CN102060544A - Quick crystallization method for realizing amorphous silicon nitride powder by taking silica powder as additive - Google Patents
Quick crystallization method for realizing amorphous silicon nitride powder by taking silica powder as additive Download PDFInfo
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- CN102060544A CN102060544A CN2010105414700A CN201010541470A CN102060544A CN 102060544 A CN102060544 A CN 102060544A CN 2010105414700 A CN2010105414700 A CN 2010105414700A CN 201010541470 A CN201010541470 A CN 201010541470A CN 102060544 A CN102060544 A CN 102060544A
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Abstract
The invention discloses a quick crystallization method for realizing amorphous silicon nitride powder by taking silica powder as additive, belonging to the technical field of preparation of ultrafine silicon nitride powder. The quick crystallization method is characterized in that the amorphous silicon nitride powder and silicon powder serving as the additive are fully mixed at the weight ratio of (98-50):(2-50); then the mixture is put into a high-temperature nitrogen furnace after being screened and dried for crystallizing the amorphous silicon nitride powder; the silicon powder is added to be subjected to combustion synthesis reaction together with nitrogen to generate alpha-phase silicon nitride while the crystallization time for the amorphous silicon nitride is effectively shortened; the final product is the alpha-phase silicon nitride powder, and the content of the silicon in the product is below 0.1%. The silicon powder serving as the crystallization can effectively accelerate the crystallization process of the amorphous silicon nitride powder, thus the nitriding of the nitrogen powder is completed while the crystallization time is greatly shortened. The method has the advantages of high production efficiency, simple equipment, quick energy conservation and high product purity, is convenient to operate, and is especially suitable for producing the high-quality silicon nitride powder with high alpha-phase content on batch by utilizing the amorphous silicon nitride powder.
Description
Technical field
The invention belongs to the preparing technical field of superfine silicon nitride powder, relate to a kind of silica flour that utilizes and do the rapid crystallization method that additive is realized the amorphous silicon nitride powder, under high-temperature pressure, can produce high-purity, alpha-phase silicon nitride ultrafine powder in batches.
Background technology
In various stupaliths, silicon nitride (Si
3N
4) pottery is the new engineering material that has development potentiality and application market most.Height ratio is strong because it has, height ratio mould, high temperature resistant, anti-oxidant and advantages such as wear-resistant and high-heat resistance shock resistant, thus silicon nitride ceramics at high temperature, at a high speed, have special use value in the Working environment of strong corrosive medium.
High quality Si
3N
4The preparation of ceramic need be used fine Si
3N
4Powder.The preparation method of present known beta-silicon nitride powder is a lot, people study maximum have following several: silica flour direct nitridation method, carbothermic reduction silicon-dioxide method, thermal decomposition method, chemical Vapor deposition process, self propagating high temperature synthesis method and sol-gel method etc.From present domestic and international research and applicable cases, the silica flour direct nitridation method is the technology of comparative maturity, but it need at high temperature just can finish reaction for a long time, consumes the more energy simultaneously, and transformation efficiency and product purity are also lower.The thermal decomposition method development in recent years is very fast, has set up plant-scale beta-silicon nitride powder production line abroad, but still exists some technical problems also need further reduce production costs generally.Though various chemical Vapor deposition processs can obtain the purity high product, its production cost is than higher, and industrial scale is also less relatively, only suitable some special dimension that is applied in.The self propagating high temperature synthesising reacting speed is very fast, and it is short to finish the reaction required time, and energy consumption is less, and production technique is simple, but temperature of reaction is wayward, and product local sintering quality is unstable and need follow-up grinding, has increased production cost.
Beta-silicon nitride powder on the market mainly is divided into amorphous phase, α phase and β mutually.Because α-Si
3N
4Coking property is better, therefore is preparation high-performance Si
3N
4The raw material commonly used of pottery.At present, main research work concentrates on high α phase Si both at home and abroad
3N
4The preparation aspect of powder.
