CN105060918A - Alpha crystal form nano alumina porous ceramic with high apparent porosity and preparation method thereof - Google Patents
Alpha crystal form nano alumina porous ceramic with high apparent porosity and preparation method thereof Download PDFInfo
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- CN105060918A CN105060918A CN201510456180.9A CN201510456180A CN105060918A CN 105060918 A CN105060918 A CN 105060918A CN 201510456180 A CN201510456180 A CN 201510456180A CN 105060918 A CN105060918 A CN 105060918A
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Abstract
The invention discloses an alpha crystal form nano alumina porous ceramic with a high apparent porosity and a preparation method thereof, and belongs to the field of nano porous materials. The preparation method comprises the following steps: filling gamma-Al2O3 powder into a graphite mould, placing the mould into a discharging plasma sintering furnace, loading an axial load pressure of 30 to 100 MPa, sintering the powder in vacuum at a temperature of 1100 to 1250 DEG C, maintaining the temperature for 3 to 5 minutes; or placing a gamma-Al2O3 blank in a conventional air furnace, sintering the blank under zero pressure at a temperature of 1350 to 1450 DEG C, and maintaining the temperature for 30 to 120 minutes to obtain the alpha crystal form nano alumina porous ceramic with a high apparent porosity; wherein the average particle size of the porous ceramic is smaller than 160 nm, and the apparent porosity is more than 95%. The provided preparation method has the advantages of low cost and good repeatability. The porous structure is formed without any sintering aid or pore forming agent. The prepared alumina porous ceramic has the advantages of evenly-distributed pores, small pore diameter, high apparent porosity (more than 95%), and excellent mechanical properties.
Description
Technical field
The invention belongs to nano-porous materials field, be specifically related to a kind of high open porosity alpha-crystal form nano aluminium oxide porous ceramics and preparation method thereof.
Background technology
Porous alumina ceramic refers to aluminum oxide to be aggregate, and by forming materials and high-temperature sintering process, inner formation communicates with each other or a class stupalith of closed pore in a large number.Because alumina source is extensive, cheap, therefore porous alumina ceramic is all widely used in various fields such as gas and liquid filtering, purification separation, chemical industry catalytic carrier, biological implantation material, sound absorption damping and sensor materials.
Porous α-Al
2o
3the preparation of pottery mainly comprises shaping, the formation of pore structure and the sintering of base substrate of base substrate.At present about porous α-Al
2o
3the method that pottery mesoporosity structure is formed mainly comprises interpolation pore-forming material hole forming method, partially sinters method, blank forming sintering process etc., and the raw material adopted is α-Al mainly
2o
3powder.These methods have the advantage of self, but also have weak point.As adopted foraminous die plate or adding pore-forming material hole forming method, not only preparation technology is comparatively complicated, and combustiblematerials may leave a large amount of ash contents after combustion; In addition due to the decomposition temperature of most of pore-forming material or temperature of combustion lower, part holes can be subsided in pore-forming material removal process.The method pore texture of partially sintering mainly relies on the sintered neck between feed particles to support, this porous skeleton structure bonding strength in use significantly reduces along with the rising of temperature, the reduction of the mechanical property causing product especially mechanical behavior under high temperature; And preparation process needs finely regulating, too low temperature easily causes subsiding of hole, and too high temperature can make again void content significantly reduce the formation with a large amount of closed pores.
Summary of the invention
The object of the invention is to overcome the deficiencies in the prior art, a kind of high open porosity alpha-crystal form nano aluminium oxide porous ceramics and preparation method thereof is provided.
Object of the present invention is achieved through the following technical solutions:
A preparation method for high open porosity alpha-crystal form nano aluminium oxide porous ceramics, comprises the steps:
By γ-Al
2o
3powder filling, in graphite jig, is placed in discharge plasma sintering stove, under 30 ~ 100MPa thrust load pressure, and 1100 ~ 1250 DEG C of vacuum sinterings, insulation 3-5min; Or by γ-Al
2o
3base substrate pressureless sintering in regular air stove, sintering temperature 1350 ~ 1450 DEG C, insulation 30 ~ 120min.
