CN103803568B - A kind of method utilizing microwave catalysis synthesis acicular mullite - Google Patents
A kind of method utilizing microwave catalysis synthesis acicular mullite Download PDFInfo
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- CN103803568B CN103803568B CN201310740092.2A CN201310740092A CN103803568B CN 103803568 B CN103803568 B CN 103803568B CN 201310740092 A CN201310740092 A CN 201310740092A CN 103803568 B CN103803568 B CN 103803568B
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- acicular mullite
- mullite
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- microwave catalysis
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Abstract
The invention discloses a kind of method utilizing microwave catalysis synthesis acicular mullite, with aluminium fluoride as catalyst, with aluminum contained compound, silicon-containing compound as raw material, a step prepares acicular mullite.With SiO2、Al2O3、AlF3Meter, is SiO in molar ratio2:Al2O3:AlF3=2.0～2.5:0～3:2～6, it is sufficiently mixed, re-compacted molding, base substrate is placed in saggar, in 1250～1400 DEG C of calcinings in microwave shuttle kiln, then calcined product is directly pulverized, prepare acicular mullite finished product.Present invention reduces heat treatment time, improve productivity, beneficially large-scale production.
Description
Technical field
The invention belongs to technical field of inorganic material, be specifically related to a kind of method utilizing microwave catalysis synthesis acicular mullite
Background technology
Acicular mullite is a kind of important one-dimentional structure material, has high temperature resistant, corrosion-resistant, antioxidation, thermal coefficient of expansion
Little, specific strength advantages of higher, is the metal of a kind of excellence, pottery, macromolecular material activeness and quietness agent, can also use simultaneously
In friction material and high-temperature agglomerant.The preparation of acicular mullite mainly has sol-gal process, hydrothermal synthesis method, solid phase anti-
Ying Fa etc., above-mentioned three kinds of methods are respectively arranged with some shortcomings: sol-gal process technique is loaded down with trivial details, high cost；Prepared by hydrothermal synthesis method
The follow-up washing process of acicular mullite loaded down with trivial details；Conventional solid reaction method productivity is low, and calcination time is long.The most academic
Boundary confirms: at a certain temperature, and fluorine gas can generate silicon tetrafluoride gas, and then and aluminium oxide with silicon dioxde reaction
Reaction, by the one-dimensional mullite material of mass transferring in gas phase one-step synthesis.
Tradition electrical heating is generally by metal heater element, ceramic heating element heating, and heat is right by heat radiation and heat
Spreading and pass material, therefore belong to external heat, this mode of heating has the disadvantage that (1) heater element surface temperature coefficient
Can not be excessive, the thermal efficiency is low, and firing rate is slow, and heating uniformity is poor；(2) heating element heater easily fractures, therefore the life-span is low.
The synthesis of mullite simultaneously needs higher temperature, and this necessarily causes rising gentle insulation for a long time, reduces the product of unit interval
Rate.
At present, microwave energy, as a kind of novel heat resource form, is the most more and more applied and is synthesized field in inorganic material.
Civilian microwave heating mainly has two frequency: 915MHz or 2450MHz.The principle of microwave heating is at alternating electromagnetic field
Make material-to-be-heated middle free charge rearrangement and dipole repeatedly rotate under polarization, thus produce powerful vibration and
Friction, in this microprocess, alternating electromagnetism can be converted into the interior energy of medium, causes medium temperature to raise, its heating side
Method need not conduction of heat from outward appearance to inner essence, and therefore microwave heating belongs to volume heating, and firing rate is exceedingly fast.Meanwhile, microwave
Non-thermal effect can catalytic chemistry reaction process, significantly shorten the response time.But synthesize acicular mullite with microwave catalysis at present
Method there is not been reported.
Summary of the invention
The purpose of the present invention, is to overcome the deficiency in prior art synthesis acicular mullite technique, it is provided that one utilizes microwave to urge
The method being combined to acicular mullite, to be heated rapidly to maximum heat treatment temperature, accelerates the aggregate velocity of mullite.
The present invention is to realize above-mentioned purpose by following technical solution.
