A high-strength ceramic product and its manufacturing process

Abstract

The present invention relates to the technical field of ceramic products, and specifically discloses a high-strength ceramic product and its manufacturing process. The manufacturing process includes the following operating steps: S1: Mix alumina, zirconia, toughening agent, sintering aid and composite additive for 40 to 65 minutes to obtain a premix; S2: Place the premix in a mold and extrude it into shape, and irradiate it with ultraviolet light for 1.5 to 2.2 hours to obtain a green body; S3: Subject the green body to pre-sintering and microwave hot pressing in sequence to obtain a ceramic product.

Description

Technical Field

[0001] The present invention relates to the technical field of ceramic products, and specifically relates to a high-strength ceramic product and its manufacturing process. Background Art

[0002] Traditional ceramics use silicate as raw material, mix it with water to make slurry, and finally obtain products through forming and sintering; with the development of new technologies, traditional ceramics can no longer meet the needs of social development, thus promoting the development of advanced ceramics; advanced ceramic materials have many excellent properties and play an important role in multiple fields such as aerospace, automotive industry, electronic equipment, medical devices, and energy technology, promoting the progress of science and technology and industry.

[0003] Advanced ceramics refer to ceramic materials with excellent properties, usually applied in high-tech fields and special engineering applications; common advanced ceramics include: oxide ceramics, silicon carbide ceramics, boron nitride ceramics, silicon boride ceramics, rare earth oxide ceramics, composite ceramics; these ceramics have more excellent properties and a wider application field compared to traditional ceramics; among them, the most representative oxide ceramics are alumina (Al 2 O 3 ) and zirconia (ZrO 2 ), which have excellent wear resistance, corrosion resistance, high-temperature stability and electrical insulation properties, and are widely used in high-temperature and high-performance fields such as abrasive tools, industrial seals, and gas turbines; zirconia can combine well with alumina to play a strengthening role. Although zirconia can improve the fracture toughness and strength of alumina, its effect is limited, thus restricting its development in more fields.

[0004] In summary, it is of great significance to prepare a high-strength ceramic product. Summary of the Invention

[0005] The purpose of the present invention is to provide a high-strength ceramic product and its manufacturing process to solve the problems raised in the above background art.

[0006] A manufacturing process of a high-strength ceramic product includes the following operating steps:

[0007] S1: Mix alumina, zirconia, toughening agent, sintering aid and composite additive for 40 - 65 minutes to obtain a premix.

[0008] S2: Place the premix in a mold for extrusion molding, and irradiate it with ultraviolet light for 1.5 - 2.2 hours to obtain a green body.

[0009] S3: Subject the green body to pre-sintering and microwave sintering in sequence to obtain a ceramic product.

[0010] Preferably, the raw materials of the premix include the following components: by weight, 65-78 parts of zirconia, 15-20 parts of alumina, 10-15 parts of toughening agent, 7-10 parts of sintering aid, and 15-18 parts of composite additive; the sintering aid includes 4-5 parts of magnesium oxide and 3-4 parts of chromium oxide.

[0011] Preferably, the preparation method of the composite additive is as follows: hyperbranched allyl polysilazane, cysteine, dimercapto polyethylene glycol, and azobisisobutyronitrile are added to tetrahydrofuran and uniformly mixed to obtain a mixed solution; the mixed solution is ball-milled and mixed with nano boron nitride and nano yttrium oxide in a nitrogen atmosphere for 2-2.5 hours and dried at 70-75 °C to obtain the composite additive.

[0012] Preferably, the raw materials of the mixed solution include the following components: by weight, 6-7 parts of hyperbranched allyl polysilazane, 0.002-0.004 parts of azobisisobutyronitrile, 1-1.5 parts of cysteine, 2-2.5 parts of dimercapto polyethylene glycol, and 15-20 parts of tetrahydrofuran; the raw materials of the composite additive include the following components: by weight, 25-30 parts of the mixed solution, 4-5 parts of nano boron nitride, and 2-3 parts of nano yttrium oxide.

