A method for producing silicon carbide nanowire reinforced high temperature resistant silicone bonding layer based on diatomic catalyst
By using Fe-Zr diatomic catalyst to catalyze the pyrolysis of organosilicon resin to generate silicon carbide nanowires, the problem of insufficient mechanical strength and thermal shock resistance of high-temperature adhesives at high temperatures is solved, and a high-strength and high-toughness adhesive layer is achieved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- HARBIN INST OF TECH
- Filing Date
- 2026-03-09
- Publication Date
- 2026-06-05
AI Technical Summary
Existing high-temperature adhesives suffer from insufficient mechanical strength, high brittleness, and poor thermal shock resistance at high temperatures, making it difficult to meet the aerospace industry's demand for high-strength, high-toughness, and long-life adhesive materials.
The pyrolysis of organosilicon resin was catalyzed by Fe-Zr diatomic catalyst to generate silicon carbide nanowires with high aspect ratio in situ, forming an enhanced high-temperature resistant organosilicon adhesive layer.
It significantly improves the high-temperature bonding strength and thermal shock resistance of the adhesive layer, achieving good bonding and crack propagation resistance at 1600℃.
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Figure CN122145189A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of high-temperature resistant adhesives and ceramic materials technology, specifically relating to a method for generating a high-temperature resistant organosilicon adhesive layer based on a diatomic catalyst using silicon carbide nanowires. Background Technology
[0002] With the rapid development of aerospace technology, high-speed aircraft and other equipment face multiple extreme conditions, including high temperatures, erosion, vibration, and complex weather environments, placing higher demands on thermal protection and structural material performance. High-temperature components in aircraft typically utilize high-temperature resistant ceramics and alloys; however, due to limitations in manufacturing processes, joining technologies are often required to assemble dissimilar materials or complex components into a single unit. Traditional mechanical joining methods suffer from stress concentration and assembly complexity, making it difficult to meet the lightweight and integrated requirements of next-generation equipment. Against this backdrop, high-temperature resistant adhesives, due to their ability to achieve uniform stress transfer and efficient bonding, have become a key approach to overcoming the bottlenecks in the engineering application of high-temperature resistant materials.
[0003] Currently, traditional organic polymer adhesives (such as epoxy resins) have limited temperature resistance, typically deteriorating above 300℃ due to molecular chain pyrolysis, failing to meet long-term high-temperature service requirements. While inorganic adhesives (such as silicates and phosphates) have higher heat resistance, they suffer from brittleness, poor thermal shock resistance, and low bond strength at high temperatures. Organosilicon resins, with their unique Si-O-Si molecular chain structure, combine the processability of high-temperature polymers with the ability to transform into inorganic ceramics in situ at high temperatures, making them ideal matrix materials for high-temperature adhesives. During high-temperature pyrolysis, they can transform into SiOC ceramics, thus maintaining certain structural stability and adhesive properties at high temperatures, and possessing broad application prospects.
[0004] However, pure silicone resins and their derived SiOC ceramics still have significant shortcomings: on the one hand, the high flexibility and limited reactivity of silicone resin molecular chains result in insufficient mechanical strength after room-temperature curing and weak interfacial bonding with the substrate; on the other hand, SiOC ceramics formed by high-temperature pyrolysis are often accompanied by volume shrinkage, porosity formation, and glass phase volatilization, making the material brittle, prone to cracking, and exhibiting decreased structural stability after long-term high-temperature service, making it difficult to meet the aerospace industry's demand for high-strength, high-toughness, and long-life adhesive materials. To improve the high-temperature performance of silicone resin-based adhesives, maintain the integrity of the ceramic structure at high temperatures, and strengthen and toughen the ceramic components at high temperatures, silicone resins can be modified by macromolecules, rigid groups, inorganic nano-ions, heteroatoms, etc., which can form a uniform structure at the molecular level starting from the polymer precursor. Among these, in-situ growth of SiCnw technology is considered the most promising reinforcement method because it can achieve uniform dispersion and tight bonding of nanowires in the matrix. However, existing technologies suffer from problems such as low catalytic efficiency, insufficient SiCnw growth density, and small aspect ratio, resulting in limited reinforcement effects. Therefore, developing efficient and controllable in-situ growth catalysts and processes is key to achieving breakthroughs in the performance of high-temperature resistant adhesives. Summary of the Invention
[0005] To overcome the shortcomings of the prior art, the present invention provides a method for generating a silicon carbide nanowire-reinforced high-temperature resistant organosilicon adhesive layer based on a diatomic catalyst.
[0006] This invention significantly improves the growth efficiency, aspect ratio, and distribution uniformity of SiCnw by forming Fe-Zr diatomic catalyst in situ through one-step pyrolysis, thereby greatly enhancing the high-temperature bonding strength and thermal shock resistance of the adhesive layer.
