CN100590096C - Method for controlling minuteness particle accumulation shape - Google Patents
Method for controlling minuteness particle accumulation shape Download PDFInfo
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- CN100590096C CN100590096C CN200810010668A CN200810010668A CN100590096C CN 100590096 C CN100590096 C CN 100590096C CN 200810010668 A CN200810010668 A CN 200810010668A CN 200810010668 A CN200810010668 A CN 200810010668A CN 100590096 C CN100590096 C CN 100590096C
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Abstract
A method used for controlling the aggregation morphology of fine particles relates to the field of material science, which makes use of fine powder particles after gas-phase separation to control theaggregation morphology of particles on substrate surfaces so as to lead the aggregation morphology to be mainly like the form of a pearl chain, with the interaction of electrostatic fields and gas flowing fields, after the high-temperature sintering process, the pearl-chain structure of particles forms ceramic fibers or the beam of ceramic fibers so as to get three-dimensional reticular porous ceramic; the method has the beneficial effect that by adopting the method for controlling the aggregation of particles, the particles can be concentrated in the form of a pearl chain, and the method hasimportant application in producing fine fibers.
Description
Technical field
The present invention relates to material science, relate in particular to a kind of method of controlling minuteness particle accumulation shape.
Background technology
Generally speaking, fine powder aggregation of particles form is uncertain, and some present the cluster shape, and some present the shape of chain.In current liquid (being made up of nonconducting mother liquor and dielectric microparticles), under the effect of electric field, the dielectric particle surface polarization charge occurs and forms electric dipole the unit for uniform suspension that the dielectric particle thermal motion forms outside.Interaction between the electric dipole impels particle to arrange along direction of an electric field, forms the chain-cluster structure, as document " Zhu Keqin, Tao Rongjia, electrorheological fluid and electric rheological effect, Proceedings of Mechanics, the 24th volume, the 2nd phase, 1994 ".This phenomenon can make electrorheological fluid solidify rapidly, and has reversibility, and estimated current becomes liquid commercialization.In gas, solid two-phase dispersion system, fine dielectric particle can form the particle chain aggregate equally under electric field action.That carry out systematic study the earliest is scholars such as G.Zebel, they are that the formation to particle chain is described in the oxide particle process of utilizing electrostatic precipitator collection iron, point out gas, Gu the formation of particle chain comes from the interaction of electric dipole equally in the two-phase system, and the notion that static forms power proposed, as document " G.Zebel; ' ü ber die aggregatbildung zwischen kugelformigen aerosolteilchen mit parallelausgerichteten dipolmomenten; ' Staub; vol.23; 263-268; 1963 " and " R.Flossmann and A.Sch ü tz, ' Untersuchungen zur Entstaubung von braunem konverterrauch nach einemneuartigen elektrostatischen verfahren, ' Staub, vol.23,443-451,1963 ".From the angle that ELECTROSTATIC DUST is collected, what mainly pay close attention to is that can minuteness particle be gathered into oversize particle under electrostatic field, is convenient to collect, and does not pay close attention to the concrete shape of particle agglomeration.But from the Materials science angle, if the aggregation of particles form can artificially be controlled, making particle chain is main accumulation shape, has very important significance for preparation function microfibre and fibrous texture stupalith so.
The Fe that scholars such as G.Kasper utilize flame to produce
2O
3Aerosol particles has carried out experimental study, the particle size range of particle is in tens nanometers, experimental result shows by control combustion gases composition and aerosol particle concentration, the particle chain aggregate can be controlled formation, as document " G.Kasper, S-N Shon and D.T.Shaw; ' controlled formation of chainaggregates from very small metal oxide particles '; Am.Ind.Hyg.Assoc.J (41), 288-296,1980 ".At document " H.Yamamoto and S.Masuda; ' Fabrication of ultrafineceramic filter; ' IEEE Trans.Ind.Appl.; vol.27; pp.307-310; 1991 " and " H.Yamamotoand S.Masuda, ' Electrostatic formation of ceramic membrane, ' Ceram.Trans., vol.31, pp.305-314,1993 " in; H.Yamamoto and S.Masuda have at first carried out utilizing electrostatic force to control the experimental study of the accumulation shape making ceramic porous membrane of minuteness particle, and minuteness particle derives from the Si that chemical Vapor deposition process (CVD, chemical vapordeposition method) generates
3N
4Particle, median size are 70 nanometers.Si
3N
4Particle has formed particle chain and has been deposited on substrate surface under electrostatic field, behind 1200 ℃ of temperature sintering, obtained the porous ceramic film of three-dimensional net structure, and the effective pore radius is in 0.2～1.0um scope.After above-mentioned two scholars, in the document " B.Su and K.L.Choy; ' Electrostaticassisted aerosol-gel deposition of porous silica films; ' J.Mater.Sci.Lett.; vol.18; pp.1705-1707; 1999 ", B.Su and K.L.Choy atomize silica aqueous solution, silica sol granule is by electric charge on the lotus in the atomization process, on the glass baseplate surface, through 500 ℃ of temperature heating, obtained cancellated SiO at last in the effect deposit of electrostatic force again
2Film.But in recent years, above-mentioned scholar belongs to silence to the research that static forms porous ceramic film.
