CN111499371A - Preparation method of magnesia-alumina spinel transparent ceramic - Google Patents
Preparation method of magnesia-alumina spinel transparent ceramic Download PDFInfo
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- CN111499371A CN111499371A CN202010277504.3A CN202010277504A CN111499371A CN 111499371 A CN111499371 A CN 111499371A CN 202010277504 A CN202010277504 A CN 202010277504A CN 111499371 A CN111499371 A CN 111499371A
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- 229910052596 spinel Inorganic materials 0.000 title claims abstract description 121
- 239000011029 spinel Substances 0.000 title claims abstract description 121
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 title claims abstract description 95
- 238000002360 preparation method Methods 0.000 title claims abstract description 21
- 235000015895 biscuits Nutrition 0.000 claims abstract description 84
- 239000000843 powder Substances 0.000 claims abstract description 60
- 229910052749 magnesium Inorganic materials 0.000 claims abstract description 53
- 239000011777 magnesium Substances 0.000 claims abstract description 53
- -1 magnesium aluminate Chemical class 0.000 claims abstract description 53
- 238000000034 method Methods 0.000 claims abstract description 20
- 238000001513 hot isostatic pressing Methods 0.000 claims abstract description 18
- 238000010438 heat treatment Methods 0.000 claims abstract description 16
- HBMJWWWQQXIZIP-UHFFFAOYSA-N silicon carbide Chemical compound [Si+]#[C-] HBMJWWWQQXIZIP-UHFFFAOYSA-N 0.000 claims abstract description 15
- 229910010271 silicon carbide Inorganic materials 0.000 claims abstract description 15
- 238000009768 microwave sintering Methods 0.000 claims abstract description 10
- 238000003825 pressing Methods 0.000 claims abstract description 10
- 238000005266 casting Methods 0.000 claims abstract description 7
- 238000000498 ball milling Methods 0.000 claims description 44
- 239000002002 slurry Substances 0.000 claims description 22
- 239000003292 glue Substances 0.000 claims description 20
- 238000002156 mixing Methods 0.000 claims description 20
- 238000001035 drying Methods 0.000 claims description 18
- 239000000178 monomer Substances 0.000 claims description 17
- 239000003999 initiator Substances 0.000 claims description 16
- 238000003756 stirring Methods 0.000 claims description 16
- 238000001816 cooling Methods 0.000 claims description 15
- 239000003054 catalyst Substances 0.000 claims description 12
- 238000009694 cold isostatic pressing Methods 0.000 claims description 12
- 239000003431 cross linking reagent Substances 0.000 claims description 12
- 239000002270 dispersing agent Substances 0.000 claims description 12
- 239000002994 raw material Substances 0.000 claims description 12
- 239000000243 solution Substances 0.000 claims description 9
- 239000007864 aqueous solution Substances 0.000 claims description 8
- 238000007873 sieving Methods 0.000 claims description 8
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- ROOXNKNUYICQNP-UHFFFAOYSA-N ammonium persulfate Chemical compound [NH4+].[NH4+].[O-]S(=O)(=O)OOS([O-])(=O)=O ROOXNKNUYICQNP-UHFFFAOYSA-N 0.000 claims description 7
- 239000012300 argon atmosphere Substances 0.000 claims description 7
- 238000001746 injection moulding Methods 0.000 claims description 7
- 239000000463 material Substances 0.000 claims description 7
- KWYHDKDOAIKMQN-UHFFFAOYSA-N N,N,N',N'-tetramethylethylenediamine Chemical compound CN(C)CCN(C)C KWYHDKDOAIKMQN-UHFFFAOYSA-N 0.000 claims description 6
- 229910001870 ammonium persulfate Inorganic materials 0.000 claims description 6
- FQPSGWSUVKBHSU-UHFFFAOYSA-N methacrylamide Chemical compound CC(=C)C(N)=O FQPSGWSUVKBHSU-UHFFFAOYSA-N 0.000 claims description 6
- 239000002245 particle Substances 0.000 claims description 6
- 239000000126 substance Substances 0.000 claims description 6
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 claims description 5
- 239000011521 glass Substances 0.000 claims description 5
- 239000012188 paraffin wax Substances 0.000 claims description 5
- QGZKDVFQNNGYKY-UHFFFAOYSA-O Ammonium Chemical compound [NH4+] QGZKDVFQNNGYKY-UHFFFAOYSA-O 0.000 claims description 4
- 239000008367 deionised water Substances 0.000 claims description 4
- 229910021641 deionized water Inorganic materials 0.000 claims description 4
- 239000007788 liquid Substances 0.000 claims description 4
- ZIUHHBKFKCYYJD-UHFFFAOYSA-N n,n'-methylenebisacrylamide Chemical compound C=CC(=O)NCNC(=O)C=C ZIUHHBKFKCYYJD-UHFFFAOYSA-N 0.000 claims description 4
- 229920000058 polyacrylate Polymers 0.000 claims description 4
- 229920002635 polyurethane Polymers 0.000 claims description 4
- 239000004814 polyurethane Substances 0.000 claims description 4
- 239000012466 permeate Substances 0.000 claims description 2
- 238000005245 sintering Methods 0.000 abstract description 17
- 230000003287 optical effect Effects 0.000 abstract description 12
- 238000001272 pressureless sintering Methods 0.000 abstract description 7
- 238000002490 spark plasma sintering Methods 0.000 abstract description 7
- 238000007731 hot pressing Methods 0.000 abstract description 6
- 238000004321 preservation Methods 0.000 abstract description 5
- CPLXHLVBOLITMK-UHFFFAOYSA-N Magnesium oxide Chemical compound [Mg]=O CPLXHLVBOLITMK-UHFFFAOYSA-N 0.000 description 44
- 239000000395 magnesium oxide Substances 0.000 description 22
- 238000002834 transmittance Methods 0.000 description 17
- 239000013078 crystal Substances 0.000 description 8
- 238000005498 polishing Methods 0.000 description 7
- VVQNEPGJFQJSBK-UHFFFAOYSA-N Methyl methacrylate Chemical compound COC(=O)C(C)=C VVQNEPGJFQJSBK-UHFFFAOYSA-N 0.000 description 4
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- 230000009286 beneficial effect Effects 0.000 description 4
- 239000011148 porous material Substances 0.000 description 4
- VAZSKTXWXKYQJF-UHFFFAOYSA-N ammonium persulfate Chemical compound [NH4+].[NH4+].[O-]S(=O)OOS([O-])=O VAZSKTXWXKYQJF-UHFFFAOYSA-N 0.000 description 3
- 238000000748 compression moulding Methods 0.000 description 3
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 2
- 238000004458 analytical method Methods 0.000 description 2
- 238000010923 batch production Methods 0.000 description 2
