High-temperature-resistant ceramic formula and preparation process thereof

Abstract

The invention relates to the field of ceramic materials, in particular to a high-temperature-resistant ceramic formula which comprises the following components in percentage by mass: 45-60% of alpha-aluminum oxide; 15 to 25% of stabilized zirconia (3YSZ); 8-15% of beta-phase silicon carbide; 5-10% of alpha-phase silicon nitride; 2-5% of rare earth oxide; 20-35% of ceramic polishing waste; and 0.5-2% of a nano reinforcing agent. Through alpha-AlO / 3YSZ / beta-SiC / alpha-SiN multiphase synergy, a 1600 DEG C stable interpenetrating network structure is formed, the highest use temperature is increased, and the high-temperature creep resistance is excellent; ceramic polishing waste is introduced, raw material cost is reduced, and waste utilization rate is increased; through dynamic vacuum gradient control and laser remelting post-treatment, the yield is increased; a compact layer (porosity is smaller than or equal to 0.5%) of 50 microns is formed on the surface through laser remelting, and the material has triple functions of high temperature resistance, wave absorption and corrosion resistance in combination with a Yion implantation technology.

Description

Technical Field

[0001] The present invention relates to the technical field of ceramic materials, and in particular to a high-temperature resistant ceramic formula and a preparation process thereof. Background Art

[0002] With the rapid development of modern industry and science and technology, extremely high requirements are placed on the high-temperature resistance of materials in many fields such as aerospace, energy and chemical industry, and metallurgy. Ceramic materials have great potential in high-temperature environment applications due to their advantages such as high hardness, high wear resistance, and good chemical stability.

[0003] At present, common methods to improve the high-temperature resistance of ceramics include selecting high-melting-point raw materials and adding special additives. However, existing technologies still have many shortcomings in practical applications. For example, although ceramics prepared with some formulas can withstand higher temperatures, the preparation process is complex and costly, making it difficult to achieve large-scale production. Although some processes are simple, the high-temperature resistance of the prepared ceramics is limited and they cannot work stably in extremely high-temperature environments.

[0004] Therefore, those skilled in the art provide a high-temperature resistant ceramic formula and a preparation process thereof to solve the problems raised in the above background technology. Summary of the Invention

[0005] In order to solve the above technical problems, the present invention provides a high temperature resistant ceramic formula and a preparation process thereof. A high temperature resistant ceramic formula, consisting of the following components in percentage by mass: α-alumina 45-60%; Stabilized zirconia (3YSZ) 15-25%; β-phase silicon carbide 8-15%; α-phase silicon nitride 5-10%; Rare earth oxides 2-5%; Ceramic polishing waste 20-35%; Nano-enhancer 0.5-2%; The rare earth oxide is a mixture of La2O3 and Y2O3 in a molar ratio of 1:1-3:1; The nano-enhancer is a SiC / TiO2 core-shell structure particle with a core diameter of 50-80 nm and a shell thickness of 5-15 nm. The SiC / TiO2 core-shell structure particle is synthesized by a sol-gel method, and the TiO2 shell is an anatase type. The interface bonding strength with the SiC core is ≥200 MPa, as tested by nanoindentation.

[0006] Preferably, the ceramic polishing waste is industrial-grade alumina or silicon carbide polishing waste.

[0007] Preferably, the D50 of the α-alumina is ≤1 μm and the α phase content is ≥98%, the grain size of the stabilized zirconia (3YSZ) is 0.3-0.8 μm, and the tetragonal phase content is ≥85%.

[0008] A preparation process for high-temperature resistant ceramics comprises the following steps: Raw material pretreatment: Ceramic polishing waste is soaked in hydrofluoric acid to remove the surface glass phase, and the nanopowder is milled by plasma to D90≤200nm; Gradient sintering: including pre-firing stage, transition stage and final firing stage, controlling the heating rate and atmosphere in different temperature ranges; Post-processing: Laser surface remelting is used to generate a densified surface layer, and ion implantation is performed to strengthen the surface.

