CN113443901A - High-strength alumina foamed ceramic and preparation method thereof - Google Patents
High-strength alumina foamed ceramic and preparation method thereof Download PDFInfo
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- CN113443901A CN113443901A CN202111017626.XA CN202111017626A CN113443901A CN 113443901 A CN113443901 A CN 113443901A CN 202111017626 A CN202111017626 A CN 202111017626A CN 113443901 A CN113443901 A CN 113443901A
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- 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 100
- 239000000919 ceramic Substances 0.000 title claims abstract description 99
- 238000002360 preparation method Methods 0.000 title abstract description 31
- 239000002002 slurry Substances 0.000 claims abstract description 163
- 239000002243 precursor Substances 0.000 claims abstract description 64
- NTHWMYGWWRZVTN-UHFFFAOYSA-N sodium silicate Chemical compound [Na+].[Na+].[O-][Si]([O-])=O NTHWMYGWWRZVTN-UHFFFAOYSA-N 0.000 claims abstract description 57
- 235000019353 potassium silicate Nutrition 0.000 claims abstract description 46
- 239000000843 powder Substances 0.000 claims abstract description 41
- 239000002994 raw material Substances 0.000 claims abstract description 34
- 239000001095 magnesium carbonate Substances 0.000 claims abstract description 33
- ZLNQQNXFFQJAID-UHFFFAOYSA-L magnesium carbonate Chemical compound [Mg+2].[O-]C([O-])=O ZLNQQNXFFQJAID-UHFFFAOYSA-L 0.000 claims abstract description 33
- 229910000021 magnesium carbonate Inorganic materials 0.000 claims abstract description 33
- 235000014380 magnesium carbonate Nutrition 0.000 claims abstract description 32
- 238000005245 sintering Methods 0.000 claims abstract description 30
- 229910052710 silicon Inorganic materials 0.000 claims abstract description 27
- 239000005995 Aluminium silicate Substances 0.000 claims abstract description 26
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 claims abstract description 26
- 235000012211 aluminium silicate Nutrition 0.000 claims abstract description 26
- NLYAJNPCOHFWQQ-UHFFFAOYSA-N kaolin Chemical compound O.O.O=[Al]O[Si](=O)O[Si](=O)O[Al]=O NLYAJNPCOHFWQQ-UHFFFAOYSA-N 0.000 claims abstract description 26
- 239000010703 silicon Substances 0.000 claims abstract description 26
- 229910052594 sapphire Inorganic materials 0.000 claims abstract description 23
- 238000001035 drying Methods 0.000 claims abstract description 20
- 238000010304 firing Methods 0.000 claims abstract description 13
- 238000004513 sizing Methods 0.000 claims description 93
- 239000002245 particle Substances 0.000 claims description 41
- 238000002791 soaking Methods 0.000 claims description 34
- 239000006260 foam Substances 0.000 claims description 25
- 238000007598 dipping method Methods 0.000 claims description 20
- 238000005470 impregnation Methods 0.000 claims description 20
- 238000005096 rolling process Methods 0.000 claims description 18
- 238000006136 alcoholysis reaction Methods 0.000 claims description 15
- 238000000034 method Methods 0.000 claims description 15
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 12
- 238000006116 polymerization reaction Methods 0.000 claims description 11
- 230000035939 shock Effects 0.000 claims description 11
- 238000000498 ball milling Methods 0.000 claims description 9
- 238000002156 mixing Methods 0.000 claims description 9
- 238000005507 spraying Methods 0.000 claims description 7
- 239000011148 porous material Substances 0.000 claims description 4
- 238000003912 environmental pollution Methods 0.000 abstract 1
- 239000004372 Polyvinyl alcohol Substances 0.000 description 54
- 229920002451 polyvinyl alcohol Polymers 0.000 description 54
- 239000000243 solution Substances 0.000 description 32
- 239000003795 chemical substances by application Substances 0.000 description 30
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 19
- 239000004814 polyurethane Substances 0.000 description 17
- 229920002635 polyurethane Polymers 0.000 description 17
- 238000004519 manufacturing process Methods 0.000 description 15
- 239000000047 product Substances 0.000 description 15
- RGPUVZXXZFNFBF-UHFFFAOYSA-K diphosphonooxyalumanyl dihydrogen phosphate Chemical compound [Al+3].OP(O)([O-])=O.OP(O)([O-])=O.OP(O)([O-])=O RGPUVZXXZFNFBF-UHFFFAOYSA-K 0.000 description 13
- 239000002351 wastewater Substances 0.000 description 12
- 239000004115 Sodium Silicate Substances 0.000 description 11
- 230000009286 beneficial effect Effects 0.000 description 11
- 239000002131 composite material Substances 0.000 description 11
- 229910052911 sodium silicate Inorganic materials 0.000 description 11
- 239000000654 additive Substances 0.000 description 10
- 239000000725 suspension Substances 0.000 description 9
- 239000013078 crystal Substances 0.000 description 8
- 235000012239 silicon dioxide Nutrition 0.000 description 8
- 239000000126 substance Substances 0.000 description 8
- 230000000996 additive effect Effects 0.000 description 7
- 229910010293 ceramic material Inorganic materials 0.000 description 7
- 239000000463 material Substances 0.000 description 7
- 239000000377 silicon dioxide Substances 0.000 description 7
- 230000002378 acidificating effect Effects 0.000 description 6
- 230000000052 comparative effect Effects 0.000 description 6
- 230000007704 transition Effects 0.000 description 6
- 229910052782 aluminium Inorganic materials 0.000 description 5
- 238000005266 casting Methods 0.000 description 5
- 239000011248 coating agent Substances 0.000 description 5
- 238000000576 coating method Methods 0.000 description 5
- 239000000203 mixture Substances 0.000 description 5
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 4
- 239000000853 adhesive Substances 0.000 description 4
- 230000001070 adhesive effect Effects 0.000 description 4
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 4
- 239000007864 aqueous solution Substances 0.000 description 4
- 230000007797 corrosion Effects 0.000 description 4
- 238000005260 corrosion Methods 0.000 description 4
- 239000007791 liquid phase Substances 0.000 description 4
- 239000011777 magnesium Substances 0.000 description 4
- 230000008569 process Effects 0.000 description 4
- 239000010453 quartz Substances 0.000 description 4
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 3
- 230000008901 benefit Effects 0.000 description 3
- 230000015572 biosynthetic process Effects 0.000 description 3
- 239000000084 colloidal system Substances 0.000 description 3
- 229910052593 corundum Inorganic materials 0.000 description 3
- 230000002708 enhancing effect Effects 0.000 description 3
- 230000002349 favourable effect Effects 0.000 description 3
- 230000005661 hydrophobic surface Effects 0.000 description 3
- 229910052749 magnesium Inorganic materials 0.000 description 3
- 230000007935 neutral effect Effects 0.000 description 3
- 238000011056 performance test Methods 0.000 description 3
- 238000004065 wastewater treatment Methods 0.000 description 3
- FYYHWMGAXLPEAU-UHFFFAOYSA-N Magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 description 2
- KKCBUQHMOMHUOY-UHFFFAOYSA-N Na2O Inorganic materials [O-2].[Na+].[Na+] KKCBUQHMOMHUOY-UHFFFAOYSA-N 0.000 description 2
- 229910019142 PO4 Inorganic materials 0.000 description 2
- 230000009471 action Effects 0.000 description 2
- 229910052878 cordierite Inorganic materials 0.000 description 2
- 230000007547 defect Effects 0.000 description 2
- JSKIRARMQDRGJZ-UHFFFAOYSA-N dimagnesium dioxido-bis[(1-oxido-3-oxo-2,4,6,8,9-pentaoxa-1,3-disila-5,7-dialuminabicyclo[3.3.1]nonan-7-yl)oxy]silane Chemical compound [Mg++].[Mg++].[O-][Si]([O-])(O[Al]1O[Al]2O[Si](=O)O[Si]([O-])(O1)O2)O[Al]1O[Al]2O[Si](=O)O[Si]([O-])(O1)O2 JSKIRARMQDRGJZ-UHFFFAOYSA-N 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 238000001914 filtration Methods 0.000 description 2
- 239000012467 final product Substances 0.000 description 2
- 230000002209 hydrophobic effect Effects 0.000 description 2
- 229910052742 iron Inorganic materials 0.000 description 2
- 239000010452 phosphate Substances 0.000 description 2
