CN102746022B - Preparation method for Al2O3 ceramic material having controllable bimodal porous structure - Google Patents

Abstract

The invention relates to a preparation method for an Al2O3 ceramic material having a controllable bimodal porous structure. According to the preparation method, a mass ratio of one pore forming agent to the other pore forming agent to alumina powder in original mixing powder is calculated according to designed volumes of the pore forming agents, and the materials are weighed, wherein the two pore forming agents have different shapes and different materials; the original mixing powder is subjected to ball mill by using a medium ethanol; and steps of drying, screening, molding and sintering are performed to obtain a porous alumina ceramic material. According to the present invention, the pore forming agents with different contents and different shapes are adopted to design and regulate so as to prepare the bimodal porous alumina ceramic material with different porosities and different pore structures, wherein the pore size of large pores can be controlled to a nano-micron scale, the pore size of small pores can be controlled to a nano-scale, the pore structure of the large pores is fibrous, and the pore structure of the small pores is spherical or flat; in addition, the raw material cost is low, the preparation process is simple, and the prepared product can provide a series of materials meeting different requirements for applications in fields of electrodes, artificial bones, catalysts, bioreactors, adsorbents, and the like.

Description

Controlled bimodal vesicular structure Al 2O 3The preparation method of stupalith

Technical field

The present invention relates to a kind of preparation method of porous structure ceramic material, particularly relate to a kind of controlled bimodal vesicular structure Al ₂O ₃The preparation method of stupalith.

Background technology

Porous ceramics has excellent filtration, adsorption and desorption performance, high temperature resistant, anti-oxidant, anti-thermal shock and resistance to chemical corrosion becomes one of focus of current porous material research.The characteristics such as its high-specific surface area, low density, fluid permeability, high specific strength, low-k and highly heatproof and shockproof provide valuable reference for many scientific research personnel.In the last few years, porous ceramic film material had been widely used in ion and heat exchanger, catalysis, sensor, bio-molecular separation and purification and refractory liner, strainer molten metal and biomedical material.Be mainly used in heat insulating for the porous material of remaining silent, for opening and porous material that internal porosity is connected, be used in strainer and catalyzer etc.It has also contained the problem of the important application of current " heat " and ecological and sustainable energy.The size of hole, shape and to distribute be design of material and synthetic key character.

Usually gac and zeolite have higher absorption property and catalytic performance, now have been widely used as sorbent material, reodorant, SYNTHETIC OPTICAL WHITNER and in various chemistry and foodstuffs industry support of the catalyst etc.The material of its huge surface-area that these characteristics cause mainly due to micropore.This porous material also contains a considerable amount of macropores, and macrovoid is not have effectively to above-mentioned characteristic, but is conducive to the diffusion of micropore fluid.On the other hand, the porous material application in a lot of fields with surface-area of less constantly increases, as food, and fermentation industry, Industrial Wastewater Treatment and medical treatment.In these materials, it it would be desirable to have wide-aperture hole, such as gac and zeolite, with the situation of guaranteeing to permeate better or better contacting between fluid and porous material.Therefore, it is highly important that for the porous material that special purpose is arranged and will possess bimodal vesicular structure is arranged.

Bimodal porous material refers in porous material the pore distribution with a kind of two kinds of different sizes (generally being divided into micropore and grand hole) continuously.The performance of bimodal porous material depends mainly on the micropore with huge surface area, and has the grand hole that includes considerable quantity in porous material, and its function is to improve the diffuse fluid speed that enters micropore.In other words, the porous material that has two kinds of different pore sizes has following advantage: has improved in work capacity such as sewage disposal, catalyzed reactions (1); (2) can be according to the differing materials function and flexible design; (3) improve the efficiency of equipment.In the last few years, there is the surface-area of less and the porous material of pore distribution that two kinds of different sizes are arranged except the purposes such as lagging material, also more and more extensive in the application such as electrode, artificial skelecton, catalyzer, bio-reactor and sorbent material of fuel cell.The method for preparing at present porous material, such as transfer printing, sacrifice template and direct foam-forming method etc.Wherein sacrifice template and refer to that these pore-forming materials can be synthesis of organic substance by the precursor of complex matrix and pore-forming material mixing, natural organic matter, liquid, salt and metal or pottery etc.Then carry out drying and sintering.Thereby obtain porous material.We can obtain the porous material of void content arrival 90% to use this method.Because of its technique simple, and can be by regulating sintering temperature, soaking time and different size and form pore-forming material conveniently are easy to the porous material of design Different Pore Structures and form, utilize different content and proportioning pore-forming material to realize that porous material has two kinds of different size apertures (particularly containing two kinds, micropore and grand hole).