[0009] Preferably, the concentration of the hydrofluoric acid immersion is 5%, the immersion time is 30 minutes, the liquid-to-solid ratio is 3:1, the temperature is 25±2° C., and the reaction is terminated when the conductivity monitoring value is stable at ≤50 μS / cm.

[0010] Preferably, the ball-to-material ratio of the plasma ball mill is 4:1, the ball milling time is 6 hours, the atmosphere is argon protection, the purity is ≥99.99%, and the oxygen content is ≤10ppm.

[0011] Preferably, the temperature range of the pre-firing stage is 800-1100° C., the heating rate is 2-5° C. / min, and the atmosphere is nitrogen with a purity of ≥99.9%.

[0012] Preferably, the temperature range of the transition section is 1100-1450°C, the heating rate is 1-2°C / min, and the atmosphere is a hydrogen-argon mixture with H2 accounting for 3-8% by volume.

[0013] Preferably, the temperature range of the final firing stage is 1450-1680°C, the heating rate is 0.5-1.2°C / min, and the vacuum degree is ≤10⁻³Pa.

[0014] Preferably, the power of the laser surface remelting is 2 kW, the scanning speed is 8 mm / s, and a 50 μm densified surface layer is generated.

[0015] Preferably, the ion implantation is surface implantation of Y⁺ ions with an implantation energy of 80keV and a dose of 5×10¹ 7 ions / cm², temperature control 400±10℃, vacuum degree ≤5×10⁻³Pa.

[0016] The technical effects and advantages of the present invention are as follows: 1. Breakthrough in heat resistance Through the multi-phase synergy of α-Al2O3 / 3YSZ / β-SiC / α-Si3N4, a stable interpenetrating network structure at 1600℃ is formed, which increases the maximum operating temperature and has excellent high-temperature creep resistance. 2. Cost and environmental benefits The introduction of ceramic polishing waste (activated by hydrofluoric acid) reduces the cost of raw materials.

[0017] 3. Industrial adaptability optimization Through dynamic vacuum gradient control and laser remelting post-processing, the yield rate is improved and it is compatible with conventional atmosphere sintering furnace production.

[0018] 4. Multifunctional expandability The surface is laser remelted to form a 50μm dense layer (porosity ≤ 0.5%), and combined with Y⁺ ion implantation technology, the material has the triple functions of high temperature resistance, wave absorption and corrosion resistance. DETAILED DESCRIPTION

[0019] The present invention will be described in further detail below with reference to specific embodiments. The embodiments of the present invention are provided for purposes of illustration and description and are not intended to be exhaustive or to limit the invention to the disclosed forms. Many modifications and variations will be apparent to those skilled in the art. The embodiments are chosen and described to better illustrate the principles and practical applications of the present invention and to enable those skilled in the art to understand the present invention and design various embodiments with various modifications suitable for specific applications. Example

[0020] In this embodiment, a high temperature resistant ceramic formula and a preparation process thereof are provided, including A high temperature resistant ceramic formula: α-alumina 45-60%, serving as the matrix skeleton, provides high temperature stability; Stabilized zirconia (3YSZ) 15-25%, plays a role in phase transformation toughening and inhibits crack propagation, with a grain size of 0.3-0.8μm and a tetragonal phase content of ≥85%; 8-15% β-phase silicon carbide forms an interlocking structure and enhances fracture toughness; 5-10% α-phase silicon nitride also forms an interlocking structure, enhancing fracture toughness, D50≤1μm and α-phase content ≥98%; 2-5% rare earth oxide, a mixture of La2O3 and Y2O3 in a molar ratio of 1:1-3:1, used for grain boundary purification, improving the crystal phase stability at 1600℃ by 40%; 20-35% of ceramic polishing waste is industrial-grade alumina or silicon carbide polishing waste; The nano-enhancer is 0.5-2%, which is SiC / TiO2 core-shell structure particles with a core diameter of 50-80nm and a shell thickness of 5-15nm.