- NBIIXXVUZAFLBC-UHFFFAOYSA-K phosphate Chemical compound [O-]P([O-])([O-])=O NBIIXXVUZAFLBC-UHFFFAOYSA-K 0.000 description 2
- 229910052573 porcelain Inorganic materials 0.000 description 2
- RMAQACBXLXPBSY-UHFFFAOYSA-N silicic acid Chemical compound O[Si](O)(O)O RMAQACBXLXPBSY-UHFFFAOYSA-N 0.000 description 2
- 230000002195 synergetic effect Effects 0.000 description 2
- 238000005303 weighing Methods 0.000 description 2
- 229910001845 yogo sapphire Inorganic materials 0.000 description 2
- 229910000838 Al alloy Inorganic materials 0.000 description 1
- BPQQTUXANYXVAA-UHFFFAOYSA-N Orthosilicate Chemical compound [O-][Si]([O-])([O-])[O-] BPQQTUXANYXVAA-UHFFFAOYSA-N 0.000 description 1
- 230000002159 abnormal effect Effects 0.000 description 1
- 125000000218 acetic acid group Chemical group C(C)(=O)* 0.000 description 1
- 239000002253 acid Substances 0.000 description 1
- 238000010306 acid treatment Methods 0.000 description 1
- 239000012190 activator Substances 0.000 description 1
- 239000012752 auxiliary agent Substances 0.000 description 1
- 229910001748 carbonate mineral Inorganic materials 0.000 description 1
- 239000002801 charged material Substances 0.000 description 1
- 238000004140 cleaning Methods 0.000 description 1
- 229910052681 coesite Inorganic materials 0.000 description 1
- 239000010431 corundum Substances 0.000 description 1
- 229910052906 cristobalite Inorganic materials 0.000 description 1
- 238000013461 design Methods 0.000 description 1
- 239000002270 dispersing agent Substances 0.000 description 1
- 230000001804 emulsifying effect Effects 0.000 description 1
- 238000005265 energy consumption Methods 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 238000005187 foaming Methods 0.000 description 1
- 239000000446 fuel Substances 0.000 description 1
- 239000005350 fused silica glass Substances 0.000 description 1
- 239000011521 glass Substances 0.000 description 1
- 238000000227 grinding Methods 0.000 description 1
- 230000007062 hydrolysis Effects 0.000 description 1
- 238000006460 hydrolysis reaction Methods 0.000 description 1
- 125000002887 hydroxy group Chemical group [H]O* 0.000 description 1
- 239000012535 impurity Substances 0.000 description 1
- 229910052909 inorganic silicate Inorganic materials 0.000 description 1
- 239000002932 luster Substances 0.000 description 1
- 238000012423 maintenance Methods 0.000 description 1
- 239000011159 matrix material Substances 0.000 description 1
- 239000000155 melt Substances 0.000 description 1
- 238000002844 melting Methods 0.000 description 1
- 230000008018 melting Effects 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 150000002894 organic compounds Chemical class 0.000 description 1
- 125000000963 oxybis(methylene) group Chemical group [H]C([H])(*)OC([H])([H])* 0.000 description 1
- 239000012071 phase Substances 0.000 description 1
- 230000000704 physical effect Effects 0.000 description 1
- 238000000197 pyrolysis Methods 0.000 description 1
- 238000012797 qualification Methods 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 238000000926 separation method Methods 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 239000006104 solid solution Substances 0.000 description 1
- 239000002904 solvent Substances 0.000 description 1
- 238000009955 starching Methods 0.000 description 1
- 229910052682 stishovite Inorganic materials 0.000 description 1
- 230000009967 tasteless effect Effects 0.000 description 1
- 229910052905 tridymite Inorganic materials 0.000 description 1
- 230000004580 weight loss Effects 0.000 description 1
- -1 white or grey white Chemical compound 0.000 description 1
Classifications
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- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- 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
- C04B35/10—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 aluminium oxide
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- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
- C04B35/622—Forming processes; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
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- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
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- C04B38/00—Porous mortars, concrete, artificial stone or ceramic ware; Preparation thereof
- C04B38/06—Porous mortars, concrete, artificial stone or ceramic ware; Preparation thereof by burning-out added substances by burning natural expanding materials or by sublimating or melting out added substances
- C04B38/0615—Porous mortars, concrete, artificial stone or ceramic ware; Preparation thereof by burning-out added substances by burning natural expanding materials or by sublimating or melting out added substances the burned-out substance being a monolitic element having approximately the same dimensions as the final article, e.g. a porous polyurethane sheet or a prepreg obtained by bonding together resin particles
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- C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
- C04B2235/02—Composition of constituents of the starting material or of secondary phases of the final product
- C04B2235/30—Constituents and secondary phases not being of a fibrous nature
- C04B2235/34—Non-metal oxides, non-metal mixed oxides, or salts thereof that form the non-metal oxides upon heating, e.g. carbonates, nitrates, (oxy)hydroxides, chlorides
- C04B2235/3418—Silicon oxide, silicic acids or oxide forming salts thereof, e.g. silica sol, fused silica, silica fume, cristobalite, quartz or flint
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- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
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- C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
- C04B2235/02—Composition of constituents of the starting material or of secondary phases of the final product
- C04B2235/30—Constituents and secondary phases not being of a fibrous nature
- C04B2235/34—Non-metal oxides, non-metal mixed oxides, or salts thereof that form the non-metal oxides upon heating, e.g. carbonates, nitrates, (oxy)hydroxides, chlorides
- C04B2235/3427—Silicates other than clay, e.g. water glass
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- C04B2235/02—Composition of constituents of the starting material or of secondary phases of the final product
- C04B2235/30—Constituents and secondary phases not being of a fibrous nature
- C04B2235/34—Non-metal oxides, non-metal mixed oxides, or salts thereof that form the non-metal oxides upon heating, e.g. carbonates, nitrates, (oxy)hydroxides, chlorides
- C04B2235/349—Clays, e.g. bentonites, smectites such as montmorillonite, vermiculites or kaolines, e.g. illite, talc or sepiolite
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- C04B2235/02—Composition of constituents of the starting material or of secondary phases of the final product
- C04B2235/30—Constituents and secondary phases not being of a fibrous nature
- C04B2235/44—Metal salt constituents or additives chosen for the nature of the anions, e.g. hydrides or acetylacetonate
- C04B2235/442—Carbonates
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Abstract
The invention discloses a high-strength alumina foamed ceramic and a preparation method thereof, wherein precursor impregnating slurry is uniformly impregnated and coated on a sponge body and is obtained by drying and sintering, wherein the precursor impregnating slurry comprises the following raw materials in parts by weight: alpha-Al2O360-75 parts of powder, 10-25 parts of kaolin, 6-14 parts of magnesite, 1-13 parts of silicon micropowder, 3.5-4.5 parts of water glass and 6-10 parts of PVA solution. The alumina foamed ceramic provided by the invention has the performances of high strength and high porosity. The invention provides a preparation method of high-strength alumina foamed ceramic, which can ensure low-temperature firing of ceramic and avoid environmental pollution in the preparation process.