- 229910010293 ceramic material Inorganic materials 0.000 description 2
- 238000007599 discharging Methods 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 238000005530 etching Methods 0.000 description 2
- 238000003760 magnetic stirring Methods 0.000 description 2
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- 229910052786 argon Inorganic materials 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 230000007797 corrosion Effects 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- 238000001879 gelation Methods 0.000 description 1
- 238000000713 high-energy ball milling Methods 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 238000006116 polymerization reaction Methods 0.000 description 1
- 238000007670 refining Methods 0.000 description 1
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- C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
- C04B35/01—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics
- C04B35/44—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics based on aluminates
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Abstract
The invention discloses a preparation method of magnesium aluminate spinel transparent ceramic, and relates to a preparation method of magnesium aluminate spinel ceramic. The invention aims to solve the problems of long heat preservation time and low heating rate of the conventional pressureless sintering. The hot-pressing sintering usually needs to add a sintering aid, the grain size is large, and a sample with a complex shape is difficult to prepare. The problem that the magnesium aluminate spinel transparent ceramic prepared by spark plasma sintering has poor optical performance. The method comprises the following steps: firstly, pressing or gel-casting magnesia-alumina spinel powder to obtain a ceramic biscuit; secondly, placing the ceramic biscuit in the center of an alumina ceramic crucible, and then sleeving the alumina ceramic crucible filled with the ceramic biscuit into a silicon carbide ceramic crucible; thirdly, placing the sleeved crucible filled with the ceramic biscuit in a microwave sintering furnace for sintering; and fourthly, placing the magnesium aluminate spinel ceramic block in a hot isostatic pressing furnace for hot isostatic pressing. The method is used for preparing the magnesium aluminate spinel transparent ceramic.
Description
Technical Field
The invention relates to a preparation method of magnesium aluminate spinel ceramic.
Background
The magnesia-alumina spinel transparent ceramic material has many excellent properties, such as low density, high hardness, high strength, corrosion resistance and high temperature stability, and has very high optical transmittance (> 80%) in the near ultraviolet to mid-infrared band, so that the magnesia-alumina spinel transparent ceramic material can be used as a candidate material in the military fields of transparent armors, infrared transparent windows of missile emitters, transparent fairings of infrared tracking missiles, laser igniters and the like.
At present, pressureless sintering/hot isostatic pressing, hot pressing/hot isostatic pressing and spark plasma sintering are commonly used for preparing magnesia-alumina spinel transparent ceramics, but the existing methods have the defects that the pressureless sintering preparation of magnesia-alumina spinel transparent ceramics usually needs longer heat preservation time (20 hours), slower temperature rise rate (1-4 ℃/min) to reach high density to remove air holes, the preparation period is longer, and the efficiency is influenced, L iF sintering aid is usually added to the preparation of magnesia-alumina spinel transparent ceramics by hot pressing sintering, the grain size is easily larger (200-300 mu m), and samples with complex shapes are difficult to prepare due to equipment limitation2O4ceramics fabricated by spark plasma sintering[J].Ceramics International 42(2016)8839-8846)。
In summary, the existing methods for preparing magnesium aluminate spinel transparent ceramics have the advantages but have the disadvantages that pressureless sintering requires long holding time and slow temperature rise rate, hot press sintering usually requires L iF sintering aid, which results in large grain size and difficulty in preparing samples with complex shapes, and magnesium aluminate spinel transparent ceramics prepared by spark plasma sintering are usually contaminated by carbon, which results in reduced optical properties.
Disclosure of Invention
The invention aims to solve the problems of long heat preservation time and low heating rate of the conventional pressureless sintering. The hot-pressing sintering usually needs to add a sintering aid, the grain size is large, and a sample with a complex shape is difficult to prepare. The problem that the magnesia-alumina spinel transparent ceramic prepared by spark plasma sintering has poor optical performance is solved, and the preparation method of the magnesia-alumina spinel transparent ceramic is provided.
A preparation method of magnesium aluminate spinel transparent ceramics is carried out according to the following steps:
firstly, pressing or gel-casting magnesia-alumina spinel powder to obtain a ceramic biscuit;
secondly, placing the ceramic biscuit in the center of an alumina ceramic crucible, and then sleeving the alumina ceramic crucible containing the ceramic biscuit into a silicon carbide ceramic crucible, wherein the gap between the alumina ceramic crucible and the silicon carbide ceramic crucible is smaller than 1mm to obtain a sleeved crucible containing the ceramic biscuit;
thirdly, placing the sleeved crucible filled with the ceramic biscuit in a microwave sintering furnace, then heating the crucible to 1350-1550 ℃ at the heating rate of 5-40 ℃/min, preserving the heat for 30-120 min under the condition that the temperature is 1350-1550 ℃, and then cooling along with the furnace to obtain the magnesia-alumina spinel ceramic block;
fourthly, placing the magnesium aluminate spinel ceramic block in a hot isostatic pressing furnace, and carrying out hot isostatic pressing for 2-5 h under the conditions of argon atmosphere, 150-190 MPa of pressure and 1500-1750 ℃ of temperature to obtain the magnesium aluminate spinel transparent ceramic.