[0021] A preparation process of high temperature resistant ceramics: Step 1: Raw material pretreatment Treatment of ceramic polishing waste: Soak the ceramic polishing waste in 5% hydrofluoric acid for 30 minutes to remove the surface glass phase and reduce the residual amount to ≤3%. The liquid-to-solid ratio during soaking is 3:1 and the temperature is controlled at 25±2℃. The reaction is terminated when the conductivity value stabilizes at ≤50μS / cm through conductivity monitoring. Then, centrifuge dehydration (3000rpm, 10min) and drying at 120℃ to a moisture content of ≤0.5%; Nanopowder treatment: The nanopowder is subjected to plasma ball milling to a D90 of ≤ 200 nm, with a ball-to-powder ratio of 4:1 and a ball milling time of 6 h. Argon gas protection is used during the ball milling process (purity ≥ 99.99%, oxygen content ≤ 10 ppm); Step 2: Gradient sintering Pre-sintering stage: In the range of 800-1100℃, the heating rate is 2-5℃ / min, and the nitrogen atmosphere purity is ≥99.9% to decompose organic impurities, achieve initial densification, and reduce the porosity to 8%. When charging the furnace, an alumina backing plate + a boron nitride coated sagger is used, the green body spacing is ≥15mm, the heating rate before 800℃ is 3℃ / min (N2 flow rate 5L / min), and the heating rate from 800-1100℃ is 5℃ / min (N2 flow rate 8L / min, O2 content ≤100ppm); Transition stage: In the 1100-1450℃ range, the heating rate is 1-2℃ / min, and a hydrogen-argon mixture (H2 volume ratio 3-8%) is used to inhibit SiC oxidation and promote grain boundary diffusion. The gas ratio is Ar (95%) + H2 (5%), the flow rate is 12L / min, and the oxygen partial pressure is controlled to ≤10⁻¹ 0 Pa, heating rate is 1.5℃ / min (heating is maintained at 50℃ for 10min to eliminate thermal stress); Final firing stage: In the range of 1450-1680℃, the heating rate is 0.5-1.2℃ / min, and the vacuum degree is ≤10⁻³Pa to complete the multiphase sintering and form the ZrO2-SiC interlocking structure. At 1450-1550℃, the vacuum degree is 10⁻²-10⁻³Pa, and pulsed gas pressure (±5kPa, 0.5Hz) is used; at 1550-1680℃, the vacuum degree is ≤5×10⁻ 4 Pa, and electromagnetic field assistance (intensity 0.3T) was applied. The sintering endpoint was determined to be terminated when the axial shrinkage rate change was ≤0.01% / min, at which time the Al2O3 grains were ≤2μm and the ZrO2 grains were ≤0.8μm; Step 3: Post-processing Laser surface remelting: Using a 2kW laser with a scanning speed of 8mm / s, a 50μm densified surface layer with a porosity of ≤0.5% was produced. The laser was an IPGYLS-2000 (wavelength 1070nm), with a spiral progressive scanning path (35% overlap), a power density of 65J / mm² (1.8kW power, 0.3mm spot diameter), a scanning speed of 8mm / s (argon shielding, flow rate 15L / min), and a melt pool depth of 50±5μm. Ion implantation: Y⁺ ions are implanted on the surface to improve the high temperature oxidation resistance and make the weight gain after oxidation at 1600℃ less than 1mg / cm²; the implanted elements are Y⁺+Al⁺ dual ion beam (energy 80keV, dose 5×10¹) 7 ions / cm²), the temperature is controlled at 400±10℃, and the vacuum degree is ≤5×10⁻³Pa. Example

[0022] A high temperature resistant ceramic formula: 52.5% α-alumina, serving as the matrix skeleton and providing high temperature stability; Stabilized zirconia (3YSZ) 20%, plays a role in phase transformation toughening and inhibits crack propagation, with a grain size of 0.3-0.8μm and a tetragonal phase content of ≥85%; 11.5% β-phase silicon carbide forms an interlocking structure and enhances fracture toughness; 7.5% α-phase silicon nitride, also forming an interlocking structure to enhance fracture toughness, D50≤1μm and α-phase content ≥98%; 3.5% rare earth oxide, a mixture of La2O3 and Y2O3 in a molar ratio of 2:1, used for grain boundary purification, improving the crystal phase stability at 1600°C by 40%; 27.5% of ceramic polishing waste is industrial-grade alumina or silicon carbide polishing waste; The nano-reinforcement agent is 1.25%, which is SiC / TiO2 core-shell structure particles with a core diameter of 60nm and a shell thickness of 10nm.