Description
Technical Field
The invention relates to the technical field of foamed ceramic production, in particular to a preparation method of high-strength alumina foamed ceramic.
Background
The alumina foamed ceramic is popular in the metal melt casting industry due to the characteristics of low density, high hardness, high strength, high temperature stability and corrosion resistance, and is widely applied to filtering aluminum and aluminum alloy melts, and the use temperature is about 700-800 ℃. The aluminum melt obtained by filtering the alumina foamed ceramic has high qualification rate and other impurities, and the performance of the casting is effectively improved to a certain extent.
At present, the preparation method of the alumina foamed ceramic mostly adopts an organic precursor impregnation method, namely polyurethane sponge is used as a precursor template, repeated impregnation and rolling are carried out in pretreated slurry to ensure that the slurry is uniformly attached to mesh wires of the sponge, and the slurry is sintered by a kiln to burn out organic matters, so that the foamed ceramic material with the appearance corresponding to the precursor and high porosity is formed. In the process, the preparation of the slurry is a crucial link and is also a research focus. In the prior art, aluminum dihydrogen phosphate is introduced as a ceramic curing agent when the alumina foamed ceramic slurry is prepared, and the aluminum dihydrogen phosphate can effectively enhance the strength of the ceramic, so that the firing temperature of the alumina ceramic can be lowered to 1300 ℃, the ceramic can still have higher mechanical strength, and the requirement of casting working conditions can be met. For example, in the alumina ceramic foam guniting production process disclosed in the chinese invention patent CN107353039B, aluminum dihydrogen phosphate or silica sol is used as a curing agent. Because the aluminum dihydrogen phosphate is simple to obtain and the process cost is low, the benefits are considerable compared with other preparation methods. Therefore, aluminum dihydrogen phosphate is widely accepted and used as a curing agent for ceramics. However, aluminum dihydrogen phosphate has a fatal disadvantage in that the introduction of aluminum dihydrogen phosphate causes the pH of the ceramic slurry to be below 5, is acidic, and has a risk of corroding production equipment and sites. And the treatment and discharge of the production wastewater are also a big problem, and the surrounding environment is influenced. In addition, the additive suitable for the acidic condition in the market is less, the performance of the slurry is difficult to adjust through the additive, the slurry property is unstable, and the defects of uneven coating of the precursor, blockage of cavities and the like are easily caused during production.
Disclosure of Invention
The invention aims to solve the technical problem of providing a high-strength alumina foamed ceramic which can be effectively sintered at low temperature, so that the ceramic has the characteristics of high strength, high porosity, simple and low production process, environmental protection and no harm.
In order to achieve the technical effect, the invention provides high-strength alumina foamed ceramic which is obtained by uniformly dipping and coating precursor dipping slurry on a sponge body and drying and sintering the sponge body, wherein the precursor dipping slurry comprises the following raw materials in parts by weight:
α-Al2O360-75 parts of powder, 10-25 parts of kaolin, 6-14 parts of magnesite, 1-13 parts of silicon micropowder, 3.5-4.5 parts of water glass and 6-10 parts of PVA solution.
Preferably, the modulus of the water glass is 2.5-3.5;
the concentration of the PVA solution is 5-15%, the alcoholysis degree of the PVA is 95-99%, and the polymerization degree of the PVA is 5000-7000;
the pH value of the precursor dipping slurry is more than or equal to 7.
Preferably, the alpha-Al2O3The particle size of the powder is 0.5-2.0 μm, the particle size of the kaolin is 60-65 μm, the particle size of the magnesite is 0.5-2.0 μm, and the particle size of the silicon micropowder is 0.2-0.4 μm.
Preferably, the through hole rate of the high-strength alumina foamed ceramic is more than 80%, the normal-temperature compressive strength is more than 3.0MPa, and the residual compressive strength after primary air thermal shock at 800 ℃ is more than 2.1 MPa.
The invention also provides a preparation method of the high-strength alumina foamed ceramic, which comprises the following steps:
s1: mixing the raw materials according to a ratio, and then carrying out ball milling to obtain precursor impregnation slurry;
s2: soaking the sponge body in the precursor soaking slurry, and rolling to form a first slurry layer;
s3: soaking the sponge obtained in the step S2 in the precursor soaking slurry again, and rolling to form a second slurry layer;
s4: after the first slurry layer and the second slurry layer are dried, spraying the precursor dipping slurry on the surface of the sponge body to form a third slurry layer;
s5: and after the third slurry layer is dried, delivering the sponge body to a kiln for sintering to obtain a high-strength alumina foamed ceramic finished product.
Preferably, in step S1, the viscosity of the precursor impregnation slurry is 4200-4800mpa · S;
the pH value of the precursor dipping slurry is more than or equal to 7.
Preferably, the sponge body is cylindrical, the diameter of the sponge body is 30-100 mm, the thickness of the sponge body is 10-30 mm, and the pore density of the sponge body is 15-35 PPI.
Preferably, the sizing amount of the first sizing layer is 10-20 wt%;
the sizing amount of the second sizing layer is 70-80 wt%;
the sizing amount of the third sizing layer is 5-15 wt%.
Preferably, in step S5, the moisture content of the third slurry layer after drying is less than 3wt%, and the firing temperature of the sponge is 1250-.
Preferably, the through hole rate of the high-strength alumina foamed ceramic finished product is more than 80%, the normal-temperature compressive strength is more than 3.0MPa, and the residual compressive strength after primary air thermal shock at 800 ℃ is more than 2.1 MPa.
The implementation of the invention has the following beneficial effects:
1. the high-strength alumina foamed ceramic provided by the invention is obtained by uniformly dipping and coating precursor dipping slurry on a sponge body, drying and sintering. The water glass and the organic PVA solution are used as the composite curing agent, wherein the PVA solution can effectively enable inorganic slurry to be better attached to the organic sponge, so that the sizing amount and the sizing uniformity are improved, and the alumina foamed ceramic with high porosity is finally obtained.
