A nano-silicon carbide whisker toughened silicon carbide ring and a preparation method thereof

Abstract

The application discloses a nano silicon carbide whisker toughened silicon carbide ring and a preparation method thereof, and relates to the technical field of ceramic materials. The nano silicon carbide whisker toughened silicon carbide ring comprises the following raw materials in parts by mass: 70-90 parts of silicon carbide matrix powder, 4-12 parts of nano silicon carbide whisker, 1-4 parts of interface modification component, 2-8 parts of carbon source sintering promoter, 0.5-5 parts of composite sintering aid, 1-6 parts of forming binder, 0.1-1.5 parts of dispersing agent and 0.2-2 parts of lubricant. The nano silicon carbide whisker and the interface modification component with the multilayer core-shell structure are introduced, so that the dispersion uniformity of the whisker in the silicon carbide matrix is effectively improved, the interface bonding state between the whisker and the matrix is optimized, and sintering densification is promoted, and therefore the fracture toughness, wear resistance, thermal shock resistance and comprehensive service life of the silicon carbide ring are remarkably improved.

Description

Technical Field

[0001] This invention relates to the field of ceramic materials technology, specifically to a nano-silicon carbide whisker-toughened silicon carbide ring and its preparation method. Background Technology

[0002] Silicon carbide ceramics possess excellent high-temperature resistance, high hardness, good wear resistance, and chemical stability, and are widely used in high-end industrial fields such as mechanical seal rings, chemical pumps and valves, semiconductor processing equipment, and aerospace.

[0003] However, the inherent high brittleness and low fracture toughness of silicon carbide ceramics make them prone to sudden fracture under impact loads or thermal stress, severely limiting their reliable application in critical structural components. To improve the fracture toughness of silicon carbide ceramics, existing technologies often employ whiskers, fibers, lamellar particles, or second-phase particles for toughening. Among these, silicon carbide whiskers exhibit good chemical compatibility and thermal matching with the silicon carbide matrix, and can improve material toughness through mechanisms such as crack deflection, whisker pull-out, bridging, and energy dissipation. However, nano-silicon carbide whiskers have a large specific surface area and high surface energy, making them prone to agglomeration and difficult to uniformly disperse in the matrix. Simultaneously, the interfacial interaction between whiskers and the silicon carbide matrix is ​​difficult to precisely control; an excessively strong interface weakens the pull-out toughening effect, while an excessively weak interface reduces load transfer capacity, thus limiting the stable performance of the toughening effect.

[0004] In addition, conventional sintering aids or single interface modifiers cannot simultaneously achieve dispersion, interfacial bonding, sintering densification, and high-temperature stability. The resulting silicon carbide rings still suffer from insufficient toughness, poor structural uniformity, and limited service life under strong wear and thermal shock environments.

[0005] Therefore, there is an urgent need to provide a silicon carbide ring material and its preparation method that can improve the dispersion of nano-silicon carbide whiskers, optimize the interface structure between whiskers and silicon carbide matrix, promote sintering densification, and enhance comprehensive mechanical properties. Summary of the Invention

[0006] The purpose of this invention is to address the problems in existing technologies, such as the easy agglomeration of nano-silicon carbide whiskers, the difficulty in controlling the interfacial interaction between whiskers and the silicon carbide matrix, and the limited toughness and reliability of silicon carbide rings. This invention provides a silicon carbide ring toughened with nano-silicon carbide whiskers and its preparation method. By introducing nano-silicon carbide whiskers and interface-modifying components, this silicon carbide ring improves the uniformity of whisker dispersion in the silicon carbide matrix, optimizes the interfacial bonding state between the whiskers and the matrix, and promotes sintering densification, thereby improving the fracture toughness, wear resistance, thermal shock resistance, and overall service life of the silicon carbide ring.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A silicon carbide ring toughened with nano-silicon carbide whiskers, wherein the silicon carbide ring comprises the following raw materials by weight: 70-90 parts of silicon carbide matrix powder, 4-12 parts of nano-silicon carbide whiskers, 1-4 parts of interface modifying component, 2-8 parts of carbon source sintering accelerator, 0.5-5 parts of composite sintering aid, 1-6 parts of molding binder, 0.1-1.5 parts of dispersant, and 0.2-2 parts of lubricant.

