CN101570895A - Formula and method for preparing mullite whisker - Google Patents
Formula and method for preparing mullite whisker Download PDFInfo
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- CN101570895A CN101570895A CNA2009100692181A CN200910069218A CN101570895A CN 101570895 A CN101570895 A CN 101570895A CN A2009100692181 A CNA2009100692181 A CN A2009100692181A CN 200910069218 A CN200910069218 A CN 200910069218A CN 101570895 A CN101570895 A CN 101570895A
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- hydrofluoric acid
- crystal whisker
- mullite whisker
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Abstract
The invention relates to a formula and a method for preparing mullite whisker by melt. The formula has the following raw materials according to percentage by weight: 25.5 to 29.7 percent of anhydrous aluminium sulfate, 4.3 to 8.5 percent of amorphous silica and 66.0 percent of anhydrous sodium sulfate. The raw materials are dried and ground by the method of mechanical ball milling through high purity zirconia balls so as to obtain uniformly mixed powder, the powder is heated at the temperature from 1001 to 1050 DEG C, and the temperature is maintained for 6 to 8 hours; after being cooled, the powder is cleaned by water to remove sodium sulfate, and the finished product of mullite whisker can be obtained after the operation of drying is carried out; hydrofluoric acid is added to the obtained product, the volume ratio of the hydrofluoric acid to the product is 0.5-2:1, the concentration of the hydrofluoric acid ranges from 5 to 15 percent, and the immersion cleaning time ranges from 10 to 60 min; and ethanol is added for dissolving SiF4 impurity, the immersion cleaning time ranges from 10 to 60 minutes, and a product can be obtained after filtration. By changing the proportion of the raw materials of the mullite whisker prepared by the molten salt method and carrying out the operation of post treatment on the synthetic product, the invention increases the purity of the synthesized mullite whisker on the basis of maintaining the advantages of high degree of dispersion, uniform distribution of particle sizes and high length-diameter ratio of the mullite whisker prepared by the molten salt method, and the product does not contain the impurities of silicon dioxide and aluminium oxide.
Description
Technical field
The present invention relates to a kind of prescription and method of mullite crystal whisker fully of founding, belong to new material technology field.
Background technology
For having the parts of excellent mechanical property and heat-shock resistance under the preparation high temperature, for example be applied in aspects such as motor car engine filtering net, aerospace engine nozzle, nuclear industry water cooling circulating line, need a kind of second phase material that can carry out reinforcement to matrix at high temperature (more than 1300 ℃).Because existing silicon carbide whisker, norbide whisker, carbon whisker, potassium titanate crystal whisker etc. are easily oxidized, decomposition temperature is low, its can not be at high temperature to body material stablize, effectively reinforcement.For above-mentioned application, mullite crystal whisker is because excellent chemical stability, and mechanical property high temperature descends and increase to some extent on the contrary, has been proved to be the most promising high temperature supporting material.The mullite crystal whisker degree of scatter height of existing molten-salt growth method preparation, size distribution is even, length-to-diameter ratio is high, but the mullite productive rate has influenced the application of mullite crystal whisker greatly about 90%.
Summary of the invention
The objective of the invention is to utilize molten-salt growth method synthesis of high purity mullite crystal whisker powder.Utilize the chemical stability of mullite crystal whisker excellence, and mechanical property high temperature descends on the contrary and to increase to some extent, preparation can be carried out second phase material of reinforcement at high temperature (more than 1300 ℃) to matrix.Can not synthesize highly purified mullite crystal whisker at existing molten-salt growth method according to the stoichiometric ratio batching, the molten-salt growth method proportion scale is optimized, chemical treatment is carried out to the mullite crystal whisker that synthesizes in the back, thereby obtains highly purified mullite crystal whisker product.
For achieving the above object, the present invention is realized by following technical proposals:
A kind of prescription for preparing mullite crystal whisker of the present invention, raw material composition and weight percent are as follows:
Anhydrous slufuric acid aluminium 25.5-29.7%,
Soft silica 4.3-8.5%,
Anhydrous sodium sulphate 66.0%.