[0007] A method for generating a silicon carbide nanowire-reinforced high-temperature resistant organosilicon adhesive layer based on a diatomic catalyst is specifically carried out according to the following steps:
[0008] I. Preparation of precursor slurry:
[0009] Iron source, zirconium source, organosilicon resin, external silicon source and external carbon source are added to an organic solvent and mixed evenly to obtain a precursor slurry;
[0010] II. Pyrolysis and Catalytic Growth:
[0011] The precursor slurry is coated between the ceramic substrates to be bonded, and then placed in a tube furnace. Under an inert atmosphere or vacuum, the tube furnace is heated from room temperature to 1400℃~1600℃ and held at this temperature. During this pyrolysis process, the iron source and zirconium source undergo ligand exchange and reaction, forming an in-situ Fe-Zr diatomic catalyst, which catalyzes the pyrolysis of organosilicon resin to produce silicon monoxide gas and carbon monoxide gas. SiCnw grows in the substrate, forming an enhanced high-temperature resistant organosilicon bonding layer, thus completing the bonding of the ceramic substrates to be bonded.
[0012] To further promote SiCnw growth, this invention introduces external silicon and carbon sources into the precursor. These external sources (silicon and carbon sources) not only provide additional reaction gases, but also optimize the adsorption performance of the catalyst and the growth kinetics of SiCnw through elemental doping, thereby achieving precise control over the quantity and morphology of SiCnw growth.
[0013] The advantages of this invention over the prior art are as follows:
[0014] This invention utilizes a Fe-Zr diatomic catalyst to achieve large-scale, uniform in-situ growth of high aspect ratio core-shell SiCnw structures in a high-temperature resistant organosilicon adhesive matrix. This method solves the problems of low efficiency of single metal catalysts and poor growth quality of SiCnw. The prepared adhesive exhibits good adhesion and crack propagation resistance at a high temperature of 1600℃. Attached Figure Description
[0015] Figure 1 The microstructure of the in-situ self-grown SiCnw catalyzed by the Fe-Zr diatomic catalyst in Example 1 is characterized. (a) and (b) are TEM images, (c) is TEM selected area electron diffraction, (d) is mapping image, and (e) and (f) are high-magnification TEM images.
[0016] Figure 2 The XPS spectra of in-situ self-grown SiCnw catalyzed by Fe-Zr diatomic catalyst in Example 1 are shown in Figure 1. (a) is the Si 2p XPS spectrum and (b) is the C 1s XPS spectrum.
[0017] Figure 3 The figures show the TG-MS curves of organosilicon resin after pyrolysis. In the figure, (a) is the temperature-dependent release curve of silicon monoxide gas, and (b) is the temperature-dependent release curve of carbon monoxide gas. Zr-Fe heterostructure promoter is Example 1, and Ferrocene promoter is Control Example 2.
[0018] Figure 4The images show SEM images of in-situ grown SiCnw in organosilicon resin. In the images, (a) and (c) are SiCnw catalyzed by ferrocene catalyst in Comparative Example 2, and (b) and (d) are SiCnw catalyzed by Fe-Zr diatomic catalyst in Example 1.
[0019] Figure 5 The figure shows the in-situ self-growth mechanism of SiCnw in silicone resin. In the figure, (a) is the SEM image of the high-temperature resistant silicone adhesive layer prepared in Example 1, (b) is the XPS spectrum of the high-temperature resistant silicone adhesive layer prepared in Example 1, and (c) is a schematic diagram of the in-situ self-growth of SiCnw.
[0020] Figure 6 SEM images of SiCnw grown in situ using different catalysts are shown. In the figure, (a) is the high-temperature resistant organosilicon adhesive layer prepared without catalyst in Comparative Example 3, (b) is the high-temperature resistant organosilicon adhesive layer prepared using FeCl3 catalyst in Comparative Example 1, (c) is the high-temperature resistant organosilicon adhesive layer prepared using ferrocene catalyst in Comparative Example 2, and (d) is the high-temperature resistant organosilicon adhesive layer prepared in Example 1.
[0021] Figure 7 SEM images of SiCnw grown in situ at different temperatures; (a) is 1300℃, (b) is 1400℃, (c) is 1500℃, and (d) is 1600℃.
[0022] Figure 8 The bonding strength of the high-temperature resistant organosilicon adhesive layer prepared without catalyst in Comparative Example 3, the high-temperature resistant organosilicon adhesive layer prepared using ferrocene catalysis in Comparative Example 2, and the high-temperature resistant organosilicon adhesive layer prepared in Example 1 is compared with that of the high-temperature resistant organosilicon adhesive layer prepared in Example 1.
[0023] Figure 9 To assess the high-temperature bonding performance of the high-temperature resistant organosilicon adhesive layer obtained by adding an external silicon source and an external carbon source in Example 2, (a) shows different contents of external silicon source and external carbon source (both ablated at 1600℃); (b) shows different temperatures (selecting silicon source and carbon source contents of 25 wt% for ablation at different temperatures). Detailed Implementation
[0024] The technical solution of the present invention will be further described below with reference to examples, but it is not limited thereto. Any modifications or equivalent substitutions to the technical solution of the present invention that do not depart from the spirit and scope of the technical solution of the present invention should be covered within the protection scope of the present invention.