Described γ-Al
2o
3base substrate obtains preferably by the method comprised the steps: get γ-Al
2o
3powder is dry-pressing formed under 10 ~ 15MPa pressure in steel die, then under 150 ~ 200MPa pressure isostatic cool pressing.
A kind of high open porosity alpha-crystal form nano aluminium oxide porous ceramics, prepared by aforesaid method, its average grain size is less than 160nm, and open porosity is greater than 95%.
Common α-Al
2o
3porous ceramics, pore framework is wherein that the sintered neck utilizing original powder to be formed in sintering process connects.Thisly connect by stochastic particle neck the bonded area that its intensity of pore framework formed depends primarily on sintered neck.In order to improve the bonding strength of pore framework, need to adopt higher temperature or through long-time heat preservation, promote the sintering between particle.But the material that can continue in these processes spreads, and causes the reduction of porosity, the formation of even closed pore.γ-Al
2o
3powder can experience in the process of heating: γ-Al
2o
3→ δ-Al
2o
3→ θ-Al
2o
3→ α-Al
2o
3a series of crystal formation change, and temperature starts to form stable crystal formation α-Al more than 1100 DEG C
2o
3.Phase transition process obtains α-Al
2o
3typical microscopic appearance is by vermiform α-Al
2o
3crystal grain is the porous form of skeleton.α-Al as previously mentioned
2o
3the pore framework formed in powder sintering process is by random α-Al
2o
3the sintered neck that particulate fraction sinters and formed, but the crystalline orientation being through the vermiform crystal grain skeleton both sides particle that phase transformation obtains is consistent, and such skeleton structure significantly can improve the mechanical strength of porous alumina ceramic.The carrying out of simultaneously adjoint phase transition process, the amplification growth of the generation hole that the pore texture of material internal can be spontaneous, auxiliary therefore without the need to any pore-forming material, pore-forming templates or sintering aid, keeps high open porosity simultaneously.
In sum, compared with existing porous alumina ceramic material and preparation technology thereof, the present invention has following clear superiority:
(1) γ-Al is adopted
2o
3powder, raw materials cost is cheaper.
(2) material grains size, pore dimension all keeps nanoscale.
(3) without the need to any pore-creating technique, without the need to adding any pore-creating template or pore-forming material, preparation process technique is simpler.
(4) the vermiform crystal grain skeleton utilizing phase transition process to be formed, the strength of materials especially hot strength significantly promotes.
(5) because the spontaneous reaming of phase transition process that is formed as of hole produces, therefore prepared porous alumina ceramic material has the useful performances such as even aperture distribution, aperture dimensions is little, open porosity is high.
(6) temperature window prepared of material is wide in range, and technology controlling and process is simple, favorable repeatability.
(7) enough the porosity of material and the adjustment of mechanical strength is taken into account by the technical arrangement plan such as aux. pressure, soaking time.
Accompanying drawing explanation
Fig. 1 is the X-ray diffraction result figure of embodiment 1 product.
Fig. 2 is the void distribution result figure of embodiment 1 product.
Fig. 3 is the scanning electron microscope (SEM) photograph of embodiment 1 product microtexture.
Fig. 4 is that the scanning electron microscope of embodiment 2 product microtexture is according to figure.
Fig. 5 is that the scanning electron microscope of embodiment 4 product microtexture is according to figure.
Fig. 6 is that the scanning electron microscope of comparative example 1 product microtexture is according to figure.
Embodiment
Below in conjunction with embodiment and accompanying drawing, further detailed description is done to the present invention, but embodiments of the present invention are not limited thereto.
Embodiment 1
(1) γ-Al is taken
2o
3powder filling, without any further process, is in the graphite jig of 12mm to internal diameter by powder 1.5g.
(2) graphite jig of filling is placed in discharge plasma sintering stove, under 100MPa thrust load pressure, 1100 DEG C of vacuum sinterings, insulation 3min, obtains alumina porous ceramic.