The method for preparing mullite crystal whisker of the present invention:
1) will prepare burden and adopt the mechanical ball milling method, and dry grind with the high-purity zirconia ball, and obtain the powder that mixes, at 1001-1050 ℃ of heating and insulation 6-8h, the cooling after washing is removed sodium sulfate, and oven dry obtains the product mullite crystal whisker;
2) product with step 1) adds hydrofluoric acid, hydrofluoric acid and product volume ratio 0.5-2: 1, and hydrofluoric acid concentration 5-15% embathes time 10-60min, adds dissolve with ethanol SiF again
4Impurity embathes time 10-60min, obtains product after the filtration.
The melt that utilizes salt at high temperature to form helps the crystalline different growth, synthetic crystal according to the specific direction growth.Tai-Ace S 150 at first forms two component system melt liquid phase with sodium sulfate in heat-processed, and along with temperature raises, Tai-Ace S 150 decomposes and with soft silica following reaction takes place:
3Al
2(SO
4)
3+2SiO
2＝3Al
2O
3·2SiO
2+9SO
3
The mullite that generates in this reaction process is separated out forming core reach certain saturation degree in the sodium sulfate high-temperature fusant after, and the mullite nucleus forms the needle-like mullite crystal whisker according to its crystal growth habit plane growth under the liquid phase environment that melt provides.Owing to adopt the Silicon-rich batching, the silicon-dioxide residue arranged in the product.
Molten-salt growth method synthetic mullite crystal whisker product is carried out purification process, introduces hydrofluoric acid, remove remaining silica in the product, following reaction takes place:
4HF+SiO
2＝SiF
4+2H
2O
Introduce dissolve with ethanol SiF again
4Impurity obtains product and detects the mullite crystal whisker diameter at 100-200nm through scanning electron microscope after the filtration, length is at 4-8 μ m, and mullite crystal whisker purity can reach 98-100wt%.
The invention has the advantages that: by changing the proportioning raw materials of process for preparing mullite crystal whisker by molten salt, and synthetic product carried out aftertreatment, keeping on molten-salt growth method synthetic mullite crystal whisker degree of scatter height, size distribution is even, length-to-diameter ratio the is high advantage basis, improve synthetic mullite crystal whisker purity, do not have silicon-dioxide and aluminum oxide impurity in the product.
Embodiment
Example 1:
Raw material adopts anhydrous slufuric acid aluminium 28.9wt%; Soft silica 5.1wt%; Anhydrous sodium sulphate 66.0wt% uses the mechanical ball milling method, with high-purity zirconia ball ball milling 4h, obtains the powder that mixes.The powder that obtains is at 1020 ℃ of heating and insulation 7h, and temperature rise rate is 300 ℃/h, and the powder after fusing cools to room temperature with the furnace.Products therefrom washes repeatedly, filters with 90 ℃ water, removes the sodium sulfate in the product, and until precipitation no longer occurs with the titration of nitrate of baryta solution till, 100 ℃ are descended dry subsequently.In 10wt% hydrofluoric acid according to adding desciccate with product volume ratio 1: 1, embathe 30min after, 20min is embathed with ethanol in the back.After, obtain highly purified mullite crystal whisker 100 ℃ of dryings.X-ray diffraction analysis shows there is not silicon-dioxide and aluminum oxide residue in the product, and mullite is unique crystalline phase in the product mutually, and purity is near 100%.Scanning electronic microscope shows that it is that 5 μ m, diameter are about 200nm that the mullite crystal whisker good dispersion of generation, whisker are about, and length-to-diameter ratio reaches 25.
