A reaction-sintered silicon carbide solderless diffusion special ceramic connection structure and its preparation method

Abstract

This invention belongs to the field of reaction-bonded silicon carbide joining technology, and provides a solderless diffusion-free special ceramic joining structure for reaction-bonded silicon carbide and its preparation method. This invention focuses on the joining surface of reaction-bonded silicon carbide. Through surface finishing and microstructuring, a controllable pyrolytic carbon infiltration layer is formed on the joining surface as a carbon source and infiltration framework. Further, a glaze glass powder containing rare-earth boron-aluminum-silicon nucleating components is prepared, and a ceramicizable microcapsule additive with organosilicon resin and phenolic resin as the core and silica as the shell is prepared. This, together with silicon carbide, metallic silicon, and deoxidizing components, constitutes a composite glaze slurry. The composite glaze slurry is then joined by constructing a gradient glaze layer consisting of an infiltration layer, a main layer, and a sealing layer, followed by butt jointing and heat preservation. Simultaneously, the glaze phase is wetted and filled, and crystallization and solidification are achieved during post-processing. This invention eliminates the need for metal solder, improves the joint density, thermal stability, and thermal cycling reliability, and is suitable for the assembly and joining of high-temperature structural ceramic components.

Description

Technical Field

[0001] This invention belongs to the field of reaction-bonded silicon carbide bonding technology, and relates to a special ceramic bonding structure for reaction-bonded silicon carbide without solder diffusion and its preparation method. Background Technology

[0002] Reaction-bonded silicon carbide (RSC) is widely used in high-temperature structural components, sealing and wear-resistant parts, semiconductor equipment, and advanced thermal engineering due to its comprehensive properties such as high strength, high hardness, wear resistance, corrosion resistance, and high-temperature stability. With the increasing size and complexity of components, as well as the rising cost of integral molding, the assembly of ceramic components using joining methods has become an important engineering approach. However, RSC is a typical difficult-to-join material.

[0003] In existing technologies, the main methods for joining silicon carbide ceramics include metal brazing, active brazing, glass or glass-ceramic brazing, and reactive bonding. While metal brazing and active brazing are mature processes, the introduction of a metallic phase often leads to problems such as thermal expansion mismatch, decreased corrosion resistance and high-temperature performance, and may cause residual stress concentration and embrittlement of the interfacial reaction layer under thermal cycling conditions. Glass or glass-ceramic brazing can improve wetting and filling to some extent, but the traditional glass phase is prone to viscosity decrease and creep at high temperatures, and the bonding interface easily forms a continuous brittle oxide layer or a glass-rich phase region, resulting in insufficient high-temperature strength and long-term reliability. Reactive bonding methods typically rely on external reaction media or silicon infiltration to achieve in-situ silicon carbide generation, but the process window is sensitive, and it is difficult to simultaneously achieve interfacial reaction and infiltration, easily leading to defects such as residual pores, uneven reaction, or residual free silicon. Summary of the Invention

[0004] To address the shortcomings of existing technologies, the present invention aims to provide a special ceramic connection structure for reaction-bonded silicon carbide without solder diffusion and its preparation method. By microstructuring the connection surface and constructing a controllable pyrolytic carbon infiltration layer, free silicon in the matrix is ​​allowed to self-infiltrate at the interface and react in situ with the carbon source to generate silicon carbide necks. Simultaneously, a composite glaze slurry containing nucleating components of glaze glass powder and ceramizable microcapsules is prepared to construct a gradient glaze layer. After connection and crystallization curing treatment, a dense, heat-resistant, and thermally cycling-resistant connection interface is obtained, thereby meeting the needs of actual production.

[0005] To achieve this objective, the present invention adopts the following technical solution:

[0006] In a first aspect, the present invention provides a method for preparing a solderless diffusion-free special ceramic connection structure of reaction-sintered silicon carbide, the method comprising:

[0007] S1, the reaction-bonded silicon carbide connector is processed to specifications, ground and polished, and processed by femtosecond laser. A slurry is sprayed on the non-connecting surface to obtain the sample to be connected.

[0008] S2, prepare an impregnation solution, impregnate, solidify and keep warm the sample to be bonded to obtain a pyrolytic carbon bonded sample;

[0009] S3, preparation of yttrium boron aluminum silicon nucleating powder and glaze glass powder;

[0010] S4, prepare silicon-oxygen-carbon ceramicized microcapsule powder, and mix it with the glaze glass powder to prepare a composite glaze slurry;

[0011] S5, the composite glaze slurry is sequentially formed into a wetting layer, a main layer and a sealing layer to obtain a gradient glaze layer to be connected sample. After aligning and assembling two gradient glaze layer to be connected samples, a heat preservation process is performed to obtain a metal-free solder diffusion connection structure blank. Then, after secondary crystallization and curing, a reaction sintered silicon carbide solder-free diffusion special ceramic connection structure is obtained.

[0012] The preparation method specifically includes:

[0013] S1. The reaction-bonded silicon carbide connector is sized, ground and polished, then cleaned and dried in anhydrous ethanol. The dried connecting surface is then processed by femtosecond laser. After laser processing, it is rinsed with anhydrous ethanol and dried. A slurry is sprayed on the non-connecting surface of the sample and dried to obtain the sample to be connected.

[0014] S2, after mixing anhydrous ethanol, n-butanol and deionized water, add nano carbon black N330, layered graphene and polyethyleneimine and disperse evenly to obtain a suspension. Add phenolic resin to the suspension to obtain an impregnation solution. Vertically immerse the connecting surface of the sample to be connected into the impregnation solution for impregnation and curing to obtain a permeable layer connected sample. Keep the permeable layer sample at a temperature to obtain a pyrolytic carbon connected sample.

[0015] S3, Yttrium nitrate hexahydrate and aluminum nitrate nonahydrate are dispersed in an ethanol-water solution, citric acid is added and the pH is adjusted to 2-3 to obtain a complex solution. Tetraethyl orthosilicate is added to ethanol, deionized water and nitric acid are added to obtain a hydrolysate. The hydrolysate is added dropwise to the complex solution and boric acid is added and stirred to obtain a sol. The sol is dried, calcined, ground, cooled, ground and sieved to obtain yttrium boron aluminum silicon nucleating powder. Silica, boron oxide, aluminum oxide, calcium oxide, magnesium oxide, sodium oxide, potassium oxide, zirconium oxide, titanium dioxide and yttrium boron aluminum silicon nucleating powder are mixed and kept at a first temperature. Then molten glass is water quenched and ball milled to obtain glaze glass powder.

[0016] S4, methylphenyl silicone resin and phenolic resin are dispersed in ethyl acetate, and Span-80 is added to obtain an oil phase. PVA (polyvinyl alcohol) is dissolved in deionized water to obtain an aqueous phase. Under shear conditions, the oil phase is added to the aqueous phase to obtain an emulsion. Tetraethyl orthosilicate is added dropwise to the emulsion and the pH is adjusted to 9-10. The reaction is stirred at a second temperature, filtered, washed, and dried to obtain silicon-oxygen-carbon ceramicized microcapsule powder. Glaze glass powder, silicon carbide powder, metallic silicon powder, boron carbide powder, anhydrous ethanol / terpineol mixed solvent and ammonium polyacrylate are ball-milled and dispersed, and then added to the silicon-oxygen-carbon ceramicized microcapsule powder to obtain a composite glaze slurry.

[0017] S5, the connecting surface of the pyrolytic carbon bonded sample is coated with a diluted composite glaze as a wetting layer. After drying, the composite glaze is coated to form the main layer. After drying, a capping glaze is prepared. Titanium dioxide is added to the composite glaze and dispersed evenly to obtain the capping glaze. The capping glaze is coated on the surface of the main layer to form the capping layer and dried. After drying, a gradient glaze layer to be bonded sample is obtained. Two gradient glaze layer to be bonded samples are aligned and assembled with the connecting surfaces facing each other. They are placed in a graphite fixture or hot press mold for a heat preservation process to obtain a metal-free solder diffusion bonding structure blank. The metal-free solder diffusion bonding structure blank is subjected to secondary crystallization and curing to obtain a reaction sintered silicon carbide solder-free diffusion special ceramic bonding structure.

[0018] After the connectors are sized and machined to specifications, a femtosecond laser forms microgrooves on the connecting surfaces, providing continuous capillary channels and diffusion paths. A composite coating of boron nitride and alumina sprayed on the non-connecting surfaces acts as an isolation layer, reducing oxidation and volatilization migration caused by direct contact between the external atmosphere and the substrate during heat treatment. In the impregnation step, carbon black and layered graphene are dispersed and stabilized in a mixed solvent and aqueous phase via polyethyleneimine adsorption. The amine groups of polyethyleneimine form an adsorption layer on the particle surface and provide electrostatic and steric hindrance effects, reducing agglomeration and maintaining the suspension system. After the addition of phenolic resin, it enters the microgrooves and near-surface micropores under pressure difference and capillary action. The curing process is essentially the condensation and cross-linking of phenolic resin, fixing the dispersed carbonaceous filler at the interface and near-surface region, forming a continuous organic network. Subsequently, under an inert atmosphere, the phenolic resin undergoes pyrolysis and carbonization, with low-molecular-weight pyrolysis products volatilizing and being discharged, and the residual skeleton transforming into pyrolytic carbon dominated by amorphous carbon.