Aluminum oxide, because of a series of excellent specific properties such as its intensity are high, hardness is large, high temperature resistant, wear-resistant, is widely used in pottery, grinding materials and grinding tool, the industrial raw materials in the fields such as production of refractory materials and new ceramic material.But its ionic linkage causes more by force the low (Al of its particle spread coefficient ³⁺In the time of 1700 ℃, spread coefficient only 10 ^-11Cm ²S ^-1) and sintering temperature higher, for example the sintering temperature of 99 alumina-ceramic can be up to nearly 1800 ℃.By the interpolation of a certain amount of sintering aid, be conducive to reduce the sintering temperature of alumina-ceramic, added sintering aid also can play the effect of pore-forming material simultaneously.By suitable sintering process, can control and obtain needed porous material.Generally, the porous ceramics part can form the densification sintering process.Extra porosity can be by adding pore-forming material degradable realization in heat treatment process.Natural organic, as starch, sugar, timber and fiber etc. is often used as pore-forming material, due to its relatively low cost, and degradable with non-toxicity.Through pore-creating perfect combustion, formed the size distribution of the sintered compact with larger hole.Along with the development of modern science and technology, the Application Areas of bimodal porous alumina is widened rapidly, and market demand is also increasing day by day, and its application prospect is boundless.

Chinese patent 200410071123.0 discloses the preparation method of alumina supporter; Chinese patent 200710173515.1 discloses a kind of preparation method with macroporous aluminium oxide of diplopore distribution; Chinese patent 200910237018.2 discloses a kind of preparation method with aluminum oxide of bimodal pore distribution; And Chinese patent 200910176631.8 discloses macroporous aluminium oxide of a kind of bimodal pore distribution and preparation method thereof.These methods are all to go out the aluminum oxide of bimodal pore distribution by sacrificing template synthesis, but do not relate to void content and the pore structure controllability of this porous alumina.

Summary of the invention

In order to overcome above-mentioned the deficiencies in the prior art, the object of the present invention is to provide a kind of controlled bimodal vesicular structure Al ₂O ₃The preparation method of stupalith, the Al prepared ₂O ₃Stupalith has micron-sized macropore and nano level aperture simultaneously, or the bimodal hole of nanoscale size.

To achieve these goals, the technical solution used in the present invention is:

A kind of controlled bimodal vesicular structure Al ₂O ₃The preparation method of stupalith comprises the following steps:

The first step, the pore-forming material of two kinds of different shapes differing materials and alumina powder are passed through to following formula:

$\frac{{\mathrm{<figure-callout\; id="1"\; label="m"\; filenames="HDA0000126485860000011.png,HDA0000126485860000012.png"\; state="\{\{state\}\}">m</figure-callout>}}_1}{{\mathrm{\&rho;}}_1}+\frac{m_2}{{\mathrm{\&rho;}}_2}=P\&times;(\frac{{\mathrm{<figure-callout\; id="1"\; label="m"\; filenames="HDA0000126485860000011.png,HDA0000126485860000012.png"\; state="\{\{state\}\}">m</figure-callout>}}_1}{{\mathrm{\&rho;}}_1}+\frac{m_2}{{\mathrm{\&rho;}}_2}+\frac{{\mathrm{<figure-callout\; id="3"\; label="m"\; filenames="HDA0000126485860000012.png,HDA0000126485860000022.png"\; state="\{\{state\}\}">m</figure-callout>}}_3}{{\mathrm{\&rho;}}_3})$

$V_1:V_2=\left(\frac{{\mathrm{<figure-callout\; id="1"\; label="m"\; filenames="HDA0000126485860000011.png,HDA0000126485860000012.png"\; state="\{\{state\}\}">m</figure-callout>}}_1}{{\mathrm{\&rho;}}_1}\right):\left(\frac{m_2}{{\mathrm{\&rho;}}_2}\right)$

Calculate the quality proportioning m of pore-forming material and aluminum oxide in the original mixed powder ₁: m ₂: m ₃, and weighing, wherein: m ₁And m ₂Be respectively the quality of two kinds of pore-forming materials; m ₃Quality for aluminum oxide; ρ ₁And ρ ₂Be respectively the density of two kinds of pore-forming materials; ρ ₃Density for aluminum oxide; The porosity that P is porous material; V ₁And V ₂Be respectively the design volume of pore-forming material;

Second step, utilize medium ethanol with 800RPM rotating speed wet ball-milling 24 hours in ball mill the aluminum oxide of weighing and pore-forming material powdered mixture, and abrading-ball is used the alumina balls that diameter is 3mm, and abrading-ball is 1: 1 with the volume ratio of mixture to be ground;