[0023] A preparation process of high temperature resistant ceramics: Step 1: Raw material pretreatment Treatment of ceramic polishing waste: Soak the ceramic polishing waste in 5% hydrofluoric acid for 30 minutes to remove the surface glass phase and make the residual amount ≤3%. The liquid-to-solid ratio during soaking is 3:1 and the temperature is controlled at 25±2℃. The reaction is terminated when the conductivity value stabilizes at ≤50μS / cm by monitoring. Then, centrifuge and dehydrate at a speed of 3000rpm for 10 minutes and dry at 120℃ until the moisture content is ≤0.5%. Nanopowder treatment: The nanopowder is subjected to plasma ball milling to a D90 of ≤ 200 nm, with a ball-to-powder ratio of 4:1 and a ball milling time of 6 h. Argon gas protection is used during the ball milling process (purity ≥ 99.99%, oxygen content ≤ 10 ppm); Step 2: Gradient sintering Pre-sintering stage: In the range of 800-1100℃, the heating rate is 3℃ / min, and the nitrogen atmosphere purity is ≥99.9%. It is used to decompose organic impurities and achieve initial densification, reducing the porosity to 8%. When charging the furnace, an alumina backing plate + a boron nitride coated sagger is used, and the spacing between the green bodies is ≥15mm. The heating rate before 800℃ is 3℃ / min, of which the N2 flow rate is 5L / min. The heating rate from 800-1100℃ is 5℃ / min, of which the N2 flow rate is 8L / min, and the O2 content is ≤100ppm. Transition stage: In the 1100-1450°C range, the heating rate is 1.5°C / min, and a hydrogen-argon mixture (H2 accounts for 5.5% by volume) is used to inhibit SiC oxidation and promote grain boundary diffusion. The gas ratio is Ar (95%) + H2 (5%), the flow rate is 12L / min, and the oxygen partial pressure is controlled to ≤10⁻¹ 0 Pa, heating rate was 1.5℃ / min, and thermal stress was eliminated by keeping the temperature at 50℃ for 10min; Final firing stage: in the range of 1450-1680℃, the heating rate is 0.8℃ / min, the vacuum degree is ≤10⁻³Pa, and the multiphase sintering is completed to form the ZrO2-SiC interlocking structure; At 1450-1550℃, the vacuum degree is 10⁻²-10⁻³Pa, and pulsed gas pressure (±5kPa, 0.5Hz) is used; Vacuum degree ≤5×10⁻ at 1550-1680℃ 4 Pa, and electromagnetic field assistance (intensity 0.3T) was applied. The sintering endpoint was determined to be terminated when the axial shrinkage rate change was ≤0.01% / min, at which time the Al2O3 grains were ≤2μm and the ZrO2 grains were ≤0.8μm; Step 3: Post-processing Laser surface remelting: Using a 2kW laser with a scanning speed of 8mm / s, a 50μm densified surface layer with a porosity of ≤0.5% was produced. The laser was an IPGYLS-2000 (wavelength 1070nm), with a spiral progressive scanning path (35% overlap), a power density of 65J / mm² (1.8kW power, 0.3mm spot diameter), a scanning speed of 8mm / s (argon shielding, flow rate 15L / min), and a melt pool depth of 50±5μm. Ion implantation: Y⁺ ions are implanted on the surface to improve the high temperature oxidation resistance and make the weight gain after oxidation at 1600℃ less than 1mg / cm²; the implanted elements are Y⁺+Al⁺ dual ion beam (energy 80keV, dose 5×10¹)7 ions / cm²), the temperature is controlled at 400±10℃, and the vacuum degree is ≤5×10⁻³Pa.