[0019] In the preparation of yttrium boron aluminum silicon nucleating powder, yttrium salts and aluminum salts complex with citric acid in an ethanol-water medium. Tetraethyl orthosilicate hydrolyzes under acidic conditions to generate silanols, which then condense into a silicon-oxygen network. After the hydrolysate is added dropwise to the complexing system, the metal complex and the silicon-oxygen network co-assemble in the sol stage. Boric acid participates in the reconstruction of the silicon-oxygen network and changes the local coordination environment. Drying and calcination decompose the organic complexing agent, and the inorganic components undergo solid-phase reactions and rearrangements to form inorganic microphases. When the yttrium boron aluminum silicon nucleating powder is co-melted with glass raw materials, the silicon-oxygen and boron-oxygen networks constitute the glass matrix. Alkali metal and alkaline earth metal oxides regulate network fracture and ion migration. Alumina, zirconium oxide, and titanium dioxide participate in network reinforcement and affect crystallization behavior. The yttrium boron aluminum silicon nucleating powder exists in the molten glass as microscale enrichment regions or residual crystal nuclei, which form embedded nucleation sites after cooling.

[0020] The preparation of silicon-oxygen-carbon ceramic microcapsule powder is based on emulsification and sol-gel encapsulation mechanisms. Organosilicon resin and phenolic resin form the oil phase core, while polyvinyl alcohol stabilizes the aqueous phase interface to form dispersed oil droplets. Tetraethyl orthosilicate hydrolyzes and condenses under alkaline conditions, depositing at the oil droplet interface to form a silica shell. The composite glaze slurry consists of glaze glass powder, silicon carbide filler, metallic silicon, boron carbide, and microcapsules. The silicon carbide filler acts as an inert framework, restricting glass phase migration and providing a solid-phase framework compatible with the matrix. Metallic silicon can participate in local composition adjustment and liquid-phase sintering during heating. Boron carbide reacts with molten silicon in a high-temperature inert atmosphere to generate silicon carbide and trace amounts of silicon boride phases. Silicon boride is distributed at the grain boundaries of newly formed silicon carbide necks, acting as grain boundary pinning and inhibiting abnormal neck growth. Simultaneously, a small amount of boron diffuses into the adjacent glaze phase, improving the chemical compatibility between the glaze phase and the silicon carbide interface. The wetting layer uses diluted glaze slurry to reduce viscosity and enhance wetting of microgrooves and pyrolytic carbon channels, allowing glass powder and reactive components to enter the near-surface structure; the main layer provides a continuous glass phase and reaction medium; the capping glaze slurry is obtained by adding and dispersing titanium dioxide in the composite glaze slurry, and titanium dioxide can act as nucleation centers related to crystallization in the glaze phase.

[0021] During the docking assembly and connection insulation process, the organic matter further decomposes, and the microcapsule core gradually pyrolyzes. Upon entering the connection temperature zone, the free silicon in the reaction-sintered silicon carbide melts and migrates to the interface along the microgrooves and carbon pore network under the drive of pressure, wetting, and capillary action. The molten silicon reacts with the pyrolyzed carbon to form silicon carbide, which advances along the carbon source connection region and forms an in-situ silicon carbide neck. The in-situ silicon carbide formation process is accompanied by volume shrinkage, forming microscale voids around the newly formed silicon carbide neck. Simultaneously, the glaze glass phase continuously softens and wets the silicon carbide surface, penetrating the aforementioned microvoids with the help of external axial pressure and capillary driving force, achieving synchronous volume compensation for the reaction shrinkage of the glass phase, and keeping the neck region continuously and densely filled. The silicon carbide filler particles in the glaze glass powder act as a skeletal support in the softened glass phase, preventing excessive loss of the glass phase under pressure and maintaining the overall thickness and geometric stability of the interface layer. The glaze glass phase softens and wets the silicon carbide and the newly formed silicon carbide, filling the remaining space in the micropores and channels. The silica shell of the silicon-oxygen-carbon ceramicized microcapsule powder is prepared from tetraethyl orthosilicate using a sol-gel method under alkaline conditions, resulting in a microporous shell structure. During the heating range of 300–600℃, the organosilicon resin and phenolic resin within the shell undergo gradual pyrolysis. The pyrolysis products are mainly small-molecule hydrocarbons, hydrogen, and carbon monoxide. These gaseous products diffuse outward through the micropores of the shell, while the shell itself maintains its structural integrity without cracking. As the temperature continues to rise above the glass softening temperature of the glaze, the silica shell gradually dissolves into the softened glass phase. The released residual carbon from the core and the silicon-oxygen-carbon phase then enter the interfacial reaction zone to participate in carbonization and network construction. The residual carbon and silicon-oxygen-carbon phase generated by the pyrolysis of the silicon-oxygen-carbon ceramicized microcapsule powder provide additional carbon sources and a silicon-oxygen-carbon network near the interface. The silicon-oxygen-carbon phase and the silicon-oxygen network of the glass phase are structurally compatible and can serve as a transition phase to participate in the continuity of the interfacial chemical environment. During cooling, the viscosity of the glass phase increases and solidifies, fixing the interfacial morphology. During the secondary crystallization and solidification stage, the glaze glass containing yttrium boron aluminum silicon nucleating powder undergoes phase separation and crystallization under heat treatment. The crystal nuclei promote the formation and growth of the crystalline phase, and the glaze layer transforms from an amorphous network to a glass-ceramic structure containing the crystalline phase. Nucleation-related components such as titanium dioxide and zirconium oxide further influence the crystallization path and crystalline phase distribution, causing the sealing layer and the main layer to form a solidified closed layer. The final bonding interface is mainly provided by the in-situ generated silicon carbide neck, and the glass-ceramicized glaze layer undertakes the functions of pore filling and structural sealing.

[0022] As a preferred technical solution of the present invention, in S1, the size of the specification processing is (20-30) mm × (20-30) mm × (4-8) mm, and the connecting surface is marked. For example, it can be (20, 21, 22, 23, 24, 25, 26, 27, 28, 29 or 30) mm × (20, 21, 22, 23, 24, 25, 26, 27, 28, 29 or 30) mm × (4, 4.4, 4.8, 5.2, 5.6, 6.0, 6.4, 6.8, 7.2, 7.6 or 8) mm, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0023] In some optional embodiments, the grinding and polishing involves sequentially using #400-#1200 metallographic sandpaper and diamond polishing fluid to grind and polish the connecting surface until the surface roughness Ra is 0.2-1.0 μm. For example, it can be sequentially using #400, #500, #600, #800, #1000, #800 or #1200 metallographic sandpaper and diamond polishing fluid to grind and polish the connecting surface until the surface roughness Ra is (0.2, 0.28, 0.36, 0.44, 0.52, 0.6, 0.68, 0.76, 0.84, 0.92 or 1.0) μm, but it is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0024] In some optional embodiments, the femtosecond laser processing employs a wavelength of 1020-1040 nm, a pulse width of 250-320 fs, a repetition rate of 100-300 kHz, and a surface energy of 0.15-0.45 J / cm². 2 The scanning speed is 120-350 mm / s, and the number of scans is 2-6 times, to obtain an orthogonal grid-like microgroove array with a groove width of 30-60 μm, a groove depth of 20-50 μm, and a groove spacing of 80-150 μm on the connecting surface. For example, it could be: using a wavelength of (1020, 1022, 1024, 1026, 1028, 1030, 1032, 1034, 1036, 1038, or 1040) nm, a pulse width of (250, 257, 264, 271, 278, 285, 292, 299, 306, 313, or 320) fs, a repetition frequency of (100, 120, 140, 160, 180, 200, 220, 240, 260, 280, or 300) kHz, and a surface energy of (0.15, 0.18, 0.21, 0.24, 0.27, 0.3, 0.33, 0.36, 0.39, 0.42, or 0.45) J / cm². 2The scanning speed is (120, 143, 166, 189, 212, 235, 258, 281, 304, 327 or 350) mm / s, the number of scans is (2, 3, 4, 5 or 6), and an orthogonal grid-like microgroove array with a groove width of (30, 33, 36, 39, 42, 45, 48, 51, 54, 57 or 60) μm, a groove depth of (20, 23, 26, 29, 32, 35, 38, 41, 44, 47 or 50) μm and a groove spacing of (80, 87, 94, 101, 108, 115, 122, 129, 136, 143 or 150) μm is obtained on the connecting surface. However, it is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0025] In some optional embodiments, the slurry is prepared by dispersing hexagonal boron nitride powder and alumina powder in an ethanol aqueous solution and ball milling to obtain a slurry, wherein the mass ratio of hexagonal boron nitride powder, alumina powder and ethanol aqueous solution is (3-5):(6-10):(35-55), and the mass ratio of anhydrous ethanol to deionized water in the ethanol aqueous solution is 1:1. For example, the mass ratio of the hexagonal boron nitride powder, alumina powder, and ethanol aqueous solution could be (3.0, 3.2, 3.4, 3.6, 3.8, 4.0, 4.2, 4.4, 4.6, 4.8, or 5.0): (6, 6.4, 6.8, 7.2, 7.6, 8.0, 8.4, 8.8, 9.2, 9.6, or 10): (35, 37, 39, 41, 43, 45, 47, 49, 51, 53, or 55), where the mass ratio of anhydrous ethanol to deionized water in the ethanol aqueous solution is 1:1. However, this is not limited to the listed values; other unlisted values ​​within this range are also applicable.

