CN110981443A - Preparation method of alumina ceramic - Google Patents
Preparation method of alumina ceramic Download PDFInfo
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Abstract
The invention discloses a preparation method of alumina ceramic, belonging to the technical field of ceramic preparation. When the carbon dioxide is used for carbonation decomposition to prepare the aluminum hydroxide, the caustic ratio of the solution is reduced, the decomposition of the aluminum hydroxide crystal seeds is inhibited, the granularity of the aluminum hydroxide formed around is thinned, the aluminum oxide particles in the ceramic are changed into the nano aluminum oxide with higher density, and the ceramic particles in the formed ceramic blank have high bonding strength, so that the toughness and the bending strength of the aluminum oxide ceramic are improved; nitrogen in ammonia gas is fixed to fermentation filter residues through microbial decay in fruit peels, the toughening modification powder can form hexagonal boron nitride crystals through hot-pressing sintering, the wear resistance of the alumina ceramic is improved, the toughness and the bending strength are improved, meanwhile, the diamond is an atomic crystal, sp3 hybrid tracks are bonded between atoms, the crystal interface energy is high, the interface bonding capacity of diamond particles and the ceramic is enhanced, the density of the alumina ceramic is increased through solidification shrinkage, and the bending strength is improved.
Description
Technical Field
The invention discloses a preparation method of alumina ceramic, belonging to the technical field of ceramic preparation.
Background
The alumina ceramic is prepared from alumina (Al)2O3) Ceramic material as main body for thick film integrated circuit. The alumina ceramic has better conductivity, mechanical strength and high temperature resistance. It should be noted that washing with ultrasonic waves is required. Alumina ceramic is a ceramic with wide application, and because of the superior performance, the alumina ceramic has been more and more widely applied in modern society, and meets the requirements of daily use and special performance. The technology of alumina ceramics is mature day by day, but some indexes are still to be improved, which needs common research.
The forming method of the alumina ceramic product comprises various methods such as dry pressing, grouting, extrusion, cold isostatic pressing, injection, tape casting, hot pressing, hot isostatic pressing and the like. In recent years, forming technical methods such as filter pressing, direct solidification injection molding, gel injection molding, centrifugal injection molding, solid free molding and the like are developed at home and abroad. Different product shapes, sizes, complex shapes and precision products require different forming methods.
Dry pressing and forming: the dry pressing technology of alumina ceramic is limited to the object with simple shape, the thickness of the inner wall of more than 1mm and the ratio of the length to the diameter of not more than 4: 1. The molding method has a uniaxial direction or a bidirectional direction. The press has two types of hydraulic and mechanical types, and can be in a semi-automatic or full-automatic forming mode. The maximum pressure of the press is 200 MPa. The output can reach 15-50 pieces per minute. Because the stroke pressure of the hydraulic press is uniform, the heights of the pressed parts are different when the powder filling is different. And (3) grouting forming method: slip casting is the earliest method of forming alumina ceramics. The plaster mold is adopted, so that the cost is low, and the large-size and complex-shape part is easy to mold. The key of slip casting is the preparation of alumina slurry. Water is usually used as a flux medium, a debonder and a binder are added, air is exhausted after the debonder and the binder are fully ground, and then the mixture is poured into a gypsum mold.
Chenhualong (chenhualong, study of water-based cast alumina ceramic substrates [ J ]. china ceramics industry, 2009, 16 (1): 13-20) indicated that the use of composite binders is easier to handle, has fewer defects, but does not affect performance than single binders. And when the composite binder obtained by experiments is 20 wt% PVA +80 wt% B-1070, a proper amount of PVA is added into the casting slurry, so that the yield value of the slurry is improved, and the slurry suitable for casting is obtained.
Research on water system tape casting of 99 alumina ceramic substrates [ J ] china ceramics, 2009, 45: 7-9) indicates that alumina slurries with high solid content and stable dispersion can be prepared under conditions of pH of 9.0 and usage of 0.5-0.6 wt% of dispersant polyacrylic acid (PAA).
Although these studies have driven the development of aqueous tape casting processes, there are still some problems to be solved: the solvent has poor wettability to powder, slow volatilization and long drying time; difficulty in defoaming slurry; after the film is formed by casting, the ceramic blank sheet has poor flexibility, is easy to generate crack defects, has low strength and the like.