A kind of method utilizing microwave catalysis synthesis acicular mullite, has following steps:
(1) by SiO2、Al2O3、AlF3It is SiO in molar ratio2:Al2O3:AlF3=2.0～2.5:0～3:2～6, by above-mentioned three
Kind of material is sufficiently mixed, and adds suitable quantity of water in mixed process, and amount of water is as the criterion facilitating subsequent forming；
(2) utilizing mould is with three-dimensional open-framework, the blank of arbitrary shape by the mixture extrusion forming of step (1)；
(3) blank of step (2) is placed in saggar, saggar is placed in microwave shuttle kiln in 1250～1400 DEG C of calcinings,
It is incubated 20 minutes～3 hours；
(4) calcined product of step (3) is directly pulverized, prepare acicular mullite finished product.
Described silicon-containing compound SiO2Can be one or more in silicon powder, fused quartz powder, Ludox, kieselguhr
Mixture.
Described aluminum contained compound Al2O3It can be the one in aluminium hydrate powder, alumina powder, schmigel, Alumina gel or many
Plant mixture.
The described blank with three-dimensional open-framework, channel diameter 6mm, hole and pitch of holes are 1cm；
The inner surface of described saggar is provided with the SiC coating of 1～2 millimeters thick.
Described mullite, its microscopic pattern majority be needle-like, minority be graininess, wherein acicular mullite a diameter of 0.1～
2 microns, a length of 2～20 microns, chemical formula is: 3Al2O3·2SiO2。
Advantages of the present invention and good effect:
The present invention eliminates washing stoving process loaded down with trivial details in conventional hydrothermal synthetic method in preparation process, it is to avoid due to time long
Between the defect such as the energy waste that causes of heat treatment, goods productivity be low.Heat with the peak power of microwave shuttle kiln in the temperature rise period,
Its firing rate, up to 100 DEG C per minute, is heated rapidly to maximum heat treatment temperature, provide significant conservation the time required for intensification；
Meanwhile, promote Silicon fluoride. mass transferring in gas phase with microwave catalysis, accelerate the aggregate velocity of mullite, also save insulation institute
The time needed.Present invention reduces heat treatment time, improve productivity, beneficially large-scale production.
Accompanying drawing explanation
Fig. 1 is scanning electron microscope (SEM) picture of the embodiment of the present invention 1 acicular mullite；
Fig. 2 is scanning electron microscope (SEM) picture of the embodiment of the present invention 2 acicular mullite.
Detailed description of the invention
The present invention is with aluminium fluoride as catalyst, with aluminum contained compound, silicon-containing compound as raw material, is placed in special saggar,
High-temperature calcination in microwave field, a step prepares acicular mullite.Below in conjunction with specific embodiment the present invention is further explained and
Illustrating, the present invention is not constituted any limitation by below embodiment.
Raw material used in embodiment is industrial raw material.
Embodiment 1
Kieselguhr, aluminium oxide, aluminium fluoride are respectively with SiO2、Al2O3、AlF3Meter, according to mol ratio
SiO2:Al2O3:AlF3Above-mentioned three kinds of raw materials are sufficiently mixed by=1:1:1, add suitable quantity of water, amount of water in mixed process
To facilitate subsequent forming to be as the criterion；Then utilize mould by said mixture extrusion forming be the high 5cm with three-dimensional open-framework,
Diameter 6cm's is cylindric, channel diameter 6mm, and hole and pitch of holes are 1cm；Pore size therein, distribution and direction are equal
Can be any, but hole density is the bigger the better, and the distance between Kong Yukong is to be preferred less than 3cm.By above-mentioned cylindric base
Material is placed in saggar, and the inner surface of described saggar is provided with the SiC coating of 1～2 millimeters thick；Saggar is placed in microwave shuttle-type again
Kiln is heated to 1300 DEG C, is incubated 40 minutes, then cools to room temperature with the furnace；Calcined product raymond grinding powder is broken to 150
Mesh, products therefrom is the mullite of white powder.Showing through X-ray diffraction analysis, products therefrom chemical formula is mullite,
That is: 3Al2O3·2SiO2；Sem observation show mullite mainly in needle-like, on a small quantity in irregular particle shape (as
Shown in Fig. 1), recording average-size is: a diameter of 0.8 μm, a length of 5 μm.