[0025] Specific Implementation Method 1: This implementation method is a method for generating a silicon carbide nanowire-reinforced high-temperature resistant organosilicon adhesive layer based on a diatomic catalyst, specifically completed according to the following steps:
[0026] I. Preparation of precursor slurry:
[0027] Iron source, zirconium source, organosilicon resin, external silicon source and external carbon source are added to an organic solvent and mixed evenly to obtain a precursor slurry;
[0028] II. Pyrolysis and Catalytic Growth:
[0029] The precursor slurry is coated between the ceramic substrates to be bonded, and then placed in a tube furnace. Under an inert atmosphere or vacuum, the tube furnace is heated from room temperature to 1400℃~1600℃ and held at this temperature. During this pyrolysis process, the iron source and zirconium source undergo ligand exchange and reaction, forming an in-situ Fe-Zr diatomic catalyst, which catalyzes the pyrolysis of organosilicon resin to produce silicon monoxide gas and carbon monoxide gas. SiCnw grows in the substrate, forming an enhanced high-temperature resistant organosilicon bonding layer, thus completing the bonding of the ceramic substrates to be bonded.
[0030] Specific Implementation Method Two: This implementation method differs from Specific Implementation Method One in that the iron source mentioned in step one is one or more of ferrocene, ferric acetylacetone, ferric nitrate, ferric chloride, ferric sulfate, ferric oxalate, nonacarbonyl ferric, cyclopentadienyl iron dimer, and dodecacarbonyl triferric. The other steps are the same as in Specific Implementation Method One.
[0031] Specific Implementation Method Three: This implementation method differs from Specific Implementation Method One or Two in that the zirconium source mentioned in step one is one or more of zirconium isopropoxide, zirconium n-butoxide, zirconium acetylacetonate, zirconium oxynitrate, zirconium chloride, zirconium sulfate, ammonium zirconium carbonate, and zirconium acetate. Other steps are the same as in Specific Implementation Method One or Two.
[0032] Specific Implementation Method Four: This implementation method differs from Specific Implementation Methods One to Three in that the organic solvent mentioned in step one is one or more of xylene, cyclohexane, n-hexane, petroleum ether, tetrahydrofuran, dioxane, N,N-dimethylformamide, N-methylpyrrolidone, methanol, ethanol, isopropanol, acetone, butanone, ethyl acetate, chloroform, and dichloromethane. The other steps are the same as in Specific Implementation Methods One to Three.
[0033] Specific Implementation Method Five: This implementation method differs from Specific Implementation Methods One to Four in that: the organosilicon resin mentioned in step one is methyl silicone resin, phenyl silicone resin, methylphenyl silicone resin, zirconium hybrid silicone resin, epoxy modified silicone resin, phenolic modified silicone resin, polyester modified silicone resin, or silanol prepolymer; the silanol prepolymer is prepared from methyltrimethoxysilane, dimethyldimethoxysilane, and naphthyltrimethoxysilane. Other steps are the same as in Specific Implementation Methods One to Four.
[0034] The preparation method of the silanol prepolymer described in this embodiment is specifically carried out according to the following steps: methyltrimethoxysilane, dimethyldimethoxysilane, and naphthyltrimethoxysilane are dissolved in anhydrous ethanol at a molar ratio of (0.8~1.2):(1.1~1.5):(0.5~0.9), and then added to a three-necked flask. The mixture is heated to 55°C in an oil bath and stirred at 55°C for 1 hour. Then, hydrochloric acid aqueous solution with a pH of 4 is added dropwise. After the addition is completed, the temperature is raised to 70°C and stirred at 70°C for another 4 hours to obtain a milky white solution. After standing and separating into layers, the lower resin solution is taken out, and excess water and ethanol are removed by rotary evaporation to obtain the silanol prepolymer. The volume ratio of methyltrimethoxysilane, anhydrous ethanol, and hydrochloric acid aqueous solution is (10g~15g):(15mL~20mL):(25mL~30mL).
[0035] Specific Implementation Method Six: This implementation method differs from Specific Implementation Methods One to Five in that: the external carbon source mentioned in step one is one or more of graphite powder, carbon black, carbon nanotubes, graphene, activated carbon, sucrose, phenolic resin, asphalt, modified biochar, or biochar; the external silicon source mentioned in step one is silicon powder or modified silicon powder. Other steps are the same as in Specific Implementation Methods One to Five.
[0036] Specific Implementation Method Seven: This implementation method differs from Specific Implementation Methods One to Six in that: the mass ratio of the iron source to the zirconium source in step one is (1~10):1; the total mass fraction of the iron source and the zirconium source in the precursor slurry in step one is 4wt%~40wt%. Other steps are the same as in Specific Implementation Methods One to Six.
[0037] Specific Implementation Method Eight: The difference between this implementation method and Specific Implementation Methods One to Seven is that the mass ratio of the external silicon source and the external carbon source in step one is (0.5~2):1; the total mass fraction of the external silicon source and the external carbon source in the precursor slurry in step one is 0wt%~30wt%; the other steps are the same as those in Specific Implementation Methods One to Seven.
[0038] Specific Implementation Method Nine: This implementation method differs from Specific Implementation Methods One to Eight in that the mass fraction of the organosilicon resin mentioned in step one is 30wt%~96wt%. The other steps are the same as those in Specific Implementation Methods One to Eight.