Therefore, domestic and foreign researchers have proposed various methods for preparing fine-crystal alumina ceramics on the basis, such as: the Chinese patent 02123648.8 proposes that the submicron alumina ceramic with the relative density of 99.9 percent and the grain size of less than 1 mu m is obtained by the steps of dry pressing, cold isostatic pressing, pressureless pre-sintering at 1200-1350 ℃, hot isostatic pressing at 1150-1350 ℃ and the like. Compared with pressureless sintering, the method requires higher cost, larger equipment investment and longer preparation period, so that the method is an important technology which does not reduce the density and can control the growth of crystal grains under the pressureless sintering condition.
Therefore, it is necessary to develop a high-density alumina ceramic with high strength and toughness in the technical field of ceramic preparation.
Disclosure of Invention
The invention mainly solves the technical problems that the existing alumina ceramic has poor bending strength and is easy to stress and break, the low-temperature sintering technology is generally adopted to inhibit the growth of alumina ceramic grains at present, but the equipment cost is high, and the density of the prepared alumina ceramic needs to be improved, and provides a preparation method of the alumina ceramic.
In order to solve the technical problems, the technical scheme adopted by the invention is as follows:
the preparation method of the alumina ceramic comprises the following steps:
(1) mixing E-51 epoxy resin granules and standard bisphenol A epoxy vinyl resin granules to obtain a ceramic slurry binder, placing the ceramic slurry binder and an alumina seed crystal liquid into a metal tank, stirring and mixing, heating to 100-110 ℃, keeping the temperature for 4-5 hours, adding vinyl trimethoxy silane, toughening modification powder and a sodium aluminate solution into the metal tank, stirring and mixing for 10-20 min to obtain a ceramic blank;
(2) mixing a ceramic blank and a sintering aid, pouring the mixture into a gypsum mold, preheating to 140-150 ℃, forming pressure of 11-13 MPa, curing and forming for 45-50 s, removing pressure, demolding, taking out, putting into a high-temperature kiln, preserving heat and sintering for 4-5 h, and naturally cooling to room temperature to obtain alumina ceramic;
the sintering aid is prepared by the following specific steps:
(1) igniting 400-500 g of rice hull to obtain rice hull ash, adding the rice hull ash into a glass tank, adding 500-600 mL of 30% sodium hydroxide solution into the glass tank to soak the rice hull ash, soaking for 10-15 min, adding 600-800 mL of 20% sulfuric acid solution into the glass tank, heating, raising the temperature, starting a stirrer to stir at a rotating speed of 70-80 r/min, carrying out heat preservation reaction for 20-30 min, and filtering to remove filter residues to obtain gel;
(2) washing the gel with deionized water for 3-5 times, then putting the washed gel into an oven, heating to 100-110 ℃, drying for 45-55 min to obtain dry gel, putting the dry gel into a nano high-pressure pulse crusher, crushing for 10-15 min to obtain nano gel powder, and mixing the nano gel powder with chromium oxide to obtain a sintering aid;
the preparation method of the alumina seed crystal liquid comprises the following specific steps:
(1) placing 700-800 mL of sodium aluminate solution into a plastic tank, introducing carbon dioxide gas into the plastic tank at a rate of 20-30 mL/min for 40-45 min, standing and settling for 3-4 h after the introduction of the gas is finished to obtain a settled mixture, placing the settled mixture into a flat disc filter, filtering to remove filtrate to obtain filter residue, placing the filter residue into an oven, heating to 90-100 ℃, and drying for 4-5 h to obtain aluminum hydroxide powder;
(2) putting aluminum hydroxide powder into a high-pressure air flow machine, carrying out air flow crushing for 10-15 min to obtain aluminum hydroxide ultrafine powder, pouring 200-220 g of the aluminum hydroxide ultrafine powder into 500-550 mL of sodium silicate solution with the mass fraction of 30% to obtain colloidal liquid, and putting the colloidal liquid into a high-speed dispersion machine to carry out high-speed dispersion at the rotating speed of 3000-3300 r/min to obtain alumina seed crystal liquid;
the toughening modification powder is prepared by the following specific steps:
according to the weight parts, 50-55 parts of rice hull ash powder, 30-40 parts of calcium borate and 10-15 parts of fresh grape skin are placed in a fermentation tank, ammonia gas is filled in the fermentation tank, the fermentation tank is sealed and fermented for 1-2 weeks to obtain a fermentation product, the fermentation product is filtered and separated to obtain fermentation filter residue, and diamond particles of 80-100 meshes and the fermentation filter residue are mixed according to the mass ratio of 4: 1 to obtain the toughening modification powder.
