CN103183512A - Preparation method for powder for silicon nitride crucible - Google Patents
Preparation method for powder for silicon nitride crucible Download PDFInfo
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- CN103183512A CN103183512A CN2011104446588A CN201110444658A CN103183512A CN 103183512 A CN103183512 A CN 103183512A CN 2011104446588 A CN2011104446588 A CN 2011104446588A CN 201110444658 A CN201110444658 A CN 201110444658A CN 103183512 A CN103183512 A CN 103183512A
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Abstract
The invention provides a preparation method for a powder for a silicon nitride crucible. The preparation method comprises the following steps of: a) mixing the mixed powder composed of silicon nitride powder and silicon powder, with absolute ethyl alcohol, and preparing a slurry, wherein the mesh number of the mixed powder is greater than 325, and the solid content of the slurry is 30-50%; and b) performing spray-drying and granulation on the slurry, and obtaining the powder for the silicon nitride crucible via discharging. In the preparation method, the spray-drying and granulation are performed by adopting raw materials without sodium ions, such as absolute ethyl alcohol; and the prepared powder for the silicon nitride crucible is high in purity and beneficial to prepare the high-purity silicon nitride crucible, and the high-purity silicon nitride crucible cannot pollute crystals in case of being applied to monocrystalline silicon production. Further, the powder for the silicon nitride crucible prepared by the preparation method does not need to be further screened and can be directly applied to the forming working procedure of preparing the silicon nitride crucible, thus simplifying production operation.
Description
Technical field
The present invention relates to the silicon nitride crucible technical field, particularly a kind of silicon nitride crucible preparation method of powder body.
Background technology
Silicon single crystal is a kind of good semiconductor material, can be used for making semiconducter device and solar cell etc.In the process of manufacture order crystal silicon, traditional method is container with the quartz crucible often, melts silicon 10h under 1600 ℃ high temperature, carries out directed crystal pulling 20h then under 1450 ℃ high temperature, and directed crystal pulling finishes back cooling blow-on, takes out crystal bar.In this process, quartz crucible at high temperature can softening transform, and owing to rapid cooling cracks, causes quartz crucible can only use once in the production of silicon single crystal, can not use repeatedly, has improved the production cost of silicon single crystal greatly.Compare with quartz crucible, silicon nitride crucible experience high temperature, sharply can not crack after the cooling, reusable, be applied to have very big advantage in the production process of silicon single crystal.
Prior art is when the preparation silicon nitride crucible, usually adopting the mixed powder of being made up of silicon nitride powder and silica flour is raw material, because silicon nitride and silicon are the ridge material, a little less than the cohesive action in the described mixed powder between the particle, regular meeting causes the powder deposition and is difficult to moulding, therefore, in described mixed powder, add polyvinyl alcohol (PVA) binding agent and carry out granulation, obtain the powder body of certain particle size; Because knowing from experience, the powder of undersized causes moulding the mobile relatively poor of slurry, be difficult to make larger-size goods, though and the excessive powder body of granularity can improve the flowability that slurry is used in moulding, but be difficult to make closely knit goods, therefore, gained powder body is screened again, obtain all silicon nitride crucible powder bodies between 20 orders～325 orders of granular size; At last, with the gained silicon nitride crucible with powder system moulding slurry, through moulding, operation such as burn till and handle, namely obtain being recycled and reused in the monocrystalline silicon production, size more greatly, comparatively closely knit silicon nitride crucible.
Prior art adopts polyvinyl alcohol adhesive, mode by granulation has prepared silicon nitride crucible powder body, and then prepared silicon nitride crucible, but, polyvinyl alcohol adhesive generally contains sodium ion, makes the silicon nitride crucible of preparation also contain impurity such as sodium with the powder body, thereby causes the purity of the follow-up silicon nitride crucible of making not high, be applied to pollute silicon single crystal in the monocrystalline silicon production, be unfavorable for its widespread use in monocrystalline silicon production.
Summary of the invention
In order to solve above technical problem, the invention provides a kind of silicon nitride crucible preparation method of powder body, the silicon nitride crucible that this preparation method makes is beneficial to and makes highly purified silicon nitride crucible with powder body purity height, is applied to can not pollute silicon single crystal in the monocrystalline silicon production.
