A method for preparing high-strength ceramics

Abstract

This invention belongs to the field of ceramic material preparation technology and discloses a method for preparing high-strength ceramics. The method uses micron-sized silicon carbide and nano-sized alumina as the base ceramic phases, adding nickel-coated alumina microspheres as a biomimetic toughening phase, combined with samarium fluoride-yttrium fluoride composite additives, nano-molybdenum powder and other sintering aids, as well as a specific molding and dispersion system and defect control agents. High-strength ceramics are obtained through biomimetic composite slurry preparation, DLP photopolymerization molding, gradient debinding, and segmented pressureless sintering. This method can prepare products with complex shapes, and the resulting ceramics have high density, high flexural strength, high fracture toughness, and excellent corrosion resistance and thermal shock resistance. They are suitable for wear-resistant parts and seals in electromechanical and petrochemical equipment, and their comprehensive performance meets the requirements of harsh working conditions.

Description

Technical Field

[0001] This invention belongs to the field of ceramic material preparation technology, and relates to a method for preparing high-strength ceramics. Background Technology

[0002] Ceramic materials, with their excellent hardness, high-temperature resistance, and chemical stability, occupy an important position in wear-resistant components (such as pump bushings) and sealing components (such as pipe sealing rings) in industries such as electromechanical and petrochemicals. As industrial equipment develops towards higher parameters, higher precision, and longer lifespans, more stringent requirements are placed on the comprehensive performance of ceramic materials. They must not only possess high mechanical strength to withstand working loads but also good toughness to resist impacts, meet the precision forming requirements of complex shapes, and maintain long-term stable service under harsh conditions such as corrosion and high temperatures. However, existing high-strength ceramic preparation technologies still have significant shortcomings in these aspects, making it difficult to fully adapt to the actual needs of industrial applications.

[0003] From the perspective of material performance synergy, existing technologies mostly improve ceramic performance through a single enhancement mechanism, leading to often irreconcilable contradictions between strength and toughness, and strength and corrosion resistance. For example, while silicon carbide-based ceramic materials can improve flexural strength through particle filling or simple whisker doping, the internal crack propagation path is singular, resulting in generally low fracture toughness and susceptibility to brittle fracture under impact or vibration loads. While alumina-zirconia ceramics offer improved toughness, their chemical corrosion resistance and high-temperature stability are insufficient, making them prone to surface corrosion in the acidic and alkaline environments common in the petrochemical industry, leading to significant performance degradation after long-term use. Furthermore, some technologies, in pursuit of high density and high strength, require extremely high sintering temperatures, which not only increase production energy consumption and costs but may also induce abnormal grain growth within the material, resulting in a decrease in the uniformity of mechanical properties.

[0004] Regarding the applicability of molding processes, traditional high-strength ceramic preparation relies heavily on compression molding or post-sintering machining. While compression molding is simple to operate, its limitations in mold structure make it difficult to produce complex, irregularly shaped parts required for electromechanical and petrochemical equipment. Furthermore, the uneven density distribution of the green body after molding makes it prone to defects such as cracking and deformation during subsequent debinding and sintering. Although post-sintering machining can correct the product shape, it damages the integrity of the material's surface microstructure, reduces surface hardness and wear resistance, and increases processing steps and costs. While ceramic 3D printing technology, which has developed in recent years, provides a new approach to preparing complex shapes, the current printing paste's dispersion stability and curing performance are difficult to balance, resulting in lower green body strength and dimensional deviations after sintering, making it difficult to meet the assembly precision requirements of precision parts.

[0005] From the perspective of operational adaptability, ceramic components for electromechanical and petrochemical equipment need to cope with the combined effects of wear, corrosion, and high temperatures in their service environment. While existing wear-resistant ceramic materials can resist wear to a certain extent, their properties are easily affected in oily or corrosive environments, resulting in low retention of mechanical properties after long-term use. On the other hand, ceramic materials that focus on corrosion resistance often have shortcomings in toughness or molding precision. For example, sealing components may not meet the sealing requirements under high-pressure conditions, making them prone to leakage problems.

[0006] In summary, the current technological bottlenecks in high-strength ceramics, particularly in areas such as synergistic performance improvement, precision forming of complex shapes, and stable adaptation to various operating conditions, have become key factors restricting their application in high-end industrial fields such as electromechanical and petrochemical industries. Therefore, developing a high-strength ceramic preparation method that can achieve synergistic optimization of strength and toughness, meet the requirements for precision fabrication of complex shapes, and adapt to harsh service conditions has significant technological value and practical necessity, and is of positive significance for promoting the performance upgrade and lifespan extension of equipment in related industrial fields. Summary of the Invention

[0007] To address the technical bottlenecks in existing high-strength ceramic preparation technologies, such as poor performance synergy, insufficient molding adaptability, and limited adaptability to operating conditions, this invention aims to provide a method for preparing high-strength ceramics. This method solves the problems of traditional ceramic materials, such as difficulty in achieving both strength and toughness, challenges in precision molding of complex shapes, and insufficient service stability under harsh electromechanical and petrochemical conditions, thereby meeting the high comprehensive performance requirements of industrial equipment for ceramic components. To achieve the above objectives, this invention provides the following technical solution.