The 3rd step is carried out the low temperature volatilization and carry out 12 hours dryings with 110 ℃ of temperature in electric drying oven with forced convection under 25 ℃～35 ℃ to ethanol, then dry mixed powder is carried out to 200 order mesh screens and sieve;

The 4th step, the powder of acquisition is packed in pressing mold, is placed on die sleeve between two compressing tablets between push-down head, first through rapidform machine precompressed at the beginning of 20 seconds after one-step forming under 125MPa, then puts into the isostatic cool pressing instrument at the 500MPa compacted under, obtains prefabricated sample;

The 5th step, it is that 10～15 ℃/min carries out sintering at temperature rise rate that prefabricated sample is put into to retort furnace, and 1550 ℃ of insulations 2 hours, the pore-forming material generation combustion reactions of inside in sintering process, final original position prepares the porous alumina ceramic material.

The pore-forming material of described two kinds of different shapes differing materials can be:

Spherical starch and fibrous carbon fiber, the volume ratio of pore-forming material and aluminum oxide is 1～4: 4.

Be perhaps flats graphite and fibrous cellulose, the volume ratio of pore-forming material and aluminum oxide is 3～7: 7.

Be perhaps particulate state polymethylmethacrylate and fibrous nylon-66 fibre, the volume ratio of pore-forming material and aluminum oxide is 1～4: 4.

In process, can also, in the original mixed powder of described step 1, add the following sintering aid that accounts for mixed powder total mass 0.5%: any in silicon-dioxide, calcium oxide, yttrium oxide and lanthanum trioxide makes reactive behavior improve, Promotion system forms, and improves the yield and quality.

Compared with prior art, the invention has the beneficial effects as follows:

It is to prepare bimodal porous alumina ceramic material by the burning pore-forming material under 1550 ℃ of conditions and in temperature-rise period in the highest sintering temperature that the present invention adopts the sacrifice template.The present invention's method compared to existing technology, can design by the pore-forming material of different content and shape regulation and control and prepare the bimodal porous alumina ceramic material of different porosities and pore structure, wherein the aperture of macropore is controlled in nano-micro level (900nm～300 μ m left and right), the aperture of aperture is controlled at nano level (220nm～500nm), and the pore structure of macropore is fibrous, the pore structure of aperture is spherical or flats.In addition, raw materials cost required for the present invention is lower, preparation technology is simple, can provide a series of materials that meet different demands for the application in the fields such as electrode, artificial skelecton, catalyzer, bio-reactor and sorbent material, and be easy to large-scale industrial production.

The accompanying drawing explanation

Fig. 1 is for usining starch that volume ratio is 50vol.% and carbon fiber as pore-forming material, the graph of pore diameter distribution of the bimodal porous alumina ceramic by sacrificing template synthesis.

Fig. 2 is for usining starch that volume ratio is 50vol.% and carbon fiber as pore-forming material, the scanning electron microscope (SEM) photograph of the bimodal porous alumina ceramic by sacrificing template synthesis.

Fig. 3 is for take graphite that volume ratio is 50vol.% and carbon fiber (long 90 μ m, diameter 14.5 μ m) as pore-forming material, the graph of pore diameter distribution of the bimodal porous alumina ceramic by sacrificing template synthesis.

Fig. 4 is for take graphite that volume ratio is 50vol.% and carbon fiber (long 90 μ m, diameter 14.5 μ m) as pore-forming material, the scanning electron microscope (SEM) photograph of the bimodal porous alumina ceramic by sacrificing template synthesis.

Embodiment

Below in conjunction with drawings and Examples, the present invention is described in further details.

Application sacrificial mold plate technique prepares the bimodal porous alumina ceramic material of different porosities and pore structure.Adopt different pore-forming materials and alumina powder to be mixed with prefabricated powder, namely pore-forming material in starting powder is mixed by a certain percentage, then pore-forming material and alumina powder also mix by a certain percentage, are pressed into after base sintering in atmospheric environment.In whole sintering process pore-forming material by with the atmospheric oxygen reactive combustion totally, form difform hole.These pore structures have copied the shape of pore-forming material, prepare bimodal porous ceramic film material.

The pore-forming material of two kinds of different shapes differing materials that embodiment 1～4 adopts is spherical starch and fibrous carbon fiber, and feedstock property is in Table 1.

