Gradient ceramic-film tube and preparation method thereof
The present invention relates to porous ceramic articles and preparation method thereof.
Inorganic ceramic membrane has high temperature resistant, acid and alkali-resistance is not corroded by bacterium, the intensity height, and characteristics such as it is easy to regenerate have wide purposes in industries such as water treatment, environmental protection, food, electric power.
Existing ceramic membrane generally is the multilayer dissymmetrical structure, is made of porous carrier, transition zone, control rete.Porous carrier (being called bottom) is the matrix of whole film pipe, and the mechanical strength of film pipe is guaranteed by it; Have on porous carrier that the aperture is very little, the control rete of very thin thickness, centrifugation is mainly reached by it; Between porous carrier and control rete, also include one or more layers intermediate layer, the multilayer dissymmetrical structure of Here it is ceramic membrane.There is following shortcoming in the ceramic membrane of this dissymmetrical structure:
1, each layer of the ceramic membrane of dissymmetrical structure forms through repeatedly moulding and sintering, is easy to generate between each layer and the last layer substrate and peels off and boundary defect, thereby can influence the quality and the performance of ceramic membrane;
2, key-course or transition zone all are on the body attached to preceding one deck macropore to the asymmetric ceramic membrane of multilayer in the preparation, because the powder granule diameter suddenlys change, following one deck powder granule will certainly stop up a part of last layer macropore, like this, will reduce the ability that sees through of ceramic membrane;
3, the ceramic membrane of dissymmetrical structure will be by moulding and sintering process repeatedly, so the preparation cost of ceramic membrane is high more a lot of than organic film, this also is that the restriction ceramic membrane is used, a big factor of development.
The method for preparing at present ceramic membrane mainly is extrusion, dry pressing and slip casting, these methods are very high to the requirement of powder material, has only powder material particle of uniform size, just can prepare the ceramic membrane of even aperture distribution, so just need sieve or the waterpower classification of sedimentation powder material; And must in raw material, add auxiliary agents such as a considerable amount of clays, feldspar, bentonite, these auxiliary agent great majority are inorganic minerals, in the forming and sintering process, can not burn mistake fully, thereby can influence the structure and the pore-size distribution of final ceramic membrane, the ceramic membrane performance is had a negative impact, can't prepare fully by the base-material powder form high-pure ceramic membranous.
The disclosed gradient creamics with ceramic membrane fenestrata of Chinese patent CN1081394, be to be major ingredient by aluminium oxide or silica or titanium dioxide, add clay and feldspar is formulated, through slip casting, heat perfusion, the forming method moulding of extruding, pile up the mode loading of kiln of crouch dress and lifting then through wet type drying, precision, under 1100~1550 ℃ of high temperature, fire and form, the ceramic membrane aperture is 0.1~15 μ m, the porosity 30~50%, thickness are 1~200 μ m, have 2~10 layers.The preparation method complex process of this ceramic membrane though its name is called graded ceramics, in fact belongs to asymmetric ceramic membrane, is not real aperture continually varying gradient ceramic-film.
The production method and the device thereof of Chinese patent ZL95102519.8 high-pure ceramic membranous canal, employing be double-deck pipe die, skin is a rigidity, internal layer is a meltability.Slurry is added in the double-deck pipe die, start centrifugal device, improve rotating speed gradually, make the descending inner wall forming that is attached to pipe die of alumina particle in the slurry.Aluminium oxide green tube after the shaping is at room temperature dry, removes internal layer meltability mould, takes out the aluminium oxide green tube.With the high purity aluminium oxide green tube of taking out sintering at high temperature, obtain required asymmetric high purity aluminium oxide stay pipe.This method need remove internal layer meltability mould, complex process at 50~100 ℃.In addition, the fusion mould may the polluted membrane pipe in knockout course, causes the film defective tube.