The invention has the beneficial effects that: compared with the pressureless sintering technology, the microwave sintering method is adopted, the temperature can be rapidly increased (the temperature increase speed is 5-40 ℃/min), and the sintering time is shortened (the sintering time is 0.5-2 hours); compared with hot-pressing sintering, the method does not need to add sintering aids, can prepare samples with complex shapes, has small crystal grain size (less than 70 mu m), belongs to polycrystalline materials, and has polycrystalline yield strength sigmasThe relationship with the average grain diameter d can be described by the Hall-Petch formula:
wherein sigma0The yield strength of the single crystal is, K is a constant, and the strength of the polycrystal is always improved along with the refinement of the crystal grains, so that the smaller the size of the crystal grains is, the higher the mechanical property of the magnesia-alumina spinel transparent ceramic is; compared with spark plasma sintering, the optical performance of the sample is better, the transmittance of the magnesia-alumina spinel transparent ceramic (3mm thick) prepared by the method in a visible-infrared band reaches more than 80%, the optical performance is good, and the use requirements in the fields of transparent armor, infrared transparent windows and the like can be met. And the magnesium aluminate spinel transparent ceramic is sintered in air by microwave, is convenient to operate, is suitable for batch production, and provides a new method for preparing the magnesium aluminate spinel transparent ceramic.
The invention is used for a preparation method of magnesia-alumina spinel transparent ceramic.
Drawings
FIG. 1 is a photograph of a polished magnesia alumina spinel transparent ceramic prepared in accordance with one embodiment;
FIG. 2 is a microstructure photograph of a polished and thermally etched surface of a transparent magnesia alumina spinel ceramic prepared according to the first embodiment;
FIG. 3 is a graph showing transmittance of a polished magnesia alumina spinel transparent ceramic prepared in accordance with the first embodiment;
FIG. 4 is a photo of a polished magnesia alumina spinel transparent ceramic prepared in example III;
FIG. 5 is a microstructure photograph of a polished and thermally etched surface of a transparent magnesia alumina spinel ceramic prepared in example III;
FIG. 6 is a graph showing transmittance curves of the polished magnesia alumina spinel transparent ceramic prepared in example three.
Detailed Description
The technical solution of the present invention is not limited to the specific embodiments listed below, and includes any combination of the specific embodiments.
The first embodiment is as follows: the preparation method of the magnesium aluminate spinel transparent ceramic is carried out according to the following steps:
firstly, pressing or gel-casting magnesia-alumina spinel powder to obtain a ceramic biscuit;
secondly, placing the ceramic biscuit in the center of an alumina ceramic crucible, and then sleeving the alumina ceramic crucible containing the ceramic biscuit into a silicon carbide ceramic crucible, wherein the gap between the alumina ceramic crucible and the silicon carbide ceramic crucible is smaller than 1mm to obtain a sleeved crucible containing the ceramic biscuit;
thirdly, placing the sleeved crucible filled with the ceramic biscuit in a microwave sintering furnace, then heating the crucible to 1350-1550 ℃ at the heating rate of 5-40 ℃/min, preserving the heat for 30-120 min under the condition that the temperature is 1350-1550 ℃, and then cooling along with the furnace to obtain the magnesia-alumina spinel ceramic block;
fourthly, placing the magnesium aluminate spinel ceramic block in a hot isostatic pressing furnace, and carrying out hot isostatic pressing for 2-5 h under the conditions of argon atmosphere, 150-190 MPa of pressure and 1500-1750 ℃ of temperature to obtain the magnesium aluminate spinel transparent ceramic.
The purity of the argon gas in the fourth step of the embodiment is more than or equal to 99.99 Vol%.
The beneficial effects of the embodiment are as follows: compared with the pressureless sintering technology, the microwave sintering method adopted by the embodiment can quickly increase the temperature (the temperature increase speed is 5-40 ℃/min) and shorten the sintering time (the sintering time is 0.5-2 hours); compared with hot-pressing sintering, the method does not need to add sintering aids, can prepare samples with complex shapes, has small crystal grain size (less than 70 mu m), belongs to polycrystalline materials, and has polycrystalline yield strength sigmasThe relationship with the average grain diameter d can be described by the Hall-Petch formula:
wherein sigma0The yield strength of the single crystal is, K is a constant, and the strength of the polycrystal is always improved along with the refinement of the crystal grains, so that the smaller the size of the crystal grains is, the higher the mechanical property of the magnesia-alumina spinel transparent ceramic is; the optical properties of the sample are better than those of spark plasma sintering, and the sample prepared by the methodThe transmittance of the magnesia-alumina spinel transparent ceramic (3mm thick) in a visible-infrared band reaches over 80 percent, the optical performance is good, and the use requirements in the fields of transparent armor, infrared transparent windows and the like can be met. And the magnesium aluminate spinel transparent ceramic is sintered in air by microwave, is convenient to operate, is suitable for batch production, and provides a new method for preparing the magnesium aluminate spinel transparent ceramic.
The second embodiment is as follows: the first difference between the present embodiment and the specific embodiment is: the chemical formula of the magnesia-alumina spinel powder in the step one is MgO. nAl2O3Wherein n is 1-1.1, the average particle size is less than 200nm, and the purity is not less than 99%. The rest is the same as the first embodiment.
The magnesia-alumina spinel powder in the first step of the embodiment is commercial powder, does not need high-energy ball milling and refining, and is suitable for manufacturing transparent ceramics.
The third concrete implementation mode: this embodiment is different from the first or second embodiment in that: the compression molding in the step one is specifically as follows: putting the magnesia-alumina spinel powder into a ball milling tank, using alcohol as a medium, carrying out ball milling and mixing, drying the ball-milled powder, and sieving to obtain raw material powder; the raw material powder is firstly molded for 1min to 3min under the pressure of 30MPa to 50MPa by dry pressing, and then molded for 10min to 20min under the pressure of 150MPa to 250MPa by cold isostatic pressing to obtain the ceramic biscuit. The other is the same as in the first or second embodiment.
The purity of the alcohol according to this embodiment is analytical grade.