Summary of the invention
The purpose of this invention is to provide a kind of method of controlling minuteness particle accumulation shape, this method can be controlled the arrangement mode of particle, and particle is assembled with the pearl chain form, aspect the preparation microfibre important application is being arranged.
Minuteness particle, particularly micron order or submicron particles, it is agglomerating very easily to bond in air, and its basic reason is three kinds of significant feature power between particle: Van der Waals force (Intermolecular Forces), electrostatic force and liquid bridge formation power.Van der Waals force is interacted by a plurality of molecular associations and produces between particle, and its EFFECTIVE RANGE reaches 50nm; Electrostatic force is to be produced by the Coulomb interactions of the charged electric charge naturally of particle, chargedly naturally mainly comprises frictional electrification, contact is charged and ultra-gamma ray shine; When the relative humidity of air surpassed 65%, water vapour began aggegation between particle surface and particle, formed the liquid bridge between particle and had strengthened cohesive force greatly.Method of the present invention is at first fully disperseed fine powder, forms gas, solid two-phase dispersed system, and utilizing electrostatic force and gas flow control minuteness particle afterwards is main accumulation shape with particle chain.
The technical solution adopted for the present invention to solve the technical problems is: a kind of method of controlling minuteness particle accumulation shape, the device of its use comprises for the powder tube, is made of porous sieve plate 1, powder 2, venting hole 3, pressurized air 4, air chamber 5 and powder output tube 6; For the powder rifle, constitute by powder, nitrogen 7, pressure-regulating valve door 8 and nozzle 9 from powder output tube 6; The powder neutralizer is made of ac high voltage source 10 and double-layer stainless steel screen cloth electrode 11; Collect mouth 16 by powder inlet 12, high voltage electrode 13, base material 14, ground-electrode 15 and remaining powder and constitute the sediment chamber.Pressurized air 4 from air compressor flows powder 2 by porous sieve plate 1 in air chamber 5, be boiling state; Powder 2 is placed on the porous sieve plate 1 in the air chamber 5 in advance, exsiccant pressurized air 4 makes 2 one-tenth flow states of powder by porous sieve plate 1, be suspended in powder particle in the gas phase and will be full of the remaining space of air chamber, the top cover of air chamber 5 is provided with venting hole 3, to reduce the pressure in the air chamber; The fine powder particle that is suspended in the gas phase is transported to for the powder rifle by a powder output tube 6; The powder that is transported to for the powder rifle mixes with nitrogen 7, and nitrogen gas pressure can be regulated by pressure-regulating valve door 8; With the mixed powder of nitrogen,, enter into the powder neutralizer through nozzle 9 ejections; The powder neutralizer is to produce negative ions by apply ac high voltage 10 at two stainless steel mesh electrodes 11, if swiftly flowing powder particle surface has unnecessary electric charge, by neutralizer the time, will be neutralized, eliminate the electrostatic force between the powder particle; Powder after the above device of process fully disperses finally enters into the sediment chamber, swiftly flowing powder at first underspeeds through flaring powder inlet 12, be reduced to 0.2～0.8m/s, between high voltage electrode 13 and ground-electrode 15, apply the high tension electrostatic field then, when this electric field of mobile powder particle process, effect deposit at electrostatic force arrives base material 14 surfaces, forms pearl chain aggregate; Do not have sedimentary powder particle to collect mouth 16 and collect, utilize once more by powder.
