. Therefore, the scope of protection of the present invention should be defined by the appended claims.

Claims

1. A method for laser-assisted silicon reactive infiltration bonding of silicon carbide ceramics and their composite materials, characterized in that: The connection method comprises the following steps: (1) coating a carbon-containing suspension on the surface of a silicon carbide component and drying the suspension, and then performing a laser cladding treatment on the surface to obtain a silicon carbide component to be connected having a laser-clad porous carbon layer on the surface; (2) Two silicon carbide components to be connected with a laser-clad porous carbon layer on their surfaces are butt-jointed and silicon particles are placed at the connection interface. After heat treatment, the laser-assisted silicon reactive infiltration connection of silicon carbide ceramics and their composite materials is completed.

2. The connection method according to claim 1, characterized in that: In step (1), the silicon carbide component is a silicon carbide ceramic or silicon carbide composite material with a pure surface, or a silicon carbide ceramic or silicon carbide composite material with a laser-clad silicon layer on the surface.

3. The connection method according to claim 1 or 2, characterized in that: The preparation process of the silicon carbide component with a laser-clad silicon layer on the surface comprises the following steps: coating a silicon powder suspension on the surface of a pure silicon carbide component and drying it, and then performing a laser cladding treatment on the surface to obtain a silicon carbide component with a laser-clad silicon layer on the surface.

4. The connection method according to any one of claims 1 to 3, characterized in that: The silicon powder content in the silicon powder suspension is 10-50 wt%, preferably 20 wt%; the average particle size of the silicon powder is 1-10 μm, preferably 1-5 μm.

5. The connection method according to any one of claims 1 to 4, characterized in that: The laser used for laser cladding treatment after coating with silicon powder suspension includes one of solid laser, gas laser, semiconductor laser and fiber laser; the laser power is 30 to 180 W, the scanning speed is 10 to 30 mm / s, the spot spacing is 0.05 to 0.20 mm, and the laser cladding atmosphere is one of vacuum, argon and nitrogen.

6. The connection method according to any one of claims 1 to 5, characterized in that: In step (1), the raw materials of the carbon-containing suspension include: 40-85wt% of phenolic resin solution, 5-40wt% of carbon black, 5-40wt% of SiC powder, and 1-5wt% of dispersant.

7. The connection method according to any one of claims 1 to 6, characterized in that: The phenolic resin solution is a mixed solution of phenolic resin and anhydrous ethanol, and the content of anhydrous ethanol is 40-70wt%; the particle size of the carbon black is 1-500nm; the particle size of the SiC powder is 0.2-10μm; and the dispersant is castor oil phosphate or castor oil.

8. The connection method according to any one of claims 1 to 7, characterized in that: In step (1), the laser for the laser cladding treatment includes one of a solid laser, a gas laser, a semiconductor laser, and a fiber laser; the laser power is 15 to 75 W and is not 75 W, the scanning speed is 10 to 30 mm / s, the spot spacing is 0.10 to 0.30 mm, and the laser cladding atmosphere is one of vacuum, argon, and nitrogen.

9. The connection method according to any one of claims 1 to 8, characterized in that: In step (2), the particle size of the silicon particles is 1 to 10 mm.

10. The connection method according to any one of claims 1 to 9, characterized in that: In step (2), the heat treatment temperature is 1500-1650° C., the holding time is 30-180 min, and the protective atmosphere is vacuum.

Images