[0008] First, the present invention provides a method for preparing high-strength ceramics, comprising the following steps:

[0009] 1) Raw material preparation: Prepare the basic ceramic phase, biomimetic toughening phase, sintering aid, molding and dispersion system and defect control agent by weight;

[0010] The basic ceramic phase includes: micron-sized silicon carbide and nano-sized alumina;

[0011] The biomimetic toughening phase is: nickel-coated alumina microspheres.

[0012] The sintering aids include: samarium fluoride-yttrium fluoride composite aids and nano molybdenum powder;

[0013] The molding and dispersion system includes: photosensitive resin, photoinitiator and compound dispersant, wherein the compound dispersant is a compound of isomeric alcohol polyoxyethylene ether and carboxymethyl cellulose;

[0014] The defect control agent includes: modified bentonite and Na2SO4·10H2O;

[0015] 2) Preparation of biomimetic composite slurry: The compound dispersant was added to the photosensitive resin and pre-stirred. The basic ceramic phase and the biomimetic toughening phase were added in sequence. After ultrasonic dispersion, nano molybdenum powder and modified bentonite were added. The mixture was ball-milled. Finally, samarium fluoride-yttrium fluoride composite additive, Na2SO4·10H2O and photoinitiator were added. The mixture was stirred to remove bubbles and obtain a homogeneous slurry.

[0016] 3) DLP photopolymerization molding: Homogeneous slurry is injected into the material tank of the DLP photopolymerization 3D printer, cured layer by layer, and then cleaned and dried to obtain a green body;

[0017] 4) Gradient degreasing: The green body is placed in a degreasing furnace, a nitrogen atmosphere is introduced, and degreasing is performed according to a preset heating program, followed by furnace cooling;

[0018] 5) Segmented pressureless sintering: The degreased green body is placed in a sintering furnace, a nitrogen atmosphere is introduced, and sintering is carried out according to a preset heating program. The green body is then cooled in the furnace to obtain high-strength ceramics.

[0019] Furthermore, in step 1) of the above preparation method, by weight:

[0020] The basic ceramic phase comprises: 45-55 parts of micron-sized silicon carbide and 15-20 parts of nano-sized alumina;

[0021] The amount of the biomimetic toughening phase added is 8-12 parts;

[0022] The sintering aid comprises: 1.5 to 2.5 parts of samarium fluoride-yttrium fluoride composite aid and 0.8 to 1.2 parts of nano molybdenum powder;

[0023] The molding and dispersion system comprises: 10-15 parts photosensitive resin, 0.3-0.5 parts photoinitiator, and 1.2-1.8 parts compound dispersant;

[0024] The defect control agent comprises 2-3 parts modified bentonite and 1-2 parts Na2SO4·10H2O.

[0025] Furthermore, in step 1) of the above preparation method, the weight ratio of samarium fluoride to yttrium fluoride in the samarium-yttrium fluoride composite additive is 1:1.2 to 1:1.5; and the weight ratio of isomeric alcohol polyoxyethylene ether to carboxymethyl cellulose in the compound dispersant is 2:1.

[0026] Furthermore, in step 1) of the above preparation method, the modified bentonite is prepared by mixing water, sodium sulfate, carboxymethyl cellulose, polyacrylamide and bentonite in a weight ratio of 30:0.2:2.5:1.5:1 to obtain modified bentonite.

[0027] Furthermore, in step 2) of the above preparation method, the pre-stirring speed is 400~600 r / min and the time is 10~20 min;

[0028] The ultrasonic dispersion has a power of 700~900W, a frequency of 18~22kHz, and a duration of 25~35min;

[0029] The grinding media for the ball milling process is zirconia beads, with a ball-to-material ratio of 3:1, a rotation speed of 280~320 r / min, and a time of 1.5~2.5 h.

[0030] The stirring speed for degassing is 180~220 r / min, and the time is 8~12 min.

[0031] Furthermore, in step 3) of the above preparation method, the exposure intensity of the DLP photopolymerization molding is 80~100mW / cm². 2 The exposure time is 8~12s / layer, and the layer thickness is 45~55μm;

[0032] The cleaning process uses an ethanol solution with a concentration of 90-98%, and the ultrasonic cleaning time is 4-6 minutes.

[0033] The drying temperature is 55~65℃ and the time is 25~35min.

[0034] Furthermore, in step 4) of the above preparation method, the flow rate of the nitrogen atmosphere is 1.5~2.5 L / min;

[0035] The preset heating program is as follows: from room temperature, the temperature is increased to 200°C at a heating rate of 0.8~1.2°C / min, and held for 1.5~2.5 hours; then, the temperature is increased to 400°C at a heating rate of 0.4~0.6°C / min, and held for 2.5~3.5 hours; finally, the temperature is increased to 600°C at a heating rate of 0.8~1.2°C / min, and held for 0.8~1.2 hours.