Table 1

Embodiment 1

A kind of controlled bimodal vesicular structure Al ₂O ₃Stupalith, aluminum oxide in material: spherical starch: the volume ratio of fibrous carbon fiber is 4: 1: 1, and preparation process comprises the following steps:

The first step, the pore-forming material of two kinds of different shapes differing materials and alumina powder are passed through to following formula:

$\frac{{\mathrm{<figure-callout\; id="1"\; label="m"\; filenames="HDA0000126485860000011.png,HDA0000126485860000012.png"\; state="\{\{state\}\}">m</figure-callout>}}_1}{{\mathrm{\&rho;}}_1}+\frac{m_2}{{\mathrm{\&rho;}}_2}=P\&times;(\frac{{\mathrm{<figure-callout\; id="1"\; label="m"\; filenames="HDA0000126485860000011.png,HDA0000126485860000012.png"\; state="\{\{state\}\}">m</figure-callout>}}_1}{{\mathrm{\&rho;}}_1}+\frac{m_2}{{\mathrm{\&rho;}}_2}+\frac{{\mathrm{<figure-callout\; id="3"\; label="m"\; filenames="HDA0000126485860000012.png,HDA0000126485860000022.png"\; state="\{\{state\}\}">m</figure-callout>}}_3}{{\mathrm{\&rho;}}_3})$

$V_1:V_2=\left(\frac{{\mathrm{<figure-callout\; id="1"\; label="m"\; filenames="HDA0000126485860000011.png,HDA0000126485860000012.png"\; state="\{\{state\}\}">m</figure-callout>}}_1}{{\mathrm{\&rho;}}_1}\right):\left(\frac{m_2}{{\mathrm{\&rho;}}_2}\right)$

Calculate the quality proportioning m of pore-forming material and aluminum oxide in the original mixed powder ₁: m ₂: m ₃, and weighing, wherein: m ₁And m ₂Be respectively the quality of two kinds of pore-forming materials; m ₃Quality for aluminum oxide; ρ ₁And ρ ₂Be respectively the density of two kinds of pore-forming materials; ρ ₃Density for aluminum oxide; The porosity that P is porous material; V ₁And V ₂Be respectively the volume of pore-forming material;

Second step, utilize medium ethanol with 800RPM rotating speed wet ball-milling 24 hours in ball mill the aluminum oxide of weighing and pore-forming material powdered mixture, and abrading-ball is used the alumina balls that diameter is 3mm, and abrading-ball is 1: 1 with the volume ratio of mixture to be ground;

The 3rd step is carried out the low temperature volatilization and carry out 12 hours dryings with 110 ℃ of temperature in electric drying oven with forced convection under 35 ℃ to ethanol, then dry mixed powder is carried out to 200 order mesh screens and sieve;

The 4th step, the powder of acquisition is packed in pressing mold, is placed on die sleeve between two compressing tablets between push-down head, first through rapidform machine precompressed at the beginning of 20 seconds after one-step forming under 125MPa, then puts into the isostatic cool pressing instrument at the 500MPa compacted under, obtains prefabricated sample;

The 5th step, it is that 15 ℃/min carries out sintering at temperature rise rate that prefabricated sample is put into to retort furnace, and 1550 ℃ of insulations 2 hours, the pore-forming material generation combustion reactions of inside in sintering process, final original position prepares the porous alumina ceramic material.

Embodiment 2

A kind of controlled bimodal vesicular structure Al ₂O ₃Stupalith, aluminum oxide in material: spherical starch: the volume ratio of fibrous carbon fiber is 14: 3: 3, and preparation process is consistent with embodiment mono-.

Embodiment 3

A kind of controlled bimodal vesicular structure Al ₂O ₃Stupalith, aluminum oxide in material: spherical starch: the volume ratio of fibrous carbon fiber is 3: 1: 1, and preparation process is consistent with embodiment mono-.

Embodiment 4

A kind of controlled bimodal vesicular structure Al ₂O ₃Stupalith, aluminum oxide in material: spherical starch: the volume ratio of fibrous carbon fiber is 2: 1: 1, adds the sintering aid silicon-dioxide of total mass 0.5% in the original mixed powder simultaneously, preparation process is consistent with embodiment mono-.

The pore-forming material of two kinds of different shapes differing materials that embodiment 5～19 adopts is flats graphite and fibrous cellulose, and feedstock property is in Table 2.

Table 2

Embodiment 5

A kind of controlled bimodal vesicular structure Al ₂O ₃Stupalith, aluminum oxide in material: fibrous cellulose: the volume ratio of flats graphite is 14: 3: 3, wherein fibrous cellulose is grown 90 μ m, diameter 14.5 μ m, preparation process comprises the following steps:

The first step, the pore-forming material of two kinds of different shapes differing materials and alumina powder are passed through to following formula:

$\frac{{\mathrm{<figure-callout\; id="1"\; label="m"\; filenames="HDA0000126485860000011.png,HDA0000126485860000012.png"\; state="\{\{state\}\}">m</figure-callout>}}_1}{{\mathrm{\&rho;}}_1}+\frac{m_2}{{\mathrm{\&rho;}}_2}=P\&times;(\frac{{\mathrm{<figure-callout\; id="1"\; label="m"\; filenames="HDA0000126485860000011.png,HDA0000126485860000012.png"\; state="\{\{state\}\}">m</figure-callout>}}_1}{{\mathrm{\&rho;}}_1}+\frac{m_2}{{\mathrm{\&rho;}}_2}+\frac{{\mathrm{<figure-callout\; id="3"\; label="m"\; filenames="HDA0000126485860000012.png,HDA0000126485860000022.png"\; state="\{\{state\}\}">m</figure-callout>}}_3}{{\mathrm{\&rho;}}_3})$

$V_1:V_2=\left(\frac{{\mathrm{<figure-callout\; id="1"\; label="m"\; filenames="HDA0000126485860000011.png,HDA0000126485860000012.png"\; state="\{\{state\}\}">m</figure-callout>}}_1}{{\mathrm{\&rho;}}_1}\right):\left(\frac{m_2}{{\mathrm{\&rho;}}_2}\right)$

Calculate the quality proportioning m of pore-forming material and aluminum oxide in the original mixed powder ₁: m ₂: m ₃, and weighing, wherein: m ₁And m ₂Be respectively the quality of two kinds of pore-forming materials; m ₃Quality for aluminum oxide; ρ ₁And ρ ₂Be respectively the density of two kinds of pore-forming materials; ρ ₃Density for aluminum oxide; The porosity that P is porous material; V ₁And V ₂Be respectively the design volume of pore-forming material;

Second step, utilize medium ethanol with 800RPM rotating speed wet ball-milling 24 hours in ball mill the aluminum oxide of weighing and pore-forming material powdered mixture, and abrading-ball is used the alumina balls that diameter is 3mm, and abrading-ball is 1: 1 with the volume ratio of mixture to be ground;

The 3rd step is carried out the low temperature volatilization and carry out 12 hours dryings with 110 ℃ of temperature in electric drying oven with forced convection under 25 ℃ to ethanol, then dry mixed powder is carried out to 200 order mesh screens and sieve;

The 4th step, the powder of acquisition is packed in pressing mold, is placed on die sleeve between two compressing tablets between push-down head, first through rapidform machine precompressed at the beginning of 20 seconds after one-step forming under 125MPa, then puts into the isostatic cool pressing instrument at the 500MPa compacted under, obtains prefabricated sample;

The 5th step, it is that 10 ℃/min carries out sintering at temperature rise rate that prefabricated sample is put into to retort furnace, and 1550 ℃ of insulations 2 hours, the pore-forming material generation combustion reactions of inside in sintering process, final original position prepares the porous alumina ceramic material.

Embodiment 6

A kind of controlled bimodal vesicular structure Al ₂O ₃Stupalith, aluminum oxide in material: fibrous cellulose: the volume ratio of flats graphite is 70: 9: 21, wherein fibrous cellulose is grown 90 μ m, diameter 14.5 μ m, preparation process is consistent with embodiment 5.

Embodiment 7

A kind of controlled bimodal vesicular structure Al ₂O ₃Stupalith, aluminum oxide in material: fibrous cellulose: the volume ratio of flats graphite is 70: 21: 9, wherein fibrous cellulose is grown 90 μ m, diameter 14.5 μ m, preparation process is consistent with embodiment 5.

Embodiment 8

A kind of controlled bimodal vesicular structure Al ₂O ₃Stupalith, aluminum oxide in material: fibrous cellulose: the volume ratio of flats graphite is 10: 3: 7, wherein fibrous cellulose is grown 90 μ m, diameter 14.5 μ m, preparation process is consistent with embodiment 5.

Embodiment 9

A kind of controlled bimodal vesicular structure Al ₂O ₃Stupalith, aluminum oxide in material: fibrous cellulose: the volume ratio of flats graphite is 10: 7: 3, and wherein fibrous cellulose is grown 90 μ m, diameter 14.5 μ m, add the sintering aid calcium oxide of total mass 0.5% in the original mixed powder, preparation process is consistent with embodiment 5 simultaneously.

Embodiment 10

A kind of controlled bimodal vesicular structure Al ₂O ₃Stupalith, aluminum oxide in material: fibrous cellulose: the volume ratio of flats graphite is 10: 3: 7, wherein fibrous cellulose is grown 90 μ m, diameter 14.5 μ m, preparation process is consistent with embodiment 5.

Embodiment 11

A kind of controlled bimodal vesicular structure Al ₂O ₃Stupalith, aluminum oxide in material: fibrous cellulose: the volume ratio of flats graphite is 30: 21: 49, wherein fibrous cellulose is grown 90 μ m, diameter 14.5 μ m, preparation process is consistent with embodiment 5.