The fourth concrete implementation mode: the difference between this embodiment mode and one of the first to third embodiment modes is: the ball milling and mixing specifically comprises the following steps: ball milling for 16-24 h at the speed of 60-90 r/min; the powder after ball milling is dried and sieved, and the method specifically comprises the following steps: drying for 5-10 h at the drying temperature of 50-80 ℃, then sieving with a 100-mesh sieve, and collecting the powder which permeates through the 100-mesh sieve to obtain the raw material powder. The others are the same as the first to third embodiments.
The fifth concrete implementation mode: the difference between this embodiment and one of the first to fourth embodiments is: the gel injection molding in the step one comprises the following specific steps:
①, preparing a premixed solution, namely mixing the organic monomer, the cross-linking agent and the deionized water, and stirring uniformly to obtain the premixed solution;
②, preparing ceramic slurry, namely adding a dispersant and magnesia-alumina spinel powder into the premixed liquid, and performing ball milling and mixing to obtain the ceramic slurry with the solid-phase volume percentage of 27-35%;
③, injection molding, namely, under vacuum, magnetically stirring the ceramic slurry with the solid-phase volume percentage of 27-35% to remove bubbles to obtain slurry with bubbles removed, adding an initiator and a catalyst into the slurry with bubbles removed, stirring for 0.5-1 min under the condition that the stirring speed is 80-120 r/min, then injecting into a mold, curing at room temperature, and demolding after complete curing to obtain a molded ceramic biscuit;
④, drying and removing the glue, namely drying the formed ceramic biscuit, removing the glue at high temperature in the air, cooling to below 200 ℃ after removing the glue, and naturally cooling to obtain the dried and removed ceramic biscuit;
⑤, cold isostatic pressing, namely, carrying out cold isostatic pressing on the dried ceramic biscuit for 10 to 20min under the condition that the pressure is 150 to 250MPa to obtain the ceramic biscuit, wherein the rest is the same as the first to fourth embodiments.
In step ③, the slurry is injected into a mold to initiate polymerization of the monomers and induce gelation of the slurry and curing at room temperature.
Sixth embodiment, the difference between this embodiment and one of the first to fifth embodiments is that the organic monomer in step ① is methacrylamide, the crosslinking agent in step ① is N, N' -methylenebisacrylamide, the dispersing agent in step ② is an aqueous solution of ammonium polyacrylate with a mass percentage of 40% to 43%, the initiator in step ③ is an aqueous solution of ammonium persulfate with a mass percentage of 8% to 12%, and the catalyst in step ③ is tetramethylethylenediamine.
The seventh embodiment is different from the first to sixth embodiments in that the mass ratio of the organic monomer to the crosslinking agent in the step ① is (10-20): 1, the mass ratio of the organic monomer to the water in the step ① is (16-20): 100, the mass ratio of the dispersing agent to the magnesium aluminate spinel powder in the step ② is (4-6): 100, and the rest is the same as the first to sixth embodiments.
Eighth embodiment, the difference between the first embodiment and the seventh embodiment is that the mass ratio of the initiator and the catalyst in the step ③ is (1.3-2): 1, the mass ratio of the initiator in the step ③ to the magnesia-alumina spinel powder in the step ② is (0.2-0.5): 100, the mold in the step ③ is an organic glass mold, and the inner surface of the organic glass mold is coated with paraffin, and the other embodiments are the same as the first embodiment to the seventh embodiment.
The paraffin coated on the inner surface of the organic glass mould in the specific embodiment can be beneficial to demoulding of the blank.
The ninth embodiment is different from the first to eighth embodiments in that the molded ceramic biscuit is dried in step ④ for 12 to 24 hours at room temperature and humidity of 80 to 90 percent, and then naturally dried in air for 48 to 72 hours to obtain a dried ceramic biscuit, the ceramic biscuit is subjected to high-temperature glue discharging in air in step ④, the temperature is controlled to be reduced to below 200 ℃ after the glue discharging, and then naturally cooled, specifically, the dried ceramic biscuit is placed in a muffle furnace, the temperature is increased to 150 to 200 ℃ at a temperature increasing rate of 0.5 to 1 ℃/min, the ceramic biscuit is subjected to heat preservation for 5 to 10 hours at a temperature of 150 to 200 ℃, the temperature is increased to 400 to 450 ℃ at a temperature increasing rate of 0.5 to 1 ℃/min, the ceramic biscuit is subjected to heat preservation for 5 to 10 hours at a temperature increasing rate of 400 to 450 ℃ at a temperature of 400 to 450 ℃, the temperature is maintained for 5 to 10 hours at a temperature increasing rate of 0.5 to 1 ℃/min, the temperature is increased to 1 ℃ at a temperature increasing rate of 0.5 to 1 ℃/min, the temperature is then naturally reduced to 650 to 700 ℃ at a temperature, and the temperature is reduced to 700 ℃ at a temperature of 1 ℃ or less than the other temperature.
Tenth embodiment, the difference between this embodiment and one of the first to ninth embodiments is that the ball milling and mixing in step ② is performed by using alumina balls as a ball milling medium, and performing ball milling for 16 to 24 hours in a roller ball milling tank made of polyurethane at a ball-to-material ratio of 3:1 and a ball milling rotation speed of 60 to 90 r/min.
The following examples were used to demonstrate the beneficial effects of the present invention:
the first embodiment is as follows:
a preparation method of magnesium aluminate spinel transparent ceramics is carried out according to the following steps:
firstly, pressing and forming magnesia-alumina spinel powder to obtain a ceramic biscuit;
secondly, placing the ceramic biscuit in the center of an alumina ceramic crucible, and then sleeving the alumina ceramic crucible containing the ceramic biscuit into a silicon carbide ceramic crucible, wherein the gap between the alumina ceramic crucible and the silicon carbide ceramic crucible is smaller than 1mm to obtain a sleeved crucible containing the ceramic biscuit;
thirdly, placing the nested crucible filled with the ceramic biscuit in a microwave sintering furnace, then heating the crucible to 1500 ℃ at the heating rate of 10 ℃/min, preserving the heat for 60min under the condition that the temperature is 1500 ℃, and then cooling along with the furnace to obtain a magnesium aluminate spinel ceramic block;
and fourthly, placing the magnesium aluminate spinel ceramic block in a hot isostatic pressing furnace, and carrying out hot isostatic pressing for 3h under the conditions of argon atmosphere, pressure of 180MPa and temperature of 1650 ℃ to obtain the magnesium aluminate spinel transparent ceramic.