The disclosed Functional Graded Ceramics film of world patent WO9821164.This invention is to use polydisperse slurry methods, obtains the functionally gradient tissue by colloid unstability technology.Its crucial part is to prepare controlled and unsettled or metastable colloid shape suspension that have wide particle diameter to distribute.Like this, when sedimentation, particle will take place poly-partially according to particle size, thereby forms porous Functional Graded Ceramics material.This porous Functional Graded Ceramics material can only be made the ceramic membrane of sheet owing to obtain by the sedimentation of particle self gravitation, can't make tubulose.And in industry, tubular film is because its area is big, and floor space is little, can realize cross-flow filtration again, thereby tubular film is the first-selection of industrial film.
The object of the present invention is to provide a kind of gradient ceramic-film tube, adopt socket shape structure, the fenestra aperture of film pipe increases by outwards being continuous gradient in the pipe, makes this gradient ceramic-film that the very high ability that sees through be arranged.
The present invention also aims to provide a kind of preparation method of gradient ceramic-film tube, adopt the centrifugal casting one-step moulding method to prepare gradient ceramic-film tube, under action of centrifugal force, the film pipe micro-pore diameter that powder material forms is complete gradient and distributes, reach key-course at the film pipe internal surface, the effect that film pipe micro-pore diameter increases from inside to outside gradually.
Gradient ceramic-film tube fenestra of the present invention aperture is to distribute inner surface aperture minimum, outer surface aperture maximum by outwards being continuous gradient in the pipe, the fenestra aperture is 0.05~20 μ m, and film pipe porosity is 30-80%, diameter 5~300mm, length 10~2000mm, wall thickness are 2~15mm.
The preparation method of gradient ceramic-film tube of the present invention comprises:
---the process mechanical agitation in carrier with base-material and the agent of aqueous fusion cohesive, make uniform slurry;
---start centrifugal casting ceramic-film tube machine, slurry is injected in the rigidity pipe die, by making the gradient ceramic-film tube green compact after centrifugal forming, the dehydration, the gravity coefficient is controlled between the 20-500 during centrifugal casting, and the time of centrifugal casting is between the 1-50 branch is planted.
---green compact 60~120 ℃ of oven dry after the demoulding, sintering, cooling promptly obtain gradient ceramic-film tube.
The weight proportion of above-mentioned slurry is as follows:
Base-material 100
Carrier 80~120
Aqueous fusion cohesive agent 0~0.4
Wherein base-material is diatomite, zirconia, aluminium oxide, one or more mixtures of silica, carrier is water or ethanol, and the agent of aqueous fusion cohesive is that polyvinyl alcohol, the poly-rare acid amides of methyl-prop, polyacrylamide, sodium carboxymethylcellulose, gum arabic are wherein a kind of.Base-material adopts calculated weight (W (meter) expression), and carrier adopts actual weight (W (reality) expression), and the calculated weight of base-material and the pass between the actual weight are:
W (meter)
Diatomite=3W (reality)
Diatomite
W (meter)
Zirconia=0.9W (reality)
Zirconia
W (meter)
Aluminium oxide=W (reality)
Aluminium oxide
W (meter)
Silica=W (reality)
Silica
The centrifugal casting ceramic-film tube machine that the present invention uses is directly driven pipe die or is driven the pipe die rotation by transmission mechanism such as belt by buncher and constitutes.What mould was used is the rigidity pipe die, and its material can be metal materials such as stainless steel, copper alloy, aluminium alloy, also can be nonmetallic materials such as duroplasts, lucite and glass.Pipe die can be the integral cannula formula, also can be the two halves formula split the folding mould.
The buncher of centrifugal casting ceramic-film tube machine directly drives pipe die or when driving pipe die and do to rotate at a high speed by transmission mechanism such as belt; under action of centrifugal force; ceramic powder particle in the composite mortar is made travel motion; bulky grain is poly-partially to the pipe die inner surface; in ceramic-film tube outer surface ceramic particle maximum; minimum particle concentrates on the endosexine of ceramic-film tube; the ceramic-film tube green compact of the complete distribution gradient of ceramic powder particle have been formed; after at high temperature partially sintering, formed the aperture and be the ceramic-film tube that complete gradient distributes.