" high α-the Si of a kind of preparation of inventions such as Russia Merzhanov
3N
4Method " (U.S. Pat 5032370); need be under higher nitrogen pressure (4～30Mpa) finish building-up reactions; the requirement to equipment is comparatively harsh; accident generation probability increases; need to add the ammonia salt that contains Cl, F in a large number simultaneously; serious to equipment corrosion, increased cost, these reasons cause being unfavorable for large-scale production.The Chen Ke of Tsing-Hua University newly waits the people to invent " method of the synthetic alpha-phase silicon nitride powder of a kind of low-pressure combustion " (the Chinese patent publication number is CN1362358A), this method need be carried out pre-treatment to silica flour, comprise pickling, supersound process, high speed ball milling, then add promoting agent, thinner and additive, with above-mentioned powder long-time ball milling on ball mill, need the plenty of time to carry out pre-treatment again.People such as Gao Liwen have invented " high α-Si
3N
4The phase silicon nitride preparation method " (the Chinese patent publication number is CN101269803A); this method is silica flour and silicon nitride powder mixing briquetting shove charge nitrogenize, though can make alpha-phase silicon nitride powder in enormous quantities, owing to need zone heating and control pressure; so complicated operation, wayward.People such as the neat Long Hao of Tsing-Hua University have invented " plasma chemical vapor phase process is produced beta-silicon nitride powder phase transfer process and system in batches " (the Chinese patent publication number is CN1397487A), this method has realized the amorphous silicon nitride batch crystallization of plasma chemical vapor phase process production is obtained the technological process of alpha-phase silicon nitride, but because the inversion of phases process is slow, usually need more than 3 hour, therefore efficient is lower, and cost is still higher.
Summary of the invention
The objective of the invention is to the promoter action of utilizing silica flour in the amorphous silicon nitride crystallization process, to show, solve the problem that amorphous silicon nitride crystallization process process time is long, cost is high, realize utilizing the amorphous silicon nitride method of crystallization scale operation α phase silicon nitride powder in batches.
A kind of method of making additive realization amorphous silicon nitride powder rapid crystallization with silica flour, the present invention be with amorphous silicon nitride powder and as the silica flour of additive according to silicon nitride powder: silica flour=(98～50): the mass ratio thorough mixing of (2～50), again through screening, drying process with after satisfying particle size range and being 0.01 μ m～200 μ m, carry out the crystallization of amorphous silicon nitride in the high temperature nitrogen of packing into the steam stove.The additive silica flour generates the α phase silicon nitride with nitrogen generation combustion synthesis reaction when effectively shortening the amorphous silicon nitride crystallization time.The finished product are alpha-phase silicon nitride powder, and silicone content is below 0.1% in the product.
Principal feature of the present invention is to make full use of the promoter action of silica flour to amorphous silicon nitride inversion of phases process, realize the amorphous silicon nitride powder rapid crystallization in short period of time, finish the silicon powder nitride process simultaneously, make high purity, high-quality α phase silicon nitride powder, and do not have remaining amorphous phase, silicone content extremely low in the product.
Crystallization product of the present invention is alpha-phase silicon nitride ultrafine powder or α/β phase composite nitride silica flour; By changing processing condition, can obtain the alpha-silicon nitride powders of different crystalline phases.When nitriding temperature was 1400～1500 ℃, product was mainly the α phase silicon nitride.When nitriding temperature is 1500～1650 ℃, a small amount of beta phase silicon nitride can occur in the product, and with the prolongation of heat treatment time, the β phase content increases gradually.
The present invention is a kind of under the high-temperature pressure condition, realizes the method for amorphous silicon nitride powder rapid crystallization production alpha-phase silicon nitride powder.Adopt silica flour as the inversion of phases additive, effectively promote the amorphous silicon nitride powder phase transition process, greatly shorten crystallization time in, finish self nitrogenize, therefore have quick, energy-conservation, can produce in batches and advantage that product purity is high.This method is particularly suitable for utilizing amorphous silicon nitride powder to produce the high α phase content of high quality silicon nitride powder in batches.