Embodiment 12

A kind of controlled bimodal vesicular structure Al ₂O ₃Stupalith, aluminum oxide in material: fibrous cellulose: the volume ratio of flats graphite is 6: 7: 7, wherein fibrous cellulose is grown 90 μ m, diameter 14.5 μ m, preparation process is consistent with embodiment 5.

Embodiment 13

A kind of controlled bimodal vesicular structure Al ₂O ₃Stupalith, aluminum oxide in material: fibrous cellulose: the volume ratio of flats graphite is 30: 49: 21, and wherein fibrous cellulose is grown 90 μ m, diameter 14.5 μ m, add the sintering aid yttrium oxide of total mass 0.5% in the original mixed powder, preparation process is consistent with embodiment 5 simultaneously.

Embodiment 14

A kind of controlled bimodal vesicular structure Al ₂O ₃Stupalith, aluminum oxide in material: fibrous cellulose: the volume ratio of flats graphite is 10: 3: 7, wherein fibrous cellulose is grown 150 μ m, diameter 14.5 μ m, preparation process is consistent with embodiment 5.

Embodiment 15

A kind of controlled bimodal vesicular structure Al ₂O ₃Stupalith, aluminum oxide in material: fibrous cellulose: the volume ratio of flats graphite is 2: 1: 1, wherein fibrous cellulose is grown 150 μ m, diameter 14.5 μ m, preparation process is consistent with embodiment 5.

Embodiment 16

A kind of controlled bimodal vesicular structure Al ₂O ₃Stupalith, aluminum oxide in material: fibrous cellulose: the volume ratio of flats graphite is 10: 7: 3, wherein fibrous cellulose is grown 150 μ m, diameter 14.5 μ m, preparation process is consistent with embodiment 5.

Embodiment 17

A kind of controlled bimodal vesicular structure Al ₂O ₃Stupalith, aluminum oxide in material: fibrous cellulose: the volume ratio of flats graphite is 10: 3: 7, wherein fibrous cellulose is grown 200 μ m, diameter 14.5 μ m, preparation process is consistent with embodiment 5.

Embodiment 18

A kind of controlled bimodal vesicular structure Al ₂O ₃Stupalith, aluminum oxide in material: fibrous cellulose: the volume ratio of flats graphite is 2: 1: 1, wherein fibrous cellulose is grown 200 μ m, diameter 14.5 μ m, preparation process is consistent with embodiment 5.

Embodiment 19

A kind of controlled bimodal vesicular structure Al ₂O ₃Stupalith, aluminum oxide in material: fibrous cellulose: the volume ratio of flats graphite is 10: 7: 3, wherein fibrous cellulose is grown 200 μ m, diameter 14.5 μ m, preparation process is consistent with embodiment 5.

The pore-forming material of two kinds of different shapes differing materials that embodiment 20～24 adopts is particulate state polymethylmethacrylate and fibrous nylon-66 fibre, and feedstock property is in Table 3.

Table 3

Embodiment 20

A kind of controlled bimodal vesicular structure Al ₂O ₃Stupalith, aluminum oxide in material: particulate state polymethylmethacrylate: the volume ratio of fibrous nylon-66 fibre is 8: 1: 1, wherein fibrous nylon-66 fibre is grown 800 μ m, diameter 19 μ m, preparation process comprises the following steps:

The first step, the pore-forming material of two kinds of different shapes differing materials and alumina powder are passed through to following formula:

$\frac{{\mathrm{<figure-callout\; id="1"\; label="m"\; filenames="HDA0000126485860000011.png,HDA0000126485860000012.png"\; state="\{\{state\}\}">m</figure-callout>}}_1}{{\mathrm{\&rho;}}_1}+\frac{m_2}{{\mathrm{\&rho;}}_2}=P\&times;(\frac{{\mathrm{<figure-callout\; id="1"\; label="m"\; filenames="HDA0000126485860000011.png,HDA0000126485860000012.png"\; state="\{\{state\}\}">m</figure-callout>}}_1}{{\mathrm{\&rho;}}_1}+\frac{m_2}{{\mathrm{\&rho;}}_2}+\frac{{\mathrm{<figure-callout\; id="3"\; label="m"\; filenames="HDA0000126485860000012.png,HDA0000126485860000022.png"\; state="\{\{state\}\}">m</figure-callout>}}_3}{{\mathrm{\&rho;}}_3})$

$V_1:V_2=\left(\frac{{\mathrm{<figure-callout\; id="1"\; label="m"\; filenames="HDA0000126485860000011.png,HDA0000126485860000012.png"\; state="\{\{state\}\}">m</figure-callout>}}_1}{{\mathrm{\&rho;}}_1}\right):\left(\frac{m_2}{{\mathrm{\&rho;}}_2}\right)$