[0036] Furthermore, in step 5) of the above preparation method, the flow rate of the nitrogen atmosphere is 2.5~3.5 L / min;

[0037] The preset heating program is as follows: from 600℃ to 1200℃ at a heating rate of 4~6℃ / min, hold for 0.8~1.2h, then at a heating rate of 2~4℃ / min to 1600℃, hold for 1.5~2.5h, and finally at a heating rate of 1.5~2.5℃ / min to 1950℃, hold for 2.5~3.5h.

[0038] Furthermore, the high-strength ceramic is used in electromechanical equipment or petrochemical equipment.

[0039] Secondly, the present invention seeks protection for high-strength ceramic materials obtained by the above-described preparation method.

[0040] Compared with the prior art, the present invention, "a method for preparing high-strength ceramics," has the following beneficial effects:

[0041] 1. Achieving synergistic optimization of mechanical properties and density of ceramic materials

[0042] This invention effectively solves the problem of "difficulty in balancing strength and toughness" in traditional ceramics through multi-component synergistic design. As shown in Example 1, the prepared ceramic material achieves a flexural strength of 425 MPa and a fracture toughness of 12.3 MPa·m. 1 / 2 The green body has a compressive strength of 3.2 MPa and a bulk density of 3.18 g / cm³. 3 Furthermore, the density is 98.8%, and the cross-section forms a mother-of-pearl-like structure with alternating silicon carbide-alumina composite ceramic sheets and metallic nickel layers, without obvious pores and cracks. Compared with ceramic materials with a single reinforcement mechanism, this invention significantly improves fracture toughness while ensuring high bending strength, and has excellent density, providing a structural basis for the stable service of the material under load conditions.

[0043] 2. Optimize the basic ceramic phase ratio to balance performance uniformity.

[0044] This invention achieves a balanced improvement in the strength, toughness, and corrosion resistance of ceramic materials by adjusting the ratio of micron-sized silicon carbide to nano-sized alumina. As shown in Example 2, when the ratio is 50:18, the ceramic not only possesses a high flexural strength of 420 MPa but also a strength of 12.1 MPa·m. 1 / 2 The fracture toughness is excellent, and the weight loss rate after immersion in 5% H2SO4 and 10% NaOH solutions for 30 days is as low as 0.22% and 0.28%, respectively. This avoids the problem of reduced corrosion resistance caused by excessive alumina content or insufficient toughness caused by excessive silicon carbide content, making the material adaptable to complex working conditions where multiple media coexist.

[0045] 3. Precisely control the amount of biomimetic toughening phase to ensure toughening effect and density.

[0046] This invention improves the toughness of ceramics while avoiding their negative impact on density by optimizing the amount of nickel-coated alumina microspheres added. As shown in Example 3, when the amount of this biomimetic toughening phase added is 10g, the fracture toughness of the ceramic reaches 12.4MPa·m. 1 / 2The material has a bending strength of 428 MPa and a density of 98.4%. The biomimetic phase is evenly distributed in the microstructure and forms a complete "ceramic sheet-metallic nickel layer" structure. Too little addition will result in insufficient toughening, while too much will cause biomimetic phase aggregation and porosity. The optimal dosage determined by this invention can maximize the biomimetic toughening effect and ensure the material's density.

[0047] 4. Optimize the sintering aid ratio to improve sintering efficiency and product quality.

[0048] This invention effectively promotes ceramic particle diffusion, reduces sintering defects, and ensures mechanical properties by adjusting the ratio of samarium fluoride-yttrium fluoride composite additives. As shown in Example 4, when the weight ratio of the two is 1:1.3, the ceramic density reaches 98.7%, the flexural strength is 423 MPa, there are no surface cracks or deformations, and the number of internal pores is small with a diameter of <0.5 μm. Deviations from the optimal ratio can lead to insufficient densification and the appearance of microcracks, or cause local pore aggregation. The additive ratio design of this invention can achieve efficient densification under medium-temperature sintering conditions, improving product quality stability.

[0049] 5. Applicable to the specific operating conditions of electromechanical and petrochemical equipment components.

[0050] The ceramic material prepared by this invention can be tailored to meet the precision molding and operational adaptability requirements of wear-resistant parts for electromechanical equipment and seals for petrochemical equipment through targeted process adjustments. As shown in Example 5, when used for wear-resistant bushings in petrochemical pumps, the dimensional deviation is ≤ ±0.04 mm, the surface roughness Ra = 0.5 μm, and the wear rate is as low as 0.018 mm. 3 / h, after soaking in machine oil at 60℃ for 30 days, the flexural strength retention rate is 96.2%; as shown in Example 6, when used for special-shaped sealing rings in petrochemical pipelines, the dimensional tolerance is ≤±0.06mm, the flatness of the sealing surface is 0.015mm, and the acid and alkali resistance weight loss rate is as low as 0.22~0.28%, which can be adapted to the wear-resistant and oil-resistant working conditions of electromechanical equipment and the high temperature and high pressure corrosion working conditions of petrochemical equipment respectively. Detailed Implementation

[0051] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0052] Unless otherwise specified, the test methods in the following examples are conventional methods, performed according to the techniques or conditions described in the literature in this field or according to the product instructions. Unless otherwise specified, the materials and reagents used in the following examples are commercially available.