The invention provides a kind of silicon nitride crucible preparation method of powder body, may further comprise the steps:
A) will be mixed with dehydrated alcohol by the mixed powder that silicon nitride powder and silica flour are formed, make slurry, the order number of described mixed powder is more than 325 orders, and described solid content of slurry is 30%～50%;
B) described slurry is carried out spray drying granulation, obtain silicon nitride crucible powder body through discharging.
Preferably, in the described step b), described spray drying granulation is:
Adopt the centrifugal spray drying granulating equipment to carry out the centrifugal spray drying granulation.
Preferably, described centrifugal spray drying granulating equipment comprises dehumidification system, and described dehumidification system comprises:
Be positioned at described dehumidification system top, described slurry can be atomized into the centrifugal atomizer of droplet;
Be positioned at described centrifugal atomizer below, can be with the kiln of described droplet drying.
Preferably, described kiln is provided with polytetrafluoroethyllining lining.
Preferably, the rotating speed of described centrifugal spray drying granulating equipment is 40r/min～80r/min.
Preferably, in the described step b), the temperature of described spray drying granulation is 140 ℃～160 ℃.
Preferably, in the described step b), the temperature of described discharging is 50 ℃～70 ℃.
Preferably, before described step a), also comprise step:
Described mixed powder is carried out ball milling, drying.
Preferably, described ball milling is:
Adopt silicon nitride ball milling jar and silicon nitride ceramic ball to carry out ball milling.
Preferably, described drying is carried out in vacuum or nitrogen atmosphere.
Compared with prior art, the present invention will be mixed with dehydrated alcohol by the mixed powder that silicon nitride powder and silica flour are formed, and makes slurry, and the order number of described mixed powder is more than 325 orders, and described solid content of slurry is 30%～50%; Described slurry is carried out spray drying granulation, obtain silicon nitride crucible powder body through discharging.The present invention is solvent with the dehydrated alcohol, it is 30%～50% slurry that described mixed powder is made solid content, make the particle in the described mixed powder be the small droplets state, when spray drying granulation, drying and mechanical effect can be made silicon nitride crucible powder body.The raw material that the present invention adopts dehydrated alcohol etc. not contain sodium ion carries out spray drying granulation, makes the gained silicon nitride crucible not contain impurity such as sodium with the powder body, thereby can make highly purified silicon nitride crucible, is applied to can not pollute silicon single crystal in the monocrystalline silicon production.
Embodiment
In order further to understand the present invention, be described below in conjunction with the preferred embodiment of the invention of embodiment, but should be appreciated that these describe just to further specifying the features and advantages of the present invention, rather than to the restriction of claim of the present invention.
The invention provides a kind of silicon nitride crucible preparation method of powder body, may further comprise the steps:
A) will be mixed with dehydrated alcohol by the mixed powder that silicon nitride powder and silica flour are formed, make slurry, the order number of described mixed powder is more than 325 orders, and described solid content of slurry is 30%～50%;
B) described slurry is carried out spray drying granulation, obtain silicon nitride crucible powder body through discharging.
The present invention mixes particle diameter mixed powder more than 325 orders, that be made up of silicon nitride powder and silica flour with dehydrated alcohol, make solid content and be 30%～50% slurry.
It is raw material that the present invention adopts the mixed powder of being made up of silicon nitride powder and silica flour, preferred employing purity is raw material at mixed powder more than 99.99%, that be made up of silicon nitride powder and silica flour, be more conducive to improve the purity of follow-up goods, the present invention does not have particular restriction to the ratio of silicon nitride powder and silica flour in the described mixed powder, and described mixed powder is the powder of this area preparation silicon nitride crucible commonly used.
In the present invention, be used for making the order number of mixed powder of slurry more than 325 orders, particle diameter is less, and described mixed powder preferably obtains through ball milling, drying.
Wherein, described ball milling makes the particle diameter of mixed powder meet the requirement of making slurry, and the present invention does not have particular restriction to described ball milling, preferably adopts silicon nitride ball milling jar and silicon nitride ceramic ball to carry out ball milling, can not introduce other impurity.
Described drying is preferably carried out in vacuum or nitrogen atmosphere, can avoid the silica flour in the described mixed powder oxidized in the dewatered while, thereby guarantee the higher degree of described mixed powder;
The temperature of described drying is preferably 100 ℃～120 ℃, more preferably 105 ℃～115 ℃; The time of described drying is preferably 30min～90min, more preferably 50min～70min.