Calculate the quality proportioning m of pore-forming material and aluminum oxide in the original mixed powder ₁: m ₂: m ₃, and weighing, wherein: m ₁And m ₂Be respectively the quality of two kinds of pore-forming materials; m ₃Quality for aluminum oxide; ρ ₁And ρ ₂Be respectively the density of two kinds of pore-forming materials; ρ ₃Density for aluminum oxide; The porosity that P is porous material; V ₁And V ₂Be respectively the volume of pore-forming material;

Second step, utilize medium ethanol with 800RPM rotating speed wet ball-milling 24 hours in ball mill the aluminum oxide of weighing and pore-forming material powdered mixture, and abrading-ball is used the alumina balls that diameter is 3mm, and abrading-ball is 1: 1 with the volume ratio of mixture to be ground;

The 3rd step is carried out the low temperature volatilization and carry out 12 hours dryings with 110 ℃ of temperature in electric drying oven with forced convection under 30 ℃ to ethanol, then dry mixed powder is carried out to 200 order mesh screens and sieve;

The 4th step, the powder of acquisition is packed in pressing mold, is placed on die sleeve between two compressing tablets between push-down head, first through rapidform machine precompressed at the beginning of 20 seconds after one-step forming under 125MPa, then puts into the isostatic cool pressing instrument at the 500MPa compacted under, obtains prefabricated sample;

The 5th step, it is that 10 ℃/min carries out sintering at temperature rise rate that prefabricated sample is put into to retort furnace, and 1550 ℃ of insulations 2 hours, the pore-forming material generation combustion reactions of inside in sintering process, final original position prepares the porous alumina ceramic material.

Embodiment 21

A kind of controlled bimodal vesicular structure Al ₂O ₃Stupalith, aluminum oxide in material: particulate state polymethylmethacrylate: the volume ratio of fibrous nylon-66 fibre is 4: 1: 1, wherein fibrous nylon-66 fibre is grown 800 μ m, diameter 19 μ m, preparation process is consistent with embodiment 20.

Embodiment 22

A kind of controlled bimodal vesicular structure Al ₂O ₃Stupalith, aluminum oxide in material: particulate state polymethylmethacrylate: the volume ratio of fibrous nylon-66 fibre is 4: 2: 1, wherein fibrous nylon-66 fibre is grown 800 μ m, diameter 19 μ m, preparation process is consistent with embodiment 20.

Embodiment 23

A kind of controlled bimodal vesicular structure Al ₂O ₃Stupalith, aluminum oxide in material: particulate state polymethylmethacrylate: the volume ratio of fibrous nylon-66 fibre is 4: 1: 2, wherein fibrous nylon-66 fibre is grown 800 μ m, diameter 19 μ m, preparation process is consistent with embodiment 20.

Embodiment 24

A kind of controlled bimodal vesicular structure Al ₂O ₃Stupalith, aluminum oxide in material: particulate state polymethylmethacrylate: the volume ratio of fibrous nylon-66 fibre is 2: 1: 1, wherein fibrous nylon-66 fibre is grown 800 μ m, diameter 19 μ m, add the sintering aid lanthanum trioxide of total mass 0.5% in the original mixed powder, preparation process is consistent with embodiment 20 simultaneously.

Embodiment 1～24 porous alumina ceramic material that the present invention prepares, respectively at analytical balance, D8 Discover type XRD diffraction analysis instrument, LEO 1530 type scanning electron microscope and AutoPore IV 9500 V1.04 type mercury injection apparatuses void content, Cross Section Morphology, specific surface area, pore volume and the pore size distribution of test samples respectively.Table 4 has been listed the test result of void content, specific surface area, pore volume and pore size distribution of the porous alumina ceramic material of embodiment 1～24 preparation.As can be seen from Table 4, use different pore-forming materials (carbon fiber and starch, Mierocrystalline cellulose and graphite or polymethylmethacrylate and nylon-66 fibre) and different length-to-diameter ratio Mierocrystalline cellulose as the different proportionings of pore-forming material to preparing to such an extent that pore structure and the form of porous alumina ceramic material has a significant impact.Because Mierocrystalline cellulose is unfavorable for just base compactness as pore-forming material, the raising of cellulosic volume content and length-to-diameter ratio, increased void content and the pore size of sintered sample.For carbon fiber and starch, as pore-forming material, the volume fraction at pore-forming material in raw mix is 20vol.%, and when 30vol.% and 50vol.%, the porous alumina ceramic sample is bimodal.For Mierocrystalline cellulose and graphite, as pore-forming material, when the length-to-diameter ratio of carbon fiber is 6.21 and the volume fraction of pore-forming material in raw mix while being 50vol.%, porous alumina ceramic sample pore size distribution is bimodal.Because Mierocrystalline cellulose and polymethylmethacrylate take fire 160 ℃ of left and right, nylon-66 fibre takes fire 253 ℃ of left and right, starch takes fire 350 ℃ of left and right, graphite takes fire 1000 ℃ of left and right, starch when sintering temperature is 1550 ℃, Mierocrystalline cellulose, the pore structure of polymethylmethacrylate and nylon-66 fibre and form can not maintain, and carbon fiber and graphite can maintain its pore structure and form.