[0013] Preferably, the preparation method of the toughening agent is as follows: carbon nanotubes and urea are ball-milled and mixed to obtain mixture A; cerium carbonate is added to nitric acid and stirred evenly, then mixture A is added, and they are mixed for 10-15 minutes, the pH value is adjusted to 10-12, and hydrothermal reaction is carried out at 120-130 °C for 40-48 hours, followed by filtration and drying; it is calcined at 500-600 °C for 1-1.5 hours to obtain the toughening agent.

[0014] Preferably, the raw materials of the toughening agent include the following components: by weight, 3-5 parts of carbon nanotubes, 1-3 parts of urea, 4-7 parts of cerium carbonate, and 10-20 parts of nitric acid.

[0015] Preferably, the temperature of pre-sintering is 600-750 °C, and the time of pre-sintering is 40-55 minutes.

[0016] Preferably, the operating steps of microwave sintering are as follows: the green body is heated at a heating rate of 12-16 °C / min at a microwave frequency of 200-300 MHz to 1000-1200 °C and held for 30-45 minutes, and then heated at a heating rate of 40-50 °C / min to 1400-1500 °C and held for 2-3.5 hours to obtain the ceramic product.

[0017] Compared with the prior art, the beneficial effects achieved by the present invention are as follows: the present invention uses alumina and zirconia as the matrix, and adds a toughening agent, magnesium oxide, and chromium oxide to prepare the ceramic product.

[0018] Among them, zirconia and alumina have similar lattice structures. The interaction between zirconia and alumina restricts the migration of grain boundaries and the growth rate of grains, and can form a solid solution with alumina, thereby improving the densification and mechanical properties of the ceramic. Zirconia and alumina also have similar thermal expansion coefficients and have a certain toughening effect; the addition of zirconia can reduce the stress accumulation in the ceramic during temperature changes, thereby improving the thermal shock stability and high-temperature resistance of the ceramic.

[0019] The addition of magnesium oxide can improve the thermal stability and chemical stability of the ceramic, reduce the defects of the crystal structure, and thereby improve the mechanical properties and thermal shock resistance of the ceramic. Chromium oxide itself has good corrosion resistance and hardness, thereby being able to improve the corrosion resistance and mechanical properties of the ceramic; chromium oxide also has a unique color and can be used to adjust the color and appearance characteristics of the ceramic; and magnesium oxide, chromium oxide, and nano-yttrium oxide play the role of sintering aids therein.

[0020] In order to further improve the fracture toughness of the ceramic product, the present invention calcines carbon nanotubes and cerium carbonate to prepare a composite toughening agent containing boron nitride and cerium oxide; carbon nanotubes have high strength and high modulus, enabling them to play a bridging role in the ceramic matrix; when the material is stressed, carbon nanotubes can bear part of the load, disperse and relieve stress concentration points, and delay the crack propagation speed; the good interfacial bonding between carbon nanotubes and the ceramic matrix can effectively improve the mechanical properties of the composite material, thereby reducing the yield of the material under stress and improving its toughness and wear resistance; the addition of cerium oxide can improve the thermal stability and mechanical properties of the ceramic product, and can also slow down the crack propagation of the ceramic product, thereby further improving the toughening effect of the ceramic product.

[0021] If alumina and zirconia are directly used as the matrix, and a toughening agent, magnesium oxide, and chromium oxide are added and uniformly mixed and then calcined, some of the nano-materials will agglomerate at high temperatures, thereby affecting the performance of the ceramic product.

[0022] In order to improve the dispersion effect of each component in the ceramic product after high-temperature sintering; the present invention uniformly mixes hyperbranched allyl polysilazane, cysteine, dihydroxy polyethylene glycol, and azobisisobutyronitrile to obtain a mixed solution; the mixed solution is ball-milled and mixed with nano-boron nitride and nano-yttrium oxide in a nitrogen atmosphere for 2 - 2.5 hours to obtain a composite additive.