The alumina ceramic is prepared from the raw materials in the step (1) in parts by weight, including E-51 epoxy resin granules, standard bisphenol A epoxy vinyl resin granules, 70-80 parts of alumina crystal liquid, 10-12 parts of vinyl trimethoxy silane, 8-10 parts of toughening modification powder and 15-18 parts of sodium aluminate solution.
The specific preparation step (2) of the alumina ceramic is that the mixing mass ratio of the ceramic blank to the sintering aid is 5: 1.
The sintering temperature in the high-temperature kiln in the specific preparation step (2) of the alumina ceramic is 1300-1350 ℃.
The sintering aid is prepared specifically in the step (1), and the temperature after heating and temperature rise is 90-100 ℃.
The sintering aid is prepared by mixing the nano gel powder and the chromium oxide in a mass ratio of 3: 1 in the step (2).
The mass fraction of the sodium aluminate solution in the specific preparation step (1) of the alumina seed crystal solution is preferably 20%.
The particle size of the aluminum hydroxide ultrafine powder obtained in the specific preparation step (2) of the aluminum oxide seed crystal liquid is 50-80 μm.
In the specific preparation steps of the toughening modification powder, the filling amount of ammonia gas is controlled to be 1/2-2/3 of the volume of a fermentation tank.
The invention has the beneficial effects that:
(1) the invention decomposes sodium aluminate by carbonation, obtains aluminum hydroxide powder by filtering and drying, disperses the aluminum hydroxide powder and sodium silicate solution at high speed to obtain uniform alumina crystal liquid, mixes standard bisphenol A epoxy vinyl resin granules as ceramic slurry adhesive into the alumina crystal liquid, heats and preserves the temperature to remove the moisture, mixes the mixture with sintering auxiliary agent after preheating, puts the mixture into a gypsum mould, cures and forms, and then sinters to obtain the alumina ceramic, when the invention prepares the aluminum hydroxide by carbonation decomposition of carbon dioxide, the caustic ratio of the solution is reduced, the decomposition of the aluminum hydroxide crystal seed is inhibited, the granularity of the aluminum hydroxide formed around is reduced, the alkalescent glue solution formed by the superfine aluminum hydroxide and the hydrolysis of the aluminum hydroxide is stably existed as the alumina crystal liquid, the aluminum oxide granules in the ceramic are changed into nano aluminum oxide with higher density, the porosity of the ceramic is reduced, meanwhile, the superfine aluminum hydroxide which is not converted into aluminum oxide in the ceramic blank has high specific surface area as a discontinuous phase, the contact area with resin of a ceramic slurry binder is large, and ceramic particles in a formed ceramic blank have high bonding strength, so that the toughness and the bending strength of the aluminum oxide ceramic are improved;
(2) in the process of fermentation treatment, nitrogen in ammonia gas is fixed in fermentation filter residues through the microbial decay action in fruit peels, the toughening modification powder can form hexagonal boron nitride crystals through hot-pressing sintering, the wear resistance of the alumina ceramic is improved, and in the process of high-temperature sintering, due to poor thermal stability of a diamond grinding material, the diamond grinding material can be oxidized in the air atmosphere, is easy to generate graphite transformation in a protective atmosphere, improves the internal structure of the alumina ceramic to have lubricity, so that the toughness and the bending strength are improved, and simultaneously, the diamond is an atomic crystal and is sp-doped interatomic3The hybrid orbit forms a bond, the crystal interface energy is high, so that the interface bonding capacity of diamond particles and ceramics is enhanced, the strength and the wear rate of the alumina ceramics are reduced, the silicon dioxide generated by aluminum hydroxide and sodium silicate in the alumina crystal liquid is used as the silicon dioxide to ensure that the ceramics are not easy to generate silver lines and cavities after being cured and sintered, the density of the alumina ceramics is increased while the curing shrinkage is carried out, the bending strength is improved, and the nano-scale silicon dioxide and chromium oxide serving as sintering aids can be liquefied before the sintering temperature of the alumina, so that the sintering temperature is reduced, the sintering speed is accelerated, the density of the alumina ceramics is improved, and the method has wide application prospect.
