CN113563090A - Granular mullite for high-temperature precision casting and manufacturing method thereof - Google Patents
Granular mullite for high-temperature precision casting and manufacturing method thereof Download PDFInfo
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- CN113563090A CN113563090A CN202110662562.2A CN202110662562A CN113563090A CN 113563090 A CN113563090 A CN 113563090A CN 202110662562 A CN202110662562 A CN 202110662562A CN 113563090 A CN113563090 A CN 113563090A
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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
- C04B35/66—Monolithic refractories or refractory mortars, including those whether or not containing clay
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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
- C04B35/16—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 silicates other than clay
- C04B35/18—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 silicates other than clay rich in aluminium oxide
- C04B35/185—Mullite 3Al2O3-2SiO2
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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
- C04B35/626—Preparing or treating the powders individually or as batches ; preparing or treating macroscopic reinforcing agents for ceramic products, e.g. fibres; mechanical aspects section B
- C04B35/62605—Treating the starting powders individually or as mixtures
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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
- 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
- C04B2235/32—Metal oxides, mixed metal oxides, or oxide-forming salts thereof, e.g. carbonates, nitrates, (oxy)hydroxides, chlorides
- C04B2235/3224—Rare earth oxide or oxide forming salts thereof, e.g. scandium oxide
Abstract
The invention discloses granular mullite for high-temperature precision casting and a manufacturing method thereof, wherein the granular mullite for high-temperature precision casting is prepared from material powder, the material powder comprises a mixture of industrial alumina and high-purity silicon oxide, the industrial alumina accounts for 71.8% of the mixture, and the material powder also comprises rare earth oxide accounting for 1% -5% of the total weight of the powder. A manufacturing method of granular mullite for high-temperature precision casting comprises the following steps: 1) selecting materials: industrial alumina: al (Al)2O3>98％，Na2O<0.5%, high purity silicon oxide: SiO 22>99％，Fe2O3<0.03%, rare earth oxide: not less than 99.95 percent; 2) smelting: mixing industrial alumina, high-purity silicon oxide and rare earth oxide, and adding electricityThe granular mullite for high-temperature precision casting and the manufacturing method thereof solve the problems that the high-temperature alloy precision casting requires isotropy of a high-temperature mould shell and sand sticking of a casting, and give full play to the excellent high-temperature thermodynamic and chemical properties of the mullite.
Description
Technical Field
The invention relates to the technical field of smelting, in particular to granular mullite for high-temperature precision casting and a manufacturing method thereof.
Background
The mullite is 3Al2O3·2SiO2Refractory material with crystal phase as main component and including natural mullite and artificially synthesized mullite. The mineral structure of mullite is an orthorhombic system, crystals are arranged in a long columnar, needle-shaped or chain shape, and the needle-shaped mullite is inserted in a product to form a firm framework. Because natural mullite is few, the purity is not high, and the mineral composition is complex, the natural mullite is generally synthesized by people. The synthesized mullite and the products thereof have excellent high-temperature mechanical and thermal properties such as higher density and purity, high-temperature structural strength, low high-temperature creep rate, small thermal expansion rate, strong chemical erosion resistance, good thermal shock resistance and the like, so the research on the high-purity mullite in the refractory material industry in recent years is more, and the main products of the mullite comprise the electrofused mullite and the calcined mullite.
The calcined mullite is prepared according to the proportion of an aluminum silicon system 3: : 2 preparing a silicon blank, burning to 1500-1700 ℃, and crushing to obtain the required granularity. The sintering method is divided into a dry method and a wet method according to the preparation mode of raw materials, wherein the dry method process is that the ingredients are ground together, and are sintered by a rotary kiln or a tunnel kiln after being pressed into balls or pressed into blanks; the wet process is that the batch is ground into slurry by adding water, then the slurry is pressed and dehydrated into mud cake, and the mud is extruded into mud segment or mud blank in vacuum and then calcined to obtain the product. Mullite is generally synthesized directly from kaolinite, sillimanite group minerals, aluminum hydroxide or alumina and silica. The clay material and alumina or sillimanite group mineral and industrial alumina react under heating condition to form primary and secondary mullite, the primary mullite is formed in the range of 1000-1200 ℃, and further raising the temperature can increase the crystallization. The formation of secondary mullite is usually completed at 1650 ℃. To produce dense mullite products, a two-step sintering process is commonly used. However, the calcined mullite only has chemical components reaching the indexes of the mullite, and the rock phase transition of the calcined mullite is a mixture of acicular mullite, prismatic mullite and glass, so that the calcined mullite cannot be processed into granular high-purity mullite and cannot reach the optimal service performance.