[0026] In some optional embodiments, the dry film thickness of the sprayed slurry is controlled to be 40-80 μm, for example, it can be 40 μm, 44 μm, 48 μm, 52 μm, 56 μm, 60 μm, 64 μm, 68 μm, 72 μm, 76 μm or 80 μm, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0027] As a preferred embodiment of the present invention, in S2, the mass ratio of anhydrous ethanol, n-butanol, deionized water, nano-carbon black N330, layered graphene, polyethyleneimine, and phenolic resin is (30-40):(8-12):(4-8):(2-4):(0.2-0.8):(0.2-0.6):(12-20), for example, it can be (30, 31, 32, 33, 34, 35, 36, 37, 38, 39 or 40):(8, 8.4, 8.8, 9.2, 9.6, 10.0, 10.4, 10.8, 11.2, 11.6 or 12):(4.0, 4.4, 4.8, 5.2, 5.6, 6.0, 6.4, 6.8, 7.2, 7.6 or 8.0): (2.0, 2.2, 2.4, 2.6, 2.8, 3.0, 3.2, 3.4, 3.6, 3.8 or 4.0): (0.2, 0.26, 0.32, 0.38, 0.44, 0.5, 0.56, 0.62, 0.68, 0.74 or 0.8): (0.2, 0.24, 0.28, 0.32, 0.36, 0.4, 0.44, 0.48, 0.52, 0.56 or 0.6): (12, 12.8, 13.6, 14.4, 15.2, 16, 16.8, 17.6, 18.4, 19.2 or 20), but not limited to the listed values; other unlisted values ​​within this range also apply.

[0028] In some optional embodiments, the phenolic resin solid content is 30-45 wt.%, for example, it can be 30 wt.%, 31.5 wt.%, 33 wt.%, 34.5 wt.%, 36 wt.%, 37.5 wt.%, 39 wt.%, 40.5 wt.%, 42 wt.%, 43.5 wt.%, or 45 wt.%, but is not limited to the listed values; other unlisted values ​​within this range are also applicable.

[0029] In some optional embodiments, the absolute pressure of the impregnation is 300-900 Pa, the holding time is 180-420 s, and after removal, it is allowed to stand at room temperature for 20-40 min to level. For example, the absolute pressure can be (300, 360, 420, 480, 540, 600, 660, 720, 780, 840 or 900) Pa, the holding time can be (180, 204, 228, 252, 276, 300, 324, 348, 372, 396 or 420) s, and after removal, it is allowed to stand at room temperature for (20, 22, 24, 26, 28, 30, 32, 34, 36, 38 or 40) min to level. However, it is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0030] In some optional embodiments, the curing temperature is 150-180°C and the time is 60-120 min, for example, the temperature can be (120, 124, 128, 132, 136, 140, 144, 148, 152, 156 or 160)°C and the time can be (60, 66, 72, 78, 84, 90, 96, 102, 108, 114 or 120) min, but it is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0031] In some optional embodiments, the heat preservation is performed in an argon atmosphere, heating to 300-350°C at 2°C / min and holding for 30-60 min, then heating to 850-1050°C at 2°C / min and holding for 60-120 min. For example, it could be an argon atmosphere, heated at 2℃ / min to (300, 305, 310, 315, 320, 325, 330, 335, 340, 345 or 350)℃ and held at that temperature for (30, 33, 36, 39, 42, 45, 48, 51, 54, 57 or 60) min, then heated at 2℃ / min to (850, 870, 890, 910, 930, 950, 970, 990, 1010, 1030 or 1050)℃ and held at that temperature for (60, 66, 72, 78, 84, 90, 96, 102, 108, 114 or 120) min, but it is not limited to the listed values; other unlisted values ​​within this range are also applicable.

[0032] As a preferred embodiment of the present invention, in S3, the mass ratio of yttrium nitrate hexahydrate, aluminum nitrate nonahydrate, ethanol aqueous solution, and citric acid is (2.5-3.5):(3.0-4.5):(25-35):(2.5-4.0), for example, it can be (2.5, 2.6, 2.7, 2.8, 2.9, 3.0, 3.1, 3.2, 3.3, 3.4 or 3.5):(3.0, 3.15, 3.3, 3...). 45, 3.6, 3.75, 3.9, 4.05, 4.2, 4.35 or 4.5: (25, 26, 27, 28, 29, 30, 31, 32, 33, 34 or 35): (2.5, 2.65, 2.8, 2.95, 3.1, 3.25, 3.4, 3.55, 3.7, 3.85 or 4.0), but not limited to the listed values; other unlisted values ​​within this range also apply.

[0033] In some optional embodiments, the volume ratio of deionized water to anhydrous ethanol in the aqueous ethanol solution is 7:3.

[0034] In some optional embodiments, the mass ratio of tetraethyl orthosilicate, ethanol, deionized water, nitric acid, and boric acid is (3-5):(10-15):(0.8-1.8):(0.05-0.15):(0.3-0.9), for example, it can be (3.0, 3.2, 3.4, 3.6, 3.8, 4.0, 4.2, 4.4, 4.6, 4.8, or 5.0):(10, 10.5, 11, 11.5, 12, 12.5, 13, 13.5, 14, 14.5, or 15):(0.8 The ranges are 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7 or 1.8; (0.05, 0.06, 0.07, 0.08, 0.09, 0.1, 0.11, 0.12, 0.13, 0.14 or 0.15); (0.3, 0.36, 0.42, 0.48, 0.54, 0.6, 0.66, 0.72, 0.78, 0.84 or 0.9), but are not limited to the listed values; other unlisted values ​​within this range also apply.

[0035] In some optional embodiments, the concentration of the nitric acid is 1M.

[0036] In some optional embodiments, the calcination is performed in an air atmosphere, with the temperature increased at 2°C / min to 750-900°C and held for 60-120 min. For example, it can be performed in an air atmosphere, with the temperature increased at 2°C / min to (750, 765, 780, 795, 810, 825, 840, 855, 870, 885 or 900)°C and held for (60, 66, 72, 78, 84, 90, 96, 102, 108, 114 or 120) min, but is not limited to the listed values; other unlisted values ​​within this range are also applicable.

[0037] In some optional embodiments, the mass ratio of silicon dioxide, boron oxide, aluminum oxide, calcium oxide, magnesium oxide, sodium oxide, potassium oxide, zirconium oxide, titanium dioxide, and yttrium boron aluminum silicon nucleating powder is (50-60):(10-16):(6-10):(4-8):(1-4):(4-8):(1-3):(3-6):(1-4):(0.5-4.0), for example, it can be (50, 51, 52, 53, 54, 55). 56, 57, 58, 59 or 60: (10, 10.6, 11.2, 11.8, 12.4, 13, 13.6, 14.2, 14.8, 15.4 or 16): (6, 6.4, 6.8, 7.2, 7.6, 8.0, 8.4, 8.8, 9.2, 9.6 or 10): (4.0, 4.4, 4.8, 5.2, 5.6, 6.0, 6.4, 6.8, 7.2, 7.6 or 8.0): (1.0, 1.3, 1.6, 1.9, 2.2, 2.5, 2.8, 3.1, 3.4, 3.7 or 4.0): (4.0, 4.4, 4.8, 5.2, 5.6, 6.0, 6.4, 6.8, 7.2, 7.6 or 8.0): (1.0, 1.2, 1.4, 1.6, 1.8, 2.0, 2.2, 2.4, 2.6, 2.8 or 3.0): (3.0, 3.3, 3.6, 3.9, 4 2, 4.5, 4.8, 5.1, 5.4, 5.7 or 6.0: (1.0, 1.3, 1.6, 1.9, 2.2, 2.5, 2.8, 3.1, 3.4, 3.7 or 4.0): (0.5, 0.85, 1.2, 1.55, 1.9, 2.25, 2.6, 2.95, 3.3, 3.65 or 4.0), but not limited to the listed values; other unlisted values ​​within this range also apply.

[0038] In some alternative embodiments, the first temperature is 1450-1550°C, for example, it can be 1450°C, 1460°C, 1470°C, 1480°C, 1490°C, 1500°C, 1510°C, 1520°C, 1530°C, 1540°C or 1550°C, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0039] In some optional embodiments, the holding time at the first temperature is 60-120 min, for example, it can be 60 min, 66 min, 72 min, 78 min, 84 min, 90 min, 96 min, 102 min, 108 min, 114 min or 120 min, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0040] In a preferred embodiment of the present invention, in step S4, the mass ratio of the methylphenyl silicone resin, phenolic resin, ethyl acetate, and Span-80 is (8-12):(3-6):(12-20):(0.1-0.4), for example, it can be (8, 8.4, 8.8, 9.2, 9.6, 10.0, 10.4, 10.8, 11.2, 11.6, or 12):(3.0, 3.3, 3.6, 3.9, 4.2, 4). 5, 4.8, 5.1, 5.4, 5.7 or 6.0: (12, 12.8, 13.6, 14.4, 15.2, 16, 16.8, 17.6, 18.4, 19.2 or 20): (0.1, 0.13, 0.16, 0.19, 0.22, 0.25, 0.28, 0.31, 0.34, 0.37 or 0.4), but not limited to the listed values; other unlisted values ​​within this range also apply.