[0053] The experimental materials and instruments used in the following examples are as follows:

[0054] I. Experimental Materials

[0055] 1. Basic ceramic phase raw materials: micron-sized silicon carbide, α phase content ≥92%, particle size 5~20μm; nano-sized alumina, particle size 50~100nm;

[0056] 2. Biomimetic toughening phase raw materials: alumina microspheres, particle size 100~200μm; nickel sulfate, analytical grade, plating solution concentration 20g / L; sodium hypophosphite, analytical grade, plating solution concentration 15g / L;

[0057] 3. Sintering aid raw materials: samarium fluoride, yttrium fluoride, analytical grade; nano molybdenum powder, particle size 20~50nm;

[0058] 4. Raw materials for molding and dispersion system: photosensitive resin containing acrylate prepolymer; photoinitiator (2-hydroxy-2-methyl-1-phenylpropanone), analytical grade; isomeric alcohol polyoxyethylene ether, industrial grade, compounded with carboxymethyl cellulose; carboxymethyl cellulose, industrial grade;

[0059] 5. Defect control agent raw materials: modified bentonite, modified with sodium carbonate and polyacrylamide; Na2SO4·10H2O, analytical grade;

[0060] 6. Auxiliary detection reagents: ethanol, 95% concentration; sulfuric acid, analytical grade, prepared as 5% H2SO4 solution; sodium hydroxide, analytical grade, prepared as 10% NaOH solution.

[0061] II. Experimental Instruments

[0062] 1. Raw material preparation and processing equipment: chemical nickel plating reactor, temperature controllable (80℃), with stirring function; ultrasonic disperser, power 800W, frequency 20kHz; ball mill, grinding media is zirconia beads, ball-to-material ratio 3:1, speed 300r / min; stirring equipment, adjustable speed (200~500r / min).

[0063] 2. Molding equipment: DLP photopolymer 3D printer (Formlabs Form 3L), exposure intensity 80~100mW / cm² 2 Exposure time 8~12s / layer, layer thickness 50μm;

[0064] 3. Degreasing and sintering equipment: Degreasing furnace (ZT-1200), controlled nitrogen atmosphere (flow rate 2L / min), heating rate 0.5~1℃ / min, maximum temperature 600℃; Pressureless sintering furnace (JXYL), controlled nitrogen atmosphere (flow rate 3L / min), heating rate 2~5℃ / min, maximum temperature 1950℃;

[0065] 4. Performance testing instruments: Three-point bending tester, loading rate 0.5 mm / min, span 30 mm; Archimedes density tester, using deionized water as medium, accuracy 0.001 g / cm³. 3 Compressive strength testing machine; Scanning electron microscope (SEM, ZEISS Sigma 500); Thermal shock testing device, temperature controllable (600℃), with rapid quenching function (25℃ deionized water); Electronic balance, accuracy 0.1mg.

[0066] Example 1

[0067] This embodiment describes the preparation method of high-strength ceramics provided by the present invention.

[0068] I. Experimental Objective

[0069] The feasibility of the biomimetic structure + DLP photopolymerization molding + segmented pressureless sintering technology solution provided by this invention was verified. The basic raw material ratio and process parameters were determined, and the bending strength, fracture toughness, density, and compressive strength of the obtained high-strength ceramic were tested.

[0070] II. Test Methods

[0071] (a) Raw material preparation

[0072] Basic ceramic phase: 50g of micron-sized silicon carbide with an α phase content ≥92% and a particle size of 5~20μm; 18g of nano-sized alumina with a particle size of 50~100nm;

[0073] Biomimetic toughening phase: 10g of nickel-coated alumina microspheres were prepared by chemical nickel plating (alumina microspheres with a particle size of 100~200μm, plating solution containing 20g / L nickel sulfate and 15g / L sodium hypophosphite, pH=8.0, reaction temperature 80℃ for 2h, and the thickness of the nickel coating layer was measured to be 5~8μm by scanning electron microscopy).

[0074] Sintering aids: Prepare 2g of samarium fluoride-yttrium fluoride composite aid (the weight ratio of samarium fluoride to yttrium fluoride is 1:1.3); 1g of nano-molybdenum powder with a particle size of 20~50nm;

[0075] Molding and dispersion system: 12g of photosensitive resin containing acrylate prepolymer; 0.4g of photoinitiator 2-hydroxy-2-methyl-1-phenylpropanone; 1.5g of compound dispersant (isomeric alcohol polyoxyethylene ether to carboxymethyl cellulose mass ratio 2:1).

[0076] Defect control agent: 2.5g of modified bentonite was used. Modification method: water, sodium sulfate, carboxymethyl cellulose, polyacrylamide and bentonite were mixed in a weight ratio of 30:0.2:2.5:1.5:1, stirred at 300r / min for 2h at 50℃, allowed to stand for 12h, dried and pulverized, and passed through a 200-mesh sieve; 1.5g of Na2SO4·10H2O.