The electrically fused mullite generally comprises high-purity electrically fused mullite and common electrically fused mullite. The raw materials of the material are industrial alumina + high-purity silica and bauxite clinker + silica.
Al of the material when mullite is synthesized by electric melting2O3/SiO2The ratio determines the ore of the electrically fused mullitePhase and crystal morphology of mullite (table 1). Electrofused mullite is made by melt crystallization, which is very similar to Al2O3-SiO2Cooling and crystallizing process of series phase diagram. In electrically melting mullite Al2O3When the content reaches 79 percent, no corundum phase is still present, and the main content is Al2O3Solid dissolution in mullite to form beta-mullite. The raw materials contain MgO, CaO and Na2O and TiO2And the impurities, the difference between the melting equipment and the electric melting temperature, and the mineral composition of the electric melting mullite have a certain corresponding relation with the rule in the table 1.
TABLE 1Al2O3/SiO2Ratio and mineral composition of electrofused mullite
The electric melting mullite can be prepared into high-purity mullite by an electric melting method according to theoretical components of the mullite, the rock phase is of a needle column-shaped mullite structure, the high-purity mullite cannot be processed into granular mullite, the high-temperature mullite cannot be made into a refractory material meeting the requirements of a high-temperature ceramic shell, and only a few primary and intermediate-grade refractory materials can be made.
The broken mullite sand grains with needle column structure are always needle column shaped, the size in the length direction is larger than that in the transverse direction, and the ceramic shell for investment casting of aviation engine and gas turbine blades has a complete manufacturing process which has two sand hanging modes. One method is that when making ceramic shell, the slurry-coated model is placed into the fluidized bed sand bed to coat sand, at this time the boiling sand is directional, the sand grain is in vertical column form, at this time the mould set and component can not stick the sand grain with small contact surface, and the sharp edge of the wax component can not coat sand grain. Another sand hanging method is that sand is sprinkled at two ends, sand grains are sprayed on a model through proper screens, each screen size corresponds to the size of the sand grains, the sand grains fall on the screens randomly and freely, the sand grains are vertical and horizontal when falling, the vertically falling sand grains smaller than the apertures of the screen holes can fall, the horizontally falling sand grains larger than the apertures of the screen holes block the screens, the sand grains cannot fall off, the falling sand grains are not easy to stick on parts due to small contact surfaces with the modules, so that the model is difficult to stick with sand, the performances of the model in all directions are inconsistent, and the needle pillar sand is not suitable for molding shells. Only the granular mullite sand and the mullite powder can produce a mullite shell and a mullite core with excellent all directions, and therefore, a granular mullite for high-temperature precision casting and a manufacturing method thereof are provided.
Disclosure of Invention
The invention aims to overcome the existing defects and provide the granular mullite for high-temperature precision casting and the manufacturing method thereof, so that the granular mullite sand and the mullite powder can be produced, the problem that the high-temperature alloy precision casting requires isotropy of a high-temperature mould shell is solved, the problem of sand sticking on the surface of a high-temperature alloy casting is solved, the excellent high-temperature thermodynamics and chemical properties of the mullite are fully exerted, and the problem in the background technology can be effectively solved.
In order to achieve the purpose, the invention provides the following technical scheme:
the granular mullite for high-temperature precision casting is prepared from material powder, wherein the material powder comprises a mixture of industrial alumina and high-purity silicon oxide, the industrial alumina accounts for 71.8% of the mixture, and the material powder also comprises a rare earth oxide accounting for 1% -5% of the total weight of the powder.