[0008] Furthermore, the interface modification component is a multi-layer core-shell structure powder with surface-activated hexagonal boron nitride microplates as the plate-like core layer, a silane grafted layer as the inner shell layer, a boric acid, melamine, and nano-silica condensate as the reactive intermediate shell layer, and a carbon source protective layer formed by phenolic resin and glucose as the outer shell layer.

[0009] Furthermore, the interface modification component comprises the following raw materials by mass: 20-35 parts hexagonal boron nitride microplates, 5-15 parts nano silica sol, 3-6 parts boric acid, 2-8 parts melamine, 1-4 parts γ-aminopropyltriethoxysilane, 2-6 parts tetraethyl orthosilicate, 2-5 parts phenolic resin, and 1-3 parts glucose.

[0010] Furthermore, the preparation method of the interface-modified component includes the following steps: S1: Add the hexagonal boron nitride microplates to a mixture of anhydrous ethanol and deionized water, control the solid-liquid mass ratio to be 1:(12-25), add glacial acetic acid to adjust the pH to 4.0-5.5, stir at 800-1200 r / min for 30-60 min, and then ultrasonically disperse at 20-40 kHz for 40-90 min to obtain a surface-activated hexagonal boron nitride dispersion.

[0011] S2: Add the γ-aminopropyltriethoxysilane dropwise to the surface-activated hexagonal boron nitride dispersion at a rate of 0.5-2.0 mL / min. After the addition is complete, raise the temperature to 55-75℃ and react at 600-1000 r / min for 2-5 h to allow the silane to hydrolyze, condense, and graft onto the surface of the hexagonal boron nitride microplates, thus obtaining an aminosilane-grafted boron nitride dispersion.

[0012] S3: The boric acid and melamine are dissolved in deionized water at 70-90℃ to form a boron-nitrogen precursor solution. The tetraethyl orthosilicate and nano-silica sol are mixed and added to the boron-nitrogen precursor solution. The pH is adjusted to 8.0-9.5 with ammonia. The mixture is then added to the aminosilane-grafted boron nitride dispersion at a dropping rate of 1-4 mL / min. The reaction temperature is controlled at 60-80℃, the stirring speed is 700-1100 r / min, and the reaction time is 3-6 h. The boric acid-melamine complex, silica sol, and tetraethyl orthosilicate hydrolysis products are deposited and condensed in situ on the aminosilane grafted layer to obtain a boron-nitrogen-silicon reactive intermediate shell dispersion.

[0013] S4: Add the phenolic resin and glucose to the boron-nitrogen-silicon reactive intermediate shell dispersion, adjust the pH to 6.5-7.5, stir at 70-85℃ for 1-3 hours, and then concentrate under reduced pressure at 90-110℃ to form a continuous carbon source protective layer outside the boron-nitrogen-silicon reactive intermediate shell, thus obtaining a wet gel-like complex.

[0014] S5: The wet gel-like composite is dried at 80-100℃ for 8-16h, pulverized and passed through a 200-400 mesh sieve, then heated to 650-850℃ at 2-6℃ / min under a nitrogen atmosphere and held for 1-3h. After cooling, the interface-modified component is obtained.

[0015] Furthermore, the particle size of the hexagonal boron nitride microflakes is 0.5-3.0 μm.

[0016] Furthermore, the silica mass fraction of the nano silica sol is 20-40%, and the average particle size is 10-80 nm.

[0017] Furthermore, the silicon carbide matrix powder includes black silicon carbide powder and β-silicon carbide powder, with a mass ratio of black silicon carbide powder to β-silicon carbide powder of (5-10):1. The average particle size of the black silicon carbide powder is 1-5 μm, and the average particle size of the β-silicon carbide powder is 30-500 nm.

[0018] Furthermore, the diameter of the nano-silicon carbide whiskers is 50-500 nm, the length is 10-50 μm, and the aspect ratio is 20-80.

[0019] Furthermore, the carbon source sintering accelerator is at least one of phenolic resin, carbon black, glucose, sucrose, and asphalt powder.

[0020] Furthermore, the composite sintering aid is at least one of boron carbide, alumina, and yttrium oxide.

[0021] Furthermore, the molding adhesive is at least one of polyvinyl alcohol and polyethylene glycol.

[0022] Furthermore, the dispersant is at least one of ammonium polyacrylate, polyvinylpyrrolidone, and sodium carboxymethyl cellulose.

[0023] Furthermore, the lubricant is at least one of stearic acid, zinc stearate, paraffin emulsion, and oleic acid.