[0023] Among them, the branched structure and silicon-nitrogen bonds of hyperbranched allyl polysilazane enable hyperbranched allyl polysilazane to form effective chemical bonding on the ceramic surface, improving its adhesion and compatibility with particles; cysteine and cysteine-terminated polyethylene glycol disulfide can form stable chemical bonds on the surface of ceramic powder due to the presence of sulfur and other groups, and cooperate with hyperbranched allyl polysilazane to improve the dispersibility and stability of the powder.

[0024] Mixing hyperbranched allyl polysilazane, cysteine, cysteine-terminated polyethylene glycol with nano-boron nitride and nano-yttrium oxide by ball milling can not only improve the uniform distribution of nano-boron nitride and nano-yttrium chloride in the premix, but also form an organic-inorganic interface on the surface of hard components such as alumina and zirconia, enhancing the adhesion and compatibility between the interface layers, preventing particle agglomeration, and thus improving the density and mechanical properties of the ceramic.

[0025] Among them, the addition of nano-boron nitride can help absorb and disperse stress, and can also increase the toughness of the ceramic material, enabling the ceramic products to resist external impacts and stresses, thereby improving the thermal shock resistance; nano-boron nitride has a small grain size, which can reduce the porosity and density fluctuations of the material, thereby improving the density of the ceramic.

[0026] Adding an appropriate amount of yttrium oxide can stabilize the crystal phase structure of zirconia, transform it into a more stable cubic phase, endow it with better thermal shock resistance, and be beneficial to the improvement of the mechanical properties and wear resistance of zirconia.

[0027] Mix the composite additive, alumina, zirconia, toughening agent, magnesia, and chromium oxide by ball milling to obtain a premix. Extrude the premix into a shape. Under ultraviolet light irradiation and the action of a photoinitiator, a click chemical reaction occurs between the vinyl groups on the hyperbranched allyl polysilazane in the composite additive and the mercapto groups on cysteine and cysteine-terminated polyethylene glycol, forming covalent bonds. Thus, organic substances and nanoparticles can effectively fill voids and defects, improve the density and strength of the material, and improve its overall performance, thereby obtaining a green body.

[0028] Pre-sinter the green body to pyrolyze and remove these organic substances, thereby reducing the residues during the sintering process and ensuring the purity and chemical stability of the final product. Pre-sintering can also bond the ceramic powder in an incompletely sintered state, improving the strength and hardness of the material.

[0029] Finally, microwave sinter the green body to obtain a ceramic product; among them, microwaves can deeply heat the interior of the material, promote the combination and growth of particles, and help form a more uniform and denser ceramic microstructure; and during the microwave sintering process, SiCNO is generated from the hyperbranched allyl polysilazane in the composite additive, which is beneficial to enhancing the high-temperature stability and chemical stability of the ceramic product. Detailed Embodiments

[0030] The following are the preferred embodiments of the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of them. For those of ordinary skill in the art of this technology, without departing from the principles of the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the scope of protection of the present invention.

[0031] In the following specific embodiments, "parts" are parts by weight. In this embodiment, it should be noted that there are no special restrictions on the purchase manufacturers of all raw materials involved in the present invention. Exemplarily, the CAS number of diallylamine is 124-02-7; the CAS number of trimethylchlorosilane is 75-77-4; the CAS number of Karstedt catalyst is 81032-58-8, the CAS number of azobisisobutyronitrile is 78-67-1; the CAS number of cysteine is 52-90-4; the product number of dithioglycol is 80020104; the product number of nano-yttrium oxide is AM-Y203-201-1, and the particle size is 50 nm; the model of nano-boron nitride is CW-BN-001; the particle size is 50 nm; the CAS number of cerium carbonate is 54451-25-1; the product number of alumina is JS3646; the product number of zirconia is DS140; the product number of carbon nanotubes is WD3713.