A manufacturing method of granular mullite for high-temperature precision casting comprises the following steps:
1) selecting materials: wherein, the ratio of industrial alumina: al (Al)2O3>98％，Na2O<0.5％
High-purity silicon oxide: SiO 22>99％，Fe2O3<0.03％
Rare earth oxide: not less than 99.95 percent;
2) smelting: uniformly mixing material powder consisting of industrial alumina, high-purity silicon oxide and rare earth oxide, and then adding the mixture into an electric arc furnace for smelting, so that the needle and columnar structures of the traditional mullite rock phase are changed, and the mullite with a uniform network rock phase structure is generated;
3) crushing: the mullite with the network rock phase structure is sequentially crushed, sieved and ground, and granular high-purity mullite sand and mullite powder with various uniform granularities and sizes are processed.
Compared with the prior art, the invention has the beneficial effects that: the granular mullite for high-temperature precision casting and the manufacturing method thereof have the following advantages:
at present, corundum materials are almost used in precision investment casting ceramic shell materials, and in use, the difficulty which is difficult to overcome exists, so that the quality of cast blades is not high, and the qualified rate is usually only 50-60%. The main problems are that the quality of the ceramic shell and the ceramic core is unstable, the shell and the core are subjected to cold and thermal impact for many times in the blade casting process, the lithofacies structure is changed after thermodynamics and thermochemistry treatment, the material volume is changed, and the high-temperature performance of the material is also changed differently.
The prior high-purity mullite rock phase is a long columnar and acicular crystal, and since the mullite sand and the mullite powder with a reticular structure and particles are produced, a plurality of problems in the shell manufacturing process of high-temperature alloy investment precision casting are well solved, and the excellent high-temperature thermodynamics and chemical properties of the mullite shell, such as high-temperature structural strength, low high-temperature creep rate, small thermal expansion coefficient, strong chemical erosion resistance, good thermal shock resistance and the like, are fully exerted. The yield of high-temperature alloy investment casting can reach more than 90%.
Detailed Description
The technical solutions in the embodiments of the present invention will be described clearly and completely with reference to the following embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
The embodiment provides a technical scheme:
the granular mullite for high-temperature precision casting is prepared from material powder, wherein the material powder comprises a mixture of industrial alumina and high-purity silicon oxide, the industrial alumina accounts for 71.8% of the mixture, and the material powder also comprises rare earth oxide accounting for 1% -5% of the total weight of the powder.
A manufacturing method of granular mullite for high-temperature precision casting comprises the following steps:
1) selecting materials: wherein, the ratio of industrial alumina: al (Al)2O3>98％，Na2O<0.5％
High-purity silicon oxide: SiO 22>99％，Fe2O3<0.03％
Rare earth oxide: not less than 99.95 percent;
2) smelting: uniformly mixing material powder consisting of industrial alumina, high-purity silicon oxide and rare earth oxide, and then adding the mixture into an electric arc furnace for smelting, so that the needle and columnar structures of the traditional mullite rock phase are changed, and the mullite with a uniform network rock phase structure is generated;
3) crushing: the mullite with the network rock phase structure is sequentially crushed, sieved and ground, and granular high-purity mullite sand and mullite powder with various uniform granularities and sizes are processed.
The rare earth refers to 15 lanthanide elements with atomic numbers of 57 to 71 in the periodic table of elements, and 17 elements including scandium and yttrium with chemical properties similar to those of the lanthanide elements, and researches show that the action mechanism of the rare earth in alumina ceramics is mainly as follows: 1. the radius of the rare earth cation is larger than that of aluminum ion, so that solid solution is difficult to form, the rare earth ion is gathered at the crystal boundary in the migration process of temperature rise, the pinning effect is generated on the migration of the crystal boundary, and the rapid growth of crystal grains is inhibited. 2. The introduction of cations in the rare earth oxide can change the ceramic structure of the matrix oxide to form cation vacancies, accelerate the movement of ions, activate sintering and densify the structure. 3. The rare earth oxide is a good surface active substance, can improve the wettability of the alumina ceramic, and reduces the melting point of the ceramic material, thereby reducing the sintering temperature.