[0039] Specific Implementation Method Ten: This implementation method differs from Specific Implementation Methods One to Nine in the following ways: the coating thickness of the precursor slurry in step two is 0.5mm to 2mm; the heat preservation time in step two is 2h to 3h; the heating rate is 2℃ / min to 5℃ / min; the cooling rate is 3℃ / min to 5℃ / min; and the inert atmosphere in step two is an argon atmosphere or a nitrogen atmosphere. Other steps are the same as in Specific Implementation Methods One to Nine.
[0040] The beneficial effects of the present invention are verified using the following embodiments:
[0041] Example 1: A method for generating a silicon carbide nanowire-reinforced high-temperature resistant organosilicon adhesive layer based on a diatomic catalyst, specifically completed according to the following steps:
[0042] I. Preparation of precursor slurry:
[0043] Iron source, zirconium source, and silanol prepolymer are added to an organic solvent and mixed evenly to obtain a precursor slurry.
[0044] The iron source mentioned in step one is ferrocene;
[0045] The zirconium source mentioned in step one is zirconium isopropoxide (CAS number is 2171-98-4).
[0046] The organic solvent mentioned in step one is anhydrous ethanol;
[0047] The preparation method of the silanol prepolymer described in step one is specifically carried out according to the following steps: methyltrimethoxysilane, dimethyldimethoxysilane, and naphthyltrimethoxysilane are dissolved in anhydrous ethanol at a molar ratio of 1:1.3:0.7, and then added to a three-necked flask. The mixture is heated to 55°C in an oil bath and stirred at 55°C for 1 hour. Then, a hydrochloric acid aqueous solution with a pH of 4 is added dropwise. After the addition is completed, the temperature is raised to 70°C, and the mixture is stirred at 70°C for another 4 hours to obtain a milky white solution. After standing and separating into layers, the lower resin solution is taken out, and excess water and ethanol are removed by rotary evaporation to obtain the silanol prepolymer. The volume ratio of methyltrimethoxysilane, anhydrous ethanol, and hydrochloric acid aqueous solution is 13.6 g:17.5 mL:27.9 mL.
[0048] The mass ratio of the iron source and the zirconium source mentioned in step one is 1:1;
[0049] The total mass fraction of iron source and zirconium source in the precursor slurry mentioned in step one is 10 wt%.
[0050] The mass fraction of silanol prepolymer in the precursor slurry described in step one is 90 wt%.
[0051] II. Pyrolysis and Catalytic Growth:
[0052] The precursor slurry is coated between the ceramic substrates to be bonded, and then placed in a tube furnace. Under argon protection, the tube furnace is heated from room temperature to 1600℃ and held for 2 hours. During this pyrolysis process, the iron source and zirconium source undergo ligand exchange and reaction, forming an in-situ Fe-Zr diatomic catalyst, which catalyzes the pyrolysis of organosilicon resin to produce silicon monoxide gas and carbon monoxide gas, and grows SiCnw in the substrate to form an enhanced high-temperature resistant organosilicon bonding layer, thus completing the bonding of the ceramic substrates to be bonded.
[0053] The heating rate in step two is 5°C / min; the cooling rate is 5°C / min.
[0054] Example 2: A method for generating a silicon carbide nanowire-reinforced high-temperature resistant organosilicon adhesive layer based on a diatomic catalyst, specifically completed according to the following steps:
[0055] I. Modified External Sources:
[0056] ① Add 3g of silicon powder to 20mL of iron tannin metal skeleton ink, ultrasonically disperse for 8h, centrifuge, filter, and then vacuum dry at 80℃ to obtain silicon powder with iron tannin coating on the surface.
[0057] The preparation method of the iron tannin metal skeleton ink described in step 1① is as follows: dissolve 1g of tannic acid in 10mL of water and stir for 30min to obtain a tannic acid solution; dissolve 1g of ferric nitrate in 10mL of water and stir for 30min to obtain a ferric nitrate solution; add 10mL of ferric nitrate solution to 10mL of tannic acid solution and stir continuously for 2h to obtain iron tannin metal skeleton ink;
[0058] ② Mix rice husks, sulfur, and melamine in a mass ratio of 4:5:5, then place them in a nitrogen atmosphere and pyrolyze them at 800℃ for 1 hour to obtain rice husk ash with N and S elements deposited on the surface.
[0059] II. Preparation of precursor slurry:
[0060] Iron source, zirconium source, silanol prepolymer, added silicon source and added carbon source are added to organic solvent and mixed evenly to obtain precursor slurry;
[0061] The iron source mentioned in step one is ferrocene;
[0062] The zirconium source mentioned in step one is zirconium isopropoxide (CAS number is 2171-98-4).
[0063] The organic solvent mentioned in step one is anhydrous ethanol;
[0064] The preparation method of the silanol prepolymer described in step one is specifically carried out according to the following steps: methyltrimethoxysilane, dimethyldimethoxysilane, and naphthyltrimethoxysilane are dissolved in anhydrous ethanol at a molar ratio of 1:1.3:0.7, and then added to a three-necked flask. The mixture is heated to 55°C in an oil bath and stirred at 55°C for 1 hour. Then, a hydrochloric acid aqueous solution with a pH of 4 is added dropwise. After the addition is completed, the temperature is raised to 70°C, and the mixture is stirred at 70°C for another 4 hours to obtain a milky white solution. After standing and separating into layers, the lower resin solution is taken out, and excess water and ethanol are removed by rotary evaporation to obtain the silanol prepolymer. The volume ratio of methyltrimethoxysilane, anhydrous ethanol, and hydrochloric acid aqueous solution is 13.6 g:17.5 mL:27.9 mL.