[0032] The preparation method of hyperbranched allyl polysilazane is as follows: (1) 200 parts of n-hexane, 50 parts of diallylamine, and 40.5 parts of triethylamine are added dropwise to a n-hexane solution of 23 parts of trimethylchlorosilane under nitrogen protection and ice-water bath conditions. After the addition, it is stirred for 15 minutes under ice-water bath conditions, and then continued to react for 2 hours at room temperature. It is left to stand until complete precipitation, the precipitate is filtered off, the excess solvent is removed by rotary evaporation, and vacuum distillation is carried out at 0.003 Mpa and 45 °C to obtain an intermediate; (2) 12 parts of the intermediate and 0.5 part of Karstedt catalyst are reacted at 85 °C for 10-15 hours, cooled to room temperature, dissolved in ether, precipitated with acetonitrile 3 times, filtered, the liquid is collected, and the solvent is removed by distillation to obtain hyperbranched allyl polysilazane.

[0033] Example 1: A manufacturing process for a high-strength ceramic product, including the following operating steps:

[0034] S1: The preparation method of the composite additive is as follows: (1) 6 parts of hyperbranched allyl polysilazane, 0.0025 part of azobisisobutyronitrile, 1 part of cysteine, and 2 parts of dithioglycol are added to 15 parts of tetrahydrofuran to obtain a mixed solution; (2) 30 parts of the mixed solution, 4 parts of nano-boron nitride, and 2 parts of nano-yttrium oxide are ball-milled and mixed for 2 hours in a nitrogen atmosphere and dried at 75 °C to obtain the composite additive;

[0035] The preparation method of the toughening agent is as follows: (1) Ball-mill and mix 3 parts of carbon nanotubes and 2 parts of urea to obtain mixture A; (2) Add 4 parts of cerium carbonate to 10 parts of nitric acid for dissolution, add mixture A, mix for 15 minutes, adjust the pH value to 10, carry out hydrothermal reaction at 120 °C for 40 hours, filter, dry, and calcine at 500 °C for 1.2 hours to obtain the toughening agent;

[0036] S2: Mix 15 parts of alumina, 65 parts of zirconia, 10 parts of toughening agent, 8 parts of sintering aid, and 18 parts of composite additive for 50 minutes to obtain a premix; among them, the sintering aid is 5 parts of magnesium oxide and 3 parts of chromium oxide;

[0037] S3: Place the premix in a mold and extrude it into shape, and irradiate it with ultraviolet light at 365 nm and 100 W for 2 hours to obtain a green body;

[0038] S4: Pre-sinter the green body at 600 °C for 40 minutes, then at a microwave frequency of 280 MHz, with a heating rate of 12 °C / min, heat up to 1000 °C and hold for 40 minutes, and then with a heating rate of 40 °C / min, heat up to 1400 °C and hold for 3.5 hours to obtain a ceramic product.

[0039] Example 2: A manufacturing process for high-strength ceramic products, including the following operating steps:

[0040] The preparation method of the composite additive is as follows: (1) Add 6 parts of hyperbranched allyl polysilazane, 0.0025 parts of azobisisobutyronitrile, 1 part of cysteine, and 2 parts of dimercapto polyethylene glycol to 15 parts of tetrahydrofuran to obtain a mixed solution; (2) Ball-mill and mix 30 parts of the mixed solution, 4 parts of nano boron nitride, and 2 parts of nano yttrium oxide in a nitrogen atmosphere for 2 hours, and dry at 75 °C to obtain the composite additive;

[0041] The preparation method of the toughening agent is as follows: (1) Ball-mill and mix 3 parts of carbon nanotubes and 2 parts of urea to obtain mixture A; (2) Add 4 parts of cerium carbonate to 10 parts of nitric acid for dissolution, add mixture A, mix for 15 minutes, adjust the pH value to 10, carry out hydrothermal reaction at 120 °C for 40 hours, filter, dry, and calcine at 500 °C for 1.2 hours to obtain the toughening agent;

[0042] S2: Mix 15 parts of alumina, 78 parts of zirconia, 12 parts of toughening agent, 8 parts of sintering aid, and 16 parts of composite additive for 50 minutes to obtain a premix; among them, the sintering aid is 5 parts of magnesium oxide and 3 parts of chromium oxide;

[0043] S3: Place the premix in a mold and extrude it into shape, and irradiate it with ultraviolet light at 365 nm and 100 W for 2 hours to obtain a green body;

[0044] S4: Pre-sinter the green body at 600 °C for 40 minutes, then under a microwave frequency of 280 MHz, with a heating rate of 12 °C / min, heat it up to 1000 °C and hold for 40 minutes, and then with a heating rate of 40 °C / min, heat it up to 1400 °C and hold for 3.5 hours to obtain the ceramic product.