The magnesia-alumina spinel powder in the step one is commercial powder with a chemical formula of MgO. nAl2O3Wherein n is 1-1.1, the particle size is 50-200 nm, and the purity is not lower than 99%.
The compression molding in the step one is specifically as follows: putting 60g of magnesia-alumina spinel powder into a ball milling tank, ball milling and mixing by taking alcohol as a medium, drying the ball milled powder, and sieving to obtain raw material powder; the raw material powder is firstly molded by dry pressing for 1min under the condition that the pressure is 30MPa, and then molded by cold isostatic pressing for 10min under the condition that the pressure is 200MPa, so that a ceramic biscuit is obtained.
The ball milling and mixing specifically comprises the following steps: ball milling for 20 hours at the speed of 70 r/min; the powder after ball milling is dried and sieved, and the method specifically comprises the following steps: drying in a rotary evaporator at 60 deg.C for 5h, sieving with 100 mesh sieve, and collecting powder passing through 100 mesh sieve to obtain raw material powder.
Polishing the magnesia-alumina spinel transparent ceramic prepared in the first embodiment to a thickness of 3mm, performing a transmittance test, specifically as shown in fig. 1 and 3, performing thermal etching on the polished magnesia-alumina spinel transparent ceramic (keeping the temperature for 40min at 1350 ℃ in air), and performing microstructure analysis on the thermally etched magnesia-alumina spinel transparent ceramic, as shown in fig. 2;
FIG. 1 is a photograph of a polished magnesia alumina spinel transparent ceramic prepared in accordance with one embodiment; as can be seen, the text below the sample is clearly seen after polishing the magnesia alumina spinel transparent ceramic prepared in the first example.
FIG. 3 is a graph showing transmittance of a polished magnesia alumina spinel transparent ceramic prepared in accordance with the first embodiment; as can be seen from the graph, the linear transmittance at 1064nm and the linear transmittance at 400nm of the sample with the thickness of 3mm after polishing of the magnesia-alumina spinel transparent ceramic prepared in the first example are 86% and 80%, respectively, and the optical performance is good.
FIG. 2 is a microstructure photograph of a polished and thermally etched surface of a transparent magnesia alumina spinel ceramic prepared according to the first embodiment; as can be seen, the magnesia alumina spinel transparent ceramic prepared in the first example has an average grain size of 20 μm, and has a dense structure without pores.
Example two:
a preparation method of magnesium aluminate spinel transparent ceramics is carried out according to the following steps:
firstly, pressing and forming magnesia-alumina spinel powder to obtain a ceramic biscuit;
secondly, placing the ceramic biscuit in the center of an alumina ceramic crucible, and then sleeving the alumina ceramic crucible containing the ceramic biscuit into a silicon carbide ceramic crucible, wherein the gap between the alumina ceramic crucible and the silicon carbide ceramic crucible is smaller than 1mm to obtain a sleeved crucible containing the ceramic biscuit;
thirdly, placing the nested crucible filled with the ceramic biscuit in a microwave sintering furnace, then heating the crucible to 1400 ℃ at the heating rate of 5 ℃/min, preserving the heat for 90min under the condition that the temperature is 1400 ℃, and then cooling along with the furnace to obtain a magnesium aluminate spinel ceramic block;
and fourthly, placing the magnesium aluminate spinel ceramic block in a hot isostatic pressing furnace, and carrying out hot isostatic pressing for 4 hours under the conditions of argon atmosphere, pressure of 180MPa and temperature of 1600 ℃ to obtain the magnesium aluminate spinel transparent ceramic.
The magnesia-alumina spinel powder in the step one is commercial powder with a chemical formula of MgO. nAl2O3Wherein n is 1-1.1, the particle size is 50-200 nm, and the purity is not lower than 99%.
The compression molding in the step one is specifically as follows: putting 70g of magnesia-alumina spinel powder into a ball milling tank, ball milling and mixing by taking alcohol as a medium, drying the ball milled powder, and sieving to obtain raw material powder; the raw material powder is firstly molded by dry pressing for 1min under the condition that the pressure is 40MPa, and then molded by cold isostatic pressing for 15min under the condition that the pressure is 250MPa, so that a ceramic biscuit is obtained.
The ball milling and mixing specifically comprises the following steps: ball milling for 18h at the speed of 80 r/min; the powder after ball milling is dried and sieved, and the method specifically comprises the following steps: drying in a rotary evaporator at 50 deg.C for 7h, sieving with 100 mesh sieve, and collecting powder passing through 100 mesh sieve to obtain raw material powder.
Polishing the magnesia-alumina spinel transparent ceramic prepared in the second embodiment to obtain a polished sample with the size and thickness of 3mm, and then carrying out a transmittance test to obtain a sample with the linear transmittance of 85% at 1064nm and 80% at 400nm, wherein the optical performance is good. The magnesia alumina spinel transparent ceramic prepared in the second example has an average grain size of 15 μm, and has a compact structure without pores.