Detailed Description
Igniting 400-500 g of rice hull to obtain rice hull ash, adding the rice hull ash into a glass tank, adding 500-600 mL of 30% sodium hydroxide solution into the glass tank to soak the rice hull ash, soaking for 10-15 min, adding 600-800 mL of 20% sulfuric acid solution into the glass tank, heating to 90-100 ℃, starting a stirrer to stir at a rotating speed of 70-80 r/min, carrying out heat preservation reaction for 20-30 min, and filtering to remove filter residues to obtain gel; washing the gel with deionized water for 3-5 times, then placing the washed gel into an oven, heating to 100-110 ℃, drying for 45-55 min to obtain dry gel, placing the dry gel into a nano high-pressure pulse pulverizer, pulverizing for 10-15 min to obtain nano gel powder, and mixing the nano gel powder and chromium oxide according to a mass ratio of 3: 1 to obtain a sintering aid for later use; placing 700-800 mL of 20% by mass sodium aluminate solution into a plastic tank, introducing carbon dioxide gas into the plastic tank at the speed of 20-30 mL/min for 40-45 min, standing and settling for 3-4 h after the gas introduction is finished to obtain a settled mixture, placing the settled mixture into a flat disc filter, filtering to remove filtrate to obtain filter residue, placing the filter residue into an oven, heating to 90-100 ℃, and drying for 4-5 h to obtain aluminum hydroxide powder; placing the aluminum hydroxide powder in a high-pressure air flow machine, carrying out air flow crushing for 10-15 min to obtain aluminum hydroxide superfine powder with the particle size of 50-80 mu m, pouring 200-220 g of the aluminum hydroxide superfine powder into sodium silicate solution with the mass fraction of 30% of 500-550 mL to obtain colloidal liquid, and placing the colloidal liquid in a high-speed dispersion machine to carry out high-speed dispersion at the rotating speed of 3000-3300 r/min to obtain alumina seed crystal liquid for later use; putting 50-55 parts of rice hull ash powder, 30-40 parts of calcium borate and 10-15 parts of fresh grape skin into a fermentation tank, filling ammonia gas, controlling the filling amount of the ammonia gas to be 1/2-2/3 of the volume of the fermentation tank, sealing and fermenting for 1-2 weeks to obtain a fermentation product, filtering and separating the fermentation product to obtain fermentation filter residues, and mixing 80-100-mesh diamond particles and the fermentation filter residues according to the mass ratio of 4: 1 to obtain toughening modification powder; mixing 20-25 parts by weight of E-51 epoxy resin granules and 50-60 parts by weight of standard bisphenol A epoxy vinyl resin granules to obtain a ceramic slurry binder, placing the ceramic slurry binder and 70-80 parts by weight of standby alumina seed crystal liquid into a metal tank, stirring and mixing, heating to 100-110 ℃, keeping the temperature for 4-5 hours, adding 10-12 parts by weight of vinyl trimethoxy silane, 8-10 parts by weight of toughening modification powder and 15-18 parts by weight of sodium aluminate solution into the metal tank, and stirring and mixing for 10-20 minutes to obtain a ceramic blank; mixing the ceramic blank and the standby sintering aid in a mass ratio of 5: 1, pouring the mixture into a gypsum mold, preheating to 140-150 ℃, forming pressure of 11-13 MPa, removing pressure, demolding and taking out after curing for 45-50 s, putting the mixture into a high-temperature kiln at 1300-1350 ℃, preserving heat and sintering for 4-5 h, and naturally cooling to room temperature to obtain the alumina ceramic.