[0045] Example 3: A manufacturing process for high-strength ceramic products, including the following operating steps:

[0046] S1: The preparation method of the composite additive is as follows: (1) Add 6 parts of hyperbranched allyl polysilazane, 0.0025 parts of azobisisobutyronitrile, 1 part of cysteine, and 2 parts of dimercapto polyethylene glycol to 15 parts of tetrahydrofuran to obtain a mixed solution; (2) Ball-mill and mix 30 parts of the mixed solution, 4 parts of nano boron nitride, and 2 parts of nano yttrium oxide in a nitrogen atmosphere for 2 hours, and dry at 75 °C to obtain the composite additive;

[0047] The preparation method of the toughening agent is as follows: (1) Ball-mill and mix 3 parts of carbon nanotubes and 2 parts of urea to obtain mixture A; (2) Add 4 parts of cerium carbonate to 10 parts of nitric acid to dissolve, add mixture A, mix for 15 minutes, adjust the pH value to 10, carry out hydrothermal reaction at 120 °C for 40 hours, filter, dry, and calcine at 500 °C for 1.2 hours to obtain the toughening agent;

[0048] S2: Mix 78 parts of alumina, 20 parts of zirconia, 15 parts of toughening agent, 8 parts of sintering aid, and 18 parts of composite additive for 50 minutes to obtain a premix; among them, the sintering aid is 5 parts of magnesium oxide and 3 parts of chromium oxide;

[0049] S3: Place the premix in a mold and extrude it into shape, and irradiate it with ultraviolet light at 365 nm and 100 W for 2 hours to obtain the green body;

[0050] S4: Pre-sinter the green body at 600 °C for 40 minutes, then under a microwave frequency of 280 MHz, with a heating rate of 12 °C / min, heat it up to 1000 °C and hold for 40 minutes, and then with a heating rate of 40 °C / min, heat it up to 1400 °C and hold for 3.5 hours to obtain the ceramic product.

[0051] Comparative Example 1 is based on Example 2, and cysteine and dimercapto polyethylene glycol are not added to the mixed solution;

[0052] S1: The preparation method of the composite additive is as follows: (1) Add 6 parts of hyperbranched allyl polysilazane, 4 parts of nano boron nitride, and 2 parts of nano yttrium oxide to 15 parts of tetrahydrofuran to obtain a mixed solution; (2) Ball-mill and mix the mixed solution in a nitrogen atmosphere for 2 hours, and dry at 75 °C to obtain the composite additive;

[0053] The preparation method of the toughening agent is as follows: (1) Ball-mill and mix 3 parts of carbon nanotubes and 2 parts of urea to obtain mixture A; (2) Dissolve 4 parts of cerium carbonate in 10 parts of nitric acid, add mixture A, mix for 15 minutes, adjust the pH value to 10, carry out hydrothermal reaction at 120 °C for 40 hours, filter, dry, and calcine at 500 °C for 1.2 hours to obtain the toughening agent;

[0054] S2: Mix 15 parts of alumina, 78 parts of zirconia, 12 parts of toughening agent, 8 parts of sintering aid, and 16 parts of composite additive for 50 minutes to obtain a premix; among them, the sintering aid is 5 parts of magnesium oxide and 3 parts of chromium oxide;

[0055] S3: Extrude the premix in a mold to obtain a green body;

[0056] S4: Pre-sinter the green body at 600 °C for 40 minutes, then under a microwave frequency of 280 MHz, at a heating rate of 12 °C / min, heat up to 1000 °C and hold for 40 minutes, and at a heating rate of 40 °C / min, heat up to 1400 °C and hold for 3.5 hours to obtain the ceramic product.