Carry out X-ray diffraction analysis test to gained sintered product to show (Fig. 1), γ-Al
2o
3powder is all transformed into α-Al at 1100 DEG C
2o
3.Adopt mercury penetration method to characterize the sintered compact hole that above-mentioned 1100 DEG C of sintering and the lower 700 DEG C of sintering of the same terms obtain, result shows: γ-Al
2o
3the aperture that powder is piled up there occurs amplification after phase transformation completes, and 1100 DEG C sinter the alumina porous ceramic aperture obtained is 40 ~ 130nm(Fig. 2), and open porosity is 98.5%.To sintered product by scanning electron microscopic observation, result shows (Fig. 3): define vermiform α-Al in sintered compact
2o
3pore framework, α-Al
2o
3average grain size be 60 ~ 120nm.The void content of the alumina porous ceramic prepared by drainage measurement is 42%.Strength test shows, prepared alumina porous ceramic bending strength reaches 170MPa.
Embodiment 2
(1) γ-Al is taken
2o
3powder filling, without any further process, is in the graphite jig of 12mm to internal diameter by powder 1.5g.
(2) graphite jig of filling is placed in discharge plasma sintering stove, under 100MPa thrust load pressure, 1250 DEG C of vacuum sinterings, insulation 3min, obtains alumina porous ceramic.
Adopt mercury penetration method to characterize sintered compact hole, result shows that prepared alumina porous ceramic aperture openings void content is 96.8%, and porous ceramics aperture is 50 ~ 120nm.The void content of the alumina porous ceramic prepared by drainage measurement is 38%.Strength test shows, prepared alumina porous ceramic bending strength reaches 185MPa.Sintered product is shown (Fig. 4) by scanning electron microscopic observation result: α-Al
2o
3average grain size be 80 ~ 150nm, even if 1250 DEG C, under 100MPa pressure, the pore texture in prepared alumina porous ceramic does not also cave in, and shows that material has excellent mechanical behavior under high temperature.
Embodiment 3
(1) γ-Al is taken
2o
3powder filling, without any further process, is in the graphite jig of 12mm to internal diameter by powder 1.5g.
(2) graphite jig of filling is placed in discharge plasma sintering stove, under 30MPa thrust load pressure, 1100 DEG C of vacuum sinterings, insulation 3min, obtains alumina porous ceramic.
Adopt mercury penetration method to characterize sintered compact hole, result shows that prepared alumina porous ceramic aperture openings void content is 98.7%, and porous ceramics aperture is 20 ~ 140nm.To sintered product by scanning electron microscopic observation, result shows: define vermiform α-Al in sintered compact
2o
3pore framework, α-Al
2o
3average grain size be 30 ~ 120nm.The void content of the alumina porous ceramic prepared by drainage measurement is 62%.Strength test shows, prepared alumina porous ceramic bending strength reaches 125MPa.
Embodiment 4
(1) γ-Al is taken
2o
3powder 1.5g, without any further process, dry-pressing formed under 15MPa pressure in steel die.
(2) by shaping γ-Al
2o
3base substrate is isostatic cool pressing under 200MPa pressure.
(3) by the pressureless sintering in regular air stove of isostatic cool pressing gained base substrate, sintering temperature 1350 DEG C, insulation 60min, obtains alumina porous ceramic.
Adopt mercury penetration method to characterize sintered compact hole, result shows that prepared alumina porous ceramic aperture openings void content is 95.7%, and porous ceramics aperture is 50 ~ 140nm.To sintered product by scanning electron microscopic observation, result shows (Fig. 5): α-Al
2o
3average grain size be 80 ~ 160nm, do not caving at 1350 DEG C without pore texture under pressure condition.The void content of the alumina porous ceramic prepared by drainage measurement is 58%.Strength test shows, prepared alumina porous ceramic bending strength reaches 125MPa.
Embodiment 1 ~ 4 shows, by the selection of temperature and pressure parameter, can realize void content and the intensity of flexible modulation alumina porous ceramic.
Comparative example 1
(1) γ-Al is taken
2o
3powder filling, without any further process, is in the graphite jig of 12mm to internal diameter by powder 1.5g.