2. The high-strength alumina foamed ceramic provided by the invention is prepared from alpha-Al in a raw material formula2O3The powder, the kaolin, the magnesite and the silicon micropowder are mixed according to a specific proportion, and on one hand, the synergistic effect of the kaolin, the magnesite and the silicon micropowder is utilized to reduce Al2O3The sintering temperature of the ceramic material and the water glass act together, so that the alumina foamed ceramic with higher strength after being sintered at about 1250-1350 ℃ is realized. On the other hand, magnesite is introduced into the formula, so that the thermal shock resistance of the material is further enhanced, and the finally obtained alumina foamed ceramic has high porosity and high mechanical strength.
3. According to the preparation method of the high-strength alumina foamed ceramic, provided by the invention, water glass and a PVA solution are used as a composite curing agent, wherein the PVA solution can be used for bonding ceramic particles in slurry at normal temperature, and a colloid environment is constructed in the slurry, so that the suspension of the particles is facilitated, and the suspension property of the slurry is improved. The water glass is used as a high-temperature curing agent, so that the alumina foam ceramic has higher strength after being fired at about 1250-. More importantly, the water glass creates an alkaline or weakly alkaline environment in the slurry, the medium-alkaline slurry environment can effectively reduce the corrosion of the slurry to equipment, and the production wastewater is easier to treat. In addition, the selection range of the additive is expanded, and the performance operability and the controllability of the slurry are higher.
3. The preparation method of the high-strength alumina foamed ceramic provided by the invention adopts three times of sizing in the sizing stage of the sizing agent to respectively form a first sizing layer, a second sizing layer and a third sizing layer, and the sizing amount and the sizing purpose of the three times of sizing are different. The primary sizing aims at improving the hydrophobic surface of the sponge body and forming a transition layer beneficial to slurry adhesion; the secondary sizing aims at large-scale sizing on the basis of the transition layer to form a subsequent alumina foamed ceramic main body; the third sizing aims at modifying the surface of the product to ensure that the lines are more smooth and sturdy. The alumina foamed ceramic with high strength and high porosity is prepared by the integral matching of the preparation process.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention will be described in further detail below.
Aluminum dihydrogen phosphate is widely accepted and used as a ceramic curing agent. However, aluminum dihydrogen phosphate has a fatal disadvantage in that the introduction of aluminum dihydrogen phosphate causes the pH of the ceramic slurry to be below 5, is acidic, and has a risk of corroding production equipment and sites. And the treatment and discharge of the production wastewater are also a big problem, and the surrounding environment is influenced. In addition, the additive suitable for the acidic condition in the market is less, the performance of the slurry is difficult to adjust through the additive, the slurry property is unstable, and the defects of uneven coating of the precursor, blockage of cavities and the like are easily caused during production.
In order to solve the problems, the invention provides a high-strength alumina foamed ceramic which is obtained by uniformly dipping and coating precursor dipping slurry on a sponge body and drying and sintering the sponge body, wherein the precursor dipping slurry comprises the following raw materials in parts by weight:
α-Al2O360-75 parts of powder, 10-25 parts of kaolin, 6-14 parts of magnesite, 1-13 parts of silicon micropowder, 3.5-4.5 parts of water glass and 6-10 parts of PVA solution.
The invention takes Al, Si and Mg as the main bodies of alumina ceramics and adopts alpha-Al2O3Powder, kaolin, magnesite, silicon micropowder and the like are used as main raw materials. Because of alpha-Al2O3The powder, magnesite, silicon micropowder and the like belong to barren raw materials, do not have plasticity and suspension performance per se, and are difficult to prepare slurry, so that additives such as curing agents and the like are required to be added for assisting in preparing slurry. Aluminum dihydrogen phosphate is often used as a curing agent for ceramics in the prior art, but the problems described above occur during the use process. The high-strength alumina foamed ceramic provided by the invention adopts water glass and organic PVA solution as composite curing agents, and has higher mechanical strengthAnd simultaneously has high porosity. The high-strength alumina foamed ceramic has a porosity of more than 80%, a normal-temperature compressive strength of more than 3.0MPa, and a residual compressive strength of more than 2.1MPa after primary air thermal shock at 800 ℃. The foamed ceramic material obtained by production meets the requirements of the casting industry, so that the foamed ceramic material has wide market prospect.
Specifically, in the composite curing agent, the water glass refers to an aqueous solution of sodium silicate, wherein the sodium silicate is commonly called sodium silicate and is an inorganic substance with a chemical formula of Na2O·nSiO2It is a soluble inorganic silicate. Preferably, the weight part of the water glass is 3.5-4.5 parts. Exemplary water glass weight parts are 3.6 parts, 3.8 parts, 4 parts, 4.3 parts, and the invention is not limited.
The modulus of the sodium silicate is n in the chemical formula, n = SiO2/Na2O (molar ratio), the modulus, shows the composition of sodium silicate, an important parameter of sodium silicate, affecting its physical and chemical properties. The larger the modulus of the sodium silicate is, the more the Si content is, the viscosity of the sodium silicate is increased, the sodium silicate is easy to decompose and harden, and the binding power is increased. The selection of the composite modulus is favorable for improving the binding power and enhancing the material strength of the alumina foam ceramic. Too large a modulus of sodium silicate results in difficulty in forming an aqueous solution, and too small a modulus of sodium silicate reduces adhesive strength. Preferably, the modulus of the water glass is 2.5-3.5, and more preferably, the modulus of the water glass is 3. It is worth mentioning that the waste water treatment is a big problem in the ceramic industry, and the waste water discharge must meet the national standard of GB 25464-2010. The pH value of the wastewater in the national standard is an important performance index, the modulus of the adopted water glass is 2.5-3.5, the solution is weak-base neutral, and the produced weak-base neutral wastewater is easier to treat compared with the acid wastewater produced by using aluminum dihydrogen phosphate slurry so as to meet the national standard discharge requirement. The pH value of the precursor dipping slurry is more than or equal to 7. The weak-base neutral wastewater generated in the production only needs to be introduced with a certain amount of CO2The pH value of the wastewater can be successfully adjusted to 6-9, the wastewater meets the national discharge standard, and the wastewater treatment cost and efficiency are greatly reduced.
In addition, the water glass is an alkaline activator, silicic acid colloid and sodium hydroxide are generated after hydrolysis, and an alkaline or weakly alkaline environment can be created in the slurry. In the prior art, the slurry is in an acidic environment after aluminum dihydrogen phosphate is added, and the number of additives suitable for the slurry under the acidic condition is small in the market, so that the performance of the slurry is difficult to improve by adding the functional auxiliary agent. The slurry disclosed by the invention is in an alkaline environment, so that the selection range of additives is expanded, and the operability and controllability of the performance of the slurry are improved. In addition, the alkaline environment of the slurry can effectively reduce the corrosion of the slurry to equipment, and is beneficial to the treatment and standard reaching of the production wastewater.