[0077] (II) Preparation steps

[0078] Preparation of biomimetic composite slurry: The compound dispersant was added to the photosensitive resin and pre-stirred at 500 r / min for 15 min. Micron-sized silicon carbide, nano-sized alumina, and nickel-coated alumina microspheres were added in sequence. The mixture was ultrasonically dispersed at 800 W and 20 kHz for 30 min. After adding nano-molybdenum powder and modified bentonite, the mixture was ball-milled at 300 r / min for 2 h using zirconia beads as the grinding medium (ball-to-material ratio 3:1). Finally, the composite additive, Na2SO4·10H2O, and photoinitiator were added, and the mixture was stirred at 200 r / min for 10 min to remove air bubbles, resulting in a mixed slurry.

[0079] DLP photopolymerization molding: using a Formlabs Form 3L printer, with an exposure intensity of 90mW / cm². 2 Exposure time 10s / layer, layer thickness 50μm, layer-by-layer curing and molding, after molding, ultrasonic cleaning with 95% ethanol for 5min, drying at 60℃ for 30min to obtain green body;

[0080] Gradient degreasing: Place the green body in a degreasing furnace with a nitrogen flow rate of 2L / min; heating program: from room temperature to 200℃ at 1℃ / min and hold for 2h, to 400℃ at 0.5℃ / min and hold for 3h, to 600℃ at 1℃ / min and hold for 1h, then cool with the furnace;

[0081] Segmented pressureless sintering: The degreased blank is placed in a sintering furnace with a nitrogen flow rate of 3L / min; the heating program is as follows: from 600℃ to 1200℃ at 5℃ / min and hold for 1h, then to 1600℃ at 3℃ / min and hold for 2h, then to 1950℃ at 2℃ / min and hold for 3h, and finally cooled in the furnace to obtain the finished product.

[0082] (III) Performance Testing

[0083] The flexural strength was tested according to GB / T 6569-2006, the fracture toughness was tested according to GB / T 23806-2009, the density was tested according to the Archimedes method, the compressive strength of the green body was tested according to GB / T 5072-2019, and the microstructure was observed by scanning electron microscopy.

[0084] III. Test Results

[0085] Mechanical properties: flexural strength 425 MPa, fracture toughness 12.3 MPa·m1 / 2 The compressive strength of the green body is 3.2 MPa;

[0086] Density properties: Bulk density 3.18 g / cm³ 3 Density 98.8%;

[0087] Microstructure: The cross-section forms a mother-of-pearl-like structure with alternating silicon carbide-alumina composite ceramic sheets and metallic nickel layers, without obvious pores and cracks.

[0088] IV. Experimental Conclusions

[0089] The basic raw material ratio and process parameters in this embodiment are feasible, and the resulting ceramic material has high density and excellent properties such as bending strength, fracture toughness, and green body compressive strength.

[0090] Example 2

[0091] This embodiment describes the optimization of the basic ceramic phase ratio.

[0092] I. Experimental Objective

[0093] The weight ratio of micron-sized silicon carbide to nano-sized alumina in the basic ceramic phase was optimized to clarify the influence of this ratio on the flexural strength, fracture toughness and other performance indicators of high-strength ceramics, determine the optimal ratio range of the two, and balance the strength and toughness of the ceramic matrix.

[0094] II. Test Methods

[0095] (a) Variable Design

[0096] Based on Example 1 (micron-sized silicon carbide: nano-sized alumina = 50:18), three variable groups were set:

[0097] Variable group 1: 48g of micron-sized silicon carbide and 20g of nano-sized alumina (ratio 48:20);

[0098] Variable group 2: 50g of micron-sized silicon carbide and 18g of nano-sized alumina (ratio 50:18, baseline);

[0099] Variable group 3: 53g of micron-sized silicon carbide and 15g of nano-sized alumina (ratio 53:15);

[0100] The remaining raw materials (10g of nickel-coated alumina microspheres, 2g of samarium fluoride-yttrium fluoride composite additive, etc.) and their proportions, preparation process parameters (slurry preparation, DLP photopolymerization molding, gradient degreasing, segmented sintering procedure) are the same as in Example 1, except that the proportions of micron-sized silicon carbide and nano-sized alumina in the basic ceramic phase are different.

[0101] (ii) Performance testing

[0102] Bending strength, fracture toughness, and density were determined according to the same standards as in Example 1; corrosion resistance was assessed by immersing the ceramic matrix in 5% H2SO4 and 10% NaOH solutions for 30 days, respectively, and calculating the weight loss rate; the microstructure of the ceramic matrix was observed using a scanning electron microscope.

[0103] III. Test Results

[0104] The performance test results are shown in Table 1.