[0065] The external carbon source mentioned in step one is rice husk ash with N and S elements deposited on the surface;
[0066] The external silicon source mentioned in step one is silicon powder with a surface coating of iron tannin;
[0067] The mass ratio of the iron source and the zirconium source mentioned in step one is 1:1;
[0068] The total mass fraction of iron source and zirconium source in the precursor slurry mentioned in step one is 10 wt%.
[0069] The mass ratio of the external silicon source to the external carbon source mentioned in step one is 1:1;
[0070] The total mass fraction of the added silicon source and added carbon source in the precursor slurry mentioned in step one is 25 wt%.
[0071] The mass fraction of silanol prepolymer in the precursor slurry described in step one is 65 wt%.
[0072] II. Pyrolysis and Catalytic Growth:
[0073] The precursor slurry is coated between the ceramic substrates to be bonded, and then placed in a tube furnace. Under vacuum, the tube furnace is heated from room temperature to 1600℃ and held for 3 hours. During this pyrolysis process, the iron source and zirconium source undergo ligand exchange and reaction, forming an in-situ Fe-Zr diatomic catalyst. This catalyst catalyzes the pyrolysis of organosilicon resin to produce silicon monoxide gas and carbon monoxide gas, which grow SiCnw in the substrate. The silicon source and carbon source provide additional reaction gases. Furthermore, the adsorption performance of the catalyst and the growth kinetics of SiCnw can be optimized through element doping, achieving fine control of the number and morphology of SiCnw growth, forming an enhanced high-temperature resistant organosilicon bonding layer, and completing the bonding of the ceramic substrates to be bonded.
[0074] The heating rate in step two is 5°C / min; the cooling rate is 5°C / min.
[0075] Example 3: A method for generating a silicon carbide nanowire-reinforced high-temperature resistant organosilicon adhesive layer based on a diatomic catalyst, specifically carried out according to the following steps:
[0076] I. Preparation of precursor slurry:
[0077] Iron source, zirconium source, and silanol prepolymer are added to an organic solvent and mixed evenly to obtain a precursor slurry.
[0078] The iron source mentioned in step one is acetylacetone iron;
[0079] The zirconium source mentioned in step one is zirconium oxynitrate;
[0080] The organic solvent mentioned in step one is anhydrous ethanol;
[0081] The preparation method of the silanol prepolymer described in step one is specifically carried out according to the following steps: methyltrimethoxysilane, dimethyldimethoxysilane, and naphthyltrimethoxysilane are dissolved in anhydrous ethanol at a molar ratio of 1:1.3:0.7, and then added to a three-necked flask. The mixture is heated to 55°C in an oil bath and stirred at 55°C for 1 hour. Then, a hydrochloric acid aqueous solution with a pH of 4 is added dropwise. After the addition is completed, the temperature is raised to 70°C, and the mixture is stirred at 70°C for another 4 hours to obtain a milky white solution. After standing and separating into layers, the lower resin solution is taken out, and excess water and ethanol are removed by rotary evaporation to obtain the silanol prepolymer. The volume ratio of methyltrimethoxysilane, anhydrous ethanol, and hydrochloric acid aqueous solution is 13.6 g:17.5 mL:27.9 mL.
[0082] The mass ratio of the iron source to the zirconium source mentioned in step one is 2.64:1;
[0083] The total mass fraction of iron source and zirconium source in the precursor slurry mentioned in step one is 15 wt%.
[0084] The mass fraction of the silanol prepolymer mentioned in step one is 85 wt%.
[0085] II. Pyrolysis and Catalytic Growth:
[0086] The precursor slurry is coated between the ceramic substrates to be bonded, and then placed in a tube furnace. Under a nitrogen atmosphere, the tube furnace is heated from room temperature to 1600℃ and held for 2.5 hours. During this pyrolysis process, the iron source and zirconium source undergo ligand exchange and reaction, forming an in-situ Fe-Zr diatomic catalyst. This catalyst catalyzes the pyrolysis of the organosilicon resin to produce silicon monoxide gas and carbon monoxide gas, which grow SiCnw in the substrate to form an enhanced high-temperature resistant organosilicon bonding layer, thus completing the bonding of the ceramic substrates to be bonded.
[0087] The heating rate in step two is 3℃ / min; the cooling rate is 2℃ / min.
[0088] Figure 1 The microstructure of the in-situ self-grown SiCnw catalyzed by the Fe-Zr diatomic catalyst in Example 1 is characterized. (a) and (b) are TEM images, (c) is TEM selected area electron diffraction, (d) is mapping image, and (e) and (f) are high-magnification TEM images.
