CN1028776C - Process for preparation of highly pure mullite crystal whisker - Google Patents
Process for preparation of highly pure mullite crystal whisker Download PDFInfo
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- CN1028776C CN1028776C CN 92102982 CN92102982A CN1028776C CN 1028776 C CN1028776 C CN 1028776C CN 92102982 CN92102982 CN 92102982 CN 92102982 A CN92102982 A CN 92102982A CN 1028776 C CN1028776 C CN 1028776C
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- mullite
- colloidal sol
- mullite crystal
- solution
- preparation
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- Compositions Of Oxide Ceramics (AREA)
Abstract
The present invention relates to a method for preparing high-purity mullite crystal whiskers for toughening high-temperature structure ceramics, metal and plastics, which belongs to the field of investigation of material, and particularly to the field of novel composite material, mainly ceramics. The processes for preparing the mullite crystal whiskers comprise: an aluminum salt in is dissolved in an alcoholic solution; the alkoxide of silicon is slowly dropped into the alcoholic solution according to the molar ratio of SiO2 to Al2O3 of 2: 3; 1 to 40 wt% of HF solution is added according to the weight ratio of mullite; the obtained gel is dried, crumbled, screened and calcined, so as to obtain high-purity white mullite crystal whiskers of various length-diameter ratios finally. The high-purity mullite crystal whiskers have no foreign particles, form a uniform rod shape and have favorable reinforced ceramic performance.
Description
The present invention relates to the brilliant suitable preparation method of a kind of high-purity mullite that is used for toughened high-temperature structural ceramics, metal and plastics, belong to the investigation of materials field, especially with the advanced composite material field of ceramic main.
At present, the reinforcement pottery is used silicon carbide whisker more, and its shortcoming is that antioxidant property is poor, and 1000 ℃ with upper surface formation SiO
2, cause the decay of performance of whisker own and composite property.And mullite crystal whisker itself is exactly an oxide compound, in oxidizing atmosphere, reducing atmosphere and all stable when 1800 ℃ of high temperature, anti-strong acid and strong base corrosion, therefore with mullite crystal whisker reinforcement ceramic composite than having use range widely with carbonization osmanthus whisker.The method for preparing mullite crystal whisker has multiplely to be introduced as Japanese Patent JP1212299, uses AlF
3As catalyzer.AlF
3Distillation at high temperature, the gas phase of generation and SiO
2Reaction generates mullite crystal whisker, and its stoicheiometry molecular formula is 3Al
2O
32SiO
2This preparation method's shortcoming is AlF
3The sublimation temperature height, thus must be when about 1500～1600 ℃ of high temperature could the mullite synthesizing whisker, and the synthetic whisker is short, is generally less than 3 microns.
The objective of the invention is to prepare mullite crystal whisker with a kind of new catalyst, adopt colloidal sol, gel method, the synthetic mullite crystal whisker to increase the length of whisker, more helps doing ceramic strengthening agent at low temperatures.
Content of the present invention is that the method for preparing mullite crystal whisker is divided following step:
(1) aluminium salt is dissolved in the hot alcoholic solution, makes and contain Al
2O
3Colloidal sol.The kind of alcohol can be a methyl alcohol, ethanol, any one in propyl alcohol and the butanols.
(2) containing Al
2O
3Above-mentioned colloidal sol in slowly drip the alkoxide of silicon, the ratio of dropping is to make SiO in the alkoxide
2Content and colloidal sol in Al
2O
3The content ratio be 2: 3 mol ratios, thereby contain 3Al in the vitreosol that guarantees to obtain at last
2O
32SiO
2
(3) calculate by the weight ratio that contains mullite in the second step colloidal sol, the adding weight percent is 1～40% HF solution, and this moment, colloidal sol became gel.
(4) gel oven dry, the fragmentation that the 3rd step was obtained dewatered under 200～1000 ℃ of temperature, crosses 60～200 mesh sieves.
(5) product that the 4th step was obtained is enclosed within Al
2O
3, in mullite or the zirconium dioxide crucible, 1200～1600 ℃ of burnings 1～48 hour.Through above steps, can make the high pure white mullite crystal whisker of various length-to-diameter ratios.
The mullite crystal whisker of the present invention's preparation does not have any Particulate Inclusion, is evenly bar-shaped.Belong to rhombic system, chemical constitution is 3Al
2O
32SiO
2After measured, whisker axially is＜001〉direction, perfect crystalline, and every whisker is pure monocrystalline.Great advantage of the present invention is the productive rate height, near 100%.