[0041] In some optional embodiments, the mass ratio of PVA, deionized water, and tetraethyl orthosilicate is (0.4-1.2):(80-120):(2-6), for example, it can be (0.4, 0.48, 0.56, 0.64, 0.72, 0.8, 0.88, 0.96, 1.04, 1.12, or 1.2):(80, 84, 88, 92, 96, 100, 104, 108, 112, 116, or 120):(2.0, 2.4, 2.8, 3.2, 3.6, 4.0, 4.4, 4.8, 5.2, 5.6, or 6.0), but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0042] In some optional embodiments, the mass ratio of the glaze glass powder, silicon carbide powder, metallic silicon powder, boron carbide powder, anhydrous ethanol / terpineol mixed solvent, ammonium polyacrylate, and silicon-oxygen-carbon ceramicized microcapsule powder is (60-90):(10-25):(5-12):(0.2-3.0):(40-80):(0.2-0.8):(0.3-3.0), for example, it can be (60, 63, 66, 69, 72, 75, 78, 81, 84, 87 or 90):(10, 11.5, 13, 14.5, 16, 17.5, 19, 20.5, 22, 23.5 or 25):(5, 5.7, 6.4, 7.1, 7.8, 8.5, 9.2, 9.9). 10.6, 11.3 or 12: (0.2, 0.48, 0.76, 1.04, 1.32, 1.6, 1.88, 2.16, 2.44, 2.72 or 3.0): (40, 44, 48, 52, 56, 60, 64, 68, 72, 76 or 80): (0.2, 0.26, 0.32, 0.38, 0.44, 0.5, 0.56, 0.62, 0.68, 0.74 or 0.8): (0.3, 0.57, 0.84, 1.11, 1.38, 1.65, 1.92, 2.19, 2.46, 2.73 or 3.0), but not limited to the listed values, other unlisted values ​​within this range also apply.

[0043] In some optional embodiments, the mass ratio of anhydrous ethanol to terpineol in the anhydrous ethanol / terpineol mixed solvent is 2:1.

[0044] In some alternative embodiments, the second temperature is 25-40°C, for example, it can be 25°C, 26.5°C, 28°C, 29.5°C, 31°C, 32.5°C, 34°C, 35.5°C, 37°C, 38.5°C or 40°C, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0045] In some optional embodiments, the stirring reaction time at the second temperature is 1-3 hours, for example, 1.0 hours, 1.2 hours, 1.4 hours, 1.6 hours, 1.8 hours, 2.0 hours, 2.2 hours, 2.4 hours, 2.6 hours, 2.8 hours or 3.0 hours, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0046] In some optional embodiments, the solid content of the composite glaze is 55-70 wt.%, for example, it can be 55 wt.%, 56.5 wt.%, 58 wt.%, 59.5 wt.%, 61 wt.%, 62.5 wt.%, 64 wt.%, 65.5 wt.%, 67 wt.%, 68.5 wt.%, or 70 wt.%, but is not limited to the listed values; other unlisted values ​​within this range are also applicable.

[0047] As a preferred technical solution of the present invention, in S5, the solid content of the diluted composite glaze is 30-45 wt.%, for example, it can be 30 wt.%, 31.5 wt.%, 33 wt.%, 34.5 wt.%, 36 wt.%, 37.5 wt.%, 39 wt.%, 40.5 wt.%, 42 wt.%, 43.5 wt.%, or 45 wt.%, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0048] In some optional embodiments, the mass of titanium dioxide in the capping glaze is 0.2-1.5% of the total mass of the composite glaze solids, for example, it can be 0.2%, 0.33%, 0.46%, 0.59%, 0.72%, 0.85%, 0.98%, 1.11%, 1.24%, 1.37% or 1.5%, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0049] In some optional embodiments, the dry film thickness of the main layer is 30-120 μm, for example, it can be 30 μm, 39 μm, 48 μm, 57 μm, 66 μm, 75 μm, 84 μm, 93 μm, 102 μm, 111 μm or 120 μm, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0050] In some optional embodiments, the dry film thickness of the capping layer is 10-30 μm, for example, it can be 10 μm, 12 μm, 14 μm, 16 μm, 18 μm, 20 μm, 22 μm, 24 μm, 26 μm, 28 μm or 30 μm, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0051] In some optional embodiments, the heat preservation procedure is as follows: argon atmosphere, axial pressure of 2-12 MPa is applied, temperature is increased to 550-650℃ at 3℃ / min and held for 20-40 min, then temperature is increased to 1480-1520℃ at 5℃ / min and held for 10-30 min, followed by cooling to 850-950℃ at 4℃ / min and then cooled to room temperature with the furnace. For example, it could be: an argon atmosphere, applying an axial pressure of (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, or 12) MPa, heating at 3℃ / min to (550, 560, 570, 580, 590, 600, 610, 620, 630, 640, or 650)℃ and holding at that temperature for (20, 22, 24, 26, 28, 30, 32, 34, 36, 38, or 40) min, then heating at 5℃ / min to (1480, 1484, 1488, 1492). Hold at 1496, 1500, 1504, 1508, 1512, 1516 or 1520)℃ for (10, 12, 14, 16, 18, 20, 22, 24, 26, 28 or 30) min, then cool at 4℃ / min to (850, 860, 870, 880, 890, 900, 910, 920, 930, 940 or 950)℃ and then cool with the furnace to room temperature. However, this is not limited to the listed values; other unlisted values ​​within this range are also applicable.

[0052] In some optional embodiments, the secondary crystallization and solidification is performed by heating at 4°C / min to 780-850°C and holding for 40-80 min, then heating to 950-1100°C and holding for 1-4 h, followed by furnace cooling. For example, it could be: heating at 4℃ / min to (780, 787, 794, 801, 808, 815, 822, 829, 836, 843 or 850)℃ and holding at that temperature for (40, 44, 48, 52, 56, 60, 64, 68, 72, 76 or 80) min, then heating to (950, 965, 980, 995, 1010, 1025, 1040, 1055, 1070, 1085 or 1100)℃ and holding at that temperature for (1.0, 1.3, 1.6, 1.9, 2.2, 2.5, 2.8, 3.1, 3.4, 3.7 or 4.0) h, followed by furnace cooling. However, this is not limited to the listed values; other unlisted values ​​within this range are also applicable.

[0053] Secondly, the present invention provides a reaction-sintered silicon carbide solderless diffusion special ceramic connection structure prepared by the preparation method described in the first aspect.

[0054] Compared with the prior art, the beneficial effects of the present invention are as follows: The present invention performs microstructural treatment on the reaction-sintered silicon carbide bonding surface and constructs a pyrolytic carbon infiltration layer, enabling the free silicon in the matrix to migrate directionally and react in situ with the carbon source during the bonding process, forming a continuous bonding pathway dominated by silicon carbide, reducing dependence on external metal solder; the glaze glass system introduces yttrium boron aluminum silicon nucleating powder and works synergistically with silicon oxygen carbon ceramicized microcapsule powder, promoting the glaze phase to complete wetting, filling, chemical coupling and crystallization solidification during the bonding and post-treatment process, forming a glass ceramicized transition layer and suppressing the adverse effects of continuous oxide film at the interface; by constructing a gradient glaze layer through the infiltration layer, the main layer and the sealing layer, the division of labor between the interface reaction zone and the sealing zone can be achieved, reducing pore residue and component segregation; the resulting bonding interface has high density and structural stability, which can improve the bonding reliability under high temperature service and thermal cycling conditions, and is suitable for the assembly and bonding of complex ceramic components. Detailed Implementation

[0055] The technical solution of the present invention will be described in detail below with reference to specific embodiments. The embodiments described herein are specific implementations of the present invention and are used to illustrate the concept of the present invention; these descriptions are explanatory and exemplary and should not be construed as limiting the implementation of the present invention or the scope of protection of the present invention. In addition to the embodiments described herein, those skilled in the art can also adopt other obvious technical solutions based on the content disclosed in the claims and the specification of this application. These technical solutions include those that make any obvious substitutions and modifications to the embodiments described herein.

[0056] The chemical reagents used in the embodiments and comparative examples of this invention are all commercially available products and have not undergone any further purification treatment.