Amorphous silicon nitride powder crystallization method of the present invention has following advantage:
1, common amorphous silicon nitride powder crystallization method needed 3～4 hours even longer (containing thermal treatment in early stage 1～2 hour) usually, transformation efficiency is low, be not suitable for producing in batches the alpha-phase silicon nitride powder, and use the inventive method, can shorten amorphous silicon nitride powder crystallization time (in the 30min) greatly, thereby improved production efficiency, be fit to mass-producing and use;
2, in amorphous silicon nitride powder, added silica flour, when effectively shortening crystallization time, finish the nitridation process of silica flour, promptly the same time is finished amorphous silicon nitride crystallization and two processes of silicon powder nitride, makes the method for the output of product α phase silicon nitride powder far above pure amorphous silicon nitride powder crystallization;
3, silica flour addition controlled (2～50%) can be grasped application flexibly according to practical condition.
Description of drawings
Fig. 1 is a powder screening plant synoptic diagram.1 is powder to be sieved, and 2 is agitator motor, and 3 is the inverted T-shaped agitator arm, and 4 is the screening plant main body, and 5 is vibrating motor, and 6 is screen cloth, and 7 are the funnel-form passage that gathers materials, and 8 is container.
Fig. 2 is the mixing apparatus of powdery row material synoptic diagram.9 is mixture, and 10 is agitator motor, and 11 is the spirrillum agitator arm, and 12 is the mixing device main body, and 13 is vibrating motor.During mixture, the mixing device main body of at first two kinds of materials being packed into starts agitator motor and vibrating motor then, under the acting in conjunction of agitator arm and vibration, and the mutual thorough mixing of superfine powder, uniform distribution is realized the mixing of two or more powder materials.
Fig. 3 is a crystallization and thermal treatment device synoptic diagram.This device mainly comprises preheating chamber, high temperature nitrogen steam stove, cooling room, gas-circulating system etc.14 is preheating chamber charging door, and 15 is preheating chamber, and 16 is preceding enclosed passage, and 17 is the high temperature nitrogen steam stove, and 18 is the back enclosed passage, and 19 is cooling room, and 20 is discharge door, and 21 is the nitrogen furnace zone of heating, and 22 is the nitrogen furnace thermal insulation layer, and P is a tensimeter.
Fig. 4 is an amorphous silicon nitride powder crystallization process schematic flow sheet.Raw material powder through technological processs such as screening, mixing, drying, charging, ventilation preheating, the nitrogenize of high temperature crystallization, coolings, is finished two processes of amorphous silicon nitride powder crystallization and silicon powder nitride successively, finally obtains product alpha-phase silicon nitride powder.
Embodiment
The present invention mainly comprises the several processing steps of powder screening, mixing, drying and thermal treatment, relates to following main device.
Powder screening plant: during the screening material, the screening plant main body of at first material being packed into starts agitator motor and vibrating motor, then under the acting in conjunction of agitator arm and vibration, superfine powder filters behind the screen cloth by the funnel-form passage that gathers materials and enters container, realizes screening process.
Mixing apparatus of powdery row material: during mixture, the mixing device main body of at first two kinds of materials being packed into starts agitator motor and vibrating motor then, under the acting in conjunction of agitator arm and vibration, the mutual thorough mixing of superfine powder, uniform distribution is realized the mixing of two or more powder materials.
The crystallization and thermal treatment device: this device mainly comprises preheating chamber, high temperature nitrogen steam stove, cooling room, gas-circulating system etc.When heat-treating, mixture is at first heated by high temperature nitrogen in preheating chamber, enters the crystallization of finishing silicon nitride powder in the nitrogen furnace and the nitridation process of silica flour afterwards, and discharging behind the cooling room internal cooling afterwards becomes final product.In the heat treatment process, guarantee all the time to be nitrogen atmosphere (or nitrogen and hydrogen mixed gas atmosphere) in the high temperature nitrogen steam stove, and be pressure-fired that gauge pressure is 0～0.02MPa; Invert point is controlled between 1400～1650 ℃ with the difference of concrete processing condition.
Realize that specific embodiment of the present invention is as follows:
A, raw material mix and broken the reunion handles
With amorphous silicon nitride powder and as the silica flour of additive according to silicon nitride powder: silica flour=(98～50): the mass ratio of (2～50) is thorough mixing in the raw material mixing system, makes two kinds of raw material uniform distribution; Mixture is sieved processing in screening system, make amorphous silicon nitride powder and be 0.01 μ m～200 μ m, guarantee to remove the macrobead powder as the particle size range of the silica flour of additive; Mixture is carried out drying treatment in dehumidification system, drying temperature is 80～120 ℃, and be 1～8 hour time of drying, removes the water that adsorbs in the powder.