Table 4

The foregoing is only one embodiment of the present invention, it not whole or unique embodiment, the conversion of any equivalence that those of ordinary skills take technical solution of the present invention by reading specification sheets of the present invention, be claim of the present invention and contain.

Claims (2)

1. a controlled bimodal vesicular structure Al ₂O ₃The preparation method of stupalith, is characterized in that, comprises the following steps:

The first step, the pore-forming material of two kinds of different shapes differing materials and alumina powder are passed through to following formula:

$\frac{m_1}{{\mathrm{\&rho;}}_1}+\frac{m_2}{{\mathrm{\&rho;}}_2}=P\&times;(\frac{m_1}{{\mathrm{\&rho;}}_1}+\frac{m_2}{{\mathrm{\&rho;}}_2}+\frac{m_3}{{\mathrm{\&rho;}}_3})$

$V_1:V_2=\left(\frac{m_1}{{\mathrm{\&rho;}}_1}\right):\left(\frac{m_2}{{\mathrm{\&rho;}}_2}\right)$

Calculate the quality proportioning m of pore-forming material and aluminum oxide in the original mixed powder ₁: m ₂: m ₃, and weighing, wherein: m ₁And m ₂Be respectively the quality of two kinds of pore-forming materials; m ₃Quality for aluminum oxide; ρ ₁And ρ ₂Be respectively the density of two kinds of pore-forming materials; ρ ₃Density for aluminum oxide; The porosity that P is porous material; V ₁And V ₂Be respectively the design volume of pore-forming material;

Second step, utilize medium ethanol with 800RPM rotating speed wet ball-milling 24 hours in ball mill the aluminum oxide of weighing and pore-forming material powdered mixture, and abrading-ball is used the alumina balls that diameter is 3mm, and abrading-ball is 1:1 with the volume ratio of mixture to be ground;

The 3rd step is carried out the low temperature volatilization and carry out 12 hours dryings with 110 ℃ of temperature in electric drying oven with forced convection under 25 ℃～35 ℃ to ethanol, then dry mixed powder is carried out to 200 order mesh screens and sieve;

The 4th step, the powder of acquisition is packed in pressing mold, is placed on die sleeve between two compressing tablets between push-down head, first through rapidform machine precompressed at the beginning of 20 seconds after one-step forming under 125MPa, then puts into the isostatic cool pressing instrument at the 500MPa compacted under, obtains prefabricated sample;

The 5th step, it is that 10～15 ℃/min carries out sintering at temperature rise rate that prefabricated sample is put into to retort furnace, and 1550 ℃ of insulations 2 hours, the pore-forming material generation combustion reactions of inside in sintering process, final original position prepares the porous alumina ceramic material;

Wherein,

The pore-forming material of described two kinds of different shapes differing materials is spherical starch and fibrous carbon fiber, the volume ratio of pore-forming material and aluminum oxide is 1～4:4, the particle diameter of described spherical starch is 9.35 μ m, the mean diameter 7.00 μ m of fibrous carbon fiber, length 50～150 μ m;

Perhaps,

The pore-forming material of described two kinds of different shapes differing materials is flats graphite and fibrous cellulose, the volume ratio of pore-forming material and aluminum oxide is 3～7:7, the particle diameter of described flats graphite is 28.7 μ m, the mean diameter 14.5 μ m of fibrous cellulose, length 90 μ m, 150 μ m or 200 μ m;

Perhaps,

The pore-forming material of described two kinds of different shapes differing materials is particulate state polymethylmethacrylate and fibrous nylon-66 fibre, the volume ratio of pore-forming material and aluminum oxide is 1～4:4, the particle diameter of described particulate state polymethylmethacrylate is 30.4 μ m, the mean diameter 19 μ m of fibrous nylon-66 fibre, length 800 μ m.

2. controlled bimodal vesicular structure Al according to claim 1 ₂O ₃The preparation method of stupalith, is characterized in that, in the original mixed powder of described step 1, adds the following sintering aid that accounts for mixed powder total mass 0.5%: any in silicon-dioxide, calcium oxide, yttrium oxide and lanthanum trioxide.

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