Example 1
Preparing a sintering aid:
igniting 400g of rice hull to obtain rice hull ash, adding the rice hull ash into a glass tank, adding 500mL of 30 mass percent sodium hydroxide solution into the glass tank to soak the rice hull ash, adding 600mL of 20 mass percent sulfuric acid solution into the glass tank after soaking for 10min, heating to 90 ℃, starting a stirrer to stir at the rotating speed of 70r/min, carrying out heat preservation reaction for 20min, and filtering to remove filter residues to obtain gel;
washing the gel with deionized water for 3 times, then placing the washed gel into an oven, heating to 100 ℃, drying for 45min to obtain dry gel, placing the dry gel into a nano high-pressure pulse crusher, crushing for 10min to obtain nano gel powder, and mixing the nano gel powder and chromium oxide according to the mass ratio of 3: 1 to obtain a sintering aid for later use;
preparing an alumina liquid crystal:
placing 700mL of 20 mass percent sodium aluminate solution into a plastic tank, introducing carbon dioxide gas into the plastic tank at the rate of 20mL/min for 40min, standing and settling for 3h after the gas introduction is finished to obtain a settled mixture, placing the settled mixture into a flat disc filter, filtering to remove filtrate to obtain filter residue, placing the filter residue into an oven, heating to 90 ℃, and drying for 4h to obtain aluminum hydroxide powder;
placing the aluminum hydroxide powder material in a high-pressure air flow machine, carrying out air flow crushing for 10min to obtain aluminum hydroxide superfine powder with the particle size of 50 mu m, pouring 200g of the aluminum hydroxide superfine powder into 500mL of sodium silicate solution with the mass fraction of 30% to obtain colloidal liquid, and placing the colloidal liquid in a high-speed dispersion machine to carry out high-speed dispersion at the rotating speed of 3000r/min to obtain aluminum oxide seed crystal liquid for later use;
preparing alumina ceramics:
putting 50 parts of rice hull ash powder, 30 parts of calcium borate and 10 parts of fresh grape skin into a fermentation tank, filling ammonia gas, controlling the filling amount of the ammonia gas to be 1/2 of the volume of the fermentation tank, sealing and fermenting for 1 week to obtain a fermentation product, filtering the fermentation product, separating to obtain fermentation filter residue, and mixing 80-mesh diamond particles and the fermentation filter residue according to the mass ratio of 4: 1 to obtain toughening modification powder;
mixing 20 parts by weight of E-51 epoxy resin granules and 50 parts by weight of standard bisphenol A epoxy vinyl resin granules to obtain a ceramic slurry binder, placing the ceramic slurry binder and 70 parts by weight of standby alumina seed crystal liquid into a metal tank, stirring and mixing, heating to 100 ℃, preserving heat for 4 hours, adding 10 parts by weight of vinyl trimethoxy silane, 8 parts by weight of the toughening modification powder and 15 parts by weight of sodium aluminate solution into the metal tank, stirring and mixing for 10 minutes to obtain a ceramic blank;
and (3) mixing the ceramic blank and the standby sintering aid in a mass ratio of 5: 1, pouring the mixture into a gypsum mold, preheating to 140 ℃, forming under the pressure of 11MPa, curing for 45s, removing the pressure, demolding, taking out, putting into a high-temperature kiln at the temperature of 1300 ℃, preserving the temperature, sintering for 4h, and naturally cooling to room temperature to obtain the alumina ceramic.
Example 2
Preparing a sintering aid:
igniting 450g of rice hull to obtain rice hull ash, adding the rice hull ash into a glass tank, adding 550mL of a sodium hydroxide solution with the mass fraction of 30% into the glass tank to soak the rice hull ash, after soaking for 12min, adding 700mL of a sulfuric acid solution with the mass fraction of 20% into the glass tank, heating to 95 ℃, starting a stirrer to stir at the rotating speed of 75r/min, carrying out heat preservation reaction for 25min, and filtering to remove filter residues to obtain gel;
washing the gel with deionized water for 4 times, then putting the washed gel into an oven, heating to 105 ℃, drying for 50min to obtain dry gel, putting the dry gel into a nano high-pressure pulse crusher, crushing for 12min to obtain nano gel powder, and mixing the nano gel powder and chromium oxide according to the mass ratio of 3: 1 to obtain a sintering aid for later use;
preparing an alumina liquid crystal:
placing 750mL of 20 mass percent sodium aluminate solution into a plastic tank, introducing carbon dioxide gas into the plastic tank at the speed of 25mL/min for 42min, standing and settling for 3.5h after the gas introduction is finished to obtain a settled mixture, placing the settled mixture into a flat disc filter, filtering to remove filtrate to obtain filter residue, placing the filter residue into an oven, heating to 95 ℃, and drying for 4.5h to obtain aluminum hydroxide powder;
placing the aluminum hydroxide powder material in a high-pressure air flow machine, carrying out air flow crushing for 12min to obtain aluminum hydroxide superfine powder with the particle size of 70 mu m, pouring 210g of the aluminum hydroxide superfine powder into 520mL of sodium silicate solution with the mass fraction of 30% to obtain colloidal liquid, and placing the colloidal liquid in a high-speed dispersion machine to carry out high-speed dispersion at the rotating speed of 3200r/min to obtain aluminum oxide seed crystal liquid for later use;