[0105] Table 1. Performance test results of different base ceramic phase ratios

[0106]

[0107] IV. Experimental Conclusions

[0108] When the ratio of micron-sized silicon carbide to nano-sized alumina is 50:18, the ceramic exhibits the best overall performance: flexural strength of 420 MPa and fracture toughness of 12.1 MPa·m. 1 / 2 The density was 98.6%, and the weight loss rates after immersion in 5% H2SO4 and 10% NaOH were as low as 0.22% and 0.28%, respectively, demonstrating a balance of strength, toughness, and corrosion resistance. This indicates that at this ratio, silicon carbide particles and alumina particles form a dense interwoven structure, which not only provides a corrosion-resistant framework for silicon carbide but also inhibits crack propagation through the dispersed distribution of alumina, achieving a balance between strength and toughness. When the ratio was 48:20, the excessive alumina content led to a decrease in corrosion resistance (the acid and alkali weight loss rates increased to 0.32% and 0.35%, respectively). When the ratio was 53:15, the excessive silicon carbide content reduced the fracture toughness to 11.2 MPa·m. 1 / 2 However, the toughness is insufficient. This indicates that the ceramic material prepared by the technical solution of this invention has excellent fracture toughness and excellent corrosion resistance. At the same time, the silicon carbide-based system has high-temperature stability and can be used for high-temperature operating conditions of electromechanical and petrochemical equipment.

[0109] Example 3

[0110] This embodiment describes the optimization of the amount of biomimetic toughening phase used.

[0111] I. Experimental Objective

[0112] The amount of nickel-coated alumina microspheres (biomimetic toughening phase) added was optimized to clarify its influence on the fracture toughness, density and flexural strength of high-strength ceramics, and to determine the optimal addition range, so as to avoid insufficient toughening effect due to too low content or excessive content affecting ceramic densification due to too high content.

[0113] II. Test Methods

[0114] (a) Variable Design

[0115] Based on Example 1 (10g of nickel-coated alumina microspheres), three variable groups were set up:

[0116] Variable group 1: 8g of nickel-coated alumina microspheres;

[0117] Variable group 2: 10g of nickel-coated alumina microspheres (standard);

[0118] Variable group 3: 12g of nickel-coated alumina microspheres;

[0119] The remaining raw materials and proportions, as well as the preparation process parameters (slurry preparation, DLP photopolymerization molding, gradient degreasing, and segmented sintering) are consistent with those in Example 1.

[0120] (ii) Performance testing

[0121] Bending strength, fracture toughness, and density were measured using the same standards as in Example 1; the distribution and bonding state of the biomimetic phase in the microstructure were observed using scanning electron microscopy.

[0122] III. Test Results

[0123] The performance test results are shown in Table 2.

[0124] Table 2. Performance test results for different amounts of biomimetic toughening phase

[0125]

[0126] IV. Experimental Conclusions

[0127] When the amount of nickel-coated alumina microspheres added is 10g, the alumina microspheres are uniformly distributed and the nickel layer is tightly bonded to the substrate, forming a continuous ceramic sheet-metal layer toughened structure. When the amount is excessive, the microspheres agglomerate, destroying the structural continuity and leading to an increase in porosity.

[0128] Example 4

[0129] This embodiment describes the optimization of the sintering aid ratio.

[0130] I. Experimental Objective

[0131] The weight ratio of samarium fluoride-yttrium fluoride composite additives was optimized to clarify the influence of this ratio on the density, flexural strength and sintering efficiency of high-strength ceramics. The optimal ratio range of the composite additives was determined, and the sintering temperature was reduced to decrease energy consumption.

[0132] II. Test Methods

[0133] (a) Variable Design

[0134] Based on Example 1 (samarium fluoride - yttrium fluoride weight ratio 1:1.3), three variable groups were set up:

[0135] Variable group 1: Samarium fluoride - Yttrium fluoride weight ratio 1:1.2;

[0136] Variable group 2: Samarium fluoride - Yttrium fluoride weight ratio 1:1.3 (benchmark);

[0137] Variable group 3: Samarium fluoride - Yttrium fluoride weight ratio 1:1.5;

[0138] The remaining raw materials and proportions, as well as the preparation process parameters (slurry preparation, DLP photocuring, gradient degreasing, and segmented sintering) are the same as in Example 1, except that the internal proportions of the composite additives are different.

[0139] (ii) Performance testing

[0140] Density and flexural strength were measured using the same standards as in Example 1; the presence of defects such as cracks and deformation on the ceramic surface after sintering was recorded; and the distribution of pores inside the ceramic was observed using a scanning electron microscope.

[0141] III. Test Results

[0142] The performance test results are shown in Table 3.

[0143] Table 3. Performance test results of different sintering aid ratios

[0144]

[0145] IV. Experimental Conclusions

[0146] When the weight ratio of samarium fluoride to yttrium fluoride is 1:1.3, a low-melting-point eutectic phase can be formed, which promotes the diffusion sintering of silicon carbide and alumina particles. When yttrium fluoride is insufficient, the amount of eutectic phase is small, resulting in insufficient densification. When yttrium fluoride is excessive, a brittle second phase is easily formed, which leads to porosity.

[0147] Example 5

[0148] This embodiment describes the use of high-strength ceramic materials prepared by the method of the present invention for wear-resistant parts of electromechanical equipment.