Three kinds of significant feature power between particle are promptly eliminated in the abundant dispersion of powder among the present invention; Van der Waals force (Intermolecular Forces), electrostatic force and liquid bridge formation power solve in the following manner: the powder thorough drying is eliminated liquid bridge formation power; Utilize high velocity air to make the inwall bump of powder and air chamber wall and confession powder rifle, eliminate interparticle molecular force; Swiftly flowing powder particle is eliminated the unnecessary electric charge of particle surface through neutralizer by the negative ions that neutralizer produces.The abundant dispersion of so-called powder is meant the agglomerating particles of eliminating fine powder, only can observe single particle.
Employed fine powder among the present invention is meant fine powder material dielectricity or electroconductibility, and its median size is less than 5 μ m; The fine powder particle is followed velocity of flow that carrier gas (nitrogen) enters the sediment chamber in 0.2～0.8m/s scope, and the concentration range of minuteness particle in carrier gas is 50～100mg/cm
3
The electric field that is used to control particle accumulation shape among the present invention must be an electrostatic field, the electric field that does not promptly have free charge to exist, the field strength range 1～4kV/cm of electrostatic field.
((under the acting in conjunction of velocity of flow 0.2～0.8m/s), the viewed particle accumulation pattern of the substrate surface of placing in the sediment chamber is flocculent structure that is made of the particle pearl chain or the boundling shape structure that is made of the particle pearl chain for field strength range 1～4kV/cm) and gas flow field at electrostatic field.
The invention has the beneficial effects as follows: the flocculent structure that the particle pearl chain constitutes or strengthen its physical strength by additive method by the boundling shape structure that the particle pearl chain constitutes, agglomerating method for example, can make the particle pearl chain change ceramic fiber into, and then can obtain the functionality ceramic material of tridimensional network, aspect the preparation fibrous type stupalith important application is being arranged.
Description of drawings
Fig. 1 is used in the present invention for powder barrel structure synoptic diagram.
Fig. 2 is used in the present invention for powder rifle structural representation.
Fig. 3 is a powder neutralizer structural representation used in the present invention.
Fig. 4 is a sediment chamber used in the present invention structural representation.
Fig. 5 is the design sketch after the fine magnesium oxide powder of one embodiment of the invention disperses.
The microscopic appearance figure of Fig. 6 magnesia particle pearl chain aggregate that to be one embodiment of the invention obtain at substrate surface.
Among the figure: 1, porous sieve plate, 2, powder, 3, venting hole, 4, pressurized air, 5, air chamber, 6, the powder output tube, 7, nitrogen, 8, the pressure-regulating valve door, 9, nozzle, 10, ac high voltage source, 11, double-layer stainless steel screen cloth electrode, 12, powder inlet, 13, high voltage electrode, 14, base material, 15, ground-electrode, 16, remaining powder collects mouthful.
Embodiment
Below in conjunction with accompanying drawing the present invention is done description in further detail:
As shown in Figures 1 to 4, serve as the concrete material of implementing with magnesium oxide (molecular formula MgO), the median size of magnesium oxide fine powder material is 5 μ m.
Pressurized air 4 (pressure is 0.5Mpa) from air compressor flows powder 2 by porous sieve plate 1 in air chamber, be boiling state; 100g magnesium oxide powder 2 is placed on the porous sieve plate 1 (aperture 400 orders) in the air chamber 5 in advance, exsiccant pressurized air 4 makes 2 one-tenth flow states of powder by porous sieve plate 1, be suspended in powder particle in the gas phase and will be full of the remaining space of air chamber, the top cover of air chamber 5 is provided with venting hole 3, to reduce the pressure in the air chamber; The fine powder particle that is suspended in the gas phase is transported to for the powder rifle by a powder output tube 6, and the powder that is transported to for the powder rifle mixes with nitrogen 7 (pressure 0.5Mpa), and nitrogen gas pressure can be regulated by pressure-regulating valve door 8; With the mixed powder of nitrogen,, enter into the powder neutralizer through nozzle 9 ejections; The powder neutralizer is to produce negative ions by apply ac high voltage 10 at two stainless steel mesh electrodes 11, if swiftly flowing powder particle surface has unnecessary electric charge, by neutralizer the time, will be neutralized, eliminate the electrostatic force between the powder particle, two stainless steel mesh distance between electrodes are 5mm, the ac high voltage peak value that applies is 10kV, and the magnesium oxide powder design sketch after the dispersion as shown in Figure 5.