[0057] Example 1

[0058] This embodiment provides a reaction-sintered silicon carbide solderless diffusion special ceramic connection structure and its preparation method. The preparation method specifically includes the following steps:

[0059] S1. The reaction-bonded silicon carbide connector is sized and polished. The sized dimensions are 30mm × 20mm × 4mm, and the connecting surfaces are marked. The polishing is performed by sequentially using #400 metallographic sandpaper and diamond polishing fluid to polish the connecting surfaces until the surface roughness Ra is 1.0μm. Afterwards, it is cleaned and dried in anhydrous ethanol. The dried connecting surfaces are then subjected to femtosecond laser processing. The femtosecond laser processing uses a wavelength of 1020nm, a pulse width of 320fs, a repetition frequency of 100kHz, and a surface energy of 0.45J / cm². 2The scanning speed was 350 mm / s, and the number of scans was 2. An orthogonal grid-like microgroove array with a groove width of 60 μm, a groove depth of 20 μm, and a groove spacing of 150 μm was obtained on the connecting surface. After laser processing, the sample was rinsed with anhydrous ethanol and dried. A slurry was then sprayed onto the non-connecting surface of the sample. The slurry was prepared by dispersing hexagonal boron nitride powder and alumina powder in an ethanol aqueous solution and ball milling to obtain the slurry. The mass ratio of hexagonal boron nitride powder, alumina powder and ethanol aqueous solution was 3:10:35, and the mass ratio of anhydrous ethanol to deionized water in the ethanol aqueous solution was 1:1. The dry film thickness of the sprayed slurry was controlled to be 80 μm. After drying, the sample to be connected was obtained.

[0060] S2, 30g anhydrous ethanol, 12g n-butanol and 4g deionized water are mixed, and then 4g nano carbon black N330, 0.2g layered graphene and 0.6g polyethyleneimine are added and dispersed evenly to obtain a suspension. 12g phenolic resin with a solid content of 45wt.% is added to the suspension to obtain an impregnation solution. The connecting surface of the sample to be connected is vertically immersed in the impregnation solution for impregnation and curing. The absolute pressure of the impregnation is 300Pa and the holding time is 420s. After removal, it is allowed to stand at room temperature for 20min to level. The curing temperature is 180℃ and the time is 60min to obtain a permeable layer connected sample. The permeable layer sample is kept at a temperature of argon atmosphere, heated to 350℃ at 2℃ / min and held for 30min, and then heated to 1050℃ at 2℃ / min and held for 60min to obtain a pyrolytic carbon connected sample.

[0061] S3, 3.5g of yttrium nitrate hexahydrate and 3.0g of aluminum nitrate nonahydrate are dispersed in 35g of an ethanol-water solution, wherein the volume ratio of deionized water to anhydrous ethanol in the ethanol-water solution is 7:3. 4.0g of citric acid is added and the pH is adjusted to 2 to obtain a complex solution. 3.0g of tetraethyl orthosilicate is added to 15g of ethanol, along with 1.8g of deionized water and 0.05g of... A hydrolysate was obtained from 1M nitric acid. The hydrolysate was added dropwise to a complex solution, and 0.9g of boric acid was added and stirred to obtain a sol. The sol was dried, calcined, and ground. The calcination was carried out in an air atmosphere, with the temperature increased to 900℃ at 2℃ / min and held for 60min. After cooling, the sol was ground and sieved to obtain yttrium boron aluminum silicon nucleating powder. 60g of silicon dioxide, 10g of boron oxide, 10g of aluminum oxide, 4g of calcium oxide, 4g of magnesium oxide, 4g of sodium oxide, 3g of potassium oxide, 3g of zirconium oxide, 4g of titanium dioxide and 0.5g of yttrium boron aluminum silicon nucleating powder were mixed and held at 1550℃ for 60min. Then, molten glass was water-quenched and ball-milled to obtain glaze glass powder.

[0062] S4, 12g of methylphenyl silicone resin and 3g of phenolic resin were dispersed in 20g of ethyl acetate, and 0.4g of Span-80 was added to obtain an oil phase. 0.4g of PVA was dissolved in 120g of deionized water to obtain an aqueous phase. Under shear conditions, the oil phase was added to the aqueous phase to obtain an emulsion. 6g of tetraethyl orthosilicate was added dropwise to the emulsion and the pH was adjusted to 9. The mixture was stirred at 25℃ for 3h, filtered, washed, and dried to obtain silicon-oxygen-carbon ceramicized microcapsule powder. 90g of glaze glass powder, 10g of silicon carbide powder, 12g of metallic silicon powder, 0.2g of boron carbide powder, 40g of anhydrous ethanol / terpineol mixed solvent, and 0.8g of ammonium polyacrylate were ball-milled and dispersed. After dispersion, 3.0g of silicon-oxygen-carbon ceramicized microcapsule powder was added to obtain a composite glaze slurry with a solid content of 55wt.%.

[0063] S5, a diluted composite glaze is applied to the bonding surface of the pyrolytic carbon-bonded sample as a wetting layer. The solid content of the diluted composite glaze is 45 wt.%. After drying, the composite glaze is applied to form the main layer, and the dry film thickness of the main layer is 30 μm. After drying, a sealing glaze is prepared by adding titanium dioxide to the composite glaze and dispersing it evenly. The mass of titanium dioxide in the sealing glaze is 1.5% of the total solid mass of the composite glaze. The sealing glaze is applied to the surface of the main layer to form a sealing layer and dried. The dry film thickness of the sealing layer is 30 μm. After drying, a gradient glaze layer sample to be bonded is obtained. Two gradient glaze layer samples to be bonded are aligned with their bonding surfaces facing each other. The blank is placed in a graphite fixture and subjected to a heat preservation process. The heat preservation process is as follows: under an argon atmosphere, an axial pressure of 12 MPa is applied, the temperature is increased to 550℃ at 3℃ / min and held for 40 min, then increased to 1520℃ at 5℃ / min and held for 10 min, and then cooled to 950℃ at 4℃ / min and then cooled to room temperature in the furnace to obtain a metal-free solder diffusion connection structure blank. The metal-free solder diffusion connection structure blank is subjected to secondary crystallization and solidification. The secondary crystallization and solidification process is as follows: the temperature is increased to 850℃ at 4℃ / min and held for 40 min, then increased to 1100℃ and held for 1 h, and then cooled in the furnace to obtain a reaction sintered silicon carbide solder diffusion-free special ceramic connection structure.

[0064] Example 2

[0065] This embodiment provides a reaction-sintered silicon carbide solderless diffusion special ceramic connection structure and its preparation method. The preparation method specifically includes the following steps:

[0066] S1. The reaction-bonded silicon carbide connectors are sized and polished. The sized dimensions are 20mm × 30mm × 8mm, and the connecting surfaces are marked. The polishing involves sequentially using #1200 metallographic sandpaper and diamond polishing fluid to polish the connecting surfaces until the surface roughness Ra is 0.2μm. Afterwards, the surfaces are cleaned and dried in anhydrous ethanol. The dried connecting surfaces are then subjected to femtosecond laser processing. The femtosecond laser processing uses a wavelength of 1040nm, a pulse width of 250fs, a repetition frequency of 300kHz, and a surface energy of 0.15J / cm². 2 The scanning speed was 120 mm / s and the number of scans was 6. An orthogonal grid-like microgroove array with a groove width of 30 μm, a groove depth of 50 μm, and a groove spacing of 80 μm was obtained on the connecting surface. After laser processing, the sample was rinsed with anhydrous ethanol and dried. A slurry was then sprayed onto the non-connecting surface of the sample. The slurry was prepared by dispersing hexagonal boron nitride powder and alumina powder in an ethanol aqueous solution and ball milling to obtain the slurry. The mass ratio of hexagonal boron nitride powder, alumina powder and ethanol aqueous solution was 5:6:55, and the mass ratio of anhydrous ethanol to deionized water in the ethanol aqueous solution was 1:1. The dry film thickness of the sprayed slurry was controlled to be 40 μm. After drying, the sample to be connected was obtained.

[0067] S2, 40g anhydrous ethanol, 8g n-butanol and 8g deionized water are mixed, and then 2g nano carbon black N330, 0.8g layered graphene and 0.2g polyethyleneimine are added and dispersed evenly to obtain a suspension. 20g phenolic resin with a solid content of 30wt.% is added to the suspension to obtain an impregnation solution. The connecting surface of the sample to be connected is vertically immersed in the impregnation solution for impregnation and curing. The absolute pressure of the impregnation is 900Pa and the holding time is 180s. After removal, it is allowed to stand at room temperature for 40min to level. The curing temperature is 150℃ and the time is 120min to obtain a permeable layer connected sample. The permeable layer sample is kept at a temperature of argon atmosphere, heated to 300℃ at 2℃ / min and held for 60min, and then heated to 850℃ at 2℃ / min and held for 120min to obtain a pyrolytic carbon connected sample.

[0068] S3, 2.5g of yttrium nitrate hexahydrate and 4.5g of aluminum nitrate nonahydrate are dispersed in 25g of an ethanol-water solution, wherein the volume ratio of deionized water to anhydrous ethanol in the ethanol-water solution is 7:3. 2.5g of citric acid is added and the pH is adjusted to 3 to obtain a complex solution. 5.0g of tetraethyl orthosilicate is added to 10g of ethanol, along with 0.8g of deionized water and 0.15g of... A hydrolysate was obtained from 1M nitric acid. The hydrolysate was added dropwise to a complexing solution, and 0.3g of boric acid was added and stirred to obtain a sol. The sol was dried, calcined, and ground. The calcination was carried out in an air atmosphere, with the temperature increased to 750℃ at 2℃ / min and held for 120min. After cooling, the sol was ground and sieved to obtain yttrium boron aluminum silicon nucleating powder. 50g of silicon dioxide, 16g of boron oxide, 6g of aluminum oxide, 8g of calcium oxide, 1g of magnesium oxide, 8g of sodium oxide, 1g of potassium oxide, 6g of zirconium oxide, 1g of titanium dioxide and 4.0g of yttrium boron aluminum silicon nucleating powder were mixed and held at 1450℃ for 120min. Then, molten glass was water-quenched and ball-milled to obtain glaze glass powder.