It is solvent that the present invention adopts dehydrated alcohol, and it is mixed with the raw material mixed powder, makes the particle of described mixed powder be the small droplets state, and the present invention preferably stirs 5min～20min, more preferably 8min～15min in encloses container, makes slurry comparatively uniformly.
After deliberation, in the present invention, described solid content of slurry is 30%～50%, is preferably 35%～45%, more preferably 38%～42%.
The present invention adds that dehydrated alcohol is made, solid content is under 30%～50% the drying and mechanical effect of slurry in the spray drying granulation process, can make highly purified silicon nitride crucible powder body, do not contain impurity such as sodium, be beneficial to and make quality silicon nitride crucible preferably, be applied to can not pollute silicon single crystal in the monocrystalline silicon production.
After making slurry, it is carried out spray drying granulation, obtain silicon nitride crucible powder body through discharging.
Wherein, described spray drying granulation is the mechanical effect by spray drying granulation equipment, make in the slurry particle at a certain temperature through balling-up, grow up, closely knit three phases, be formed for preparing the powder body of silicon nitride crucible, namely the order number of described powder body is between 20 orders～325 orders.In the present invention, described spray drying granulation can adopt the centrifugal spray drying granulating equipment to carry out the centrifugal spray drying granulation, also can carry out in the mode of pressure spray dryer granulation, the preferred centrifugal spray drying granulating equipment that adopts carries out the centrifugal spray drying granulation, namely need not to remove the particle of order number below 20 orders through screening again, thereby the simplification production operation is enhanced productivity.
When carrying out the centrifugal spray drying granulation, used centrifugal spray drying granulating equipment is this area granulating equipment such as drying tower commonly used, it comprises feeder system, heating system, dehumidification system, filtering system, material-receiving system and Controlling System, described feeder system is used for supplying with material, described heating system is that moisture eliminator is carried the dry warm air of using, described dehumidification system is that material and warm air carry out heat and mass, make the important place of dry materials, described filtering system is used for reclaiming the air-flow product, reduce dust pollution, described material-receiving system is used for collecting product, and described Controlling System plays control action kou.
Wherein, described dehumidification system comprise be positioned at described dehumidification system top, described slurry can be atomized into the centrifugal atomizer of droplet and be positioned at described centrifugal atomizer below, can be with the kiln of described droplet drying etc., the present invention preferably arranges polytetrafluoroethyllining lining with described kiln, described polytetrafluoroethyllining lining is high temperature resistant, frictional coefficient is extremely low, has lubrication, make metallic elements such as non-metallic elements such as in granulation process, can not bringing B, P because of granulating equipment into and Fe, thereby further improve the purity of granulation gained powder body; The present invention is preferably 40r/min～80r/min with the rotating speed of described centrifugal spray drying granulating equipment, 50r/min～70r/min more preferably, and centrifugal atomizing becomes droplet by described centrifugal atomizer to make described slurry.
Described filtering system preferably includes first step filtering system and second stage filtering system, described first step filtering system preferably includes the peritonaeum bag dust collector, the gas that will contain powder filters, efficiency of dust collection is more than 99.5%, described second stage filtering system preferably includes wet cleaner, will carry out secondary filtration through the gas of first step filtering system, to realize the environmental protection production of no dust pollution, and powder and ethanol can be reclaimed effectively, reduce production costs.
After the mode that adopts the pressure spray dryer granulation was finished granulation, the present invention preferably sieved, and removes the particle of order number below 20 orders with screening, obtains described silicon nitride crucible powder body.
In the present invention, the temperature of described spray drying granulation is preferably 140 ℃～160 ℃, and more preferably 145 ℃～155 ℃, under this temperature, can dry better, obtain described silicon nitride crucible powder body.
The temperature of described discharging is preferably 50 ℃～70 ℃, more preferably 55 ℃～65 ℃, the present invention preferably beats it by being installed on the outer pneumatic hammer of described dehumidification system, silicon nitride crucible through discharging obtains is not attached in the described dehumidification system with the powder body, and easily collecting is in described material-receiving system.
The silicon nitride crucible of preparation is carried out attribute test with the powder body, it is consistent with the purity of raw material silicon nitride and silicon mixed powder to obtain its purity, and can be directly silicon nitride crucible is carried out moulding, operation such as burnt till with the powder body, obtaining silicon nitride crucible, the density of gained silicon nitride crucible is at 3.17g/cm
3～3.29g/cm
3Between, porosity is less than 2%, namely near compacting body.When using this silicon nitride crucible manufacture order crystal silicon, the not sticking crucible of gained silicon single crystal takes out easily, and its purity is higher after testing, meets the use standard, and this silicon nitride crucible is reusable, has reduced the production cost of silicon single crystal.