[0149] I. Experimental Objective

[0150] To verify the applicability of the technical solution of this invention in preparing wear-resistant parts for electromechanical equipment (taking wear-resistant bushings for petrochemical pumps as an example), and to clarify whether the product molding accuracy, wear resistance and oil resistance meet the working conditions of electromechanical equipment.

[0151] II. Test Methods

[0152] (I) Product Design and Manufacturing

[0153] Product specifications: To manufacture wear-resistant bushings with a diameter of φ50mm×10mm (parts for simulating petrochemical pumps), with an inner hole tolerance of ±0.05mm and a surface roughness requirement of Ra≤0.8μm;

[0154] Raw materials and processes: The baseline raw material formula of Example 1 is used, except that a fine grinding process is added after the segmented sintering (precision grinding with diamond grinding wheel, grinding machine speed of 3000 r / min, feed rate of 5 μm / time). The rest of the preparation process (slurry preparation, DLP photopolymerization molding, gradient degreasing, segmented sintering) is the same as that of Example 1.

[0155] (ii) Performance testing

[0156] Forming accuracy: The deviations in the inner diameter, outer diameter, and length of the bushing are detected using a coordinate measuring machine;

[0157] Wear resistance: Refer to GB / T 12444-2006 "Metallic materials wear test method", use a pin-disc wear tester, load 50N, speed 200r / min, wear time 2h, and calculate the wear amount;

[0158] Oil resistance: The bushing was immersed in 46# machine oil and kept at 60℃ for 30 days. The appearance changes were observed and the retention rate of bending strength after immersion was tested.

[0159] III. Test Results

[0160] The performance test results are shown in Table 4.

[0161] Table 4. Performance test results of wear-resistant parts of electromechanical equipment

[0162]

[0163] IV. Experimental Conclusions

[0164] The wear-resistant bushing for electromechanical equipment prepared in this embodiment exhibits excellent performance: dimensional deviation ≤ ±0.04mm, surface roughness Ra=0.5μm, meeting the precision fit requirements of electromechanical equipment; and wear rate as low as 0.018mm. 3 / h, after soaking in 60℃ machine oil for 30 days, the flexural strength retention rate is 96.2%, with no appearance defects, and it can be used for wear-resistant and oil-resistant working conditions of petrochemical pumps and other electromechanical equipment.

[0165] Example 6

[0166] This embodiment describes the use of high-strength ceramic materials prepared by the method of the present invention for sealing components of petrochemical equipment.

[0167] I. Experimental Objective

[0168] To verify the applicability of the technical solution of this invention in preparing sealing parts for petrochemical equipment (taking irregularly shaped sealing rings as an example), and to clarify whether the product molding precision, corrosion resistance and sealing performance meet the requirements of petrochemical equipment under high temperature and corrosive conditions.

[0169] II. Test Methods

[0170] (I) Product Design and Manufacturing

[0171] Product specifications: To manufacture irregularly shaped sealing rings (simulating petrochemical pipeline sealing components) with an outer diameter of 80mm × inner diameter of 50mm × thickness of 10mm, with a dimensional tolerance of ±0.1mm and a sealing surface flatness of ≤0.02mm;

[0172] Raw materials and processes: The base raw material formulation of Example 1 is used. The interlayer bonding parameters are optimized during DLP curing (exposure time is extended to 12s / layer). After segmented sintering, a sealing surface polishing process is added (diamond polishing paste, particle size W1, polishing pressure 0.2MPa is used). The rest of the process is the same as in Example 1.

[0173] (ii) Performance testing

[0174] Molding accuracy: The flatness of the sealing surface is detected by a laser interferometer, and the dimensional tolerance is detected by a coordinate measuring machine;

[0175] Corrosion resistance: The sealing ring was immersed in 5% H2SO4 and 10% NaOH solutions (simulating petrochemical corrosive media) respectively, and kept at 60℃ for 30 days. The weight loss rate was calculated.

[0176] III. Test Results

[0177] The performance test results are shown in Table 5.

[0178] Table 5. Performance test results of seals for petrochemical equipment

[0179]

[0180] IV. Experimental Conclusions

[0181] The sealing ring for petrochemical equipment prepared in this embodiment has excellent performance: dimensional tolerance ≤ ±0.06mm, flatness of sealing surface 0.015mm, meeting the requirements for precise sealing fit; the weight loss rate after soaking in 5% H2SO4 and 10% NaOH is as low as 0.22% and 0.28% respectively, making it suitable for use in petrochemical equipment.

[0182] The embodiments described above are only some, not all, of the embodiments of the present invention. The detailed description of the embodiments of the present invention is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments. All other embodiments obtained by those skilled in the art through related deductions and substitutions based on the inventive concept, without inventive effort, are within the scope of protection of the present invention.