Embodiment 2
Fused quartz powder, alumina powder, aluminium fluoride are respectively with SiO2、Al2O3、AlF3Meter, according to mol ratio
SiO2:Al2O3:AlF3Above-mentioned three kinds of raw materials are sufficiently mixed by=1:0.5:2, add suitable quantity of water, add water in mixed process
Amount is to facilitate subsequent forming to be as the criterion；Then utilizing mould is with three-dimensional open-framework by said mixture extrusion forming
The cuboid of 6cm × 5cm × 5cm, channel diameter 6mm, hole and pitch of holes are 1cm；Above-mentioned cuboid blank is placed in saggar
In, the inner surface of described saggar is provided with the SiC coating of 1～2 millimeters thick；Again saggar is placed in microwave shuttle kiln and is heated to
1250 DEG C, it is incubated 20 minutes, then cools to room temperature with the furnace；Calcined product raymond grinding powder is broken to 150 mesh, and gained produces
Thing is the mullite of white powder.Showing through X-ray diffraction analysis, products therefrom chemical formula is mullite, it may be assumed that
3Al2O3·2SiO2；Sem observation show mullite mainly in needle-like, on a small quantity in irregular particle shape (such as Fig. 2
Shown in), recording average-size is: a diameter of 0.7 μm, a length of 4 μm.
Embodiment 3
Ludox, schmigel, aluminium fluoride are respectively with SiO2、Al2O3、AlF3Meter, according to mol ratio
SiO2:Al2O3:AlF3Above-mentioned three kinds of raw materials are sufficiently mixed, then utilize mould to be added by said mixture by=1.2:0.5:2
Molded is the cuboid of the 6cm × 5cm with three-dimensional open-framework × 5cm, channel diameter 6mm, and hole and pitch of holes are 1cm；
Being placed in saggar by above-mentioned cuboid blank, the inner surface of described saggar is provided with the SiC coating of 1～2 millimeters thick；Again by casket
Alms bowl is placed in microwave shuttle kiln and is heated to 1350 DEG C, is incubated 60 minutes, then cools to room temperature with the furnace；By calcined product thunder
Covering pulverizing and be broken to 150 mesh, products therefrom is the mullite of white powder.Showing through X-ray diffraction analysis, gained produces
Thing chemical formula is mullite, it may be assumed that 3Al2O3·2SiO2；Sem observation show mullite mainly in needle-like, on a small quantity
In irregular particle shape, recording average-size is: a diameter of 0.9 μm, a length of 7 μm.
Embodiment 4
Ludox, aluminium fluoride are respectively with SiO2、AlF3Meter, according to mol ratio SiO2:AlF3=2.5:6, by above-mentioned 2 kinds of raw materials
Being sufficiently mixed, then utilizing mould is the 6cm × 5cm with three-dimensional open-framework × 5cm by said mixture extrusion forming
Cuboid, channel diameter 6mm, hole and pitch of holes are 1cm；Above-mentioned cuboid blank is placed in saggar, described saggar
Inner surface be provided with the SiC coating of 1～2 millimeters thick；Saggar is placed in microwave shuttle kiln again and is heated to 1400 DEG C, insulation
2 hours, then cool to room temperature with the furnace；Calcined product raymond grinding powder is broken to 150 mesh, and products therefrom is white powder
The mullite of shape.Showing through X-ray diffraction analysis, products therefrom chemical formula is mullite, it may be assumed that 3Al2O3·2SiO2；Scanning
Electron microscope observation show mullite mainly in needle-like, recording average-size is: a diameter of 1 μm, a length of 9 μm.