In order further to understand the present invention, below in conjunction with embodiment the preparation method of silicon nitride crucible provided by the invention with the powder body described particularly.
Embodiment 1
Adopting silicon nitride ball milling jar and silicon nitride ceramic ball is that mixed powder 99.99%, that be made up of silicon nitride powder and silica flour carries out ball milling with purity, obtain the mixed powder of order number more than 325 orders, it is carried out drying in 110 ℃ in nitrogen atmosphere, behind the 1h, dried mixed powder is mixed with dehydrated alcohol, in encloses container, stir 10min, make uniform solid content and be 40% slurry;
The slurry that makes is being provided with in 150 ℃ carrying out the centrifugal spray drying granulation in the teflon-lined drying tower, rotating speed is 60r/min, be discharging in 60 ℃ the environment in temperature, pneumatic hammer by being installed in the drying tower outer wall is to the hammering of drying tower, make the silicon nitride crucible that obtains use the powder body drop in collector, and will contain the gas filtration of powder by the peritonaeum bag dust collector, the efficiency of dust collection of this peritonaeum bag dust collector is more than 99.5%, gas after will filtering again carries out the secondary filtration dedusting by wet cleaner, efficient recovery powder and ethanol.
The silicon nitride crucible of preparation is carried out attribute test with the powder body, and it is consistent with the purity of raw material mixed powder to obtain its purity;
Directly silicon nitride crucible is carried out moulding, operation such as burnt till with the powder body, obtain density at 3.17g/cm
3～3.29g/cm
3Between, porosity is less than 2% namely near the silicon nitride crucible of compacting body, when using this silicon nitride crucible manufacture order crystal silicon, the sticking crucible of gained silicon single crystal takes out easily, its purity is higher after testing, meets the use standard.
Embodiment 2
Adopting silicon nitride ball milling jar and silicon nitride ceramic ball is that mixed powder 99.99%, that be made up of silicon nitride powder and silica flour carries out ball milling with purity, obtain the mixed powder of order number more than 325 orders, it is carried out drying in a vacuum in 100 ℃, behind the 1h, dried mixed powder is mixed with dehydrated alcohol, in encloses container, stir 5min, make uniform solid content and be 50% slurry;
The slurry that makes is being provided with in 140 ℃ carrying out the centrifugal spray drying granulation in the teflon-lined drying tower, rotating speed is 40r/min, be discharging in 70 ℃ the environment in temperature, pneumatic hammer by being installed in the drying tower outer wall is to the hammering of drying tower, make the silicon nitride crucible that obtains use the powder body drop in collector, and will contain the gas filtration of powder by the peritonaeum bag dust collector, the efficiency of dust collection of this peritonaeum bag dust collector is more than 99.5%, gas after will filtering again carries out the secondary filtration dedusting by wet cleaner, efficient recovery powder and ethanol.
The silicon nitride crucible of preparation is carried out attribute test with the powder body, and it is consistent with the purity of raw material mixed powder to obtain its purity;
Directly silicon nitride crucible is carried out moulding, operation such as burnt till with the powder body, obtain density at 3.17g/cm
3～3.29g/cm
3Between, porosity is less than 2% namely near the silicon nitride crucible of compacting body, when using this silicon nitride crucible manufacture order crystal silicon, the sticking crucible of gained silicon single crystal takes out easily, its purity is higher after testing, meets the use standard.
Embodiment 3
Adopting silicon nitride ball milling jar and silicon nitride ceramic ball is that mixed powder 99.99%, that be made up of silicon nitride powder and silica flour carries out ball milling with purity, obtain the mixed powder of order number more than 325 orders, it is carried out drying in a vacuum in 120 ℃, behind the 1h, dried mixed powder is mixed with dehydrated alcohol, in encloses container, stir 20min, make uniform solid content and be 30% slurry;
The slurry that makes is being provided with in 160 ℃ carrying out the centrifugal spray drying granulation in the teflon-lined drying tower, rotating speed is 80r/min, be discharging in 50 ℃ the environment in temperature, pneumatic hammer by being installed in the drying tower outer wall is to the hammering of drying tower, make the silicon nitride crucible that obtains use the powder body drop in collector, and will contain the gas filtration of powder by the peritonaeum bag dust collector, the efficiency of dust collection of this peritonaeum bag dust collector is more than 99.5%, gas after will filtering again carries out the secondary filtration dedusting by wet cleaner, efficient recovery powder and ethanol.