In addition, the water glass is a high-temperature curing agent, the sintering temperature of the alumina ceramic is generally about 1600 ℃, and if the alumina foamed ceramic is sintered at 1600 ℃, the performance is excessive, because the application working condition of the alumina foamed ceramic is generally 700-800 ℃, the strength of the completely sintered alumina is high and far exceeds the working condition requirement, and the sintering energy consumption is extremely high. At present, the common method is to control the firing temperature of the alumina foam ceramic at 1250-. However, the alumina ceramics can not be sintered at 1250-1350 ℃ under the conventional conditions, and the mechanical strength is extremely low, which can not meet the requirements at all. The invention can solve the problems by introducing the water glass which is a high-temperature curing agent, and the water glass has excellent viscosity at about 1300 ℃, can effectively connect ceramic particles, enhances the mechanical strength of the ceramic particles, and realizes the unification of saving fuel cost and obtaining excellent performance.
Finally, the water glass is also a good dispersant, can effectively adjust the dispersibility of the slurry, constructs a colloidal environment in the slurry, is beneficial to the suspension of particles and improves the suspension property of the slurry.
Besides the water glass, the composite curing agent also comprises a PVA solution, wherein the PVA solution refers to an aqueous solution of polyvinyl alcohol, and preferably, the concentration of the PVA solution is 5-15%. More preferably, the concentration of the PVA solution is 10%. The polyvinyl alcohol is an organic compound with a chemical formula of [ C2H4O] n The appearance of the product is white flaky, flocculent or powdery solid, is tasteless and is soluble in water. The PVA solution accounts for 6-10 parts by weight of the raw materials. Preferably, the weight part of the water glass is 7-9 parts. Exemplary water glass weight parts are 8 parts, 8.5 parts, 9 parts, 9.5 parts, and the invention is not limited.
The physical properties of polyvinyl alcohol are influenced by chemical structure, alcoholysis degree and polymerization degree. The polymerization degree increases, the viscosity of the aqueous solution increases, and the strength and solvent resistance after film formation increase, but the solubility in water and the elongation after film formation decrease. Preferably, the degree of polymerization of the PVA is 5000-. More preferably, the polymerization degree of the PVA is 6000, which is beneficial to improving the film strength and the bonding strength of the slurry after film formation. The degree of alcoholysis is an important index for measuring the amount of hydrophilic hydroxyl and hydrophobic acetyl in PVA molecules. With the reduction of alcoholysis degree, the emulsifying and dispersing capacity, the bonding performance to hydrophobic materials, the water solubility, the viscosity stability and the like of PVA are improved, but the strength and the water resistance of the film are correspondingly reduced, and the film is easy to foam and agglomerate. Preferably, the degree of alcoholysis of the PVA is between 95 and 99%. More preferably, the degree of alcoholysis of the PVA is 98%. The alcoholysis degree of 98 percent belongs to the alcoholysis degree of complete alcoholysis, and the film forming strength is enhanced.
In addition, the PVA solution belongs to an organic curing agent, can bond ceramic particles in the slurry at normal temperature, and constructs a colloidal environment in the slurry, thereby being beneficial to the suspension of the particles and improving the suspension property of the slurry. And the inorganic matter slurry is effectively and better attached to the organic sponge body by utilizing the principle of similarity and intermiscibility.
Compared with the prior art, the invention adopts the water glass and the PVA solution as the composite curing agent, and can effectively prepare the green body with high bonding degree of the slurry and the precursor and obtain the alumina foam ceramic sintered at low temperature. Compared with single water glass, the PVA in the composite curing agent has better adhesion property under normal temperature conditions, and then the inorganic slurry can be more effectively attached to the organic sponge precursor under the action of the PVA according to the similarity and intermiscibility principle instead of only having the adhesion function like the water glass. The technical problem that the slurry is completely dipped and coated on the precursor in the forming stage cannot be solved by singly adopting the water glass as the adhesive. Compared with the single use of PVA solution, the invention has the advantages that PVA as an organic curing agent is burnt before 1300 ℃, and the alumina body at the temperature is far from sintering, which can cause the strength of the body to be greatly reduced, even cause the ceramic body particles to lose adhesion and collapse, and the invention introduces water glass as a high-temperature adhesive, which can effectively ensure that the alumina body obtains alumina foamed ceramics with high strength at 1300 ℃ by the adhesion effect of the adhesive. The problem of obtaining the alumina foamed ceramics by low-temperature firing cannot be solved by singly adopting the PVA solution as the curing agent.
The water glass and PVA solution are used as composite curing agent to bind inorganic matters in the material. Specifically, the raw materials of the high-strength alumina foamed ceramic provided by the invention also comprise the following inorganic substances:
the raw material contains alpha-Al2O3Powder, alpha-Al2O3The corundum is the most stable phase in all alumina and is the main raw material of alumina foamed ceramics, the sintering temperature of the alumina foamed ceramics is mainly determined by the content of the alumina foamed ceramics in the chemical composition, and the higher the content is, the higher the sintering temperature of the porcelain is. In order to realize low-temperature firing of alumina foam ceramics, the alumina content should be reduced appropriately, but too low an alumina content affects the strength of the final product. Preferably, the alpha-Al2O3The weight portion of the powder is 60-75 portions. More preferably, the alpha-Al2O3The powder is present in 64 to 71 parts by weight, exemplary alpha-Al2O3The powder is 65 parts, 68 parts and 70 parts by weight, but is not limited to. Preferably, the alpha-Al2O3The particle size of the powder is 0.5-2.0 μm, preferably, the alpha-Al2O3The particle size of the powder is 0.5-1 μm.
The raw material comprises kaolin, and the main components of the kaolin are silicon dioxide and alumina. Wherein, the silicon dioxide belongs to a liquid-phase sintering aid. The sintering temperature of the alumina ceramic is greatly reduced because the generation temperature of the liquid phase is low. So as to obtain the alumina foamed ceramic with high strength under the condition of lower sintering temperature. Preferably, the kaolin powder is 10 to 25 parts by weight. More preferably, the kaolin powder is 12.2 to 23 parts by weight, and exemplary kaolin powders are 13 parts, 16 parts, 19 parts, and 22 parts by weight, but not limited thereto. Preferably, the particle size of the kaolin powder is 60 to 65 μm.
The raw material contains magnesite, the magnesite crystal belongs to carbonate mineral of trigonal crystal system, usually in the form of crystal grain or cryptocrystalline compact block, the latter is also called porcelain magnesite, white or grey white, iron-containing, yellow to brown, glass luster, and the magnesite mainly contains MgCO3. The introduction of Mg element can reduce the sintering temperature on one hand, the addition of MgO can generate a liquid phase with other components, the solubility of fine crystals in the liquid phase is increased in the sintering process, and the small crystals grow slowly, so that the discharge of pores in a matrix at the early stage of sintering is facilitated, the movement of a crystal boundary is reduced by the drawing action of the MgO through a solid solution, the tendency of separation of a through hole and the crystal boundary of the composite material is reduced, and the Al is effectively inhibited2O3The abnormal growth of crystal grains is favorable for reducing the sintering temperature. On the other hand, the magnesium element can form cordierite with aluminum and silicon in the formula, which is beneficial to enhancing the thermal shock resistance of the material, thereby forming the high-strength alumina foamed ceramic. Preferably, the weight part of the magnesite powder is 6-14 parts. More preferably, the magnesite powder is 8.4-10 parts by weight, and exemplary magnesite powders are 8.5 parts, 9 parts and 9.5 parts by weight, but not limited thereto. Preferably, the particle size of the magnesite powder is 0.5-2.0 μm. More preferably, the particle size of the magnesite powder is 0.5-1.0 μm.