[0024] A method for preparing nano-silicon carbide whisker-toughened silicon carbide rings includes the following steps: A1: Add the nano-silicon carbide whiskers, interface-modifying components, and dispersant to a solvent, control the solid content to be 15-35 wt%, stir at 600-1000 r / min for 30-60 min, and ultrasonically disperse at 20-40 kHz for 30-90 min to obtain a whisker-interface-modifying component pre-dispersion.

[0025] A2: Add the silicon carbide matrix powder, carbon source sintering accelerator and composite sintering aid to the whisker-interface modified component pre-dispersion liquid, and ball mill at 200-450 r / min for 4-12 h to obtain composite slurry.

[0026] A3: Add a pre-mixed solution of molding binder and lubricant to the composite slurry, stir at 50-80℃ for 0.5-2h, filter through a 100-200 mesh sieve, and spray granulate at an inlet temperature of 160-220℃ and an outlet temperature of 80-110℃ to obtain granulated powder.

[0027] A4: The granulated powder is loaded into a ring mold and cold isostatically pressed at 80-180MPa to obtain a silicon carbide cyclohexane preform.

[0028] A5: The silicon carbide cyclocarbide blank is heated to 300-600℃ at 0.5-3℃ / min and held for 1-4h for degreasing, then heated to 1900-2200℃ at 2-6℃ / min and held for 1-4h for sintering, and after cooling, it is ground to obtain a nano-silicon carbide whisker-toughened silicon carbide ring.

[0029] Furthermore, in step A1, the solvent is anhydrous ethanol, deionized water, or a mixture of both.

[0030] Furthermore, in step A5, the sintering is carried out under an argon atmosphere or vacuum conditions.

[0031] Furthermore, the nano-silicon carbide whisker-toughened silicon carbide rings are used in the manufacture of special ceramic products such as ceramic valves and ceramic cylinder valve plates.

[0032] This formulation addresses the issues of nano-silicon carbide whisker agglomeration, interface control, and sintering densification through a multi-component synergistic approach. The silicon carbide matrix powder forms a continuous framework and enhances sintering activity; the nano-silicon carbide whiskers, as a homogeneous reinforcing phase, improve fracture toughness through crack deflection, bridging, and pull-out. The interface modification component uses surface-activated hexagonal boron nitride microflakes as the core layer, covered by a silane graft layer, a boric acid / melamine / nano-silica reactive intermediate shell layer, and a carbon source protective layer. Boron nitride improves stress distribution, the silane layer enhances compatibility and inhibits agglomeration, the intermediate shell layer forms a continuous and uniform transition interface, and the carbon source protective layer, in synergy with the carbon source sintering promoter, provides activated carbon to promote densification and inhibit oxide residue. The addition of composite sintering aids and a dispersion, bonding, and lubrication system achieves a continuous synergistic effect between uniform molding and sintering promotion, ultimately improving the fracture toughness, wear resistance, thermal shock resistance, and service life of the silicon carbide rings.

[0033] Compared with the prior art, the beneficial effects of the present invention are: 1. By introducing interface-modifying components, this invention significantly improves the dispersion uniformity of nano-silicon carbide whiskers in a silicon carbide matrix and optimizes the interfacial bonding state between the whiskers and the matrix. This allows toughening mechanisms such as whisker pull-out, bridging, and deflection to be stably utilized during crack propagation, thereby significantly improving the flexural strength and fracture toughness of silicon carbide rings.

[0034] 2. Thanks to the regulatory effect of the multi-layer core-shell interface modification components on the micro-stress distribution, and the synergistic promotion of sintering densification by the carbon source sintering promoter and the composite sintering aid, the silicon carbide ring surface structure obtained by this invention is more uniform and dense, exhibiting better structural stability under high temperature rapid cooling and heating cycle conditions, and its wear resistance and thermal shock resistance are superior to the existing technology level.