Example 2:
Raw material adopts anhydrous slufuric acid aluminium 25.5wt%; Soft silica 8.5wt%; Anhydrous sodium sulphate 66.0wt% uses the mechanical ball milling method, with high-purity zirconia ball ball milling 4h, obtains the powder that mixes.The powder that obtains is at 1005 ℃ of heating and insulation 6h, and temperature rise rate is 300 ℃/h, and the powder after fusing cools to room temperature with the furnace.Products therefrom washes repeatedly, filters with 90 ℃ water, removes the sodium sulfate in the product, and until precipitation no longer occurs with the titration of nitrate of baryta solution till, 100 ℃ are descended dry subsequently.In 15wt% hydrofluoric acid according to adding desciccate with product volume ratio 2: 1, embathe 60min after, 60min is embathed with ethanol in the back.After, obtain highly purified mullite crystal whisker 100 ℃ of dryings.X-ray diffraction analysis shows there is not silicon-dioxide and aluminum oxide residue in the product, and mullite is unique crystalline phase in the product mutually, and purity is greater than 98%.Scanning electronic microscope shows that it is that 5 μ m, diameter are about 200nm that the mullite crystal whisker good dispersion of generation, whisker are about, and length-to-diameter ratio reaches 25.
Example 3:
Raw material adopts anhydrous slufuric acid aluminium 29.7wt%; Soft silica 4.3wt%; Anhydrous sodium sulphate 66.0wt% uses the mechanical ball milling method, with high-purity zirconia ball ball milling 4h, obtains the powder that mixes.The powder that obtains is at 1050 ℃ of heating and insulation 8h, and temperature rise rate is 300 ℃/h, and the powder after fusing cools to room temperature with the furnace.Products therefrom washes repeatedly, filters with 90 ℃ water, removes the sodium sulfate in the product, and until precipitation no longer occurs with the titration of nitrate of baryta solution till, 100 ℃ are descended dry subsequently.In 5wt% hydrofluoric acid according to adding desciccate with product volume ratio 0.5: 1, embathe 10min after, 10min is embathed with ethanol in the back.After, obtain highly purified mullite crystal whisker 100 ℃ of dryings.X-ray diffraction analysis shows there is not silicon-dioxide and aluminum oxide residue in the product, and mullite is unique crystalline phase in the product mutually, and purity is greater than 98%.Scanning electronic microscope shows that it is that 5 μ m, diameter are about 200nm that the mullite crystal whisker good dispersion of generation, whisker are about, and length-to-diameter ratio reaches 25.
The prescription and the method for a kind of process for preparing mullite crystal whisker by molten salt that the present invention proposes, be described by preferred embodiment, person skilled obviously can be in not breaking away from content of the present invention, spirit and scope to structure as herein described with equipment is changed or suitably change and combination, realize the technology of the present invention.Special needs to be pointed out is, the replacement that all are similar and change apparent to those skilled in the artly, they are regarded as being included in spirit of the present invention, scope and the content.
Claims (2)
1. prescription for preparing mullite crystal whisker is characterized in that raw material is formed and weight percent is as follows:
Anhydrous slufuric acid aluminium 25.5-29.7%,
Soft silica 4.3-8.5%,
Anhydrous sodium sulphate 66.0%.