Example three:
a preparation method of magnesium aluminate spinel transparent ceramics is carried out according to the following steps:
firstly, gel-casting magnesia-alumina spinel powder to obtain a ceramic biscuit;
secondly, placing the ceramic biscuit in the center of an alumina ceramic crucible, and then sleeving the alumina ceramic crucible containing the ceramic biscuit into a silicon carbide ceramic crucible, wherein the gap between the alumina ceramic crucible and the silicon carbide ceramic crucible is smaller than 1mm to obtain a sleeved crucible containing the ceramic biscuit;
thirdly, placing the sleeved crucible filled with the ceramic biscuit in a microwave sintering furnace, then heating the crucible to 1550 ℃ at the heating rate of 30 ℃/min, preserving the heat for 30min under the condition that the temperature is 1550 ℃, and then cooling along with the furnace to obtain a magnesium aluminate spinel ceramic block;
and fourthly, placing the magnesium aluminate spinel ceramic block in a hot isostatic pressing furnace, and carrying out hot isostatic pressing for 2h under the conditions of argon atmosphere, 160MPa of pressure and 1750 ℃ of temperature to obtain the magnesium aluminate spinel transparent ceramic.
In the step one, the magnesia-alumina spinel powder is commercial powder and has a chemical formula of MgO. nAl2O3Wherein n is 1-1.1, the particle size is 50-200 nm, and the purity is not lower than 99%.
The gel injection molding in the step one comprises the following specific steps:
①, preparing a premixed solution, namely mixing the organic monomer, the cross-linking agent and the deionized water, and stirring uniformly to obtain the premixed solution;
the mass ratio of the organic monomer to the cross-linking agent in the step ① is 20:1, and the mass ratio of the organic monomer to the water in the step ① is 20: 100;
②, preparing ceramic slurry, namely adding a dispersant and magnesia-alumina spinel powder into the premixed liquid, and performing ball milling and mixing to obtain the ceramic slurry with the solid phase volume percentage of 28%;
the mass ratio of the dispersing agent to the magnesium aluminate spinel powder in the step ② is 4: 100;
③, injection molding, namely magnetically stirring ceramic slurry with the solid phase volume percentage of 28% for 1 hour to remove bubbles under the conditions of vacuum and the rotating speed of a magnetic stirring rotor of 150r/min to obtain slurry with bubbles removed, adding an initiator and a catalyst into the slurry with bubbles removed, stirring for 0.6min under the condition of the stirring speed of 100r/min, then injecting into a mold, curing at room temperature, demolding after complete curing to obtain a molded ceramic biscuit;
the mass ratio of the initiator and the catalyst in the step ③ is 2:1, and the mass ratio of the initiator in the step ③ to the magnesium aluminate spinel powder in the step ② is 0.23: 100;
④, drying and removing the glue, namely drying the formed ceramic biscuit, removing the glue at high temperature in the air, cooling to below 200 ℃ after removing the glue, and naturally cooling to obtain the dried and removed ceramic biscuit;
⑤, cold isostatic pressing, namely, carrying out cold isostatic pressing on the dried and de-glued ceramic biscuit for 20min under the condition that the pressure is 250MPa to obtain the ceramic biscuit.
The organic monomer in step ① is methacrylamide (MAM), the cross-linking agent in step ① is N, N' -Methylene Bisacrylamide (MBAM), and the dispersing agent in step ② is 43% by weight of ammonium polyacrylate aqueous solution (PAA-NH for short)4) The initiator in the step ③ is ammonium persulfate aqueous solution (APS for short) with the mass percent of 10%, and the catalyst in the step ③ is tetramethylethylenediamine (TMEDA for short).
The mold described in step ③ is a plexiglass mold with the inner surface of the plexiglass mold coated with paraffin.
The step ④ is to dry the formed ceramic biscuit for 12 hours under the condition of room temperature and humidity of 90 percent, then dry the ceramic biscuit for 50 hours naturally in the air to obtain the dried ceramic biscuit, the step ④ is to discharge the glue at high temperature in the air, the temperature is controlled to be lower than 200 ℃ after the glue is discharged, and then the ceramic biscuit is cooled naturally, specifically, the dried ceramic biscuit is placed in a muffle furnace, the temperature is raised to 200 ℃ under the condition of the temperature raising speed of 0.5 ℃/min, the temperature is kept for 5 hours under the condition of the temperature of 200 ℃, the temperature is raised to 400 ℃ under the condition of the temperature raising speed of 1 ℃/min, the temperature is kept for 5 hours under the condition of the temperature of 400 ℃, the temperature is kept for 5 hours under the condition of the temperature raising speed of 1 ℃/min, the temperature is raised to 650 ℃ under the condition of 650 ℃, the temperature is kept for 10 hours under the speed of 2 ℃/min after the glue is discharged, the temperature is lowered to be lower than 200 ℃, and then the ceramic biscuit is cooled naturally.
And ②, performing ball milling and mixing, namely performing ball milling for 18 hours by taking alumina balls as a ball milling medium under the conditions that a roller ball milling tank is made of polyurethane, the ball-material ratio is 3:1, and the ball milling rotating speed is 65 r/min.
Polishing the magnesia-alumina spinel transparent ceramic prepared in the third embodiment to a thickness of 3mm, performing a transmittance test (see fig. 4 and 6 in detail), thermally etching the polished magnesia-alumina spinel transparent ceramic (keeping the temperature at 1450 ℃ for 40min in air), and performing microstructure analysis on the thermally etched magnesia-alumina spinel transparent ceramic, as shown in fig. 5;
FIG. 4 is a photo of a polished magnesia alumina spinel transparent ceramic prepared in example III; as can be seen, the transparent ceramic of magnesium aluminate spinel prepared in the third example is polished to clearly see the characters below the sample.
FIG. 6 is a graph showing the transmittance of a polished magnesia alumina spinel transparent ceramic prepared in example III; as can be seen from the graph, the linear transmittance at 1064nm and the linear transmittance at 400nm of the sample with the thickness of 3mm after polishing of the magnesia-alumina spinel transparent ceramic prepared in the third example are 86% and 82%, respectively, and the optical performance is good.
FIG. 5 is a microstructure photograph of a polished and thermally etched surface of a transparent magnesia alumina spinel ceramic prepared in example III; as can be seen, the magnesia alumina spinel transparent ceramic prepared in example three has an average grain size of 70 μm, a dense structure and no pores.
