CN102060544B - 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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Abstract
The invention belongs to the preparation technology field of a superfine silicon nitride powder, and relates to a quick crystallization method for realizing the amorphous silicon nitride powder by taking silica powder as an additive. The high-purity and high alpha phase silicon nitride superfine powder can be produced in batch at high temperature and normal pressure. The method includes a raw material mixing system, a raw material screening system, a raw material drying system and a raw material crystallizing and thermal treatment system. The silicon powder serving as the crystallization additive 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 products are high quality and high alpha phase silicon nitride powder. Compared with the known amorphous silicon nitride crystallization process, the method has the advantages of high production efficiency, simple equipment, quick energy conservation, batch production 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 in 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 utilize silica flour to do quick crystallization method that additive realizes amorphous silicon nitride powder, high-purity, alpha-phase silicon nitride ultrafine powder can be produced in batches under high-temperature pressure.
Background technology
In various stupalith, silicon nitride (Si
3n
4) pottery is the new engineering material most with development potentiality and application market.Because it has high than the advantage such as strong, Gao Bimo, high temperature resistant, anti-oxidant and wear-resistant and high-heat resistance shock resistant, so silicon nitride ceramics is 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 needs the Si using high-quality
3n
4powder.The preparation method of beta-silicon nitride powder known is at present a lot, and having of people's most study is following several: silica flour direct nitridation method, carbothermic reduction titanium dioxide silicon process, thermal decomposition method, chemical Vapor deposition process, self-propagating high-temperature synthesis and sol-gel method etc.From current investigation and application situation both domestic and external, silica flour direct nitridation method is the technique of comparative maturity, but its needs at high temperature just can complete reaction for a long time, and consume comparatively multiple-energy-source, transformation efficiency and product purity are also lower simultaneously.Thermal decomposition method development in recent years is very fast, has established plant-scale beta-silicon nitride powder production line abroad, but still there are some technical problems generally and need reduce production cost further.Although various chemical Vapor deposition process can obtain the higher product of purity, its production cost is higher, and industrial scale is also relatively little, is only suitable for being applied in some special dimension.SHS process speed of response is very fast, and complete reaction required time short, 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, adds production cost.
Beta-silicon nitride powder on market is mainly divided into amorphous phase, α phase and β phase.Due to α-Si
3n
4coking property is better, is therefore preparation high-performance Si
3n
4the conventional raw material of pottery.At present, the emphasis of domestic and international research work concentrates on high α phase Si
3n
4the preparation aspect of powder.
Invention such as Russia Merzhanov etc. " one prepares high α-Si
3n
4method " (US Patent No. 5032370); need under higher nitrogen pressure (4 ~ 30Mpa) to complete building-up reactions; comparatively harsh to the requirement of equipment; accident Probability increases; to need to add a large amount of ammonia salt containing Cl, F; serious to equipment corrosion, add cost, these reasons cause being unfavorable for large-scale production simultaneously.The human hairs such as Tsing-Hua University Chen Ke is new understand " a kind of method of low-pressure combustion synthesis alpha-phase silicon nitride powder " (China Patent Publication No. is CN1362358A), the method needs to carry out pre-treatment to silica flour, comprise pickling, supersound process, high speed ball milling, then promoting agent, thinner and additive is added, again by above-mentioned powder long-time ball milling on ball mill, the plenty of time is needed to carry out pre-treatment.The human hairs such as Gao Liwen understand " high α-Si
3n
4phase silicon nitride preparation method " (China Patent Publication No. is CN101269803A); the method is by silica flour and silicon nitride powder mixing briquetting shove charge nitrogenize; although can obtain alpha-phase silicon nitride powder in enormous quantities; due to needs zone heating and control pressure; therefore complicated operation, wayward.The human hairs such as the neat Long Hao of Tsing-Hua University understand " plasma chemical vapor phase process batch production beta-silicon nitride powder phase transfer process and system " (China Patent Publication No. is CN1397487A), the method achieve the technological process that the amorphous silicon nitride batch crystallization of Both Plasma Chemical Vapor method being produced obtains alpha-phase silicon nitride, but because inversion of phases process is slow, usual needs more than 3 hour, therefore efficiency is lower, and cost is still higher.