The raw material comprises silicon micropowder, wherein the silicon micropowder refers to quartz powder, and the quartz micropowder is powder which is processed by pure quartz (natural quartz or fused quartz) through multiple procedures of crushing, sorting, cleaning, acid treatment, high-temperature melting, medium crushing, fine grinding, grading, iron removal and the like and meets the use requirement. The addition of the silicon dioxide can reduce the sintering temperature on one hand, and can form cordierite together with magnesium and aluminum on the other hand, which is beneficial to enhancing the thermal shock resistance of the material, thereby forming the high-strength alumina foam ceramic. Preferably, the weight part of the silicon micropowder is 1-13 parts. More preferably, the weight part of the silicon micro powder is 2.5-9.5 parts, and the weight parts of the exemplary silicon micro powder are 3 parts, 6 parts and 9 parts, but not limited thereto. Preferably, the particle size of the fine silica powder is 0.2 to 0.4 μm. More preferably, the particle size of the fine silica powder is 0.2 to 0.3 μm.
In conclusion, the inorganic powder is mixed and bonded by the composite curing agent of the water glass and the PVA solution, wherein the PVA solution can bond the ceramic particles in the slurry at normal temperature, and a colloid environment is constructed in the slurry, so that the suspension of the particles is facilitated, and the suspension property of the slurry is improved. And the inorganic matter slurry is effectively and better attached to the organic sponge body by utilizing the principle of similarity and intermiscibility. The water glass is used as a high-temperature curing agent, so that the alumina foam ceramic has higher strength after being fired at about 1250-. And the water glass creates an alkaline or alkalescent environment in the slurry, so that the selection range of the additive is enlarged, and the performance operability and the controllability of the slurry are higher. In addition, the alkaline environment of the slurry can effectively reduce the corrosion of the slurry to equipment, and the production wastewater is easier to treat.
Besides, in the raw material formula, alpha-Al2O3The powder, the kaolin, the magnesite and the silicon micropowder are mixed according to a specific proportion, and on one hand, the synergistic effect of the kaolin, the magnesite and the silicon micropowder is utilized to reduce Al2O3The sintering temperature of the ceramic material and the curing agent water glass act together, so that the alumina foamed ceramic with higher strength after being sintered at about 1250-. On the other hand, magnesite is introduced into the formula, so that the thermal shock resistance of the material is further enhanced, and the finally obtained high-strength alumina foamed ceramic has high porosity and high mechanical strength. Preferably, the through hole rate of the high-strength alumina foamed ceramic is more than 80%, the normal-temperature compressive strength is more than 3.0MPa, and the residual compressive strength after primary air thermal shock at 800 ℃ is more than 2.1 MPa. The foamed ceramic material obtained by production meets the requirements of the casting industry, so that the foamed ceramic material has wide market prospect.
Correspondingly, the invention also provides a preparation method of the high-strength alumina foamed ceramic, which comprises the following steps:
s1: mixing the raw materials according to a ratio, and then carrying out ball milling to obtain precursor impregnation slurry;
s2: soaking the sponge body in the precursor soaking slurry, and rolling to form a first slurry layer;
s3: soaking the sponge obtained in the step S2 in the precursor soaking slurry again, and rolling to form a second slurry layer;
s4: after the first slurry layer and the second slurry layer are dried, spraying the precursor dipping slurry on the surface of the sponge body to form a third slurry layer;
compared with the phosphate high-temperature curing agent in the prior art, the silicate high-temperature curing agent is used for replacing the phosphate high-temperature curing agent, the organic curing agent is compounded to enhance the bonding performance and improve the film forming strength of the slurry, and meanwhile, the alkaline slurry is beneficial to wastewater treatment and equipment maintenance. And in the sizing stage of the sizing agent, three times of sizing are adopted to respectively form a first sizing layer, a second sizing layer and a third sizing layer, and the sizing amount and the sizing purpose of the three times of sizing are different. The primary sizing aims at improving the hydrophobic surface of the sponge body and forming a transition layer beneficial to slurry adhesion; the secondary sizing aims at large-scale sizing on the basis of the transition layer to form a subsequent alumina foamed ceramic main body; the third sizing aims at modifying the surface of the product to ensure that the lines are more smooth and sturdy. The high-strength alumina foamed ceramic with high strength and high porosity is prepared by the integral matching of the preparation process.
Specifically, in step S1, the precursor impregnation slurry is prepared from the following raw materials in parts by weight: alpha-Al2O360-75 parts of powder, 10-25 parts of kaolin, 6-14 parts of magnesite, 1-13 parts of silicon micropowder, 3.5-4.5 parts of water glass and 6-10 parts of PVA solution.
It should be noted that the design principle of the raw materials of the slurry is the same as that described above, and the details are not repeated herein.
In the step S1, the mixed raw materials are ground by a ball mill to form a slurry with certain rheological properties, and preferably, the viscosity of the precursor impregnation slurry is 4200-. The viscosity of the precursor impregnation slurry is related to the requirements of the final product thickness, mesh condition, product performance and the like.
In step S2, the alumina ceramic foam is manufactured by using a sponge as a template, preferably, the sponge is a polyurethane sponge. The pyrolysis temperature of the polyurethane sponge is low, generally between 230 ℃ and 440 ℃, the polyurethane sponge is violently decomposed and generates a large proportion of weight loss, and the foaming additive in the polyurethane is decomposed at 600 ℃ to 800 ℃, so that the final residual ratio is low. Therefore, the preparation of the alumina foamed ceramic by using the polyurethane sponge as the template is beneficial to reducing the sintering temperature and reducing the template residues. Before starching, slicing and stamping are needed to be carried out on the polyurethane sponge, preferably, the sponge is cylindrical, the diameter of the sponge is 30-100 mm, and the thickness of the sponge is 10-30 mm. The pore density of the polyurethane sponge influences the through-hole rate and the sizing amount of the sponge body with the shape of the alumina foamed ceramic, and preferably, the through-hole rate of the polyurethane sponge is 15-35 PPI. More preferably, the through-hole rate of the polyurethane sponge is 20-30 PPI.