The high-purity industrial alumina is selected as the alumina, the high-purity silicon oxide is selected as the silicon oxide, the common high-purity rare earth oxide which is easy to purchase and solve is selected as the rare earth, the proportion of the alumina and the silicon oxide is adjusted according to the change and the influence of the smelting process, and the high-purity mullite is guaranteed to be produced. The transformation of the mullite reticular structure rock phase is well controlled by adjusting the addition proportion of the rare earth, so that the reticular structure rock phase is produced and is crushed and processed into granular mullite sand and mullite powder.
The above description is only an embodiment of the present invention, and not intended to limit the scope of the present invention, and all modifications of equivalent structures and equivalent processes, which are made by the present specification, or directly or indirectly applied to other related technical fields, are included in the scope of the present invention.
Claims (2)
1. The granular mullite for high-temperature precision casting is characterized in that: the granular mullite for high-temperature precision casting is prepared from material powder, wherein the material powder comprises a mixture of industrial alumina and high-purity silicon oxide, the industrial alumina accounts for 71.8% of the mixture, and the material powder also comprises rare earth oxide accounting for 1% -5% of the total weight of the material powder.
2. A method for manufacturing granular mullite for high-temperature precision casting is characterized by comprising the following steps:
1) selecting materials: wherein, the ratio of industrial alumina: al (Al)2O3>98％，Na2O<0.5％
High-purity silicon oxide: SiO 22>99％，Fe2O3<0.03％
Rare earth oxide: not less than 99.95 percent;
2) smelting: uniformly mixing material powder consisting of industrial alumina, high-purity silicon oxide and rare earth oxide, and then adding the mixture into an electric arc furnace for smelting, so that the needle and columnar structures of the traditional mullite rock phase are changed, and the mullite with a uniform network rock phase structure is generated;
3) crushing: the mullite with the network rock phase structure is sequentially crushed, sieved and ground, and granular high-purity mullite sand and mullite powder with various uniform granularities and sizes are processed.
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113860896A (en) * | 2021-11-03 | 2021-12-31 | 贵州安吉华元科技发展有限公司 | High-temperature precision casting low-creep corundum mullite and manufacturing method thereof |
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| CN85108307A (en) * | 1985-11-24 | 1987-06-03 | 梅河口市砂轮厂 | Lead with aluminum oxide and to fuse into high-purity electrofused mullite |
| CN1303834A (en) * | 1999-11-22 | 2001-07-18 | 冶金工业部洛阳耐火材料研究院 | Corundum-mullite product |
| CN1974475A (en) * | 2006-12-21 | 2007-06-06 | 上海交通大学 | Making process of electrofused mullite |
| CN101585706A (en) * | 2009-07-03 | 2009-11-25 | 陕西科技大学 | Method for preparing mullite refractory material aggregate |
| CN102126865A (en) * | 2011-01-18 | 2011-07-20 | 上海海事大学 | Method for producing high-purity fused mullite |
| CN110451996A (en) * | 2019-08-26 | 2019-11-15 | 湖南德景源科技有限公司 | Lithium electricity saggar mullite preparation process |
-
2021
- 2021-06-15 CN CN202110662562.2A patent/CN113563090A/en active Pending
Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN85108307A (en) * | 1985-11-24 | 1987-06-03 | 梅河口市砂轮厂 | Lead with aluminum oxide and to fuse into high-purity electrofused mullite |
| CN1303834A (en) * | 1999-11-22 | 2001-07-18 | 冶金工业部洛阳耐火材料研究院 | Corundum-mullite product |
| CN1974475A (en) * | 2006-12-21 | 2007-06-06 | 上海交通大学 | Making process of electrofused mullite |
| CN101585706A (en) * | 2009-07-03 | 2009-11-25 | 陕西科技大学 | Method for preparing mullite refractory material aggregate |
| CN102126865A (en) * | 2011-01-18 | 2011-07-20 | 上海海事大学 | Method for producing high-purity fused mullite |
| CN110451996A (en) * | 2019-08-26 | 2019-11-15 | 湖南德景源科技有限公司 | Lithium electricity saggar mullite preparation process |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113860896A (en) * | 2021-11-03 | 2021-12-31 | 贵州安吉华元科技发展有限公司 | High-temperature precision casting low-creep corundum mullite and manufacturing method thereof |
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Application publication date: 20211029 |