B, raw material preheating and to the nitriding furnace feed
Pack into the mixture pine after the drying screening in the charge vessels crucible and send into preheating chamber, preheating is 1～10 minute under nitrogen atmosphere.
C, amorphous silicon nitride powder crystallization and additive silicon powder nitride process
Enter material in the high temperature nitrogen steam stove and be heated to certain temperature in 1400～1650 ℃ of scopes rapidly under nitrogen atmosphere, crystallization takes place in amorphous silicon nitride powder under this temperature, form the α phase silicon nitride powder; Silica flour and nitrogen generation combustion synthesis reaction as additive generates the α phase silicon nitride powder simultaneously.Silica flour and nitrogen have promoted the amorphous silicon nitride crystallization process effectively when combustion reactions takes place, accelerated its crystallization velocity greatly.In the whole nitridation process, the nitrogen furnace internal pressure keeps pressure-fired always, and gauge pressure is 0～0.02MPa.
D, crystallization product process of cooling
After mixture is finished phase inversion and nitridation process, enter cooling room and cooled off by the normal temperature high pure nitrogen.
E, discharging process
Cooled product is taken out from the charge crucible, collect product.
Product is the ultrafine powder of silicon nitride or the α/β phase composite nitride silica flour of high α phase content.
Embodiment 1:
With median size is that the silica flour of the amorphous silicon nitride powder of 0.2 μ m and 10 μ m is put into screening plant respectively and sieved, and removes the macrobead because of the formation of reasons such as reunions.Again with two kinds of powders according to silicon nitride powder: the mass ratio of silica flour=95: 5 is put into the mixing apparatus of powdery row material thorough mixing, then mixing raw material is put into vacuum drying oven, 90 ℃ dry 8 hours down.The raw material that drying is good is put into screening plant once more and is sieved, and further removes large size reunion powder, puts into the crystallization and thermal treatment device then, and through the thermal treatment 30 minutes under 1450 ℃ of nitrogen atmospheres of ventilation back, the cooling of coming out of the stove obtains the superfine silicon nitride powder.α phase silicon nitride content is more than 80% in the X-ray diffraction analysis product, non-crystallized amorphous silicon nitride content＜20%, and remaining silicone content＜0.5%, no beta phase silicon nitride produces.
Embodiment 2:
With median size is that the silica flour of the amorphous silicon nitride powder of 0.2 μ m and 10 μ m is put into screening plant respectively and sieved, and removes the macrobead because of the formation of reasons such as reunions.Again with two kinds of powders according to silicon nitride powder: the mass ratio of silica flour=70: 30 is put into the mixing apparatus of powdery row material thorough mixing, then mixing raw material is put into vacuum drying oven, 90 ℃ dry 8 hours down.The raw material that drying is good is put into screening plant once more and is sieved, and further removes large size reunion powder, puts into the crystallization and thermal treatment device then, and through the thermal treatment 20 minutes under 1450 ℃ of nitrogen atmospheres of ventilation back, the cooling of coming out of the stove obtains the superfine silicon nitride powder.α phase silicon nitride content is more than 90% in the X-ray diffraction analysis product, non-crystallized amorphous silicon nitride content＜5%, and remaining silicone content＜5%, no beta phase silicon nitride produces.
Embodiment 3:
With median size is that the silica flour of the amorphous silicon nitride powder of 0.2 μ m and 10 μ m is put into screening plant respectively and sieved, and removes the macrobead because of the formation of reasons such as reunions.Again with two kinds of powders according to silicon nitride powder: the mass ratio of silica flour=50: 50 is put into the mixing apparatus of powdery row material thorough mixing, then mixing raw material is put into vacuum drying oven, 90 ℃ dry 8 hours down.The raw material that drying is good is put into screening plant once more and is sieved, and further removes large size reunion powder, puts into the crystallization and thermal treatment device then, and through the thermal treatment 15 minutes under 1500 ℃ of nitrogen atmospheres of ventilation back, the cooling of coming out of the stove obtains the superfine silicon nitride powder.α phase silicon nitride content is more than 75% in the X-ray diffraction analysis product, beta phase silicon nitride content＜20%, remaining silicone content＜5%, non-crystallized amorphous silicon nitride content＜1%.