Summary of the invention
The object of the invention is to the promoter action utilizing silica flour to show in amorphous silicon nitride crystallization process, solve the problem that amorphous silicon nitride crystallization process process time is long, cost is high, realize the method utilizing amorphous silicon nitride batch crystallization scale operation α phase silicon nitride powder.
A kind of method realizing amorphous silicon nitride powder rapid crystallization with silica flour as additive, the present invention be using amorphous silicon nitride powder and as the silica flour of additive according to silicon nitride powder: silica flour=(98 ~ 70): the mass ratio of (2 ~ 30) fully mixes, again through screening, drying process with after meeting particle size range and being 0.01 μm ~ 200 μm, load the crystallization of carrying out amorphous silicon nitride in high temperature nitrogen steam stove.Additive silica flour, while effectively shortening amorphous silicon nitride crystallization time, generates α phase silicon nitride with nitrogen generation combustion synthesis reaction.The finished product are alpha-phase silicon nitride powder, and in product, silicone content is below 0.1%.
Principal feature of the present invention makes full use of the promoter action of silica flour to amorphous silicon nitride inversion of phases process, amorphous silicon nitride powder rapid crystallization is realized in short period of time, complete silicon powder nitride process simultaneously, obtained high purity, high-quality α phase silicon nitride powder, and in product, do not have residual amorphous phase, silicone content extremely low.
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, the alpha-silicon nitride powders of different crystalline phase can be obtained.When nitriding temperature is 1400 ~ 1500 DEG C, product is mainly α phase silicon nitride.When nitriding temperature is 1500 ~ 1650 DEG C, in product, there will be a small amount of beta phase silicon nitride, and with the prolongation of heat treatment time, β phase content increases gradually.
The present invention is a kind of under high-temperature pressure condition, realizes the method that amorphous silicon nitride powder rapid crystallization produces alpha-phase silicon nitride powder.Adopt silica flour as inversion of phases additive, while effectively promoting amorphous silicon nitride powder phase transition process, greatly shortening crystallization time, complete self nitrogenize, therefore have quick, energy-conservation, can be mass and the high advantage of product purity.The method is particularly suitable for utilizing amorphous silicon nitride powder to produce high quality height α phase content 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 needs 3 ~ 4 hours even longer (containing thermal treatment in early stage 1 ~ 2 hour) usually, transformation efficiency is low, be not suitable for batch production alpha-phase silicon nitride powder, and use the inventive method, amorphous silicon nitride powder crystallization time (within 30min) can be shortened greatly, thus improve production efficiency, be applicable to mass-producing application;
2, in amorphous silicon nitride powder, with the addition of silica flour, while effective shortening crystallization time, complete the nitridation process of silica flour, namely the same time completes amorphous silicon nitride crystallization and silicon powder nitride two processes, makes the method for output far above pure amorphous silicon nitride powder crystallization of product α phase silicon nitride powder;
3, silica flour addition controlled (2 ~ 30%), can grasp application flexibly according to practical condition.
Accompanying drawing explanation
Fig. 1 is Powder screen separating device schematic diagram.1 is powder to be sieved, and 2 is agitator motor, and 3 is inverted T-shaped agitator arm, and 4 is screening plant main body, and 5 is vibrating motor, and 6 is screen cloth, and 7 to gather materials passage for funnel-form, and 8 is container.
Fig. 2 is mixing apparatus of powdery row material schematic diagram.9 is mixture, and 10 is agitator motor, and 11 is spirrillum agitator arm, and 12 is mixing device main body, and 13 is vibrating motor.During mixture, first two kinds of materials are loaded mixing device main bodys, then start agitator motor and vibrating motor, under the acting in conjunction of agitator arm and vibration, superfine powder fully mixes mutually, is uniformly distributed, and realizes the mixing of two or more powder materials.
Fig. 3 is crystallization and thermal treatment device schematic 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 front enclosed passage, and 17 is high temperature nitrogen steam stove, and 18 is rear enclosed passage, and 19 is cooling room, and 20 is discharge door, and 21 is nitrogen furnace zone of heating, and 22 is nitrogen furnace thermal insulation layer, and P is tensimeter.
Fig. 4 is amorphous silicon nitride powder crystallization process schematic flow sheet.Raw material powder through the technological process such as screening, mixing, drying, charging, ventilation preheating, the nitrogenize of high temperature crystallization, cooling, completes amorphous silicon nitride powder crystallization and silicon powder nitride two processes, finally obtains product alpha-phase silicon nitride powder successively.