[0035] 3. This invention enables nano-silicon carbide whiskers to stably exert a toughening effect through a continuous synergistic mechanism of dispersion improvement, interface control, sintering promotion and molding homogenization. This avoids the precipitous performance deterioration caused by a single toughening method or improper process parameters. Thus, while ensuring high mechanical strength, it significantly improves the service life and reliability of silicon carbide rings under strong wear and thermal shock environments. Attached Figure Description

[0036] Figure 1 This is a SEM image of the interface-modified component prepared in Preparation Example 1 of the present invention. Detailed Implementation

[0037] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are merely some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0038] Preparation Example 1 Preparation of interface-modifying components: 1. Raw material components: 28 parts hexagonal boron nitride microplates, 10 parts nano silica sol, 4.5 parts boric acid, 5 parts melamine, 2.5 parts γ-aminopropyltriethoxysilane, 4 parts tetraethyl orthosilicate, 3.5 parts phenolic resin, and 2 parts glucose.

[0039] The deionized water and anhydrous ethanol used in the preparation method are process solvents for dispersion, dissolution, washing and crosslinking. They are basically removed after drying and are not used as a limit for the content of dry basis components.

[0040] The hexagonal boron nitride microsheets have a D50 particle size of 2μm and were purchased from Xinyang Defupeng New Materials Co., Ltd.

[0041] The nano-silica sol has a silica mass fraction of 30%, an average particle size of 15nm, and was purchased from Hubei Zhenghe Technology Co., Ltd., model JA-30.

[0042] The phenolic resin is a thermosetting phenolic resin with a free phenol content of ≤5%, and was purchased from Shandong Longhui Chemical Co., Ltd.

[0043] 2. Preparation method: S1: 28 parts by mass of hexagonal boron nitride micro flakes were added to a mixture of 260 parts by mass of anhydrous ethanol and 160 parts by mass of deionized water, with a mass ratio of hexagonal boron nitride micro flakes to the mixture of 1:15; 10% by mass of glacial acetic acid was added at 25°C in air atmosphere to adjust the pH of the system to 4.8, and the mixture was stirred at 1000 r / min for 45 min; then it was ultrasonically dispersed at 30 kHz for 60 min, with the temperature of the dispersion controlled at 28°C during the ultrasonication process, to obtain a surface-activated hexagonal boron nitride dispersion.

[0044] S2: At 25°C and in air atmosphere, 2.5 parts of γ-aminopropyltriethoxysilane were added dropwise to the surface-activated hexagonal boron nitride dispersion obtained in step S1 at a dropping rate of 1.0 mL / min; after the addition was completed, the temperature was raised to 65°C and reacted at 800 r / min for 3 h to allow the γ-aminopropyltriethoxysilane to hydrolyze, condense and graft onto the surface of the hexagonal boron nitride microplates, thus obtaining an aminosilane-grafted boron nitride dispersion.

[0045] S3: Add 4.5 parts boric acid and 5 parts melamine to 80 parts deionized water and stir at 85°C for 40 min to form a boron-nitrogen precursor solution; separately, mix 4 parts tetraethyl orthosilicate and 10 parts nano-silica sol, stir at 600 r / min for 20 min, and add to the boron-nitrogen precursor solution, then add 25% ammonia water to adjust the pH of the mixture to 8.8; then add the mixture dropwise to the aminosilane-grafted boron nitride dispersion obtained in step S2 at a dropping rate of 2.0 mL / min, controlling the reaction temperature at 70°C and the stirring speed at 900 r / min during the dropwise addition; after the dropwise addition is completed, continue to react at 70°C for 4 h to allow the boric acid-melamine complex, nano-silica sol, and tetraethyl orthosilicate hydrolysis products to be deposited and condensed in situ on the aminosilane grafted layer, obtaining a boron-nitrogen-silica reactive intermediate shell dispersion.

[0046] S4: Add 3.5 parts phenolic resin and 2 parts glucose to the boron-nitrogen-silica reactive intermediate shell dispersion obtained in step S3, and adjust the pH to 7.0 with 10% glacial acetic acid. Stir for 2 hours at 80℃, 800 r / min, and air atmosphere to uniformly coat the outer side of the boron-nitrogen-silica reactive intermediate shell with phenolic resin and glucose. Then concentrate under reduced pressure at 100℃ and -0.08 MPa for 2.5 hours until the solid content of the system is 70 wt%, obtaining a wet gel-like complex.

[0047] S5: Spread the wet gel-like composite obtained in step S4 to a thickness of 8 mm, and dry it at 90°C for 12 h to reduce its moisture content to below 1.0 wt%. After pulverizing the dried material, pass it through a 300-mesh sieve. Place the sieved powder in a nitrogen atmosphere with a nitrogen flow rate of 1.0 L / min, heat it to 750°C at a rate of 4°C / min, and hold it at that temperature for 2 h. After the holding time is completed, cool it to below 60°C in the furnace to obtain the interface-modified component.