preparing alumina ceramics:
putting 52 parts of rice hull ash powder, 35 parts of calcium borate and 12 parts of fresh grape skin into a fermentation tank, filling ammonia gas, controlling the filling amount of the ammonia gas to be 1/2 of the volume of the fermentation tank, sealing and fermenting for 1 week to obtain a fermentation product, filtering the fermentation product, separating to obtain fermentation filter residue, and mixing 90-mesh diamond particles and the fermentation filter residue according to the mass ratio of 4: 1 to obtain toughening modification powder;
mixing 22 parts by weight of E-51 epoxy resin granules and 55 parts by weight of standard bisphenol A epoxy vinyl resin granules to obtain a ceramic slurry binder, placing the ceramic slurry binder and 75 parts by weight of standby alumina seed crystal liquid into a metal tank, stirring and mixing, heating to 105 ℃, preserving heat for 4.5 hours, adding 11 parts by weight of vinyl trimethoxy silane, 9 parts by weight of the toughening modification powder and 17 parts by weight of sodium aluminate solution into the metal tank, stirring and mixing for 15 minutes to obtain a ceramic blank;
and mixing the ceramic blank and the standby sintering aid in a mass ratio of 5: 1, pouring the mixture into a gypsum mold, preheating to 145 ℃, forming under 12MPa, curing for 47s, removing pressure, demolding, taking out, putting into a high-temperature kiln at 1320 ℃, carrying out heat preservation sintering for 4.5h, and naturally cooling to room temperature to obtain the alumina ceramic.
Example 3
Preparing a sintering aid:
igniting 500g of rice hull to obtain rice hull ash, adding the rice hull ash into a glass tank, adding 600mL of sodium hydroxide solution with the mass fraction of 30% into the glass tank to soak the rice hull ash, adding 800mL of sulfuric acid solution with the mass fraction of 20% into the glass tank after soaking for 15min, heating to 100 ℃, starting a stirrer to stir at the rotating speed of 80r/min, carrying out heat preservation reaction for 30min, and filtering to remove filter residues to obtain gel;
washing the gel with deionized water for 5 times, then putting the washed gel into an oven, heating to 110 ℃, drying for 55min to obtain dry gel, putting the dry gel into a nano high-pressure pulse crusher, crushing for 15min to obtain nano gel powder, and mixing the nano gel powder and chromium oxide according to the mass ratio of 3: 1 to obtain a sintering aid for later use;
preparing an alumina liquid crystal:
placing 800mL of 20 mass percent sodium aluminate solution into a plastic tank, introducing carbon dioxide gas into the plastic tank at the speed of 30mL/min for 45min, standing and settling for 4h after the gas introduction is finished to obtain a settled mixture, placing the settled mixture into a flat disc filter, filtering to remove filtrate to obtain filter residue, placing the filter residue into an oven, heating to 100 ℃, and drying for 5h to obtain aluminum hydroxide powder;
placing the aluminum hydroxide powder material in a high-pressure air flow machine, carrying out air flow crushing for 15min to obtain aluminum hydroxide superfine powder with the particle size of 80 mu m, pouring 220g of the aluminum hydroxide superfine powder into 550mL of sodium silicate solution with the mass fraction of 30% to obtain colloidal liquid, and placing the colloidal liquid in a high-speed dispersion machine to carry out high-speed dispersion at the rotating speed of 3300r/min to obtain aluminum oxide seed crystal liquid for later use;
preparing alumina ceramics:
putting 55 parts of rice hull ash powder, 40 parts of calcium borate and 15 parts of fresh grape skin into a fermentation tank, filling ammonia gas, controlling the filling amount of the ammonia gas to be 2/3 of the volume of the fermentation tank, sealing and fermenting for 2 weeks to obtain a fermentation product, filtering and separating the fermentation product to obtain fermentation filter residue, and mixing 100-mesh diamond particles and the fermentation filter residue according to the mass ratio of 4: 1 to obtain toughening modification powder;
mixing 25 parts by weight of E-51 epoxy resin granules and 60 parts by weight of standard bisphenol A epoxy vinyl resin granules to obtain a ceramic slurry binder, placing the ceramic slurry binder and 80 parts by weight of standby alumina seed crystal liquid into a metal tank, stirring and mixing, heating to 110 ℃, preserving heat for 5 hours, adding 12 parts by weight of vinyl trimethoxy silane, 10 parts by weight of the toughening modification powder and 18 parts by weight of sodium aluminate solution into the metal tank, stirring and mixing for 20 minutes to obtain a ceramic blank;
and mixing the ceramic blank and the standby sintering aid in a mass ratio of 5: 1, pouring the mixture into a gypsum mold, preheating to 150 ℃, forming at 13MPa, curing for 50s, removing pressure, demolding, taking out, putting into a high-temperature kiln at 1350 ℃, preserving heat, sintering for 5h, and naturally cooling to room temperature to obtain the alumina ceramic.