Example four:
a preparation method of magnesium aluminate spinel transparent ceramics is carried out according to the following steps:
firstly, gel-casting magnesia-alumina spinel powder to obtain a ceramic biscuit;
secondly, placing the ceramic biscuit in the center of an alumina ceramic crucible, and then sleeving the alumina ceramic crucible containing the ceramic biscuit into a silicon carbide ceramic crucible, wherein the gap between the alumina ceramic crucible and the silicon carbide ceramic crucible is smaller than 1mm to obtain a sleeved crucible containing the ceramic biscuit;
thirdly, placing the sleeved crucible filled with the ceramic biscuit in a microwave sintering furnace, then heating the crucible to 1350 ℃ at the heating rate of 15 ℃/min, preserving the heat for 120min under the condition that the temperature is 1350 ℃, and then cooling along with the furnace to obtain a magnesium aluminate spinel ceramic block;
and fourthly, placing the magnesium aluminate spinel ceramic block in a hot isostatic pressing furnace, and carrying out hot isostatic pressing for 5 hours under the conditions of argon atmosphere, 190MPa of pressure and 1500 ℃ of temperature to obtain the magnesium aluminate spinel transparent ceramic.
In the step one, the magnesia-alumina spinel powder is commercial powder and has a chemical formula of MgO. nAl2O3Wherein n is 1-1.1, the particle size is 50-200 nm, and the purity is not lower than 99%.
The gel injection molding in the step one comprises the following specific steps:
①, preparing a premixed solution, namely mixing the organic monomer, the cross-linking agent and the deionized water, and stirring uniformly to obtain the premixed solution;
the mass ratio of the organic monomer to the cross-linking agent in the step ① is 20:1, and the mass ratio of the organic monomer to the water in the step ① is 20: 100;
②, preparing ceramic slurry, namely adding a dispersant and magnesia-alumina spinel powder into the premixed liquid, and performing ball milling and mixing to obtain the ceramic slurry with the solid-phase volume percentage of 33.4%;
the mass ratio of the dispersing agent to the magnesium aluminate spinel powder in the step ② is 5: 100;
③, injection molding, namely magnetically stirring the ceramic slurry with the solid phase volume percentage of 33.4% for 1 hour to remove bubbles under the conditions of vacuum and the rotating speed of a magnetic stirring rotor of 150r/min to obtain the slurry after bubbles are removed, adding an initiator and a catalyst into the slurry after bubbles are removed, stirring for 1min under the condition of the stirring speed of 120r/min, then injecting into a mold, curing at room temperature, demolding after complete curing to obtain a molded ceramic biscuit;
the mass ratio of the initiator and the catalyst in the step ③ is 2:1, and the mass ratio of the initiator in the step ③ to the magnesium aluminate spinel powder in the step ② is 0.44: 100;
④, drying and removing the glue, namely drying the formed ceramic biscuit, removing the glue at high temperature in the air, cooling to below 200 ℃ after removing the glue, and naturally cooling to obtain the dried and removed ceramic biscuit;
⑤, cold isostatic pressing, namely, carrying out cold isostatic pressing on the dried and de-glued ceramic biscuit for 20min under the condition that the pressure is 150MPa to obtain the ceramic biscuit.
The organic monomer in step ① is methacrylamide (MAM), the cross-linking agent in step ① is N, N' -Methylene Bisacrylamide (MBAM), and the dispersing agent in step ② is 43% by weight of ammonium polyacrylate aqueous solution (PAA-NH for short)4) The initiator in the step ③ is ammonium persulfate aqueous solution (APS for short) with the mass percent of 10%, and the catalyst in the step ③ is tetramethylethylenediamine (TMEDA for short).
The mold described in step ③ is a plexiglass mold with the inner surface of the plexiglass mold coated with paraffin.
The step ④ is to dry the formed ceramic biscuit for 24 hours under the condition of room temperature and humidity of 90%, then dry naturally for 72 hours in the air to obtain the dried ceramic biscuit, the step ④ is to discharge the glue at high temperature in the air, the temperature is controlled to be lower than 200 ℃ after the glue is discharged, and then the ceramic biscuit is naturally cooled, specifically, the dried ceramic biscuit is placed in a muffle furnace, the temperature is raised to 200 ℃ under the condition of the temperature raising speed of 0.5 ℃/min, the temperature is kept for 5 hours under the condition of the temperature of 200 ℃, the temperature is raised to 400 ℃ under the condition of the temperature raising speed of 1 ℃/min, the temperature is kept for 5 hours under the condition of the temperature of 400 ℃, the temperature is finally raised to 650 ℃ under the condition of the temperature of 650 ℃ under the temperature of 1 ℃/min, the temperature is kept for 10 hours under the condition of the temperature of 1 ℃/min after the glue is discharged, the temperature is lowered to be lower than 200 ℃ under the condition of 650 ℃, and then the ceramic biscuit is naturally cooled.
And ②, performing ball milling and mixing, namely performing ball milling for 24 hours by taking alumina balls as a ball milling medium under the conditions that a roller ball milling tank is made of polyurethane, the ball-material ratio is 3:1, and the ball milling rotating speed is 90 r/min.
Polishing the magnesia-alumina spinel transparent ceramic prepared in the fourth example to obtain a polished sample with the size and thickness of 3mm, and then carrying out a transmittance test to obtain a sample with the linear transmittance of 85% at 1064nm and 81% at 400nm, wherein the sample has good optical properties.
The magnesia alumina spinel transparent ceramic prepared in the fourth example has an average grain size of 2 μm, and has a compact structure without pores.