[0048] from Figure 1 As can be seen, the figure shows a typical and relatively uniformly distributed micron-scale sheet-like structure, which is highly consistent with the characteristics of the hexagonal boron nitride microplates used as the sheet-like core layer in Preparation Example 1. At the same time, it can be observed that the surface and edges of these two-dimensional sheet-like particles have certain attachments, roughness and thickening phenomena, and are no longer the original absolutely smooth cleavage surfaces of pure boron nitride.

[0049] Comparative Preparation Example 1 The interface modification component was prepared by referring to the preparation method in Preparation Example 1, except that the hexagonal boron nitride microplates were replaced with an equal mass of alumina microplates, and everything else remained the same as in Preparation Example 1.

[0050] Comparative Preparation Example 2 The preparation of the interface-modifying component was carried out in accordance with the preparation method in Preparation Example 1, except that γ-aminopropyltriethoxysilane was replaced with an equal mass of γ-glycidoxypropyltrimethoxysilane, and the rest remained the same as in Preparation Example 1.

[0051] Comparative preparation example 3 The preparation of the interface modification component was carried out in accordance with the preparation method in Preparation Example 1, except that the melamine was replaced with an equal mass of urea, and everything else remained the same as in Preparation Example 1.

[0052] Comparative preparation example 4 The preparation of the interface-modifying component was carried out in accordance with the preparation method in Preparation Example 1, except that the phenolic resin was replaced with an equal mass of polyvinyl alcohol, and everything else remained the same as in Preparation Example 1.

[0053] Comparative preparation example 5 The preparation of the interface-modified component is the same as in Preparation Example 1, except that in step S5, heating to 750°C at 4°C / min and holding for 2 hours is replaced with heating to 300°C at 4°C / min and holding for 2 hours. All other steps are the same as in Preparation Example 1.

[0054] Example 1

[0055] Preparation of a nano-silicon carbide whisker-reinforced silicon carbide ring: 1. Raw material components: The composition includes 80 parts silicon carbide matrix powder, 8 parts nano-silicon carbide whiskers, 3 parts interface modifier, 5 parts carbon source sintering accelerator, 2 parts composite sintering aid, 4 parts molding binder, 0.8 parts dispersant, and 0.7 parts lubricant. The silicon carbide matrix powder comprises 70 parts of black silicon carbide powder and 10 parts of β-silicon carbide powder. The average particle size of the black silicon carbide powder is 3 μm, and it was purchased from Zhengzhou Haixu Abrasive Co., Ltd. The average particle size of the β-silicon carbide powder is 300 nm, and it was purchased from Xi'an Boer New Materials Co., Ltd.

[0056] The silicon carbide nano whiskers have a diameter of 400 nm, a length of 20 μm, and an aspect ratio of 50. They were purchased from Zixing Silicon Nano New Materials Co., Ltd.

[0057] The interface modification component is the interface modification component prepared in Preparation Example 1.

[0058] The carbon source sintering accelerator is composed of 3 parts phenolic resin and 2 parts carbon black.

[0059] The composite sintering aid consists of 1.2 parts boron carbide, 0.5 parts alumina, and 0.3 parts yttrium oxide.

[0060] The molding adhesive is polyvinyl alcohol.

[0061] The dispersant is polyvinylpyrrolidone.

[0062] The lubricant is zinc stearate.

[0063] 2. Preparation method: A1: Add 8 parts of nano-silicon carbide whiskers, 3 parts of interface modification components and 0.8 parts of polyvinylpyrrolidone to 35.4 parts of anhydrous ethanol, and control the solid content of the pre-dispersion liquid to 25 wt%; stir at 800 r / min for 45 min at 25℃ and in air atmosphere; then ultrasonically disperse at 30 kHz for 60 min, and control the temperature at 25℃ during the ultrasonication process to obtain the whisker-interface modification component pre-dispersion liquid.

[0064] A2: Add 70 parts of black silicon carbide powder, 10 parts of β-silicon carbide powder, 3 parts of phenolic resin, 2 parts of carbon black, 1.2 parts of boron carbide, 0.5 parts of alumina, and 0.3 parts of yttrium oxide to the pre-dispersion liquid of whisker-interface modified components obtained in step A1; mix by ball milling at 350 r / min for 8 h at 25 °C and in air atmosphere using zirconia grinding balls to obtain composite slurry.