Comparative example 1: essentially the same procedure as in example 2 was followed except that the sintering aid was absent.
Comparative example 2: the procedure was essentially the same as in example 2, except that the alumina seed crystal liquid was absent.
Comparative example 3: alumina ceramics manufactured by Ningbo company.
The bending strength test is carried out by adopting a universal testing machine.
Fracture toughness test the fracture toughness of ceramic materials was measured using the vickers hardness method.
Density test the alumina ceramic density tester is used for detection.
Table 1: measurement results of alumina ceramic Properties
| Detecting items | Example 1 | Example 2 | Example 3 | Comparative example 1 | Comparative example 2 | Comparative example 3 |
| Bending strength (MPa) | 1529 | 1538 | 1543 | 1023 | 1035 | 1055 |
| Fracture toughness (MPa/m)2） | 23.12 | 23.89 | 24.56 | 12.32 | 12.54 | 13.67 |
| Density (g/cm)3） | 3.85 | 3.92 | 3.98 | 1.25 | 1.34 | 1.58 |
From the above, it can be seen from table 1 that the alumina ceramic of the present invention has high bending strength, good fracture toughness, high density, good compactness, and wide application prospect.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, but rather as the subject matter of the invention is to be construed in all aspects and as broadly as possible, and all changes, equivalents and modifications that fall within the true spirit and scope of the invention are therefore intended to be embraced therein.
Claims (9)
1. The preparation method of the alumina ceramic is characterized by comprising the following specific preparation steps:
(1) mixing E-51 epoxy resin granules and standard bisphenol A epoxy vinyl resin granules to obtain a ceramic slurry binder, placing the ceramic slurry binder and an alumina seed crystal liquid into a metal tank, stirring and mixing, heating to 100-110 ℃, keeping the temperature for 4-5 hours, adding vinyl trimethoxy silane, toughening modification powder and a sodium aluminate solution into the metal tank, stirring and mixing for 10-20 min to obtain a ceramic blank;
(2) mixing a ceramic blank and a sintering aid, pouring the mixture into a gypsum mold, preheating to 140-150 ℃, forming pressure of 11-13 MPa, curing and forming for 45-50 s, removing pressure, demolding, taking out, putting into a high-temperature kiln, preserving heat and sintering for 4-5 h, and naturally cooling to room temperature to obtain alumina ceramic;
the sintering aid is prepared by the following specific steps:
(1) igniting 400-500 g of rice hull to obtain rice hull ash, adding the rice hull ash into a glass tank, adding 500-600 mL of 30% sodium hydroxide solution into the glass tank to soak the rice hull ash, soaking for 10-15 min, adding 600-800 mL of 20% sulfuric acid solution into the glass tank, heating, raising the temperature, starting a stirrer to stir at a rotating speed of 70-80 r/min, carrying out heat preservation reaction for 20-30 min, and filtering to remove filter residues to obtain gel;
(2) washing the gel with deionized water for 3-5 times, then putting the washed gel into an oven, heating to 100-110 ℃, drying for 45-55 min to obtain dry gel, putting the dry gel into a nano high-pressure pulse crusher, crushing for 10-15 min to obtain nano gel powder, and mixing the nano gel powder with chromium oxide to obtain a sintering aid;
the preparation method of the alumina seed crystal liquid comprises the following specific steps:
(1) placing 700-800 mL of sodium aluminate solution into a plastic tank, introducing carbon dioxide gas into the plastic tank at a rate of 20-30 mL/min for 40-45 min, standing and settling for 3-4 h after the introduction of the gas is finished to obtain a settled mixture, placing the settled mixture into a flat disc filter, filtering to remove filtrate to obtain filter residue, placing the filter residue into an oven, heating to 90-100 ℃, and drying for 4-5 h to obtain aluminum hydroxide powder;