Introduce several embodiments of the present invention below:
Embodiment 1:
With 187.5 gram Al(NO
3)
39H
2O is dissolved in 353.3 milliliters of ethanol of 54 ℃, drips 37.2 milliliters of tetraethoxy (SiO
2Be no less than 28.0%), be transparent to solution, drip 10 milliliters of 40wt%HF solution, colloidal sol is clear gel 60-70 ℃ of insulation 3 hours.Gel is in 100 ℃ of dryings.Dry back powder is crossed 200 mesh sieves, and 700 ℃ in Al
2O
3Calcination removed moisture in 2 hours in the crucible, again in 1350 ℃ in Al
2O
3The sealing calcining is 10 hours in the crucible, obtains to be about 10-20 micron, the highly pure mullite crystal whisker of the about 0.1-1.0 micron of diameter, Al
2O
3Content is 71.2wt%, inclusion-free, no powder particle, productive rate 100%.
Embodiment 2
With 1 mole of Al
2(SO
4)
3Be dissolved in 400 milliliters of Virahols of 70 ℃, drip and contain 0.67 mole of SiO
2Tetraethoxy, drip 40wt%HF solution again and make colloidal sol for 20 milliliters.75 ℃ of constant temperature 12 hours are made clear gel.Gel is slowly dry in 90 ℃.Do quick-fried back powder and cross 60 mesh sieves, 650 ℃ in mullite crucible calcination removed moisture content in 3 hours, in 1300 ℃ of sealing calcinings 5 hours in mullite crucible, obtain length 5-10 micron, the highly pure mullite crystal whisker of diameter 0.08-0.8 micron, Al again
2O
3Content is 72.0wt%, inclusion-free, no powder particle, productive rate 100%.
Claims (3)
1, a kind of method for preparing mullite crystal whisker is characterized in that preparation process divides following step:
(1) aluminium salt is dissolved in the hot alcoholic solution, makes and contain Al
2O
3Colloidal sol;
(2) containing Al
2O
3Colloidal sol in slowly drip tetraethoxy, the ratio of dropping is SiO wherein
2Al in content and the colloidal sol
2O
3Content to compare be 2: 3 mol ratios, solution is vitreosol;
(3) calculate by the weight ratio of contained mullite in the second step colloidal sol, add the HF solution of 1～40wt%, colloidal sol becomes gel;
(4) gel oven dry, the fragmentation that the 3rd step was obtained dewatered under 200～1000 ℃ of temperature, crosses 60～200 mesh sieves;
(5) product that the 4th step was obtained is enclosed within Al
2O
3, in mullite or the zirconium dioxide crucible, 1200～1600 ℃ of calcinings 1～48 hour.
2, preparation method as claimed in claim 1 is characterized in that wherein said aluminium salt is any in Tai-Ace S 150, aluminum nitrate and the aluminum chloride; Described alcohol is any in methyl alcohol, ethanol, propyl alcohol and the butanols.
3, preparation method as claimed in claim 2 is characterized in that wherein said aluminium salt is aluminum nitrate; Described alcohol is ethanol; The ratio of described adding HF solution is 5-10%, and described dehydration temperaturre is 500～800 ℃, and described calcining temperature is 1300～1400 ℃.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 92102982 CN1028776C (en) | 1992-04-30 | 1992-04-30 | Process for preparation of highly pure mullite crystal whisker |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 92102982 CN1028776C (en) | 1992-04-30 | 1992-04-30 | Process for preparation of highly pure mullite crystal whisker |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN1064713A CN1064713A (en) | 1992-09-23 |
| CN1028776C true CN1028776C (en) | 1995-06-07 |
Family
ID=4939950
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN 92102982 Expired - Fee Related CN1028776C (en) | 1992-04-30 | 1992-04-30 | Process for preparation of highly pure mullite crystal whisker |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN1028776C (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1301348C (en) * | 2004-07-02 | 2007-02-21 | 北京理工大学 | Method for preparing mullite single crystal nano belt |
Families Citing this family (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1049416C (en) * | 1993-09-29 | 2000-02-16 | 中国建筑材料科学研究院 | Technology for production of fiber reinforced glass and glass-ceramic base composite material |
| CN1303037C (en) * | 2005-10-18 | 2007-03-07 | 山东大学 | Preparation method of mullite whiskers |
| CN101935877B (en) * | 2010-09-03 | 2012-05-23 | 昆明理工大学 | Method for synthesizing mullite whiskers by normal pressure sintering |
| CN106747541B (en) * | 2016-12-05 | 2020-03-17 | 中南大学 | Method for in-situ synthesis of mullite whisker self-toughened mullite ceramic |
| CN108315810B (en) * | 2018-02-24 | 2020-09-22 | 陕西大秦钾业有限公司 | Method for synthesizing mullite whisker by taking kaliophilite as raw material |
| CN110204346A (en) * | 2019-07-03 | 2019-09-06 | 辽宁科技大学 | A kind of preparation method of mullite crystal whisker enhancing high alumina castable firing prefabricated section |
-
1992
- 1992-04-30 CN CN 92102982 patent/CN1028776C/en not_active Expired - Fee Related
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1301348C (en) * | 2004-07-02 | 2007-02-21 | 北京理工大学 | Method for preparing mullite single crystal nano belt |
Also Published As
| Publication number | Publication date |
|---|---|
| CN1064713A (en) | 1992-09-23 |
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