(2) graphite jig of filling is placed in discharge plasma sintering stove, under 100MPa thrust load pressure, 1300 DEG C of vacuum sinterings, insulation 3min, obtains alumina porous ceramic.
To sintered product by scanning electron microscopic observation, result shows (Fig. 6): under 100MPa thrust load pressure, and pore texture starts to cave at 1300 DEG C and above temperature, and forming section closes pore, and porous ceramics hole rate reduces.
Embodiment above describes ultimate principle of the present invention, principal character and advantage of the present invention.The technician of relevant industries should understand, and the present invention is not restricted to the described embodiments.What cited embodiment and specification sheets described just illustrates ultimate principle of the present invention, and under the condition not departing from spirit and scope of the invention, the present invention has multiple changes and improvements, and these changes and improvements all fall within the scope of protection of the present invention.
Claims (5)
1. a preparation method for high open porosity alpha-crystal form nano aluminium oxide porous ceramics, is characterized in that comprising the steps:
By γ-Al
2o
3powder filling, in graphite jig, is placed in discharge plasma sintering stove, under 30 ~ 100MPa thrust load pressure, and 1100 ~ 1250 DEG C of vacuum sinterings, insulation 3-5min;
Or by γ-Al
2o
3base substrate pressureless sintering in regular air stove, sintering temperature 1350 ~ 1450 DEG C, insulation 30 ~ 120min.
2. the preparation method of high open porosity alpha-crystal form nano aluminium oxide porous ceramics according to claim 1, is characterized in that: described γ-Al
2o
3base substrate is obtained by the method comprised the steps: get γ-Al
2o
3powder is dry-pressing formed under 10 ~ 15MPa pressure in steel die, then under 150 ~ 200MPa pressure isostatic cool pressing.
3. a high open porosity alpha-crystal form nano aluminium oxide porous ceramics, be is characterized in that: prepared by the method described in claim 1 or 2.
4. high open porosity alpha-crystal form nano aluminium oxide porous ceramics according to claim 3, is characterized in that: its average grain size is less than 160nm.
5. high open porosity alpha-crystal form nano aluminium oxide porous ceramics according to claim 3, is characterized in that: its open porosity is greater than 95%.
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106747563A (en) * | 2016-12-08 | 2017-05-31 | 济南大学 | A kind of method that discharge plasma sintering method prepares porous silicon carbide ceramic |
| CN108977883A (en) * | 2018-09-18 | 2018-12-11 | 武汉理工大学 | A method of porous aluminas monocrystal material is prepared using microwave sintering |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN1856443A (en) * | 2003-04-02 | 2006-11-01 | 圣戈本陶瓷及塑料股份有限公司 | Nanoporous ultrafine alpha-alumina powders and freeze drying process of preparing same |
| CN101558025A (en) * | 2006-12-11 | 2009-10-14 | 康宁股份有限公司 | Alpha-alumina inorganic membrane support and method of making the same |
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2015
- 2015-07-30 CN CN201510456180.9A patent/CN105060918A/en active Pending
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN1856443A (en) * | 2003-04-02 | 2006-11-01 | 圣戈本陶瓷及塑料股份有限公司 | Nanoporous ultrafine alpha-alumina powders and freeze drying process of preparing same |
| CN101558025A (en) * | 2006-12-11 | 2009-10-14 | 康宁股份有限公司 | Alpha-alumina inorganic membrane support and method of making the same |
Non-Patent Citations (1)
| Title |
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| 黎少华等: "薄水铝石粒度对煅烧形成α-Al2O3粉体的影响", 《过程工程学报》 * |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106747563A (en) * | 2016-12-08 | 2017-05-31 | 济南大学 | A kind of method that discharge plasma sintering method prepares porous silicon carbide ceramic |
| CN108977883A (en) * | 2018-09-18 | 2018-12-11 | 武汉理工大学 | A method of porous aluminas monocrystal material is prepared using microwave sintering |
| CN108977883B (en) * | 2018-09-18 | 2020-12-08 | 武汉理工大学 | Method for preparing porous alumina single crystal material by adopting microwave sintering |
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Application publication date: 20151118 |