(2) putting aluminum hydroxide powder into a high-pressure air flow machine, carrying out air flow crushing for 10-15 min to obtain aluminum hydroxide ultrafine powder, pouring 200-220 g of the aluminum hydroxide ultrafine powder into 500-550 mL of sodium silicate solution with the mass fraction of 30% to obtain colloidal liquid, and putting the colloidal liquid into a high-speed dispersion machine to carry out high-speed dispersion at the rotating speed of 3000-3300 r/min to obtain alumina seed crystal liquid;
the toughening modification powder is prepared by the following specific steps:
according to the weight parts, 50-55 parts of rice hull ash powder, 30-40 parts of calcium borate and 10-15 parts of fresh grape skin are placed in a fermentation tank, ammonia gas is filled in the fermentation tank, the fermentation tank is sealed and fermented for 1-2 weeks to obtain a fermentation product, the fermentation product is filtered and separated to obtain fermentation filter residue, and diamond particles of 80-100 meshes and the fermentation filter residue are mixed according to the mass ratio of 4: 1 to obtain the toughening modification powder.
2. The method for preparing an alumina ceramic according to claim 1, wherein: the alumina ceramic is prepared from the raw materials in the step (1) in parts by weight, including E-51 epoxy resin granules, standard bisphenol A epoxy vinyl resin granules, 70-80 parts of alumina crystal liquid, 10-12 parts of vinyl trimethoxy silane, 8-10 parts of toughening modification powder and 15-18 parts of sodium aluminate solution.
3. The method for preparing an alumina ceramic according to claim 1, wherein: the specific preparation step (2) of the alumina ceramic is that the mixing mass ratio of the ceramic blank to the sintering aid is 5: 1.
4. The method for preparing an alumina ceramic according to claim 1, wherein: the sintering temperature in the high-temperature kiln in the specific preparation step (2) of the alumina ceramic is 1300-1350 ℃.
5. The method for preparing an alumina ceramic according to claim 1, wherein: the sintering aid is prepared specifically in the step (1), and the temperature after heating and temperature rise is 90-100 ℃.
6. The method for preparing an alumina ceramic according to claim 1, wherein: the sintering aid is prepared by mixing the nano gel powder and the chromium oxide in a mass ratio of 3: 1 in the step (2).
7. The method for preparing an alumina ceramic according to claim 1, wherein: the mass fraction of the sodium aluminate solution in the specific preparation step (1) of the alumina seed crystal solution is preferably 20%.
8. The method for preparing an alumina ceramic according to claim 1, wherein: the particle size of the aluminum hydroxide ultrafine powder obtained in the specific preparation step (2) of the aluminum oxide seed crystal liquid is 50-80 μm.
9. The method for preparing an alumina ceramic according to claim 1, wherein: in the specific preparation steps of the toughening modification powder, the filling amount of ammonia gas is controlled to be 1/2-2/3 of the volume of a fermentation tank.
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| CN114872390A (en) * | 2022-05-23 | 2022-08-09 | 哈尔滨工业大学 | Ceramic/fiber reinforced composite protective armor structure |
| CN114988918A (en) * | 2022-06-13 | 2022-09-02 | 湖南省新化县鑫星电子陶瓷有限责任公司 | Surface metallization method of alumina ceramic |
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| CN114872390A (en) * | 2022-05-23 | 2022-08-09 | 哈尔滨工业大学 | Ceramic/fiber reinforced composite protective armor structure |
| CN114988918A (en) * | 2022-06-13 | 2022-09-02 | 湖南省新化县鑫星电子陶瓷有限责任公司 | Surface metallization method of alumina ceramic |
| CN114988918B (en) * | 2022-06-13 | 2023-04-07 | 湖南省新化县鑫星电子陶瓷有限责任公司 | Surface metallization method of alumina ceramic |
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