[0069] S4, 8g of methylphenyl silicone resin and 6g of phenolic resin were dispersed in 12g of ethyl acetate, and 0.1g of Span-80 was added to obtain an oil phase. 1.2g of PVA was dissolved in 80g of deionized water to obtain an aqueous phase. Under shear conditions, the oil phase was added to the aqueous phase to obtain an emulsion. 2g of tetraethyl orthosilicate was added dropwise to the emulsion and the pH was adjusted to 10. The mixture was stirred at 40℃ for 1h, filtered, washed, and dried to obtain silicon-oxygen-carbon ceramicized microcapsule powder. 60g of glaze glass powder, 25g of silicon carbide powder, 5g of metallic silicon powder, 3.0g of boron carbide powder, 80g of anhydrous ethanol / terpineol mixed solvent, and 0.2g of ammonium polyacrylate were ball-milled and dispersed. After dispersion, 0.3g of silicon-oxygen-carbon ceramicized microcapsule powder was added to obtain a composite glaze slurry with a solid content of 70wt.%.

[0070] S5, a diluted composite glaze is applied to the bonding surface of the pyrolytic carbon-bonded sample as a wetting layer. The solid content of the diluted composite glaze is 30 wt.%. After drying, the composite glaze is applied to form the main layer, and the dry film thickness of the main layer is 120 μm. After drying, a sealing glaze is prepared by adding titanium dioxide to the composite glaze and dispersing it evenly. The mass of titanium dioxide in the sealing glaze is 0.2% of the total solid mass of the composite glaze. The sealing glaze is applied to the surface of the main layer to form a sealing layer and dried. The dry film thickness of the sealing layer is 10 μm. After drying, a gradient glaze layer sample to be bonded is obtained. Two gradient glaze layers to be bonded are then bonded. The samples were aligned and assembled with their connecting surfaces facing each other, and placed in a hot press mold for a heat preservation process. The heat preservation process was as follows: argon atmosphere, 2MPa axial pressure applied, temperature increased to 650℃ at 3℃ / min and held for 20min, then increased to 1480℃ at 5℃ / min and held for 30min, followed by cooling to 850℃ at 4℃ / min and then furnace-cooled to room temperature to obtain a metal-free solder diffusion connection structure blank. The metal-free solder diffusion connection structure blank was then subjected to secondary crystallization and solidification. The secondary crystallization and solidification process was as follows: temperature increased to 780℃ at 4℃ / min and held for 80min, then increased to 950℃ and held for 4h, followed by furnace-cooled to obtain a reaction-sintered silicon carbide solder diffusion-free special ceramic connection structure.

[0071] Example 3

[0072] This embodiment provides a reaction-sintered silicon carbide solderless diffusion special ceramic connection structure and its preparation method. The preparation method specifically includes the following steps:

[0073] S1. The reaction-bonded silicon carbide connectors are sized and polished. The sized dimensions are 25mm × 25mm × 6mm, and the connecting surfaces are marked. The polishing involves sequentially using #600 metallographic sandpaper and diamond polishing fluid to polish the connecting surfaces until the surface roughness Ra is 0.5μm. Afterwards, the surfaces are cleaned and dried in anhydrous ethanol. The dried connecting surfaces are then subjected to femtosecond laser processing. The femtosecond laser processing uses a wavelength of 1030nm, a pulse width of 280fs, a repetition frequency of 200kHz, and a surface energy of 0.3J / cm². 2The scanning speed was 200 mm / s and the number of scans was 4. An orthogonal grid-like microgroove array with a groove width of 45 μm, a groove depth of 35 μm, and a groove spacing of 120 μm was obtained on the connecting surface. After laser processing, the sample was rinsed with anhydrous ethanol and dried. A slurry was then sprayed onto the non-connecting surface of the sample. The slurry was prepared by dispersing hexagonal boron nitride powder and alumina powder in an ethanol aqueous solution and ball milling to obtain the slurry. The mass ratio of hexagonal boron nitride powder, alumina powder and ethanol aqueous solution was 4:8:45, and the mass ratio of anhydrous ethanol to deionized water in the ethanol aqueous solution was 1:1. The dry film thickness of the sprayed slurry was controlled to be 60 μm. After drying, the sample to be connected was obtained.

[0074] S2, 35g anhydrous ethanol, 10g n-butanol and 6g deionized water are mixed, and then 3g nano carbon black N330, 0.5g layered graphene and 0.4g polyethyleneimine are added and dispersed evenly to obtain a suspension. 16g phenolic resin with a solid content of 38wt.% is added to the suspension to obtain an impregnation solution. The connecting surface of the sample to be connected is vertically immersed in the impregnation solution for impregnation and curing. The absolute pressure of the impregnation is 600Pa and the holding time is 300s. After removal, it is allowed to stand at room temperature for 30min to level. The curing temperature is 160℃ and the time is 90min to obtain a permeable layer connected sample. The permeable layer sample is kept at a temperature of argon atmosphere, heated to 320℃ at 2℃ / min and held for 45min, and then heated to 950℃ at 2℃ / min and held for 90min to obtain a pyrolytic carbon connected sample.

[0075] S3, 3.0 g of yttrium nitrate hexahydrate and 3.8 g of aluminum nitrate nonahydrate are dispersed in 30 g of an ethanol-water solution, wherein the volume ratio of deionized water to anhydrous ethanol in the ethanol-water solution is 7:3. 3.0 g of citric acid is added and the pH is adjusted to 2.5 to obtain a complex solution. 4.0 g of tetraethyl orthosilicate is added to 12 g of ethanol, along with 1.2 g of deionized water and 0.10 g of... Hydrolysate was obtained from 1M nitric acid. The hydrolysate was added dropwise to the complexing solution, and 0.6g of boric acid was added and stirred to obtain a sol. The sol was dried, calcined, and ground. The calcination was carried out in an air atmosphere, with the temperature increased to 800℃ at 2℃ / min and held for 90min. After cooling, the sol was ground and sieved to obtain yttrium boron aluminum silicon nucleating powder. 55g of silicon dioxide, 12g of boron oxide, 8g of aluminum oxide, 6g of calcium oxide, 2.5g of magnesium oxide, 6g of sodium oxide, 2g of potassium oxide, 4.5g of zirconium oxide, 2.5g of titanium dioxide and 2.0g of yttrium boron aluminum silicon nucleating powder were mixed and held at 1500℃ for 90min. Then, molten glass was water quenched and ball-milled to obtain glaze glass powder.

[0076] S4, 10g of methylphenyl silicone resin and 4g of phenolic resin were dispersed in 16g of ethyl acetate, and 0.2g of Span-80 was added to obtain an oil phase. 0.8g of PVA was dissolved in 100g of deionized water to obtain an aqueous phase. Under shear conditions, the oil phase was added to the aqueous phase to obtain an emulsion. 4g of tetraethyl orthosilicate was added dropwise to the emulsion and the pH was adjusted to 9.5. The mixture was stirred at 30℃ for 2 hours, filtered, washed, and dried to obtain silicon-oxygen-carbon ceramicized microcapsule powder. 75g of glaze glass powder, 18g of silicon carbide powder, 8g of metallic silicon powder, 1.5g of boron carbide powder, 60g of anhydrous ethanol / terpineol mixed solvent, and 0.5g of ammonium polyacrylate were ball-milled and dispersed. After dispersion, 1.5g of silicon-oxygen-carbon ceramicized microcapsule powder was added to obtain a composite glaze slurry with a solid content of 60wt.%.

[0077] S5, a diluted composite glaze is applied to the bonding surface of the pyrolytic carbon-bonded sample as a wetting layer. The solid content of the diluted composite glaze is 38 wt.%. After drying, the composite glaze is applied to form the main layer, and the dry film thickness of the main layer is 80 μm. After drying, a sealing glaze is prepared by adding titanium dioxide to the composite glaze and dispersing it evenly. The mass of titanium dioxide in the sealing glaze is 0.8% of the total solid mass of the composite glaze. The sealing glaze is applied to the surface of the main layer to form a sealing layer and dried. The dry film thickness of the sealing layer is 20 μm. After drying, a gradient glaze layer sample to be bonded is obtained. Two gradient glaze layers to be bonded are then bonded. The samples were aligned and assembled with their connecting surfaces facing each other, and placed in a graphite fixture for a heat preservation process. The heat preservation process was as follows: argon atmosphere, axial pressure of 8 MPa was applied, the temperature was increased to 600℃ at 3℃ / min and held for 30 min, then increased to 1500℃ at 5℃ / min and held for 20 min, followed by cooling to 900℃ at 4℃ / min and then furnace-cooled to room temperature to obtain a blank of a metal-free solder diffusion connection structure. The blank of the metal-free solder diffusion connection structure was subjected to secondary crystallization and solidification. The secondary crystallization and solidification was as follows: the temperature was increased to 800℃ at 4℃ / min and held for 60 min, then increased to 1000℃ and held for 2 h, and then furnace-cooled to obtain a reaction-sintered silicon carbide solder diffusion-free special ceramic connection structure.