[0089] from Figure 1 It can be seen that: Figure 1 As shown in a and b, the SiCnw produced by pyrolysis exhibits a distinct core-shell structure, with SiC as the core and SiO2 and ZrO2 formed by pyrolysis as the outer layer. Elemental analysis confirms that it is mainly composed of Si, C, O, and Zr. Figure 1 d). Selected area electron diffraction pattern and high-magnification TEM image ( Figure 1 c) and e) show that the core-shell structure SiCnw exhibits a distinct twinning structure and stacking faults. For example... Figure 1 As shown in f, the boundary between the SiC core and the oxide layer is clear, and the oxide layer has no obvious lattice structure. The gradient interface generated by this core-shell structure is tightly filled during the ceramic densification and graphitization process, which can balance load transfer and energy absorption, thereby enhancing the high-temperature strength, toughness and fatigue resistance of the material.
[0090] Figure 2 The XPS spectra of in-situ self-grown SiCnw catalyzed by Fe-Zr diatomic catalyst in Example 1 are shown in Figure 1. (a) is the Si 2p XPS spectrum and (b) is the C 1s XPS spectrum.
[0091] XPS spectroscopy was used to analyze the surface chemical state and elemental composition of the ceramic phase. High-resolution Si 2p spectroscopy confirmed the presence of SiO2 peaks, crystalline silicon, and Si-C bonds; C 1s spectroscopy indicated the presence of CO, C=O, Si-C, and graphite peaks in the pyrolyzed hybrid silicon resin. These results indicate that a core-shell structure, SiCnw, coated with SiO2 and ZrO2, was formed inside the pyrolyzed hybrid silicon resin. This is because the Fe-Zr diatomic catalyst has a high adsorption capacity for SiO(g) and CO(g), and its heterostructure surface provides additional reaction sites, promoting the rapid conversion of pyrolysis gases into the core-shell structure SiCnw.
[0092] Figure 3 The figures show the TG-MS curves of organosilicon resin after pyrolysis. In the figure, (a) is the temperature-dependent release curve of silicon monoxide gas, and (b) is the temperature-dependent release curve of carbon monoxide gas. Zr-Fe heterostructure promoter is Example 1, and Ferrocene promoter is Control Example 2.
[0093] like Figure 3As shown in a and b, the hybrid silica resin containing the Fe-Zr diatomic catalyst exhibits significantly lower levels of SiO(g) and CO(g) in its volatile components compared to the resin containing the iron catalyst. This indicates that the Fe-Zr diatomic catalyst possesses a higher adsorption capacity for SiO(g) and CO(g). Furthermore, the number of in-situ grown SiCnw increases significantly with decreasing SiO(g) and CO(g) concentrations. This is because the Fe-Zr diatomic catalyst has a nanoflower-like surface with a larger specific surface area, providing more reaction sites for gas deposition and thus promoting its rapid conversion into SiCnw.
[0094] Figure 4 The images show SEM images of in-situ grown SiCnw in organosilicon resin. In the images, (a) and (c) are SiCnw catalyzed by ferrocene catalyst in Comparative Example 2, and (b) and (d) are SiCnw catalyzed by Fe-Zr diatomic catalyst in Example 1.
[0095] Figure 4 As shown in a and c, the SiCnw catalyzed by the ferrocene catalyst has a small number of particles with a small aspect ratio, a diameter of about 200 nm and a length of only tens of micrometers, making it difficult to effectively enhance the ceramic phase. Figure 4 Figures b and d show that the Fe-Zr diatomic catalyst catalyzes a greater number of SiCnw cells with a significantly improved aspect ratio, reaching a diameter of approximately 100 nm and a length of several hundred micrometers. The results indicate that the Fe-Zr diatomic catalyst is more conducive to the adsorption of CO(g) and SiO(g), thereby improving the growth efficiency of SiCnw cells.
[0096] Figure 5 The figure shows the in-situ self-growth mechanism of SiCnw in silicone resin. In the figure, (a) is the SEM image of the high-temperature resistant silicone adhesive layer prepared in Example 1, (b) is the XPS spectrum of the high-temperature resistant silicone adhesive layer prepared in Example 1, and (c) is a schematic diagram of the in-situ self-growth of SiCnw.
[0097] like Figure 5 As shown in Figure a, the Fe-Zr diatomic catalyst remains at the tip of SiCnw throughout the growth process, confirming that it liquefies to form a catalytic center, absorbs CO(g) and SiO(g) to promote the in-situ growth of SiCnw, and then the iron droplets gradually evaporate, leading to the refinement of SiCnw. Figure 5 XPS analysis of b showed that residual iron was mainly Fe. 3+ Fe 2+ and Fe 0The presence of these peaks, corresponding to characteristic peaks of 712.87 eV / 730.21 eV, 713.21 eV, and 725.12 eV respectively, indicates that some iron is oxidized to FeO and Fe2O3. The zirconium atoms in the Fe-Zr catalyst not only enhance the adsorption efficiency of the catalytic center for gases but also improve its thermal stability, suppress iron volatilization, and extend the growth time, thereby refining SiCnw and achieving a higher aspect ratio. Figure 5 Based on the above research, a VLS growth mechanism for promoting SiCnw growth using Fe-Zr diatomic catalysts was proposed.