Embodiment
The present invention mainly comprises powder screening, mixing, the dry and several processing step of thermal treatment, relates to following main device.
Powder screen separating device: during screening materials carrying, first material is loaded screening plant main body, then start agitator motor and vibrating motor, under the acting in conjunction of agitator arm and vibration, superfine powder filters after screen cloth and enters container by the funnel-form passage that gathers materials, and realizes screening process.
First two kinds of materials are loaded mixing device main body by mixing apparatus of powdery row material: during mixture, then start agitator motor and vibrating motor, under the acting in conjunction of agitator arm and vibration, superfine powder fully mixes mutually, is uniformly distributed, and realizes the mixing of two or more powder materials.
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, first mixture is heated by high temperature nitrogen in preheating chamber, enters afterwards in nitrogen furnace and completes the crystallization of silicon nitride powder and the nitridation process of silica flour, and discharging after cooling in cooling room afterwards, becomes final product.In heat treatment process, ensure in high temperature nitrogen steam stove to be nitrogen atmosphere (or nitrogen and hydrogen mixed gas atmosphere) all the time, and be pressure-fired, gauge pressure is 0 ~ 0.02MPa; Invert point controls between 1400 ~ 1650 DEG C with the difference of concrete technology condition.
Realize specific embodiment of the present invention as follows:
The mixing of a, raw material and broken process of reuniting
Using amorphous silicon nitride powder and as the silica flour of additive according to silicon nitride powder: silica flour=(98 ~ 70): the mass ratio of (2 ~ 30) fully mixes in raw material mixing system, make two kinds of raw materials be uniformly distributed; Mixture is carried out in screening system screening process, make amorphous silicon nitride powder and be 0.01 μm ~ 200 μm as the particle size range of the silica flour of additive, guarantee removing macrobead powder; Mixture is carried out drying treatment in dehumidification system, and drying temperature is 80 ~ 120 DEG C, and time of drying is 1 ~ 8 hour, removes the water adsorbed in powder.
B, raw material preheating and to nitriding furnace feed
Mixture pine after drying being sieved to load in charge vessels crucible and sends into preheating chamber, preheating 1 ~ 10 minute in a nitrogen atmosphere.
C, amorphous silicon nitride powder crystallization and additive silicon powder nitride process
The material entered in high temperature nitrogen steam stove is rapidly heated to certain temperature within the scope of 1400 ~ 1650 DEG C in a nitrogen atmosphere, and amorphous silicon nitride powder at such a temperature crystallization occurs, and forms α phase silicon nitride powder; Simultaneously generate α phase silicon nitride powder as the silica flour of additive and nitrogen generation combustion synthesis reaction.Silica flour and nitrogen, while there is combustion reactions, effectively promote amorphous silicon nitride crystallization process, greatly accelerate its crystallization velocity.In whole nitridation process, nitrogen furnace internal pressure keeps pressure-fired always, and gauge pressure is 0 ~ 0.02MPa.
D, crystallization product process of cooling
After mixture completes phase inversion and nitridation process, enter cooling room and cooled by normal temperature high pure nitrogen.
E, discharging process
Cooled product is taken out from charge crucible, collects product.
Product is ultrafine powder of silicon nitride or the α/β phase composite nitride silica flour of high α phase content.
Embodiment 1:
Be that screening plant Inside sifter put into respectively by the amorphous silicon nitride powder of 0.2 μm and the silica flour of 10 μm by median size, remove the macrobead because the reasons such as reunion are formed.Again by two kinds of powders according to silicon nitride powder: the mass ratio of silica flour=95:5 puts into mixing apparatus of powdery row material fully mixing, then mixing raw material is put into vacuum drying oven, at 90 DEG C dry 8 hours.Dried raw material is put into screening plant Inside sifter again, removes further large size reunion powder, then put into crystallization and thermal treatment device, thermal treatment 30 minutes under 1450 DEG C of nitrogen atmospheres after ventilation, cooling of coming out of the stove, obtains superfine silicon nitride powder.α phase silicon nitride content more than 80% in X-ray diffraction analysis product, non-crystallized amorphous silicon nitride content <20%, remaining silicone content <0.5%, produces without beta phase silicon nitride.