The present invention need not powder material is carried out classification; because powder granule is different with the density of carrier water; under action of centrifugal force; powder granule can be made travel motion in the slurry of water base or alcohol radical; bulky grain in the powder is because weight is bigger; will be poly-partially to the pipe die inner surface, promptly the closer to the ceramic-film tube outer surface, particle is big more.Minimum particle then concentrates on the endosexine of ceramic-film tube.Because particle gets rid of up one by one during moulding, the film pipe of making like this is very fine and close.Be exactly in layer after the moulding, as the annual ring of big tree, being completely, gradient distributes.Its inside of film pipe of making under action of centrifugal force like this is not have pore or other defective.Even the appearance of last layer big slightly hole, the little ceramic particle of following one deck will be blocked it at once, so its aperture of gradient ceramic-film tube of adopting the present invention to make is very even.As long as the particle in the raw material has the fine powder of some, just can obtain the enough little ceramic-film tube in key-course aperture.And made ceramic-film tube distribution gradient.The film pipe internal surface is owing to its powder granule minimum, and the fenestra aperture of formation is also minimum, is key-course.
The inventor finds through investigative test, preparing the gradient ceramic-film tube best results under the following condition: the long-time mechanical agitation of process in carrier water with diatomite base-material and the agent of aqueous fusion cohesive, after making uniform slurry, start centrifugal casting ceramic-film tube machine, composite mortar is injected in the stainless steel pipe die of rotation at a high speed, pass through centrifugal forming, dehydration, rotate and make diatomite gradient ceramic-film tube green compact after 20 minutes, green compact are after oven dry under 80~120 ℃, through the demoulding, lifting, sintering, film pipe sintering temperature is 1150 ℃, is incubated 3 hours, promptly obtains the diatomite gradient ceramic-film tube after the cooling.
According to the film pipe diameter difference of manufacturing, centrifugal casting ceramic-film tube machine rotating speed is also different, and film pipe diameter is big more, require rotating speed low more, the rotating speed of centrifugal casting ceramic-film tube machine when the gravity coefficient is controlled between the 20-500, can obtain gradient ceramic-film tube of the present invention by its gravity coefficient control.
Gradient ceramic-film tube of the present invention and preparation method thereof compared with prior art has following advantage:
(1) gradient ceramic-film tube provided by the invention, film pore footpath distribution gradient can prevent effectively that in use the deep layer of fenestra from polluting, stop up, and the reduction that slows down filtration flux makes to clean to be easy to carry out.
(2) the gradient ceramic-film tube reproducibility is good, and flux all can return to initial flux after machinery was cleaned with water, recoiled;
(3) gradient ceramic-film tube provided by the invention, flux is big, porosity is high, the aperture is even, the clarification performance is good;
(4) gradient ceramic-film tube provided by the invention, the degerming performance is good, and the bacterium rejection rate is up to 99.999%;
(5) gradient ceramic-film tube of the present invention except that itself can also can be used as film support directly as the filter element, is modified thereon, prepares nano level ceramic-film tube;
(6) the inventive method can be prepared the ceramic-film tube that complete gradient distributes, and preparation and sintering all be once to finish, and need not powder material is sieved.And preparation, sintering all are once to finish;
(7) densification of film pipe, inner pore-free or other defective made of the inventive method.As long as the particle in the raw material has the fine powder of some, just can obtain the enough little ceramic-film tube in key-course aperture;
(8) the film pipe porosity height made of the inventive method, aperture are evenly and can regulate its size by preparation technology;
(9) the inventive method can be prepared high-pure ceramic membranous canal that be made up of matrix powder, that do not add any auxiliary agent fully;
(10) gradient ceramic-film tube of the inventive method preparation, drinking water in can be used for following embodiment, beer, mature vinegar and the air cleaning, in food industry, use gradient ceramic-film tube can substitute used filtration means at present, wide application prospect is arranged in industries such as liquor, grape wine, yellow rice wine, fruit wine, fruit juice, beverages.In addition, gradient ceramic-film tube can also be handled dust and smoke pollution and sewage disposals such as electric power, oil, chemical industry by high efficiency, low cost, in the environmental protection field broad prospect of application is arranged.In addition, the graded ceramics membrane technology also can be used for sewage disposal.On chemical industry, can be used as the membrane material of catalyst carrier and membrane reactor in addition.