[0065] A3: Add 4 parts of polyvinyl alcohol to 20 parts of deionized water and stir at 90°C for 60 min to prepare a polyvinyl alcohol aqueous solution; add the polyvinyl alcohol aqueous solution to the composite slurry obtained in step A2, and then add 0.7 parts of zinc stearate, and stir at 65°C, 600 r / min and air atmosphere for 1 h; then filter through a 150 mesh sieve, and spray granulate the filtered slurry at an inlet temperature of 190°C and an outlet temperature of 95°C to obtain granulated powder.

[0066] A4: The granulated powder obtained in step A3 is loaded into a ring mold and pre-pressed at 25°C for 2 minutes to remove air; then it is cold isostatically pressed at 150MPa and held for 5 minutes to obtain a silicon carbide cyclohexane preform.

[0067] A5: The silicon carbide cyclocarbide blank obtained in step A4 is placed in an argon atmosphere with an argon flow rate of 1.2 L / min; it is heated to 500℃ at a rate of 1℃ / min and held for 2 hours for degreasing, and then heated to 2100℃ at a rate of 4℃ / min and held for 3 hours for sintering. After sintering, it is cooled in the furnace to below 80℃ in an argon atmosphere and then removed. After grinding, a nano-silicon carbide whisker-toughened silicon carbide ring is obtained.

[0068] Example 2

[0069] The preparation of a nano-silicon carbide whisker-toughened silicon carbide ring is carried out according to the preparation method in Example 1, except that the carbon source sintering promoter is replaced with 3 parts glucose and 2 parts phenolic resin, and the rest is the same as in Example 1.

[0070] Example 3

[0071] The preparation of a nano-silicon carbide whisker-toughened silicon carbide ring is carried out according to the preparation method in Example 1, except that the molding binder polyvinyl alcohol is replaced with an equal mass of polyethylene glycol, and the rest is the same as in Example 1.

[0072] Example 4

[0073] The preparation of a nano-silicon carbide whisker-toughened silicon carbide ring is carried out according to the preparation method in Example 1, except that the dispersant polyvinylpyrrolidone is replaced with an equal mass of ammonium polyacrylate, and the rest is the same as in Example 1.

[0074] Example 5

[0075] The preparation of a nano-silicon carbide whisker-toughened silicon carbide ring is carried out according to the preparation method in Example 1, except that the lubricant zinc stearate is replaced with an equal mass of stearic acid, and the rest is the same as in Example 1.

[0076] Comparative Examples 1-5 The preparation of a nano-silicon carbide whisker-toughened silicon carbide ring is carried out by referring to the preparation method in Example 1, except that the interface modification component is replaced with an equal mass of the interface modification component prepared in Comparative Preparation Examples 1-5, and the rest is the same as in Example 1.

[0077] Comparative Example 6 The preparation of a silicon carbide ring toughened with nano-silicon carbide whiskers is carried out by referring to the preparation method in Example 1, except that the nano-silicon carbide whiskers are replaced with equal parts by mass of nano-silicon carbide particles with an average particle size of 200 nm, and the rest is the same as in Example 1.

[0078] Comparative Example 7 The preparation of a nano-silicon carbide whisker-toughened silicon carbide ring is carried out by referring to the preparation method in Example 1, except that the β-silicon carbide powder is replaced with an equal amount of black silicon carbide powder, and the rest is the same as in Example 1.

[0079] Comparative Example 8 The preparation of a nano-silicon carbide whisker-toughened silicon carbide ring is carried out according to the preparation method in Example 1, except that the sintering in step A5, which involves heating to 2100°C at 4°C / min and holding for 3 hours, is replaced by heating to 1000°C at 4°C / min and holding for 3 hours. The rest is the same as in Example 1.

[0080] Performance testing: 1. Bending strength test: The test was conducted in accordance with GB / T6569-2006. The silicon carbide ring specimens prepared in each embodiment and comparative example were processed into cuboid specimens with a length of 40 mm and a width and thickness of 3 mm. The specimens were subjected to bending loading using a universal testing machine at room temperature. The maximum load at which the specimen broke was recorded, and the bending strength was calculated.