Embodiment 2:
Be that screening plant Inside sifter put into respectively by the amorphous silicon nitride powder of 0.2 μm and the silica flour of 10 μm by median size, remove the macrobead because the reasons such as reunion are formed.Again by two kinds of powders according to silicon nitride powder: the mass ratio of silica flour=70:30 puts into mixing apparatus of powdery row material fully mixing, then mixing raw material is put into vacuum drying oven, at 90 DEG C dry 8 hours.Dried raw material is put into screening plant Inside sifter again, removes further large size reunion powder, then put into crystallization and thermal treatment device, thermal treatment 20 minutes under 1450 DEG C of nitrogen atmospheres after ventilation, cooling of coming out of the stove, obtains superfine silicon nitride powder.α phase silicon nitride content more than 90% in X-ray diffraction analysis product, non-crystallized amorphous silicon nitride content <5%, remaining silicone content <5%, produces without beta phase silicon nitride.
Claims (3)
1. one kind realizes the method for amorphous silicon nitride powder rapid crystallization as additive with silica flour, it is characterized in that using amorphous silicon nitride powder and as the silica flour of additive according to silicon nitride powder: silica flour=(98 ~ 70): the mass ratio of (2 ~ 30) fully mixes, again through screening, drying process with after meeting particle size range and being 0.01 μm ~ 200 μm, load the crystallization of carrying out amorphous silicon nitride in high temperature nitrogen steam stove; Additive silica flour is while effectively shortening amorphous silicon nitride crystallization time, and generate α phase silicon nitride with nitrogen generation combustion synthesis reaction, the finished product are alpha-phase silicon nitride powder, and in product, silicone content is below 0.1%.
2. the method realizing amorphous silicon nitride powder rapid crystallization with silica flour as additive as claimed in claim 1, is characterized in that: the method comprises the crystallization and thermal treatment system of raw material mixing system, material screening system, raw material drying system and raw material;
Concrete technology step is:
(1) using amorphous silicon nitride powder and as the silica flour of additive according to silicon nitride powder: silica flour=(98 ~ 70): the mass ratio of (2 ~ 30) fully mixes in raw material mixing system, make two kinds of raw materials be uniformly distributed;
(2) mixture is carried out in screening system screening process, make amorphous silicon nitride powder and be 0.01 μm ~ 200 μm as the particle size range of the silica flour of additive, guarantee removing macrobead powder;
(3) mixture is carried out drying treatment in dehumidification system, drying temperature is 80 ~ 120 DEG C, and time of drying is 1 ~ 8 hour, removes the water adsorbed in powder;
(4) mixture is sent in crystallization and thermal treatment system, in a nitrogen atmosphere, successively through warm, crystallization and nitridation process, process of cooling, complete whole thermal treatment process, obtain ultrafine powder of silicon nitride or the α/β phase composite nitride silica flour of high α phase content.
3. the method realizing amorphous silicon nitride powder rapid crystallization with silica flour as additive as claimed in claim 2, it is characterized in that in processing step (4) crystallization and nitridation process, nitrogen furnace internal pressure keeps pressure-fired always, and gauge pressure is 0 ~ 0.02MPa.
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| 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 |
| CN110256084B (en) * | 2019-07-31 | 2021-10-08 | 上海泛联科技股份有限公司 | Preparation method of alpha-phase silicon nitride ceramic 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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| 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 |
| CN1657404A (en) * | 2004-02-18 | 2005-08-24 | 中国科学院理化技术研究所 | Method for synthesizing silicon nitride powder by atmospheric pressure combustion |
| CN101318637A (en) * | 2008-07-15 | 2008-12-10 | 北京科技大学 | Process for producing nano-silicon nitride ceramics powder |
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| Publication number | Priority date | Publication date | Assignee | Title |
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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 |
| CN1657404A (en) * | 2004-02-18 | 2005-08-24 | 中国科学院理化技术研究所 | Method for synthesizing silicon nitride powder by atmospheric pressure combustion |
| CN101318637A (en) * | 2008-07-15 | 2008-12-10 | 北京科技大学 | Process for producing nano-silicon nitride ceramics powder |
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| 硅粉常压直接氮化制备氮化硅粉的研究;尹少武 等;《硅酸盐通报》;20080430;第27卷(第2期);第230-235页 * |
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