Claims

1. A method of producing a high-strength ceramic, characterized by, The method comprises the following steps: 1) raw material preparation: prepare the base ceramic phase, biomimetic toughening phase, sintering aid, forming and dispersion system and defect control agent according to weight parts; The base ceramic phase comprises micron-sized silicon carbide and nanometer-sized aluminum oxide; The biomimetic toughening phase is surface nickel-coated alumina microspheres; The sintering aid comprises samarium fluoride-yttrium fluoride composite aid and nanometer molybdenum powder; The forming and dispersion system comprises photosensitive resin, photoinitiator and compound dispersant, wherein the compound dispersant is a compound of isomeric alcohol polyoxyethylene ether and carboxymethyl cellulose; The defect control agent comprises modified bentonite and Na2SO4·10H2O; 2) biomimetic composite slurry preparation: pre-stir the compound dispersant in the photosensitive resin, sequentially add the base ceramic phase and the biomimetic toughening phase, add nanometer molybdenum powder and modified bentonite after ultrasonic dispersion, perform ball milling treatment, finally add samarium fluoride-yttrium fluoride composite aid, Na2SO4·10H2O and photoinitiator, stir to remove bubbles, and obtain a homogeneous slurry; 3) DLP photocuring forming: inject the homogeneous slurry into a DLP photocuring 3D printer tank, perform layer-by-layer curing forming, clean and dry after forming, and obtain a green body; 4) gradient debinding: place the green body in a debinding furnace, introduce a nitrogen atmosphere, perform debinding treatment according to a preset temperature rising program, and cool down with the furnace; 5) segmented pressureless sintering: place the debound body in a sintering furnace, introduce a nitrogen atmosphere, perform sintering treatment according to a preset temperature rising program, and cool down with the furnace, to obtain a high-strength ceramic; In step 1), according to weight parts: The base ceramic phase comprises 45-55 parts of micron-sized silicon carbide and 15-20 parts of nanometer-sized aluminum oxide; The addition amount of the biomimetic toughening phase is 8-12 parts; The sintering aid comprises 1.5-2.5 parts of samarium fluoride-yttrium fluoride composite aid and 0.8-1.2 parts of nanometer molybdenum powder; The forming and dispersion system comprises 10-15 parts of photosensitive resin, 0.3-0.5 parts of photoinitiator and 1.2-1.8 parts of compound dispersant; The defect control agent comprises 2-3 parts of modified bentonite and 1-2 parts of Na2SO4·10H2O; In the samarium fluoride-yttrium fluoride composite aid, the weight ratio of samarium fluoride to yttrium fluoride is 1:1.2-1:1.5; and in the compound dispersant, the weight ratio of isomeric alcohol polyoxyethylene ether to carboxymethyl cellulose is 2:

1.

2. The production method according to claim 1, characterized by, In step 1), the preparation method of the modified bentonite is as follows: mix water, sodium sulfate, carboxymethyl cellulose, polyacrylamide and bentonite according to a weight ratio of 30:0.2:2.5:1.5:1, and obtain the modified bentonite.

3. The preparation method according to claim 1, characterized in that, In step 2), the stirring speed of the pre-stirring is 400-600 r / min, and the stirring time is 10-20 min; The ultrasonic dispersion power is 700-900 W, the frequency is 18-22 kHz, and the time is 25-35 min; The grinding medium of the ball milling treatment is zirconia beads, the ball-to-material ratio is 3:1, the stirring speed is 280-320 r / min, and the time is 1.5-2.5 h; The stirring speed for removing bubbles is 180-220 r / min, and the time is 8-12 min.

4. The method of claim 1, wherein, In step 3), the exposure intensity of the DLP light curing forming is 80-100 mW / cm 2 , the exposure time is 8-12 s per layer, and the layer thickness is 45-55 μm. The cleaning uses an ethanol solution with a concentration of 90-98%, and the ultrasonic cleaning time is 4-6 min. The drying temperature is 55-65℃, and the time is 25-35 min.

5. The preparation method according to claim 1, characterized in that, In step 4), the flow rate of the nitrogen atmosphere is 1.5-2.5 L / min; The preset temperature rising program is: rising from room temperature to 200℃ at a temperature rising rate of 0.8-1.2℃ / min, holding for 1.5-2.5 h, then rising to 400℃ at a temperature rising rate of 0.4-0.6℃ / min, holding for 2.5-3.5 h, and finally rising to 600℃ at a temperature rising rate of 0.8-1.2℃ / min, holding for 0.8-1.2 h.

6. The method of claim 1, wherein, In step 5), the flow rate of the nitrogen atmosphere is 2.5-3.5 L / min; The preset temperature rising program is: rising from 600℃ to 1200℃ at a temperature rising rate of 4-6℃ / min, holding for 0.8-1.2 h, then rising to 1600℃ at a temperature rising rate of 2-4℃ / min, holding for 1.5-2.5 h, and finally rising to 1950℃ at a temperature rising rate of 1.5-2.5℃ / min, holding for 2.5-3.5 h.

7. A high-strength ceramic material obtained by the preparation method of any one of claims 1-6.

8. The high strength ceramic material of claim 7, wherein, The high-strength ceramic material is used in electromechanical equipment or petrochemical equipment.

Images