Silicon nitride crucible after the screening is carried out attribute test with the powder body, and it is consistent with the purity of raw material mixed powder to obtain its purity;
Directly silicon nitride crucible is carried out moulding, operation such as burnt till with the powder body, obtain density at 3.17g/cm
3～3.29g/cm
3Between, porosity is less than 2% namely near the silicon nitride crucible of compacting body, when using this silicon nitride crucible manufacture order crystal silicon, the sticking crucible of gained silicon single crystal takes out easily, its purity is higher after testing, meets the use standard.
The explanation of above embodiment just is used for helping to understand method of the present invention and core concept thereof.Should be pointed out that for those skilled in the art, under the prerequisite that does not break away from the principle of the invention, can also carry out some improvement and modification to the present invention, these improvement and modification also fall in the protection domain of claim of the present invention.
Claims (10)
1. a silicon nitride crucible may further comprise the steps with the preparation method of powder body:
A) will be mixed with dehydrated alcohol by the mixed powder that silicon nitride powder and silica flour are formed, make slurry, the order number of described mixed powder is more than 325 orders, and described solid content of slurry is 30%～50%;
B) described slurry is carried out spray drying granulation, obtain silicon nitride crucible powder body through discharging.
2. preparation method according to claim 1 is characterized in that, in the described step b), described spray drying granulation is:
Adopt the centrifugal spray drying granulating equipment to carry out the centrifugal spray drying granulation.
3. preparation method according to claim 2 is characterized in that, described centrifugal spray drying granulating equipment comprises dehumidification system, and described dehumidification system comprises:
Be positioned at described dehumidification system top, described slurry can be atomized into the centrifugal atomizer of droplet;
Be positioned at described centrifugal atomizer below, can be with the kiln of described droplet drying.
4. preparation method according to claim 3 is characterized in that, described kiln is provided with polytetrafluoroethyllining lining.
5. preparation method according to claim 2 is characterized in that, the rotating speed of described centrifugal spray drying granulating equipment is 40r/min～80r/min.
6. preparation method according to claim 1 is characterized in that, in the described step b), the temperature of described spray drying granulation is 140 ℃～160 ℃.
7. preparation method according to claim 1 is characterized in that, in the described step b), the temperature of described discharging is 50 ℃～70 ℃.
8. preparation method according to claim 1 is characterized in that, before described step a), also comprises step:
Described mixed powder is carried out ball milling, drying.
9. preparation method according to claim 8 is characterized in that, described ball milling is:
Adopt silicon nitride ball milling jar and silicon nitride ceramic ball to carry out ball milling.
10. preparation method according to claim 8 is characterized in that, described drying is carried out in vacuum or nitrogen atmosphere.
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| CN2011104446588A CN103183512A (en) | 2011-12-27 | 2011-12-27 | Preparation method for powder for silicon nitride crucible |
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Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1799995A (en) * | 2005-12-21 | 2006-07-12 | 北京科技大学 | Method for synthesizing isotropic silicon nitride powder adopting layer type material-distribution |
| CN101289319B (en) * | 2008-06-03 | 2010-06-30 | 浙江东新密封有限公司 | Reaction sintering silicon carbide ceramic and production method thereof |
| CN102170716A (en) * | 2010-12-09 | 2011-08-31 | 江苏华盛精细陶瓷科技有限公司 | Method for manufacturing silicon nitride heating body |
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2011
- 2011-12-27 CN CN2011104446588A patent/CN103183512A/en active Pending
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1799995A (en) * | 2005-12-21 | 2006-07-12 | 北京科技大学 | Method for synthesizing isotropic silicon nitride powder adopting layer type material-distribution |
| CN101289319B (en) * | 2008-06-03 | 2010-06-30 | 浙江东新密封有限公司 | Reaction sintering silicon carbide ceramic and production method thereof |
| CN102170716A (en) * | 2010-12-09 | 2011-08-31 | 江苏华盛精细陶瓷科技有限公司 | Method for manufacturing silicon nitride heating body |
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Application publication date: 20130703 |