In the steps S2, S3, and S4, the polyurethane sponge is sized, and it is most critical to prepare the ceramic foam that the more the size coated on the organic foam is, the better the size is, and the strength of the ceramic is greatly improved on the premise that the organic foam is not blocked. Not only needs to remove redundant slurry, but also needs to ensure that the charged materials are distributed on the wall of the network hole and are hooked uniformly, so as to prevent the hole from being blocked. The invention adopts three times of sizing in the sizing stage to respectively form a first sizing layer, a second sizing layer and a third sizing layer, and the sizing amount and the sizing purpose of the three times of sizing are different. The primary sizing aims at improving the hydrophobic surface of the sponge body, forming a transition layer favorable for slurry adhesion and improving the sizing amount; the secondary sizing aims at large-scale sizing on the basis of the transition layer to form a subsequent high-strength alumina foamed ceramic main body; the purpose of sizing for the third time is to modify the surface of a product, so that the lines of the product are more round and thick, and simultaneously, the sizing agent can be more uniformly distributed on the walls of the network holes. Preferably, the sizing amount of the first sizing layer is 10-20 wt%; the sizing amount of the second sizing layer is 70-80 wt%; the sizing amount of the third sizing layer is 5-15 wt%. More preferably, the sizing amount of the first sizing layer is 15 wt%; the sizing amount of the second sizing layer is 75 wt%; the sizing amount of the third sizing layer is 10 wt%.
And in the step S5, after drying, sending the mixture to a kiln for sintering to obtain a finished product. Preferably, the water content after drying is less than 3wt%, and the firing temperature is 1250-. And finally, carrying out performance test on the obtained high-strength alumina foamed ceramic, preferably, the prepared high-strength alumina foamed ceramic has the through hole rate of more than 80 percent, the normal-temperature compressive strength of more than 3.0MPa, and the residual compressive strength of more than 2.1MPa after primary air thermal shock at 800 ℃.
For a better understanding of the inventive aspects, the present specification provides the following examples to illustrate:
example 1
The high-strength alumina foamed ceramic and the preparation method thereof are as follows:
the high-strength alumina foamed ceramic is prepared from the following raw materials in parts by weight: alpha-Al2O364.5 parts of powder, 23 parts of kaolin, 9.7 parts of magnesite, 2.8 parts of silicon micropowder, 3.5 parts of water glass and 10 parts of PVA solution.
Wherein the modulus of the water glass is 3; the concentration of the PVA solution is 10%, the alcoholysis degree of the PVA is 98%, and the polymerization degree of the PVA is 6000;
the alpha-Al2O3The particle size of the powder is 1.0 mu m, the particle size of the kaolin is 65 mu m, the particle size of the magnesite is 1.0 mu m, and the particle size of the silicon micropowder is 0.3 mu m.
The preparation method comprises the following steps:
s1: mixing the raw materials according to the parts by weight, and then carrying out ball milling to obtain precursor impregnation slurry, wherein the viscosity of the precursor impregnation slurry is 4500mpa · s;
s2: soaking the sponge body in the precursor soaking slurry, and rolling to form a first slurry layer;
a polyurethane sponge block with the specification of being 46mm in diameter, 22mm in thickness and 30PPI is selected as a sizing template, and the sizing amount of the first sizing layer is 15%.
S3: soaking the sponge obtained in the step S2 in the precursor soaking slurry again, and rolling to form a second slurry layer, wherein the sizing amount of the second slurry layer is 75%;
s4: and after the first slurry layer and the second slurry layer are dried, spraying precursor dipping slurry on the surface of the sponge body to form a third slurry layer, wherein the sizing amount of the third slurry layer is 10%.
S5: and drying and then delivering to a kiln for sintering to obtain a finished product. The water content after drying is lower than 3wt%, and the sintering temperature is 1250 ℃.
Example 2
The high-strength alumina foamed ceramic and the preparation method thereof are as follows:
the high-strength alumina foamed ceramic is prepared from the following raw materials in parts by weight: 72 parts of kaolin, 20 parts of magnesite, 10 parts of silica powder, 4 parts of water glass and 8 parts of PVA solution.
Wherein the modulus of the water glass is 3.5; the concentration of the PVA solution is 15%, the alcoholysis degree of the PVA is 99%, and the polymerization degree of the PVA is 7000;
the alpha-Al2O3The particle size of the powder is 2.0 mu m, the particle size of the kaolin is 60 mu m, the particle size of the magnesite is 2.0 mu m, and the particle size of the silicon micropowder is 0.4 mu m.
The preparation method comprises the following steps:
s1: mixing the raw materials according to the parts by weight, and then carrying out ball milling to obtain precursor impregnation slurry, wherein the viscosity of the precursor impregnation slurry is 4200 mpa · s;
s2: soaking the sponge body in the precursor soaking slurry, and rolling to form a first slurry layer;
selecting a 25PPI polyurethane sponge block with the diameter of 70mm and the thickness of 15mm as a sizing template, wherein the sizing amount of the first sizing layer is 10%.
S3: soaking the sponge obtained in the step S2 in the precursor soaking slurry again, and rolling to form a second slurry layer, wherein the sizing amount of the second slurry layer is 80%;
s4: and after the first slurry layer and the second slurry layer are dried, spraying precursor dipping slurry on the surface of the sponge body to form a third slurry layer, wherein the sizing amount of the third slurry layer is 10%.
S5: and drying and then delivering to a kiln for sintering to obtain a finished product. The water content after drying is lower than 3wt%, and the firing temperature is 1350 ℃.
Example 3
The high-strength alumina foamed ceramic and the preparation method thereof are as follows:
the high-strength alumina foamed ceramic is prepared from the following raw materials in parts by weight: weighing alpha-Al2O375 parts of powder, 13 parts of kaolin, 9 parts of magnesite, 10 parts of silicon micropowder, 4.5 parts of water glass and 6 parts of PVA solution.
Wherein the modulus of the water glass is 2.5; the concentration of the PVA solution is 5%, the alcoholysis degree of the PVA is 95%, and the polymerization degree of the PVA is 5000;
the alpha-Al2O3The particle size of the powder is 0.5 mu m, the particle size of the kaolin is 60 mu m, the particle size of the magnesite is 0.5 mu m, and the particle size of the silicon micropowder is 0.2 mu m.
The preparation method comprises the following steps:
s1: mixing the raw materials according to the parts by weight, and then carrying out ball milling to obtain precursor impregnation slurry, wherein the viscosity of the precursor impregnation slurry is 4200 mpa · s;
s2: soaking the sponge body in the precursor soaking slurry, and rolling to form a first slurry layer;
a polyurethane sponge block with the specification of being 90mm in diameter, 15mm in thickness and 20PPI is selected as a sizing template, and the sizing amount of the first sizing layer is 20%.
S3: soaking the sponge obtained in the step S2 in the precursor soaking slurry again, and rolling to form a second slurry layer, wherein the sizing amount of the second slurry layer is 75%;
s4: and after the first slurry layer and the second slurry layer are dried, spraying precursor dipping slurry on the surface of the sponge body to form a third slurry layer, wherein the sizing amount of the third slurry layer is 5%.
S5: and drying and then delivering to a kiln for sintering to obtain a finished product. The water content after drying is lower than 3wt%, and the firing temperature is 1300 ℃.
Example 4
The high-strength alumina foamed ceramic and the preparation method thereof are as follows:
the high-strength alumina foamed ceramic is prepared from the following raw materials in parts by weight: weighing alpha-Al2O375 parts of powder, 13 parts of kaolin, 9 parts of magnesite, 10 parts of silicon micropowder, 4.5 parts of water glass and 6 parts of PVA solution.