[0057] Comparative Example 2 is based on Example 2, and carbon nanotubes are not added to the toughening agent;

[0058] S1: The preparation method of the composite additive is as follows: (1) Add 6 parts of hyperbranched allyl polysilazane, 0.0025 parts of azobisisobutyronitrile, 1 part of cysteine, and 2 parts of dimercapto polyethylene glycol to 15 parts of tetrahydrofuran to obtain a mixed solution; (2) Ball-mill and mix 30 parts of the mixed solution, 4 parts of nano boron nitride, and 2 parts of nano yttrium oxide in a nitrogen atmosphere for 2 hours, and dry at 75 °C to obtain the composite additive;

[0059] The preparation method of the toughening agent is as follows: Dissolve 4 parts of cerium carbonate in 10 parts of nitric acid, add urea, mix for 15 minutes, adjust the pH value to 10, carry out hydrothermal reaction at 120 °C for 40 hours, filter, dry, and calcine at 500 °C for 1.2 hours to obtain the toughening agent;

[0060] S2: Mix 15 parts of alumina, 78 parts of zirconia, 12 parts of toughening agent, 8 parts of sintering aid, and 16 parts of composite additive for 250 minutes to obtain a premix; among them, the sintering aid is 5 parts of magnesium oxide and 3 parts of chromium oxide;

[0061] S3: Extrude the premix in a mold and irradiate it with ultraviolet light at 365 nm and 100 W for 2 hours to obtain a green body;

[0062] S4: Pre-sinter the green body at 600 °C for 40 minutes, then under a microwave frequency of 280 MHz, increase the temperature at a rate of 12 °C / min to 1000 °C and hold for 40 minutes, then increase the temperature at a rate of 40 °C / min to 1400 °C and hold for 3.5 hours to obtain the ceramic product.

[0063] Comparative Example 3 is based on Example 2, directly performing high-temperature sintering on the green body;

[0064] S1: The preparation method of the composite additive is as follows: (1) Add 6 parts of hyperbranched allyl polysilazane, 0.0025 parts of azobisisobutyronitrile, 1 part of cysteine, and 2 parts of dimercapto polyethylene glycol to 15 parts of tetrahydrofuran to obtain a mixed solution; (2) Ball-mill and mix 30 parts of the mixed solution, 4 parts of nano boron nitride, and 2 parts of nano yttrium oxide in a nitrogen atmosphere for 3 hours, and dry at 75 °C to obtain the composite additive;

[0065] The preparation method of the toughening agent is as follows: (1) Ball-mill and mix 3 parts of carbon nanotubes and 2 parts of urea to obtain mixture A; (2) Dissolve 4 parts of cerium carbonate in 10 parts of nitric acid, add mixture A, mix for 15 minutes, adjust the pH value to 10, perform hydrothermal reaction at 120 °C for 40 hours, filter, dry, and calcine at 500 °C for 1.2 hours to obtain the toughening agent;

[0066] S2: Mix 15 parts of alumina, 78 parts of zirconia, 12 parts of toughening agent, 8 parts of sintering aid, and 16 parts of composite additive for 50 minutes to obtain a premix; among them, the sintering aid is 5 parts of magnesium oxide and 3 parts of chromium oxide;

[0067] S3: Place the premix in a mold and extrude it, irradiate it with ultraviolet light at 365 nm and 100 W for 2 hours to obtain the green body;

[0068] S4: Increase the temperature of the green body at a rate of 12 °C / min to 1000 °C and hold for 40 minutes, then increase the temperature at a rate of 40 °C / min to 1400 °C and hold for 3.5 hours to obtain the ceramic product.

[0069] Comparative Example 4 is based on Example 2. First, obtain modified allyl polysilazane by ultraviolet light irradiation, and then prepare the composite additive;

[0070] S1: The preparation method of the composite additive is as follows: (1) Add 6 parts of hyperbranched allyl polysilazane, 0.0025 parts of azobisisobutyronitrile, 1 part of cysteine, and 2 parts of dimercapto polyethylene glycol to 15 parts of tetrahydrofuran, irradiate it with ultraviolet light at 365 nm and 100 W for 2 hours, and dry at 75 °C to obtain modified allyl polysilazane; (2) Ball-mill and mix 10 parts of modified allyl polysilazane, 4 parts of nano boron nitride, and 2 parts of nano yttrium oxide in a nitrogen atmosphere for 2 hours to obtain the composite additive;