Powder after the process said apparatus fully disperses finally enters into the sediment chamber, swiftly flowing powder at first reduces velocity of flow through flaring powder inlet 12, be reduced to 0.2～0.8m/s, between high voltage electrode 13 and ground-electrode 15, apply the high tension electrostatic field then, the dc high voltage that applies on the high voltage electrode is 3kV, and field intensity is 4kV/cm.When the mobile powder particle when this electric field, to base material 14 surfaces, form pearl chain aggregate in the effect deposit of electrostatic force; Do not have sedimentary powder particle to collect mouth 16 and collect, utilize once more by powder.
The microscopic appearance of the magnesia particle pearl chain aggregate that obtains on base material (10 * 10 * 5mm aluminium sesquioxide ceramic block) surface as shown in Figure 6.
Claims (4)
1, a kind of method of controlling minuteness particle accumulation shape, it is characterized in that, this method comprises the steps: that powder (2) is placed on the interior porous sieve plate (1) of air chamber (5) in advance, dried compressed air (4) from air compressor flows powder (2) by porous sieve plate (1) in air chamber (5), be boiling state; The top cover of air chamber (5) is provided with venting hole (3), to reduce the pressure in the air chamber; The fine powder particle that is suspended in the gas phase is transported to for the powder rifle by a powder output tube (6), the powder that is transported to for the powder rifle mixes with nitrogen (7), nitrogen gas pressure is regulated by pressure-regulating valve door (8), with the mixed powder of nitrogen, through nozzle (9) ejection, enter into the powder neutralizer; The powder neutralizer is to produce negative ions by apply ac high voltage (10) at two stainless steel mesh electrodes (11), if swiftly flowing powder particle surface has unnecessary electric charge, by neutralizer the time, will be neutralized, eliminate the electrostatic force between the powder particle; Powder after the process said apparatus fully disperses finally enters into the sediment chamber, swiftly flowing powder (2) at first passes through flaring powder inlet (12) and underspeeds, be reduced to 0.2～0.8m/s, between high voltage electrode (13) and ground-electrode (15), apply the high tension electrostatic field then, when this electric field of mobile powder particle process, effect deposit at electrostatic force arrives base material (14) surface, forms pearl chain aggregate; Do not have sedimentary powder particle to collect mouthful (16) by powder and collect, utilize once more, described powder (2) is the fine powder material of dielectricity or electroconductibility, and its median size is less than 5 μ m.
2, a kind of method of controlling minuteness particle accumulation shape as claimed in claim 1 is characterized in that, the field intensity of electrostatic field is 1～4kV/cm in the described sediment chamber.
3, a kind of method of controlling minuteness particle accumulation shape as claimed in claim 1 or 2 is characterized in that, the inlet of described sediment chamber is a horn shape, and the diameter ratio of entrance and exit is 5: 1.
4, a kind of method of controlling minuteness particle accumulation shape as claimed in claim 1 is characterized in that, described minuteness particle accumulation shape is the flocculent structure of particle pearl chain formation or the boundling shape structure that is made of the particle pearl chain.
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| KR101154164B1 (en) * | 2008-12-08 | 2012-06-14 | 삼성에스디아이 주식회사 | Optical filter and method of manufacturing the same |
| CN108627378A (en) * | 2018-05-14 | 2018-10-09 | 公安部物证鉴定中心 | A kind of method of dispersed individual fiber |
| CN111454743B (en) * | 2020-06-01 | 2022-03-18 | 中国石油化工股份有限公司 | Electrostatic separation device and process for removing solid particles in catalytic cracking slurry oil and slurry oil purification device |
| CN112461884A (en) * | 2020-12-07 | 2021-03-09 | 中国计量大学 | Nano powder dispersing method and device based on ion flow control |
| CN113478809B (en) * | 2021-07-06 | 2023-05-30 | 上海科技大学 | Additive manufacturing method of micro-nano structure |
| CN117655356A (en) * | 2022-08-25 | 2024-03-08 | 上海科技大学 | Be applied to space electric field controlling means of 3D printing |
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