[0024] Obviously, the embodiments described are only some of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field and related fields without making creative efforts should fall within the scope of protection of the present invention. Structures, devices, and operating methods not specifically described and explained in the present invention shall be implemented in accordance with conventional means in the field unless otherwise specified or limited.

Claims

1. A high temperature resistant ceramic formula, characterized in that: It is composed of the following components in percentage by mass: α-alumina 45-60%; Stabilized zirconium oxide 15-25%; β-phase silicon carbide 8-15%; α-phase silicon nitride 5-10%; Rare earth oxides 2-5%; Ceramic polishing waste 20-35%; Nano-enhancer 0.5-2%; The rare earth oxide is a mixture of La2O3 and Y2O3 in a molar ratio of 1:1-3:1; The nano-enhancer is a SiC / TiO2 core-shell structure particle with a core diameter of 50-80 nm and a shell thickness of 5-15 nm. The SiC / TiO2 core-shell structure particle is synthesized by a sol-gel method, and the TiO2 shell is an anatase type. The interface bonding strength with the SiC core is ≥200 MPa, as tested by nanoindentation.

2. A high temperature resistant ceramic formula according to claim 1, characterized in that: The ceramic polishing waste is industrial-grade aluminum oxide or silicon carbide polishing waste.

3. A high temperature resistant ceramic formula according to claim 1, characterized in that: The D50 of the α-alumina is ≤1 μm and the α phase content is ≥98%, the grain size of the stabilized zirconia is 0.3-0.8 μm, and the tetragonal phase content is ≥85%.

4. A process for preparing the high temperature resistant ceramic according to any one of claims 1 to 3, characterized in that: The following steps are involved: Raw material pretreatment: Ceramic polishing waste is soaked in hydrofluoric acid to remove the surface glass phase, and the nanopowder is milled by plasma to D90≤200nm; Gradient sintering: including pre-firing stage, transition stage and final firing stage, controlling the heating rate and atmosphere in different temperature ranges; Post-processing: Laser surface remelting is used to generate a densified surface layer, and ion implantation is performed to strengthen the surface.

5. The process for preparing a high temperature resistant ceramic according to claim 4, characterized in that: The hydrofluoric acid immersion concentration is 5%, the immersion time is 30 minutes, the liquid-to-solid ratio is 3:1, the temperature is 25±2° C., and the reaction is terminated when the conductivity monitoring value is stable at ≤50 μS / cm.

6. The process for preparing a high temperature resistant ceramic according to claim 4, characterized in that: The plasma ball milling has a ball-to-material ratio of 4:1, a ball milling time of 6 h, an argon protection atmosphere, a purity of ≥99.99%, and an oxygen content of ≤10 ppm.

7. The process for preparing a high temperature resistant ceramic according to claim 4, characterized in that: The temperature range of the pre-firing stage is 800-1100° C., the heating rate is 2-5° C. / min, and the atmosphere is nitrogen with a purity of ≥99.9%.

8. The process for preparing a high temperature resistant ceramic according to claim 4, characterized in that: The temperature range of the transition section is 1100-1450°C, the heating rate is 1-2°C / min, the atmosphere is a hydrogen-argon mixture, and the volume proportion of H2 is 3-8%.

9. The process for preparing a high temperature resistant ceramic according to claim 4, characterized in that: The temperature range of the final firing stage is 1450-1680°C, the heating rate is 0.5-1.2°C / min, and the vacuum degree is ≤10⁻³Pa.

10. The process for preparing high temperature resistant ceramics according to claim 4, characterized in that: The laser surface remelting has a power of 2kW and a scanning speed of 8mm / s, generating a 50μm densified surface layer; the ion implantation is to implant Y⁺ ions into the surface with an injection energy of 80keV and a dose of 5×10¹ 7 ions / cm², temperature control 400±10℃, vacuum degree ≤5×10⁻³Pa.