[0081] 2. Fracture toughness test: The test was conducted in accordance with GB / T23806-2025. The silicon carbide ring specimens prepared in each embodiment and comparative example were processed into specimens with dimensions of 3mm×4mm×36mm and a span L of 30mm. A single-sided pre-crack with a depth of about 1 / 3 of the specimen thickness was pre-made in the thickness direction of the specimen. A three-point bending test was performed on a universal testing machine at a loading rate of 0.05mm / min. The maximum load at which the specimen fractured was recorded, and the fracture toughness was calculated.

[0082] 3. Wear resistance test: The test was conducted in accordance with GB / T45880-2025. The silicon carbide ring samples prepared in each example and comparative example were processed into flat plate samples. The test surface was ground, polished, cleaned and dried and then fixed on the test table. Ceramic balls of the same material and diameter were used as the grinding pair. Under the dry friction conditions at room temperature, the ball-disc friction and wear test was carried out with the same normal load, rotation speed, friction radius and friction time. After the test, the wear amount was measured and the wear rate was calculated.

[0083] 4. Thermal Shock Resistance Test: The test was conducted according to GB / T37246-2018. The silicon carbide ring samples prepared in each example and comparative example were placed in a high-temperature furnace and heated to the set thermal shock temperature (600℃) and held at that temperature until the sample temperature was uniform. Afterward, the samples were quickly transferred to room temperature water for cooling and immersed for 5 minutes before being removed. The sample surface was visually inspected for cracks, chips, or peeling, supplemented by observation with a 20x magnifying glass. The number of thermal cycles required to produce visible cracks or damage on the sample surface was taken as the thermal shock resistance test.

[0084]

[0085] As can be seen from the performance test results in Table 1, all embodiments using the complete formula and specific preparation method of this invention maintained the highest levels in flexural strength, fracture toughness, and thermal shock resistance, while exhibiting the lowest wear rate, demonstrating excellent and stable comprehensive mechanical and thermal properties. In contrast, when the raw material structure of the interface modification component was changed or replaced, when nano-whiskers were replaced with ordinary particles, or when the silicon carbide matrix ratio was changed, the mechanical strength and thermal shock resistance of the material deteriorated to varying degrees, and the wear resistance also worsened. Especially when the sintering temperature was significantly reduced, the various performance indicators of the material showed a precipitous deterioration, and the mechanical structure almost failed. This fully verifies that the nano-silicon carbide whiskers, multi-layer core-shell interface modification components, and scientific sintering process in this invention play an indispensable key role in synergistically improving the fracture toughness and wear resistance of silicon carbide rings.

[0086] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A nano-silicon carbide whisker-toughened silicon carbide ring, characterized in that, The silicon carbide ring comprises the following raw materials by weight: 70-90 parts silicon carbide matrix powder, 4-12 parts nano silicon carbide whiskers, 1-4 parts interface modifying component, 2-8 parts carbon source sintering accelerator, 0.5-5 parts composite sintering aid, 1-6 parts molding binder, 0.1-1.5 parts dispersant, and 0.2-2 parts lubricant; The interface modification component is a multi-layer core-shell structure powder with a plate-like core layer of surface-activated hexagonal boron nitride microplates, an inner shell layer of silane grafting layer, a reactive intermediate shell layer of boric acid, melamine, and nano-silica condensate, and an outer shell layer of carbon source protection layer formed by phenolic resin and glucose.

2. The nano-silicon carbide whisker-toughened silicon carbide ring according to claim 1, characterized in that, The interface modification component comprises the following raw materials by mass: 20-35 parts hexagonal boron nitride microplates, 5-15 parts nano silica sol, 3-6 parts boric acid, 2-8 parts melamine, 1-4 parts γ-aminopropyltriethoxysilane, 2-6 parts tetraethyl orthosilicate, 2-5 parts phenolic resin, and 1-3 parts glucose.