Embodiment 5
Ludox, Alumina gel, aluminium fluoride are respectively with SiO2、Al2O3、AlF3Meter, according to mol ratio SiO2:
Al2O3:AlF3Above-mentioned 3 kinds of raw materials are sufficiently mixed, then utilize mould by said mixture extrusion forming by=2.5:1:4
For the cuboid of the 6cm × 5cm × 5cm with three-dimensional open-framework, channel diameter 6mm, hole and pitch of holes are 1cm；Will
Above-mentioned cuboid blank is placed in saggar, and the inner surface of described saggar is provided with the SiC coating of 1～2 millimeters thick；Again by saggar
It is placed in microwave shuttle kiln and is heated to 1400 DEG C, be incubated 3 hours, then cool to room temperature with the furnace；Calcined product thunder is covered
Pulverizing is broken to 150 mesh, and products therefrom is the mullite of white powder.Show through X-ray diffraction analysis, products therefrom
Chemical formula is mullite, it may be assumed that 3Al2O3·2SiO2；Sem observation shows that mullite, mainly in needle-like, records flat
The most a size of: a diameter of 1.2 μm, a length of 10 μm.
Various raw materials and the span of various technological parameter cited by the present invention can realize the present invention, the most another at this
One is illustrated.
Claims (5)
1. the method utilizing microwave catalysis synthesis acicular mullite, has following steps:
(1) oxide containing silicon, be SiO in molar ratio containing aluminum oxide, aluminium fluoride2:Al2O3:AlF3=2.0～2.5:0～3:2～6,
Being sufficiently mixed by above-mentioned three kinds of materials, add suitable quantity of water in mixed process, amount of water is as the criterion facilitating subsequent forming；
(2) utilizing mould is with three-dimensional open-framework, the blank of arbitrary shape by the mixture extrusion forming of step (1)；
(3) blank of step (2) is placed in the saggar that inner surface is provided with 1～2 millimeters thick SiC coatings, saggar is put
In 1250～1400 DEG C of calcinings in microwave shuttle kiln, it is incubated 20 minutes～3 hours；
(4) calcined product of step (3) is directly pulverized, prepare acicular mullite finished product.
The method utilizing microwave catalysis synthesis acicular mullite the most according to claim 1, it is characterised in that described
Silicon-containing compound is one or more mixture in silicon powder, fused quartz powder, Ludox, kieselguhr.
The method utilizing microwave catalysis synthesis acicular mullite the most according to claim 1, it is characterised in that described
Aluminum contained compound is one or more mixture in aluminium hydrate powder, alumina powder, schmigel, Alumina gel.
The method utilizing microwave catalysis synthesis acicular mullite the most according to claim 1, it is characterised in that described
With the blank of three-dimensional open-framework, channel diameter 6mm, hole and pitch of holes are 1cm.
The method utilizing microwave catalysis synthesis acicular mullite the most according to claim 1, it is characterised in that described
Mullite, its microscopic pattern majority be needle-like, minority be graininess, wherein a diameter of 0.1～2 micron of acicular mullite,
A length of 2～20 microns, chemical formula is: 3Al2O3·2SiO2。
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| CN1303037C (en) * | 2005-10-18 | 2007-03-07 | 山东大学 | Preparation method of mullite whiskers |
| CN101550011B (en) * | 2009-05-25 | 2011-10-05 | 天津城市建设学院 | Method for preparing SiC/Mullite composite sphere |
| CN101570895A (en) * | 2009-06-11 | 2009-11-04 | 天津大学 | Formula and method for preparing mullite whisker |
| CN101700887B (en) * | 2009-10-30 | 2011-05-18 | 陕西科技大学 | Method for preparing nano-mullite powder by sol-gel-microwave hydrothermal method |
| CN101759430B (en) * | 2010-01-19 | 2012-05-02 | 天津大学 | Method for preparing porous mullite |
| KR101921358B1 (en) * | 2011-05-12 | 2018-11-22 | 다우 글로벌 테크놀로지스 엘엘씨 | A mullite body and method of forming the mullite body |
| CN102603276A (en) * | 2012-03-13 | 2012-07-25 | 中国科学院宁波材料技术与工程研究所 | Mullite fiber preparation method |
| CN103073322B (en) * | 2013-02-02 | 2014-03-12 | 西南科技大学 | Preparation method of mullite whisker in-situ toughened chromium phosphate aluminum wave-transmitting material |
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