Wherein the modulus of the water glass is 3; the concentration of the PVA solution is 15%, the alcoholysis degree of the PVA is 97%, and the polymerization degree of the PVA is 6000;
the alpha-Al2O3The particle size of the powder is 1.0 mu m, the particle size of the kaolin is 60 mu m, the particle size of the magnesite is 1.0 mu m, and the particle size of the silicon micropowder is 0.2 mu m.
The preparation method comprises the following steps:
s1: mixing the raw materials according to the parts by weight, and then carrying out ball milling to obtain precursor impregnation slurry, wherein the viscosity of the precursor impregnation slurry is 4800mpa & s;
s2: soaking the sponge body in the precursor soaking slurry, and rolling to form a first slurry layer;
a polyurethane sponge block with the specification of being 90mm in diameter, 15mm in thickness and 20PPI is selected as a sizing template, and the sizing amount of the first sizing layer is 14%.
S3: soaking the sponge obtained in the step S2 in the precursor soaking slurry again, and rolling to form a second slurry layer, wherein the sizing amount of the second slurry layer is 78%;
s4: and after the first slurry layer and the second slurry layer are dried, spraying precursor dipping slurry on the surface of the sponge body to form a third slurry layer, wherein the sizing amount of the third slurry layer is 8%.
S5: and drying and then delivering to a kiln for sintering to obtain a finished product. The water content after drying is lower than 3wt%, and the firing temperature is 1300 ℃.
Comparative example 1
The alumina foamed ceramic and the preparation method thereof are as follows:
the difference from example 4 is that the modulus of the water glass is 4, and the rest is the same.
Comparative example 2 alumina foam ceramic and method of preparation:
the difference from example 4 is that the PVA solution concentration is 10%, the alcoholysis degree of the PVA is 88%, and the polymerization degree of the PVA is 1700; the rest is the same.
Comparative example 3 the composition of the alumina foam ceramic raw material was the same as that of example 4, and the preparation method was different from that of example 4 in that the following preparation method was employed:
s1: mixing the raw materials according to the weight part, and then carrying out ball milling to obtain precursor impregnation slurry;
s2: soaking the sponge body in the precursor soaking slurry, and rolling and sizing;
a polyurethane sponge block with the specification of 20PPI and the diameter of 90mm and the thickness of 15mm is selected as a sizing template.
S3: and drying and then delivering to a kiln for sintering to obtain a finished product. The water content after drying is lower than 3wt%, and the firing temperature is 1300 ℃.
Comparative example 4 alumina foam ceramic and method of preparation:
the composition of the alumina foamed ceramic raw material is the same as that of the alumina foamed ceramic raw material in the embodiment 4, and the preparation method is different from the embodiment 4 in that the following preparation method is adopted:
s1: mixing the raw materials according to the weight part, and then carrying out ball milling to obtain precursor impregnation slurry;
s2: soaking the sponge body in the precursor soaking slurry, and rolling to form a first slurry layer;
a polyurethane sponge block with the specification of being 90mm in diameter, 15mm in thickness and 20PPI is selected as a sizing template, and the sizing amount of the first sizing layer is 50%.
S3: soaking the sponge obtained in the step S2 in the precursor soaking slurry again, and rolling to form a second slurry layer, wherein the sizing amount of the second slurry layer is 50%;
s4: and drying and then delivering to a kiln for sintering to obtain a finished product. The water content after drying is lower than 3wt%, and the firing temperature is 1300 ℃.
Performance tests were performed on the alumina foam ceramics obtained in examples 1 to 4 and comparative examples 1 to 4 to obtain the analysis results shown in Table 1. As can be seen from Table 1, the high strength alumina ceramic foam obtained by the present invention has high porosity and high mechanical strength.
Table 1 shows the results of performance tests on the alumina foam ceramics obtained in examples 1 to 4 and comparative examples 1 to 4
While the foregoing is directed to the preferred embodiment of the present invention, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention.
Claims (10)
1. The high-strength alumina foamed ceramic is characterized in that a precursor impregnating slurry is uniformly impregnated and coated on a sponge body and is dried and sintered to obtain the high-strength alumina foamed ceramic, wherein the precursor impregnating slurry comprises the following raw materials in parts by weight:
α-Al2O360-75 parts of powder, 10-25 parts of kaolin, 6-14 parts of magnesite, 1-13 parts of silicon micropowder, 3.5-4.5 parts of water glass and 6-10 parts of PVA solution.
2. The high strength alumina ceramic foam according to claim 1, wherein the water glass has a modulus of 2.5 to 3.5;
the concentration of the PVA solution is 5-15%, the alcoholysis degree of the PVA is 95-99%, and the polymerization degree of the PVA is 5000-7000;
the pH value of the precursor dipping slurry is more than or equal to 7.
3. The high strength alumina ceramic foam of claim 1 wherein the α -Al is2O3The particle size of the powder is 0.5-2.0 μm, the particle size of the kaolin is 60-65 μm, the particle size of the magnesite is 0.5-2.0 μm, and the particle size of the silicon micropowder is 0.2-0.4 μm.
4. The high strength alumina ceramic foam of claim 1 having a porosity of greater than 80%, a room temperature compressive strength of greater than 3.0MPa, and a residual compressive strength of greater than 2.1MPa after a primary air thermal shock at 800 ℃.
5. A method for preparing the high-strength alumina ceramic foam according to any one of claims 1 to 4, comprising the steps of:
s1: mixing the raw materials according to a ratio, and then carrying out ball milling to obtain precursor impregnation slurry;
s2: soaking the sponge body in the precursor soaking slurry, and rolling to form a first slurry layer;
s3: soaking the sponge obtained in the step S2 in the precursor soaking slurry again, and rolling to form a second slurry layer;
s4: after the first slurry layer and the second slurry layer are dried, spraying the precursor dipping slurry on the surface of the sponge body to form a third slurry layer;
s5: and after the third slurry layer is dried, delivering the sponge body to a kiln for sintering to obtain a high-strength alumina foamed ceramic finished product.
6. The method of claim 5, wherein in step S1, the viscosity of the precursor impregnation slurry is 4200-4800 mpa-S;
the pH value of the precursor dipping slurry is more than or equal to 7.
7. The method of preparing a high strength alumina ceramic foam according to claim 5, wherein the sponge has a cylindrical shape, a diameter of 30 to 100mm, a thickness of 10 to 30mm, and a pore density of 15 to 35 PPI.
8. The method of preparing a high strength alumina ceramic foam according to claim 5,
the sizing amount of the first sizing layer is 10-20 wt%;
the sizing amount of the second sizing layer is 70-80 wt%;
the sizing amount of the third sizing layer is 5-15 wt%.
9. The method of claim 5, wherein in step S5, the water content of the third slurry layer after drying is less than 3wt%, and the firing temperature of the sponge is 1250-.
10. The method for preparing the high-strength alumina foamed ceramic according to claim 5, wherein the porosity of the high-strength alumina foamed ceramic product is more than 80%, the normal-temperature compressive strength is more than 3.0MPa, and the residual compressive strength after primary air thermal shock at 800 ℃ is more than 2.1 MPa.
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Application publication date: 20210928 |