Fig. 1 is the cross section structure schematic diagram of gradient ceramic-film tube of the present invention.
Be described in further detail the present invention below by embodiment and accompanying drawing.
Embodiment 1
As shown in Figure 1, gradient ceramic-film tube is rounded, the ceramic particle distribution gradient, by increasing gradually to the pipe outside in the pipe, granule 1 is inboard near pipe, bulky grain 2 is near the pipe outside, and the hole between the particle also increases to the pipe outside gradually by pipe is interior, thereby forms the gradient ceramic-film tube of aperture distribution gradient.
Embodiment 2
The ceramic-film tube formula of size is:
Diatomite 100kg
Water 250kg
Polyacrylamide 0.3kg
According to above-mentioned prescription, be mixed with composite mortar, through 12 hours mechanical agitation, make uniform slurry.Start centrifugal casting ceramic-film tube machine, composite mortar is injected in the stainless steel pipe die of rotation at a high speed, the pipe die rotating speed is 12000rpm, by centrifugal forming, dehydration, rotate and make diatomite gradient ceramic-film tube green compact after 20 minutes, green compact are through demoulding after drying, lifting back sintering, and film pipe sintering temperature is 1150 ℃, temperature retention time 3 hours promptly obtains gradient ceramic-film tube after the cooling.Key-course fenestra aperture is 0.2 μ m, film pipe porosity 80%, and diameter 25mm, length 500mm, the film tube thickness is 3mm.
Diatomite is a kind of biogenic silicastone, mainly by ancient times diatom and other microorganism siliceous remains form, main component is opal and mutation thereof, diatom in the diatomite has many difformities, as discoid, needle-like, tubular, pinniform etc., the high 80-90% of reaching of aperture, porosity that countless gaps are arranged on the silicon shell, diatomaceous operational characteristic is characteristics such as fine and smooth, loose, light weight, porous, suction and permeability be strong.In the present embodiment by inner surface to the film tube section of outer surface, diatomaceous particle increases gradually, at this moment filtration channel is not only the duct that forms between the diatomite particle, and the micropore of diatomite particle inside also can and diatomite particle between the duct converge, form huge pore network.Therefore, the diatomite gradient ceramic-film tube of being made by present embodiment has very high porosity and has the super large flux.Be used for city tap-water and filter, initial flux can reach 8.5m
3/ m
2H, stabilized flux also can reach 1.5m
3/ m
2More than the h.Filter the germ performance and can reach below the 0.2 μ m, can the pathogenic germs such as Escherichia coli, cholera bacteria, sand door Salmonella, shigella dysenteriae, Klebsiella pneumoniae and mould of filtering 99.999% or more, capable of direct drinking through the running water of this film pipe filtration.The present invention for various natural calamities after the control of epidemic situation effective instrument is provided.Drinking water is one of main path of propagating of epidemic situation because carry disease germs, and this film pipe then can filtering be drunk the various germs of water transmission eqpidemic disease, makes cheap water purifier and can provide aseptic drinkable water for the disease-resistant disaster relief, avoids the propagation of epidemic situation.In addition, this film pipe can also be made the infiltration cylinder, need not hydraulic pressure promptly can the aseptic drinkable water of output, and can use repeatedly after cleaning with water, do not have the running water area for the vast rural area of China, be a good drinking water treatment device.
Industries such as beer, grape wine, beverage, fruit juice, medicine generally all are to adopt diatomite filtration at present, replace original diatomite filtration generally can the quality of filtrate not to be exerted an influence with the diatomite gradient ceramic-film tube.But also can significantly reduce its technical process, a step produces sterile product.