Claims (3)
1. make the method that additive is realized amorphous silicon nitride powder rapid crystallization with silica flour for one kind, it is characterized in that with amorphous silicon nitride powder and as the silica flour of additive according to silicon nitride powder: silica flour=(98～50): the mass ratio thorough mixing of (2～50), again through screening, drying process with after satisfying particle size range and being 0.01 μ m～200 μ m, carry out the crystallization of amorphous silicon nitride in the high temperature nitrogen of packing into the steam stove; The additive silica flour generates the α phase silicon nitride with nitrogen generation combustion synthesis reaction when effectively shortening the amorphous silicon nitride crystallization time, the finished product are alpha-phase silicon nitride powder, and silicone content is below 0.1% in the product.
2. as claimed in claim 1ly make the method that additive is realized amorphous silicon nitride powder rapid crystallization with silica flour, it is characterized in that: this method comprises the crystallization and thermal treatment system of raw material mixing system, material screening system, raw material drying system and raw material;
Concrete processing step is:
(1) with amorphous silicon nitride powder and as the silica flour of additive according to silicon nitride powder: silica flour=(98～50): the mass ratio of (2～50) is thorough mixing in the raw material mixing system, makes two kinds of raw material uniform distribution;
(2) mixture is sieved processing in screening system, make amorphous silicon nitride powder and be 0.01 μ m～200 μ m, guarantee to remove the macrobead powder as the particle size range of the silica flour of additive;
(3) mixture is carried out drying treatment in dehumidification system, drying temperature is 80～120 ℃, and be 1～8 hour time of drying, removes the water that adsorbs in the powder;
(4) mixture is sent in the crystallization and thermal treatment system, under nitrogen atmosphere, pass through warm, crystallization and nitridation process, process of cooling successively, finish whole thermal treatment process, obtain the ultrafine powder of silicon nitride or the α/β phase composite nitride silica flour of high α phase content.
3. as claimed in claim 2ly make the method that additive is realized amorphous silicon nitride powder rapid crystallization with silica flour, it is characterized in that the nitrogen furnace internal pressure keeps pressure-fired in processing step (4) crystallization and the nitridation process always, gauge pressure is 0～0.02MPa.
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN107285288A (en) * | 2017-07-12 | 2017-10-24 | 深圳市东川技术研究有限公司 | The preparation method of nano silicon nitride powders |
| CN110256084A (en) * | 2019-07-31 | 2019-09-20 | 上海泛联科技股份有限公司 | A kind of preparation method of α phase silicon nitride ceramic powder |
| CN116789086A (en) * | 2023-05-08 | 2023-09-22 | 衡阳凯新特种材料科技有限公司 | Production process of silicon nitride powder |
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| CN1433959A (en) * | 2002-01-22 | 2003-08-06 | 北京科技大学 | Process for combustion synthesizing high alpha phase superfine silicon carbide powder and silicon nitride whisker |
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Patent Citations (3)
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| CN1433959A (en) * | 2002-01-22 | 2003-08-06 | 北京科技大学 | Process for combustion synthesizing high alpha phase superfine silicon carbide powder and silicon nitride whisker |
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN107285288A (en) * | 2017-07-12 | 2017-10-24 | 深圳市东川技术研究有限公司 | The preparation method of nano silicon nitride powders |
| CN110256084A (en) * | 2019-07-31 | 2019-09-20 | 上海泛联科技股份有限公司 | A kind of preparation method of α phase silicon nitride ceramic powder |
| CN116789086A (en) * | 2023-05-08 | 2023-09-22 | 衡阳凯新特种材料科技有限公司 | Production process of silicon nitride powder |
| CN116789086B (en) * | 2023-05-08 | 2024-01-12 | 衡阳凯新特种材料科技有限公司 | Production process of silicon nitride powder |
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