Claims (10)
1. The preparation method of the magnesia-alumina spinel transparent ceramic is characterized by comprising the following steps of:
firstly, pressing or gel-casting magnesia-alumina spinel powder to obtain a ceramic biscuit;
secondly, placing the ceramic biscuit in the center of an alumina ceramic crucible, and then sleeving the alumina ceramic crucible containing the ceramic biscuit into a silicon carbide ceramic crucible, wherein the gap between the alumina ceramic crucible and the silicon carbide ceramic crucible is smaller than 1mm to obtain a sleeved crucible containing the ceramic biscuit;
thirdly, placing the sleeved crucible filled with the ceramic biscuit in a microwave sintering furnace, then heating the crucible to 1350-1550 ℃ at the heating rate of 5-40 ℃/min, preserving the heat for 30-120 min under the condition that the temperature is 1350-1550 ℃, and then cooling along with the furnace to obtain the magnesia-alumina spinel ceramic block;
fourthly, placing the magnesium aluminate spinel ceramic block in a hot isostatic pressing furnace, and carrying out hot isostatic pressing for 2-5 h under the conditions of argon atmosphere, 150-190 MPa of pressure and 1500-1750 ℃ of temperature to obtain the magnesium aluminate spinel transparent ceramic.
2. The method of claim 1, wherein the magnesium aluminate spinel transparent ceramic powder of the first step has a chemical formula of MgO-nAl2O3Wherein n is 1-1.1, the average particle size is less than 200nm, and the purity is not less than 99%.
3. The method for preparing magnesium aluminate spinel transparent ceramic according to claim 1, wherein the press forming in the first step is specifically as follows: putting the magnesia-alumina spinel powder into a ball milling tank, using alcohol as a medium, carrying out ball milling and mixing, drying the ball-milled powder, and sieving to obtain raw material powder; the raw material powder is firstly molded for 1min to 3min under the pressure of 30MPa to 50MPa by dry pressing, and then molded for 10min to 20min under the pressure of 150MPa to 250MPa by cold isostatic pressing to obtain the ceramic biscuit.
4. The method for preparing the magnesium aluminate spinel transparent ceramic according to claim 3, wherein the ball milling and mixing specifically comprises the following steps: ball milling for 16-24 h at the speed of 60-90 r/min; the powder after ball milling is dried and sieved, and the method specifically comprises the following steps: drying for 5-10 h at the drying temperature of 50-80 ℃, then sieving with a 100-mesh sieve, and collecting the powder which permeates through the 100-mesh sieve to obtain the raw material powder.
5. The method for preparing a magnesium aluminate spinel transparent ceramic according to claim 1, wherein the gel-casting in the first step is specifically:
①, preparing a premixed solution, namely mixing the organic monomer, the cross-linking agent and the deionized water, and stirring uniformly to obtain the premixed solution;
②, preparing ceramic slurry, namely adding a dispersant and magnesia-alumina spinel powder into the premixed liquid, and performing ball milling and mixing to obtain the ceramic slurry with the solid-phase volume percentage of 27-35%;
③, injection molding, namely, under vacuum, magnetically stirring the ceramic slurry with the solid-phase volume percentage of 27-35% to remove bubbles to obtain slurry with bubbles removed, adding an initiator and a catalyst into the slurry with bubbles removed, stirring for 0.5-1 min under the condition that the stirring speed is 80-120 r/min, then injecting into a mold, curing at room temperature, and demolding after complete curing to obtain a molded ceramic biscuit;
④, drying and removing the glue, namely drying the formed ceramic biscuit, removing the glue at high temperature in the air, cooling to below 200 ℃ after removing the glue, and naturally cooling to obtain the dried and removed ceramic biscuit;
⑤, cold isostatic pressing, namely, carrying out cold isostatic pressing on the dried and de-glued ceramic biscuit for 10min to 20min under the condition that the pressure is 150MPa to 250MPa to obtain the ceramic biscuit.
6. The method for preparing magnesium aluminate spinel transparent ceramic according to claim 5, wherein the organic monomer in step ① is methacrylamide, the cross-linking agent in step ① is N, N' -methylene bisacrylamide, the dispersing agent in step ② is 40-43% by weight of ammonium polyacrylate aqueous solution, the initiator in step ③ is 8-12% by weight of ammonium persulfate aqueous solution, and the catalyst in step ③ is tetramethylethylenediamine.
7. The preparation method of the magnesium aluminate spinel transparent ceramic according to claim 5, wherein the mass ratio of the organic monomer to the cross-linking agent in the step ① is (10-20): 1, the mass ratio of the organic monomer to the water in the step ① is (16-20): 100, and the mass ratio of the dispersing agent to the magnesium aluminate spinel powder in the step ② is (4-6): 100.
8. The preparation method of the magnesium aluminate spinel transparent ceramic according to claim 5, wherein the mass ratio of the initiator to the catalyst in the step ③ is (1.3-2): 1, the mass ratio of the initiator in the step ③ to the magnesium aluminate spinel powder in the step ② is (0.2-0.5): 100, the mold in the step ③ is an organic glass mold, and paraffin is coated on the inner surface of the organic glass mold.
9. The preparation method of the magnesium aluminate spinel transparent ceramic according to claim 5, characterized in that the shaped ceramic biscuit is dried in ④ for 12-24 h at room temperature and humidity of 80-90%, and then naturally dried in air for 48-72 h to obtain a dried ceramic biscuit, the ceramic biscuit is removed at high temperature in air in ④, and then is controlled to be cooled to below 200 ℃ and then naturally cooled, and specifically, the dried ceramic biscuit is placed in a muffle furnace, and the temperature is raised to 150-200 ℃ at a temperature raising rate of 0.5-1 ℃/min, and is kept at 150-200 ℃ for 5-10 h, and then is raised to 400-450 ℃ at a temperature raising rate of 0.5-1 ℃/min, and is kept at 400-450 ℃ for 5-10 h, and finally is cooled to 650-1 ℃ at a temperature raising rate of 0.5-1 ℃/min, and is cooled at a temperature raising rate of 650-1 ℃/min, and then is cooled to 700 ℃ at a temperature raising rate of 0.5-1 ℃/min.
10. The preparation method of the magnesium aluminate spinel transparent ceramic according to claim 5, wherein the ball milling and mixing in step ② are specifically performed by taking alumina balls as a ball milling medium and performing ball milling for 16-24 h in a roller ball milling tank made of polyurethane at a ball-material ratio of 3:1 and a ball milling rotation speed of 60-90 r/min.
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