3. The nano-silicon carbide whisker-toughened silicon carbide ring according to claim 2, characterized in that, The preparation method of the interface-modified component includes the following steps: S1: Add the hexagonal boron nitride microplates to a mixture of anhydrous ethanol and deionized water, control the solid-liquid mass ratio to be 1:(12-25), add glacial acetic acid to adjust the pH to 4.0-5.5, stir at 800-1200 r / min for 30-60 min, and then ultrasonically disperse at 20-40 kHz for 40-90 min to obtain a surface-activated hexagonal boron nitride dispersion; S2: Add the γ-aminopropyltriethoxysilane dropwise to the surface-activated hexagonal boron nitride dispersion at a rate of 0.5-2.0 mL / min. After the addition is complete, raise the temperature to 55-75℃ and react at 600-1000 r / min for 2-5 h to obtain an aminosilane-grafted boron nitride dispersion. S3: The boric acid and melamine are dissolved in deionized water at 70-90℃ to form a boron-nitrogen precursor solution. The tetraethyl orthosilicate and nano-silica sol are mixed and added to the boron-nitrogen precursor solution. The pH is adjusted to 8.0-9.5 with ammonia. The mixture is then added to the aminosilane-grafted boron nitride dispersion at a dropping rate of 1-4 mL / min. The reaction temperature is controlled at 60-80℃, the stirring speed is 700-1100 r / min, and the reaction time is 3-6 h to obtain a boron-nitrogen-silicon reactive intermediate shell dispersion. S4: Add the phenolic resin and glucose to the boron-nitrogen-silicon reactive intermediate shell dispersion, adjust the pH to 6.5-7.5, stir at 70-85℃ for 1-3 hours, and then concentrate under reduced pressure at 90-110℃ to obtain a wet gel-like complex. S5: The wet gel-like composite is dried at 80-100℃ for 8-16h, pulverized and passed through a 200-400 mesh sieve, then heated to 650-850℃ at 2-6℃ / min under a nitrogen atmosphere and held for 1-3h. After cooling, the interface-modified component is obtained.

4. The nano-silicon carbide whisker-toughened silicon carbide ring according to claim 1, characterized in that, The silicon carbide matrix powder includes black silicon carbide powder and β-silicon carbide powder, with a mass ratio of black silicon carbide powder to β-silicon carbide powder of (5-10):

1.

5. The nano-silicon carbide whisker-toughened silicon carbide ring according to claim 1, characterized in that, The diameter of the silicon carbide nano whiskers is 50-500 nm.

6. The nano-silicon carbide whisker-toughened silicon carbide ring according to claim 1, characterized in that, The carbon source sintering accelerator is at least one of phenolic resin, carbon black, glucose, sucrose, and asphalt powder. The composite sintering aid is at least one of boron carbide, alumina, and yttrium oxide.

7. The nano-silicon carbide whisker-toughened silicon carbide ring according to claim 1, characterized in that, The molding adhesive is at least one of polyvinyl alcohol and polyethylene glycol.

8. The nano-silicon carbide whisker-toughened silicon carbide ring according to claim 1, characterized in that, The dispersant is at least one of ammonium polyacrylate, polyvinylpyrrolidone, and sodium carboxymethyl cellulose. The lubricant is at least one of stearic acid, zinc stearate, paraffin emulsion, and oleic acid.

9. A method for preparing a nano-silicon carbide whisker-toughened silicon carbide ring according to any one of claims 1-8, characterized in that, Includes the following steps: A1: Add the nano-silicon carbide whiskers, interface-modifying components and dispersant to a solvent, control the solid content to be 15-35wt%, stir at 600-1000r / min for 30-60min, and ultrasonically disperse at 20-40kHz for 30-90min to obtain a whisker-interface-modifying component pre-dispersion. A2: Add the silicon carbide matrix powder, carbon source sintering accelerator and composite sintering aid to the whisker-interface modified component pre-dispersion liquid, and ball mill and mix at 200-450 r / min for 4-12 h to obtain composite slurry; A3: Add a pre-mixed solution of molding binder and lubricant to the composite slurry, stir at 50-80℃ for 0.5-2h, filter through a 100-200 mesh sieve, and spray granulate at an inlet temperature of 160-220℃ and an outlet temperature of 80-110℃ to obtain granulated powder. A4: The granulated powder is loaded into a ring mold and cold isostatically pressed at 80-180MPa to obtain a silicon carbide cyclohexane preform. A5: The silicon carbide cyclocarbide blank is heated to 300-600℃ at 0.5-3℃ / min and held for 1-4h for degreasing, then heated to 1900-2200℃ at 2-6℃ / min and held for 1-4h for sintering, and after cooling, it is ground to obtain a nano-silicon carbide whisker-toughened silicon carbide ring.

10. The method for preparing a nano-silicon carbide whisker-toughened silicon carbide ring according to claim 9, characterized in that, In step A1, the solvent is anhydrous ethanol, deionized water, or a mixture of both. In step A5, the sintering is carried out under an argon atmosphere or vacuum conditions.

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