2. according to the method for the formulation mullite crystal whisker of claim 1, it is characterized in that:
1) will prepare burden and adopt the mechanical ball milling method, and dry grind with the high-purity zirconia ball, and obtain the powder that mixes, at 1001-1050 ℃ of heating and insulation 6-8h, the cooling after washing is removed sodium sulfate, and oven dry obtains the product mullite crystal whisker;
2) product with step 1) adds hydrofluoric acid, hydrofluoric acid and product volume ratio 0.5-2: 1, and hydrofluoric acid concentration 5-15% embathes time 10-60min, adds dissolve with ethanol SiF4 impurity again, embathes time 10-60min, obtains product after the filtration.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNA2009100692181A CN101570895A (en) | 2009-06-11 | 2009-06-11 | Formula and method for preparing mullite whisker |
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|---|---|---|---|
| CNA2009100692181A CN101570895A (en) | 2009-06-11 | 2009-06-11 | Formula and method for preparing mullite whisker |
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Cited By (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101969703A (en) * | 2010-10-28 | 2011-02-09 | 上海尚诺碳晶科技有限公司 | Medium-high temperature carbon crystal electric heating material, medium-high temperature carbon crystal electric heating plate and relevant preparation method |
| CN101767793B (en) * | 2010-01-19 | 2011-09-21 | 天津大学 | Method for preparing mullite nanowire |
| CN102304750A (en) * | 2011-09-20 | 2012-01-04 | 江西旭阳雷迪高科技股份有限公司 | Method for synthesizing mullite whiskers |
| CN103803568A (en) * | 2013-12-23 | 2014-05-21 | 天津大学 | Method for catalytic synthesis of needle-like mullite by using microwaves |
| CN104313695A (en) * | 2014-10-31 | 2015-01-28 | 成都理工大学 | Mullite nano-whisker prepared by using pyrite tailing as raw material and preparation method of mullite nano-whisker |
| CN108315810A (en) * | 2018-02-24 | 2018-07-24 | 陕西大秦钾业有限公司 | A method of using kaliophilite as Material synthesis mullite crystal whisker |
| CN111943699A (en) * | 2020-08-24 | 2020-11-17 | 宜兴瑞泰耐火材料有限公司 | Large length-diameter ratio mullite whisker-combined andalusite refractory brick for propane dehydrogenation device and preparation process thereof |
| CN112853495A (en) * | 2021-01-11 | 2021-05-28 | 东北大学 | Method for preparing sea urchin-like structure mullite whiskers by using crystalline silicon cutting waste |
| CN114808104A (en) * | 2022-05-11 | 2022-07-29 | 江西陶瓷工艺美术职业技术学院 | Mullite whisker synthesized at low temperature by taking desert yellow sand as raw material and preparation method thereof |
-
2009
- 2009-06-11 CN CNA2009100692181A patent/CN101570895A/en active Pending
Cited By (11)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101767793B (en) * | 2010-01-19 | 2011-09-21 | 天津大学 | Method for preparing mullite nanowire |
| CN101969703A (en) * | 2010-10-28 | 2011-02-09 | 上海尚诺碳晶科技有限公司 | Medium-high temperature carbon crystal electric heating material, medium-high temperature carbon crystal electric heating plate and relevant preparation method |
| CN102304750A (en) * | 2011-09-20 | 2012-01-04 | 江西旭阳雷迪高科技股份有限公司 | Method for synthesizing mullite whiskers |
| CN103803568A (en) * | 2013-12-23 | 2014-05-21 | 天津大学 | Method for catalytic synthesis of needle-like mullite by using microwaves |
| CN104313695A (en) * | 2014-10-31 | 2015-01-28 | 成都理工大学 | Mullite nano-whisker prepared by using pyrite tailing as raw material and preparation method of mullite nano-whisker |
| CN104313695B (en) * | 2014-10-31 | 2017-06-06 | 成都理工大学 | A kind of mullite nano whisker prepared as raw material with pyrite tailing and preparation method thereof |
| CN108315810A (en) * | 2018-02-24 | 2018-07-24 | 陕西大秦钾业有限公司 | A method of using kaliophilite as Material synthesis mullite crystal whisker |
| CN111943699A (en) * | 2020-08-24 | 2020-11-17 | 宜兴瑞泰耐火材料有限公司 | Large length-diameter ratio mullite whisker-combined andalusite refractory brick for propane dehydrogenation device and preparation process thereof |
| CN112853495A (en) * | 2021-01-11 | 2021-05-28 | 东北大学 | Method for preparing sea urchin-like structure mullite whiskers by using crystalline silicon cutting waste |
| CN112853495B (en) * | 2021-01-11 | 2022-03-11 | 东北大学 | Method for preparing sea urchin-like structure mullite whiskers by using crystalline silicon cutting waste |
| CN114808104A (en) * | 2022-05-11 | 2022-07-29 | 江西陶瓷工艺美术职业技术学院 | Mullite whisker synthesized at low temperature by taking desert yellow sand as raw material and preparation method thereof |
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Open date: 20091104 |