[0098] Figure 6 SEM images of SiCnw grown in situ using different catalysts are shown. In the figure, (a) is the high-temperature resistant organosilicon adhesive layer prepared without catalyst in Comparative Example 3, (b) is the high-temperature resistant organosilicon adhesive layer prepared using FeCl3 catalyst in Comparative Example 1, (c) is the high-temperature resistant organosilicon adhesive layer prepared using ferrocene catalyst in Comparative Example 2, and (d) is the high-temperature resistant organosilicon adhesive layer prepared in Example 1.
[0099] from Figure 6 It can be seen that: without a catalyst ( Figure 6 a) Growth kinetics are limited, resulting in the formation of large-diameter short-cut nanorods. FeCl3 catalyst ( Figure 6 b) High-temperature agglomeration and poisoning are common, which is detrimental to SiCnw growth. Ferrocene catalyst ( Figure 6 c) Although it has good dispersibility, it has poor thermal performance and low efficiency, producing only a small amount of SiCnw. Fe-Zr diatomic catalyst ( Figure 6 d) By leveraging synergistic effects, a large number of SiCnw particles with high aspect ratio and uniform distribution are grown, effectively repairing porosity and achieving enhancement and toughening of the ceramic phase.
[0100] The growth temperature of 1600℃ in step two of Example 1 was replaced with 1300℃, 1400℃, and 1500℃, respectively; SEM images characterizing the in-situ grown SiCnw at different temperatures are shown in [reference]. Figure 7 As shown;
[0101] Figure 7 SEM images of SiCnw grown in situ at different temperatures; (a) is 1300℃, (b) is 1400℃, (c) is 1500℃, and (d) is 1600℃.
[0102] like Figure 7 As shown in Figure a, at 1300℃, the decomposition rates of SiO(g) and CO(g) are low, and only a small number of SiCnw particles with uneven diameters are observed. With increasing temperature, gas thermal motion intensifies, and the number of SiCnw particles increases significantly. At 1400℃ and 1500℃ (… Figure 7(b, c) The carbothermic reduction reaction produces more gas, promoting the growth of smaller diameter SiCnw. At 1600℃ ( Figure 7 d) With the release of a large amount of gas, the density of SiCnw increases dramatically and its aspect ratio becomes higher, resulting in a stronger reinforcing effect on the ceramic structure. However, excessively high temperatures can lead to gas supersaturation, which can easily form byproducts such as amorphous SiC, thus hindering the growth of SiCnw.
[0103] Figure 8 The bonding strength of the high-temperature resistant organosilicon adhesive layer prepared without catalyst in Comparative Example 3, the high-temperature resistant organosilicon adhesive layer prepared using ferrocene catalysis in Comparative Example 2, and the high-temperature resistant organosilicon adhesive layer prepared in Example 1 is compared with that of the high-temperature resistant organosilicon adhesive layer prepared in Example 1.
[0104] from Figure 8 It is known that after ablation at 1600℃, the bonding strength of silicone resin without a catalyst is only 2.16 MPa. The in-situ growth of SiCnw under ferrocene catalysis increases this to 2.93 MPa, but the enhancement effect is insufficient due to the limited quantity grown. In Example 1, the Fe-Zr diatomic catalyst catalyzes the growth of a large amount of SiCnw, significantly enhancing and toughening the ceramic phase, resulting in a bonding strength of 4.89 MPa and a substantial improvement in mechanical properties.
[0105] The total mass fraction of the added silicon source and the added carbon source in Example 2 was changed to 5 wt%; the mass fraction of the silanol prepolymer was changed to 85 wt%, and everything else was the same as in Example 2.
[0106] In Example 2, the total mass fraction of the added silicon source and the added carbon source was changed to 15 wt%; the mass fraction of the silanol prepolymer was changed to 75 wt%, and everything else was the same as in Example 2.
[0107] In Example 2, the total mass fraction of the added silicon source and the added carbon source was changed to 35 wt%; the mass fraction of the silanol prepolymer was changed to 55 wt%, and everything else was the same as in Example 2.
[0108] The high-temperature adhesion properties of the obtained high-temperature resistant silicone adhesive layers were tested, see [see details]. Figure 9 As shown in (a);
[0109] In Example 2, the growth temperature in step two is 1600℃; the growth temperature in step two of Example 2 is changed to 1000℃, 1200℃, and 1400℃.
[0110] The high-temperature adhesion properties of the obtained high-temperature resistant silicone adhesive layers were tested, see [see details]. Figure 9 As shown in (b);
[0111] Figure 9To assess the high-temperature bonding performance of the high-temperature resistant organosilicon adhesive layer obtained by adding an external silicon source and an external carbon source in Example 2, (a) shows different contents of external silicon source and external carbon source (both ablated at 1600℃); (b) shows different temperatures (selecting silicon source and carbon source contents of 25 wt% for ablation at different temperatures).
[0112] Figure 9 Example (a) is compared with Example 2, except that the mass fractions of the added silicon source and the added carbon source are changed;
[0113] Figure 9 Example (b) is compared with Example 2, except that the mass fractions of the added silicon source and the added carbon source are changed;
[0114] like Figure 9 As shown in (a), the adhesive performance after high-temperature ablation significantly improves with increasing silicon and carbon source content. The highest adhesive strength, reaching 9.97 MPa, is achieved after ablation at 1600℃ when the content is 25 wt%. Further increases in content lead to reduced SiCnw crystallinity due to excess silicon source, resulting in volume shrinkage; while excess carbon source reduces the crosslinking density of the inorganic network, affecting thermal stability and mechanical properties. Figure 9 As shown in (b), the bonding performance improves with increasing temperature, indicating a deeper degree of ceramization transformation. The bonding performance is significantly improved at 1600℃, corresponding to the large-scale growth of SiCnw.