[0078] Example 4

[0079] This embodiment provides a reaction-sintered silicon carbide solderless diffusion special ceramic connection structure and its preparation method. The preparation method specifically includes the following steps:

[0080] S1. The reaction-bonded silicon carbide connector is sized and polished. The sized dimensions are 28mm × 28mm × 7mm, and the connecting surface is marked. The polishing is performed by sequentially using #1000 metallographic sandpaper and diamond polishing fluid to polish the connecting surface until the surface roughness Ra is 0.8μm. Afterwards, it is cleaned and dried in anhydrous ethanol. The dried connecting surface is then subjected to femtosecond laser processing. The femtosecond laser processing uses a wavelength of 1035nm, a pulse width of 290fs, a repetition frequency of 250kHz, and a surface energy of 0.25J / cm². 2 The scanning speed was 280 mm / s, and the number of scans was 5. An orthogonal grid-like microgroove array with a groove width of 50 μm, a groove depth of 40 μm, and a groove spacing of 130 μm was obtained on the connecting surface. After laser processing, the sample was rinsed with anhydrous ethanol and dried. A slurry was then sprayed onto the non-connecting surface of the sample. The slurry was prepared by dispersing hexagonal boron nitride powder and alumina powder in an ethanol aqueous solution and ball milling to obtain the slurry. The mass ratio of hexagonal boron nitride powder, alumina powder and ethanol aqueous solution was 4.5:8:50, and the mass ratio of anhydrous ethanol to deionized water in the ethanol aqueous solution was 1:1. The dry film thickness of the sprayed slurry was controlled to be 70 μm. After drying, the sample to be connected was obtained.

[0081] S2, 38g anhydrous ethanol, 9g n-butanol and 5g deionized water are mixed, and then 3.5g nano carbon black N330, 0.6g layered graphene and 0.5g polyethyleneimine are added and dispersed evenly to obtain a suspension. 18g phenolic resin with a solid content of 40wt.% is added to the suspension to obtain an impregnation solution. The connecting surface of the sample to be connected is vertically immersed in the impregnation solution for impregnation and curing. The absolute pressure of the impregnation is 400Pa and the holding time is 200s. After removal, it is allowed to stand at room temperature for 35min to level. The curing temperature is 170℃ and the time is 100min to obtain a permeable layer connected sample. The permeable layer sample is kept at a temperature of argon atmosphere, heated to 340℃ at 2℃ / min and held for 50min, and then heated to 1000℃ at 2℃ / min and held for 80min to obtain a pyrolytic carbon connected sample.

[0082] S3, 3.2g of yttrium nitrate hexahydrate and 4.0g of aluminum nitrate nonahydrate were dispersed in 28g of an aqueous ethanol solution, wherein the volume ratio of deionized water to anhydrous ethanol in the aqueous ethanol solution was 7:3. 3.5g of citric acid was added and the pH was adjusted to 2.8 to obtain a complex solution. 4.5g of tetraethyl orthosilicate was added to 14g of ethanol, along with 1.5g of deionized water and 0.12g of... A hydrolysate was obtained from 1M nitric acid. The hydrolysate was added dropwise to a complexing solution, and 0.5g of boric acid was added and stirred to obtain a sol. The sol was dried, calcined, and ground. The calcination was carried out in an air atmosphere, with the temperature increased to 850℃ at 2℃ / min and held for 100min. After cooling, the sol was ground and sieved to obtain yttrium boron aluminum silicon nucleating powder. 52g of silicon dioxide, 14g of boron oxide, 9g of aluminum oxide, 7g of calcium oxide, 3g of magnesium oxide, 7g of sodium oxide, 2g of potassium oxide, 5g of zirconium oxide, 3g of titanium dioxide and 3.0g of yttrium boron aluminum silicon nucleating powder were mixed and held at 1520℃ for 80min. Then, molten glass was water-quenched and ball-milled to obtain glaze glass powder.

[0083] S4, 9g of methylphenyl silicone resin and 5g of phenolic resin were dispersed in 18g of ethyl acetate, and 0.3g of Span-80 was added to obtain an oil phase. 1.0g of PVA was dissolved in 90g of deionized water to obtain an aqueous phase. Under shear conditions, the oil phase was added to the aqueous phase to obtain an emulsion. 5g of tetraethyl orthosilicate was added dropwise to the emulsion and the pH was adjusted to 9.2. The mixture was stirred at 35℃ for 2.5h, filtered, washed, and dried to obtain silicon-oxygen-carbon ceramicized microcapsule powder. 80g of glaze glass powder, 15g of silicon carbide powder, 10g of metallic silicon powder, 2.0g of boron carbide powder, 60g of anhydrous ethanol / terpineol mixed solvent, and 0.6g of ammonium polyacrylate were ball-milled and dispersed. After dispersion, 2.0g of silicon-oxygen-carbon ceramicized microcapsule powder was added to obtain a composite glaze slurry with a solid content of 65wt.%.

[0084] S5, a diluted composite glaze is applied to the bonding surface of the pyrolytic carbon-bonded sample as a wetting layer. The solid content of the diluted composite glaze is 40 wt.%. After drying, the composite glaze is applied to form the main layer, and the dry film thickness of the main layer is 100 μm. After drying, a sealing glaze is prepared by adding titanium dioxide to the composite glaze and dispersing it evenly. The mass of titanium dioxide in the sealing glaze is 1.0% of the total solid mass of the composite glaze. The sealing glaze is applied to the surface of the main layer to form a sealing layer and dried. The dry film thickness of the sealing layer is 25 μm. After drying, a gradient glaze layer sample to be bonded is obtained. Two gradient glaze layers to be bonded are then bonded. The samples were aligned and assembled with their connecting surfaces facing each other, and placed in a hot press mold for a heat preservation process. The heat preservation process was as follows: argon atmosphere, 10 MPa axial pressure was applied, the temperature was increased to 620℃ at 3℃ / min and held for 30 min, then increased to 1510℃ at 5℃ / min and held for 25 min, and then cooled to 880℃ at 4℃ / min and then cooled to room temperature in the furnace to obtain a blank of a metal-free solder diffusion connection structure. The blank of the metal-free solder diffusion connection structure was subjected to secondary crystallization and solidification. The secondary crystallization and solidification was as follows: the temperature was increased to 820℃ at 4℃ / min and held for 70 min, then increased to 1050℃ and held for 3 h, and then cooled in the furnace to obtain a reaction sintered silicon carbide solder diffusion-free special ceramic connection structure.

[0085] Comparative Example 1

[0086] This comparative example provides a reaction-sintered silicon carbide solderless diffusion special ceramic connection structure and its preparation method. The difference between it and Example 1 is that in S1, the connection surface is not processed by femtosecond laser, and a microgroove array structure is not constructed. The connection surface is only kept as a flat surface after grinding and polishing. Other process parameters and operating conditions are exactly the same as in Example 1.

[0087] Comparative Example 2

[0088] This comparative example provides a reaction-sintered silicon carbide solderless diffusion special ceramic connection structure and its preparation method. The difference between this and Example 1 is that impregnation and curing treatment is not performed in S2, and the inert atmosphere heat preservation pyrolysis step is not performed. Pyrolytic carbon penetration layer is not constructed on the connection surface and near the surface. Other process parameters and operating conditions are exactly the same as in Example 1.

[0089] Comparative Example 3

[0090] This comparative example provides a reaction-sintered silicon carbide solderless diffusion special ceramic connection structure and its preparation method. The difference between this and Example 1 is that yttrium boron aluminum silicon nucleating powder is not added when preparing the glaze glass powder in S3. Other process parameters and operating conditions are exactly the same as in Example 1.

[0091] Comparative Example 4

[0092] This comparative example provides a reaction-sintered silicon carbide solderless diffusion special ceramic connection structure and its preparation method. The difference between this example and Example 1 is that silicon-oxygen-carbon ceramic microcapsule powder is not added when preparing the composite glaze slurry in S4. Other process parameters and operating conditions are exactly the same as in Example 1.

[0093] The performance of the reaction-sintered silicon carbide solderless diffusion special ceramic connection structures prepared in Examples 1-4 and Comparative Examples 1-4 was tested using the following methods:

[0094] The shear strength test method is ASTM C1469;

[0095] The airtightness test method is ISO 20485:2017;

[0096] The test method for residual free silicon content is ISO 21068-2 (take samples from the connection area).

[0097] The test results are shown in Table 1.

[0098] Table 1. Test results of reaction-sintered silicon carbide solderless diffusion-free special ceramic connection structures of Examples 1-4 and Comparative Examples 1-4

[0099] Example 1 80 <![CDATA[3×10 -8 ]]> 5.2 Example 2 82 <![CDATA[4×10 -8 ]]> 5.4 Example 3 81 <![CDATA[4×10 -8 ]]> 5.1 Example 4 80 <![CDATA[3×10 -8 ]]> 5.6 Comparative Example 1 43 <![CDATA[2×10 -7 ]]> 7.8 Comparative Example 2 27 <![CDATA[1×10 -6 ]]> 13.5 Comparative Example 3 57 <![CDATA[7×10⁻ 8 ]]> 6.7 Comparative Example 4 46 <![CDATA[1×10 -7 ]]> 10.3

[0100] As shown in Table 1, compared with Example 1, Comparative Example 1 showed a decrease in shear strength, a decrease in airtightness, and an increase in residual free silicon content; Comparative Example 2 showed a decrease in shear strength, a decrease in airtightness, and an increase in residual free silicon content; Comparative Example 3 showed a decrease in shear strength, a decrease in airtightness, and an increase in residual free silicon content; and Comparative Example 4 showed a decrease in shear strength, a decrease in airtightness, and an increase in residual free silicon content.