Embodiment 3
The ceramic-film tube formula of size is:
Zirconia 100kg
Water 90kg
Poly-methyl butene acid amides 0.3kg
According to above-mentioned prescription, be mixed with composite mortar, through 12 hours mechanical agitation, make uniform slurry.Start centrifugal casting ceramic-film tube machine, composite mortar is injected in the high speed rotation brass pipe die of splitting after the merging of two halves formula is fixed, the pipe die rotating speed is 8000rpm, by centrifugal forming, dehydration, rotate and make zirconium oxide gradient ceramic-film tube green compact after 20 minutes, sintering behind green compact process demoulding after drying, the landfill, film pipe sintering temperature is 1650 ℃, temperature retention time 6 hours promptly obtains the zirconium oxide gradient ceramic-film tube after the cooling.Key-course fenestra aperture is 0.1 μ m, film pipe porosity 45%, and diameter 45mm, length 1000mm, the film tube thickness is 5mm.
The gradient ceramic-film tube of making is used for air cleaning, the air integral asepsis after the filter, and stabilized flux can reach 150m
3/ m
2More than the h.
Embodiment 4
The ceramic-film tube formula of size is
Aluminium oxide 100kg
Water 100kg
Polyvinyl alcohol 0.3kg
According to above-mentioned prescription, be mixed with composite mortar, through 12 hours mechanical agitation, make uniform slurry.Start centrifugal casting ceramic-film tube machine, composite mortar is injected in the aluminium alloy pipe die of rotation at a high speed, the pipe die rotating speed is 5000rpm, by centrifugal forming, dehydration, rotate and make aluminium oxide gradient ceramic-film tube green compact after 20 minutes, green compact are through demoulding after drying, lifting back sintering, and film pipe sintering temperature is 1600 ℃, temperature retention time 3 hours promptly obtains the aluminium oxide gradient ceramic-film tube after the cooling.Key-course fenestra aperture is 0.5 μ m, film pipe porosity 48%, and diameter 100mm, length 1500mm, the film tube thickness is 10mm.
The gradient ceramic-film tube of making is used to filter draft beer, can remove the small materials such as yeast, protein and polyphenol complex in the beer, improves the biology and the abiotic stability of beer.Beer behind cottonseed cake filtration or diatomite filtration is called draft beer or draft beer, stores to surpass a week biological haze to take place.The daily bottled beer of drinking of people is generally bottled beer, promptly must make residual yeast and other assorted bacterium stop breeding through pasteurization after bottling, generally can keep 60-90 days or longer.Though the taste of draft beer is better than bottled beer, can not long preservation, bring certain difficulty for transportation and sale etc.Sterilize and the energy long preservation without low-temperature heat in order to make draft beer, promptly diatomite filtration, plate-frame filtering, dead-end filtration and the sterilising filtration by the past is reduced to oxidation step aluminium gradient ceramic-film tube cross-flow microfiltration, so not only simplified process for beer production, can make aseptic draft beer once going on foot, improve the quality of beer.And can reduce the beer loss, and reduce environmental pollution, can promote the Beer Brewage serialization.And will reduce the manufacturing cost of beer greatly, have huge commercial value and vast market prospect.
Embodiment 5
The ceramic-film tube formula of size is
Silica 1 00kg
Ethanol 100kg
According to above-mentioned prescription, be mixed with composite mortar, through 12 hours mechanical agitation, make uniform slurry.Start centrifugal casting ceramic-film tube machine, composite mortar is injected in the lucite pipe die of rotation at a high speed, the pipe die rotating speed is 12000rpm, by centrifugal forming, dehydration, rotate and make silica gradient ceramic-film tube green compact after 20 minutes, green compact are through demoulding after drying, landfill, sintering, and film pipe sintering temperature is 950 ℃, temperature retention time 3 hours promptly obtains gradient ceramic-film tube after the cooling.Key-course fenestra aperture is 0.2 μ m, film pipe porosity 40%, and diameter 25mm, length 500mm, the film tube thickness is 3mm.
The silica gradient ceramic-film tube of making is used to filter mature vinegar, can remove the suspensions such as yeast, bacterium and vinegar mud in the mature vinegar, and the mature vinegar color and luster after the filter is old black, aseptic, has improved the biology and the abiotic stability of mature vinegar.Thoroughly solved mature vinegar and placed the problem that precipitation appears in the back, so not only simplified the mature vinegar production technology, can make aseptic mature vinegar, improved the quality of mature vinegar, solved mature vinegar can't enter the international market because of sedimentation problem a difficult problem once going on foot.