Claims
1. A method for generating a silicon carbide nanowire-reinforced high-temperature resistant organosilicon adhesive layer based on a diatomic catalyst, characterized in that... The method is specifically implemented according to the following steps: I. Preparation of precursor slurry: Iron source, zirconium source, organosilicon resin, external silicon source and external carbon source are added to an organic solvent and mixed evenly to obtain a precursor slurry; II. Pyrolysis and Catalytic Growth: The precursor slurry is coated between the ceramic substrates to be bonded, and then placed in a tube furnace. Under an inert atmosphere or vacuum, the tube furnace is heated from room temperature to 1400℃~1600℃ and held at this temperature. During this pyrolysis process, the iron source and zirconium source undergo ligand exchange and reaction, forming an in-situ Fe-Zr diatomic catalyst, which catalyzes the pyrolysis of organosilicon resin to produce silicon monoxide gas and carbon monoxide gas. SiCnw grows in the substrate, forming an enhanced high-temperature resistant organosilicon bonding layer, thus completing the bonding of the ceramic substrates to be bonded.
2. The method for generating a silicon carbide nanowire-reinforced high-temperature resistant organosilicon adhesive layer based on a diatomic catalyst according to claim 1, characterized in that... The iron source mentioned in step one is one or more of ferrocene, ferric acetylacetone, ferric nitrate, ferric chloride, ferric sulfate, ferric oxalate, nonacarbonyl ferric, cyclopentadienyl iron dimer, and dodecacarbonyl triferric.
3. The method for generating a silicon carbide nanowire-reinforced high-temperature resistant organosilicon adhesive layer based on a diatomic catalyst according to claim 1, characterized in that... The zirconium source mentioned in step one is one or more of zirconium isopropoxide, zirconium n-butoxide, zirconium acetylacetonate, zirconium oxynitrate, zirconium chloride, zirconium sulfate, ammonium zirconium carbonate, and zirconium acetate.
4. The method for generating a silicon carbide nanowire-reinforced high-temperature resistant organosilicon adhesive layer based on a diatomic catalyst according to claim 1, characterized in that... The organic solvent mentioned in step one is one or more of xylene, cyclohexane, n-hexane, petroleum ether, tetrahydrofuran, dioxane, N,N-dimethylformamide, N-methylpyrrolidone, methanol, ethanol, isopropanol, acetone, butanone, ethyl acetate, chloroform, and dichloromethane.
5. The method for generating a silicon carbide nanowire-reinforced high-temperature resistant organosilicon adhesive layer based on a diatomic catalyst according to claim 1, characterized in that... The organosilicon resin mentioned in step one is methyl silicone resin, phenyl silicone resin, methylphenyl silicone resin, zirconium hybrid silicone resin, epoxy modified silicone resin, phenolic modified silicone resin, polyester modified silicone resin, or silanol prepolymer; the silanol prepolymer is prepared from methyltrimethoxysilane, dimethyldimethoxysilane, and naphthyltrimethoxysilane.
6. The method for generating a silicon carbide nanowire-reinforced high-temperature resistant organosilicon adhesive layer based on a diatomic catalyst according to claim 1, characterized in that... The external carbon source mentioned in step one is one or more of graphite powder, carbon black, carbon nanotubes, graphene, activated carbon, sucrose, phenolic resin, asphalt, modified biochar, and biochar; the external silicon source mentioned in step one is silicon powder or modified silicon powder.
7. The method for generating a silicon carbide nanowire-reinforced high-temperature resistant organosilicon adhesive layer based on a diatomic catalyst according to claim 1, characterized in that... The mass ratio of iron source to zirconium source in step one is (1~10):1; the total mass fraction of iron source and zirconium source in the precursor slurry in step one is 4wt%~40wt%.
8. The method for generating a silicon carbide nanowire-reinforced high-temperature resistant organosilicon adhesive layer based on a diatomic catalyst according to claim 1, characterized in that... The mass ratio of the added silicon source to the added carbon source in step one is (0.5~2):1; the total mass fraction of the added silicon source and carbon source in the precursor slurry in step one is 0wt%~30wt%.
9. The method for generating a silicon carbide nanowire-reinforced high-temperature resistant organosilicon adhesive layer based on a diatomic catalyst according to claim 1, characterized in that... The mass fraction of the silicone resin mentioned in step one is 30wt%~96wt%.
10. The method for generating a silicon carbide nanowire-reinforced high-temperature resistant organosilicon adhesive layer based on a diatomic catalyst according to claim 1, characterized in that... In step two, the coating thickness of the precursor slurry is 0.5 mm to 2 mm; the heat preservation time in step two is 2 h to 3 h; the heating rate is 2 °C / min to 5 °C / min; the cooling rate is 3 °C / min to 5 °C / min; and the inert atmosphere in step two is argon or nitrogen.