[0101] This is because, in Comparative Example 1, without femtosecond laser processing of the interface and the construction of a microgroove array structure, capillary wetting and mechanical interlocking are weakened, making it difficult for the diluted glaze slurry to penetrate near the surface. Insufficient local wetting leads to unfilled areas and micropores, limiting the molten silicon reaction front, reducing interfacial continuity, decreasing strength and airtightness, and increasing free silicon residue. In Comparative Example 2, without a pyrolytic carbon penetration layer, the interface lacks a continuous carbon source and channel. Molten silicon is more likely to solidify into a silicon phase rather than transforming into newly formed silicon carbide. The bonding becomes dominated by a glassy phase, making it prone to debonding and cracking under thermal stress, increasing leakage rate and significantly increasing free silicon. In Comparative Example 3, when the glaze glass powder does not contain yttrium boron aluminum silicon nucleating powder, the secondary crystallization nucleation density decreases, the glassy phase becomes more continuous, the probability of amorphous residual stress and microcracks increases, and the strength and airtightness deteriorate. When the composite glaze slurry in Comparative Example 4 does not contain silicon-oxygen-carbon ceramicized microcapsule powder, it lacks an additional carbon source and silicon-oxygen-carbon transition network. The reaction filling and chemical coupling of molten silicon on the pores are weakened, the stress buffer of the glaze layer decreases, and the residual free silicon and through pores increase.

[0102] The above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A method for preparing a solderless diffusion-free special ceramic connection structure of reaction-sintered silicon carbide, characterized in that, The preparation method includes: S1, the reaction-bonded silicon carbide connector is processed to specifications, ground and polished, and processed by femtosecond laser. A slurry is sprayed on the non-connecting surface to obtain the sample to be connected. S2, prepare an impregnation solution, impregnate, solidify and keep warm the sample to be bonded to obtain a pyrolytic carbon bonded sample; S3, preparation of yttrium boron aluminum silicon nucleating powder and glaze glass powder; S4, prepare silicon-oxygen-carbon ceramicized microcapsule powder, and mix it with the glaze glass powder to prepare a composite glaze slurry; S5, the joint surface of the pyrolytic carbon bonded sample is coated with diluted composite glaze as a wetting layer, and after drying, the composite glaze is coated to form the main layer. The sealing glaze is applied to the surface of the main layer to form the sealing layer, and a gradient glaze layer bonded sample is obtained. The two gradient glaze layer bonded samples are aligned and assembled and then subjected to a heat preservation process to obtain a metal-free solder diffusion bonded structure blank. After secondary crystallization and curing, a reaction sintered silicon carbide solder-free diffusion special ceramic bonded structure is obtained. The femtosecond laser processing uses a wavelength of 1020-1040 nm, a pulse width of 250-320 fs, a repetition rate of 100-300 kHz, and a surface energy of 0.15-0.45 J / cm². 2 The scanning speed is 120-350 mm / s, the number of scans is 2-6, and an orthogonal grid-like microgroove array with a groove width of 30-60 μm, a groove depth of 20-50 μm, and a groove spacing of 80-150 μm is obtained on the connecting surface. The impregnation solution is prepared by mixing anhydrous ethanol, n-butanol, deionized water, nano carbon black N330, layered graphene, polyethyleneimine and phenolic resin in a mass ratio of (30-40):(8-12):(4-8):(2-4):(0.2-0.8):(0.2-0.6):(12-20). The yttrium boron aluminum silicon nucleating powder is prepared by sol-gelling, drying, calcining and grinding yttrium nitrate hexahydrate, aluminum nitrate nonahydrate, ethanol aqueous solution, citric acid, tetraethyl orthosilicate, ethanol, deionized water, nitric acid and boric acid in a mass ratio of (2.5-3.5):(3.0-4.5):(25-35):(2.5-4.0):(3-5):(10-15):(0.8-1.8):(0.05-0.15):(0.3-0.9). The silicon-oxygen-carbon ceramicized microcapsule powder is prepared by reacting methylphenyl organosilicon resin, phenolic resin, ethyl acetate, Span-80, PVA, deionized water and tetraethyl orthosilicate in a mass ratio of (8-12):(3-6):(12-20):(0.1-0.4):(0.4-1.2):(80-120):(2-6). The composite glaze is prepared by mixing the glaze glass powder, silicon carbide powder, metallic silicon powder, boron carbide powder, anhydrous ethanol / terpineol mixed solvent, ammonium polyacrylate and the silicon-oxygen-carbon ceramicized microcapsule powder; The sealing layer is formed by sealing glaze, which is obtained by adding titanium dioxide to a composite glaze. The mass of titanium dioxide in the capping glaze is 0.2-1.5% of the total solid mass of the composite glaze.

2. The method for preparing a reaction-sintered silicon carbide solderless diffusion special ceramic connection structure according to claim 1, characterized in that, In S1: The dimensions of the specified processing are (20-30) mm × (20-30) mm × (4-8) mm, and the connecting surfaces are marked; The grinding and polishing process involves sequentially using #400-#1200 metallographic sandpaper and diamond polishing liquid to grind and polish the connecting surfaces until the surface roughness Ra is 0.2-1.0μm.

3. The method for preparing a solderless diffusion-free special ceramic connection structure of reaction-sintered silicon carbide according to claim 1, characterized in that, In S1: The slurry is prepared by dispersing hexagonal boron nitride powder and alumina powder in an ethanol aqueous solution and ball milling to obtain a slurry. The mass ratio of hexagonal boron nitride powder, alumina powder and ethanol aqueous solution is (3-5):(6-10):(35-55), and the mass ratio of anhydrous ethanol to deionized water in the ethanol aqueous solution is 1:

1.

4. The method for preparing a reaction-sintered silicon carbide solderless diffusion special ceramic connection structure according to claim 1, characterized in that, In S2: The heat preservation is performed under an argon atmosphere.

5. The method for preparing a reaction-sintered silicon carbide solderless diffusion special ceramic connection structure according to claim 4, characterized in that, In S2: The heat preservation process is as follows: argon atmosphere, temperature is increased to 300-350℃ at 2℃ / min and held for 30-60min, then temperature is increased to 850-1050℃ at 2℃ / min and held for 60-120min.

6. The method for preparing a solderless diffusion-free special ceramic connection structure of reaction-sintered silicon carbide according to claim 1, characterized in that, In S3: The glaze glass powder is prepared by mixing silicon dioxide, boron oxide, aluminum oxide, calcium oxide, magnesium oxide, sodium oxide, potassium oxide, zirconium oxide, titanium dioxide and the yttrium boron aluminum silicon nucleating powder, followed by heat preservation, water quenching and ball milling.

7. The method for preparing a reaction-sintered silicon carbide solderless diffusion special ceramic connection structure according to claim 6, characterized in that, In S3: The mass ratio of silicon dioxide, boron oxide, aluminum oxide, calcium oxide, magnesium oxide, sodium oxide, potassium oxide, zirconium oxide, titanium dioxide and yttrium boron aluminum silicon nucleating powder is (50-60): (10-16): (6-10): (4-8): (1-4): (4-8): (1-3): (3-6): (1-4): (0.5-4.0).

8. The method for preparing a reaction-sintered silicon carbide solderless diffusion special ceramic connection structure according to claim 1, characterized in that, In S4: In the composite glaze slurry, the mass ratio of glaze glass powder, silicon carbide powder, metallic silicon powder, boron carbide powder, anhydrous ethanol / terpineol mixed solvent, ammonium polyacrylate, and silicon-oxygen-carbon ceramic microcapsule powder is (60-90):(10-25):(5-12):(0.2-3.0):(40-80):(0.2-0.8):(0.3-3.0). The solid content of the composite glaze is 55-70 wt.%.

9. The method for preparing a reaction-sintered silicon carbide solderless diffusion special ceramic connection structure according to claim 1, characterized in that, In S5: The solid content of the diluted composite glaze is 30-45 wt.%.

10. The method for preparing a reaction-sintered silicon carbide solderless diffusion special ceramic connection structure according to claim 1, characterized in that, In S5: The heat preservation procedure is as follows: argon atmosphere, apply axial pressure of 2-12MPa, heat up to 550-650℃ at 3℃ / min and hold for 20-40min, then heat up to 1480-1520℃ at 5℃ / min and hold for 10-30min, then cool down to 850-950℃ at 4℃ / min and then cool down to room temperature with the furnace. The secondary crystallization and solidification process involves heating at 4℃ / min to 780-850℃ and holding for 40-80 minutes, then heating to 950-1100℃ and holding for 1-4 hours, followed by furnace cooling.

11. A reaction-sintered silicon carbide solderless diffusion special ceramic connection structure is obtained by the preparation method according to any one of claims 1-10.