[0071] The toughening agent is prepared by: (1) ball-milling 3 parts of carbon nanotubes and 2 parts of urea to obtain a mixture A; (2) adding 4 parts of cerium carbonate to 10 parts of nitric acid to dissolve, adding the mixture A, mixing for 15 minutes, adjusting the pH value to 10, performing a hydrothermal reaction at 120° C. for 40 hours, filtering, drying, and calcining at 500° C. for 1.2 hours to obtain a toughening agent;

[0072] S2: 15 parts of aluminum oxide, 78 parts of zirconium oxide, 12 parts of toughening agent, 8 parts of sintering aid, and 16 parts of composite additive are mixed for 50 minutes to obtain a premix; wherein the sintering aid is 5 parts of magnesium oxide and 3 parts of chromium oxide;

[0073] S3: placing the premix in a mold and extruding it to obtain a green body;

[0074] S4: The green body is pre-sintered at 600°C for 40 minutes, then heated to 1000°C at a heating rate of 12°C / min at a microwave frequency of 280 MHz and kept warm for 40 minutes, and then heated to 1400°C at a heating rate of 40°C / min and kept warm for 3.5 hours to obtain a ceramic product.

[0075] Test 1: Thermal shock resistance test: 7 ceramic products of Examples 1 to 3 and Comparative Examples 1 to 4 were taken respectively and placed under 20°C and 200°C for heat exchange treatment twice; and the fracture toughness of Examples 1 to 3 and Comparative Examples 1 to 4 before and after thermal shock resistance was tested, and the average value of the final results was taken, as shown in Table 1;

[0076]

[0077] Table 1

[0078] Conclusion: Comparative Example 1 is based on Example 2, but cysteine ​​and dithiol polyethylene glycol are not added to the mixed solution; the adhesion and compatibility between the organic-inorganic interface formed with the surface of hard components such as alumina and zirconia are reduced, resulting in a decrease in the fracture toughness of the ceramic product. Comparative Example 2 is based on Example 2, but carbon nanotubes are not added to the toughening agent, so that the fracture toughness of the ceramic product is reduced; because carbon nanotubes have high strength and high modulus, they can play a bridging role in the ceramic matrix. When the material is subjected to stress, carbon nanotubes can not only bear part of the load, but also disperse and relieve stress concentration points, thereby slowing down the rate of crack propagation.

[0079] Comparative Example 3 is based on Example 2. The green body is directly subjected to hot press sintering. During the same sintering time as that of microwave hot pressing, its production cycle needs to be lengthened, and the performance of the ceramic product decreases. Because pre-sintering can pyrolyze and remove these organic substances, thereby reducing the residues during the sintering process, and bonding the ceramic powder in an incompletely sintered state to improve the performance of the ceramic. Microwave can deeply heat the interior of the material, promote the combination and growth of particles, help to form a more uniform structure, which is beneficial to improving the performance of the ceramic product. Comparative Example 4 is based on Example 2. First, modified allyl polysilazane is obtained by ultraviolet light irradiation, and then a composite additive is prepared, such that the organic substances and nanoparticles cannot effectively fill the voids and defects, thereby reducing the density and strength of the material, resulting in a decrease in the performance of the ceramic product.

[0080] Performance Test 2:

[0081] <![CDATA[Apparent density (g·cm -3 )]]> Example 2 5.74 Comparative Example 1 5.32 Comparative Example 2 5.68 Comparative Example 3 5.17 Comparative Example 4 5.52

[0082] Table 2

[0083] Conclusion: Comparative Example 1 is based on Example 2. Cysteine and dihydroxy polyethylene glycol are not added to the mixed solution, resulting in a decrease in the dispersibility of the composite additive, thereby reducing the density of the ceramic product. Comparative Example 2 is based on Example 2, and it is found that its influence on the density of the ceramic product is small. Comparative Example 3 is based on Example 2. The green body is directly subjected to high-temperature sintering, resulting in a decrease in the density of the ceramic product. Because microwave can deeply heat the interior of the material, promote the combination and growth of particles, and help to form a more uniform and denser ceramic microstructure, the density of Comparative Example 2 decreases. Comparative Example 4 is based on Example 2. First, modified allyl polysilazane is obtained by ultraviolet light irradiation, and then a composite additive is prepared, such that the organic substances and nanoparticles cannot effectively fill the voids and defects, resulting in a decrease in the density of the ceramic product.

[0084] Finally, it should be noted that the above are only the preferred embodiments of the present invention, but the protection scope of this application is not limited thereto. Any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed in this application, within the spirit and principle of the present invention, should be covered by the protection scope of this application. Without conflict, the embodiments of this application and the features in the embodiments can be combined with each other. Therefore, the protection scope of this application should be subject to the protection scope of the claims.

Claims

1. A process for producing high-strength ceramic products, characterized in that: The steps include: S1: (1) adding hyperbranched allyl polysilazane, cysteine, dithiopolyethylene glycol and azobisisobutyronitrile to tetrahydrofuran and uniformly mixing to obtain a mixed solution; ball-milling the mixed solution with nano-boron nitride and nano-yttrium oxide in a nitrogen atmosphere for 2-2.5 hours, and drying at 70-75° C. to obtain a composite additive; (2) mixing carbon nanotubes and urea by ball milling to obtain a mixture A; adding cerium carbonate to nitric acid and stirring evenly, adding the mixture A, mixing for 10 to 15 minutes, adjusting the pH value to 10 to 12, performing a hydrothermal reaction at 120 to 130° C. for 40 to 48 hours, filtering, and drying; calcining the mixture at 500 to 600° C. for 1 to 1.5 hours to obtain a toughening agent; (3) mixing alumina, zirconia, toughening agent, sintering aid and composite additive for 40 to 65 minutes to obtain a premix; S2: placing the premix in a mold for extrusion molding, and irradiating with ultraviolet light for 1.5 to 2.2 hours to obtain a green body; S3: pre-sintering and microwave sintering the green body in sequence to obtain a ceramic product; The raw materials of the premix are composed of the following components: by weight, 65-78 parts of zirconium oxide, 15-20 parts of aluminum oxide, 10-15 parts of toughening agent, 7-10 parts of sintering aid and 15-18 parts of composite additive; the sintering aid includes 4-5 parts of magnesium oxide and 3-4 parts of chromium oxide.

2. The manufacturing process of a high-strength ceramic product according to claim 1, characterized in that: The raw materials of the mixed solution include the following components: by weight, 6-7 parts of hyperbranched allyl polysilazane, 0.002-0.004 parts of azobisisobutyronitrile, 1-1.5 parts of cysteine, 2-2.5 parts of dithiol polyethylene glycol and 15-20 parts of tetrahydrofuran; the raw materials of the composite additive include the following components: by weight, 25-30 parts of the mixed solution, 4-5 parts of nano boron nitride and 2-3 parts of nano yttrium oxide.

3. The manufacturing process of a high-strength ceramic product according to claim 1, characterized in that: The raw materials of the toughening agent include the following components: by weight, 3 to 5 parts of carbon nanotubes, 1 to 3 parts of urea, 4 to 7 parts of cerium carbonate and 10 to 20 parts of nitric acid.

4. The manufacturing process of a high-strength ceramic product according to claim 1, characterized in that: The pre-sintering temperature is 600-750° C., and the pre-sintering time is 40-55 minutes.

5. The manufacturing process of a high-strength ceramic product according to claim 1, characterized in that: The microwave sintering operation steps are: heating the green body to 1000-1200°C at a heating rate of 12-16°C / min at a microwave frequency of 200-300 MHz and keeping the temperature for 30-45 minutes, and heating the green body to 1400-1500°C at a heating rate of 40-50°C / min and keeping the temperature for 2-3.5 hours to obtain a ceramic product.

6. A ceramic product prepared according to the manufacturing process of a high-strength ceramic product according to any one of claims 1 to 5.

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