CN102746022A - 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 porous structure ceramic preparation methods, particularly relate to a kind of controlled bimodal vesicular structure Al ₂O ₃The preparation method of stupalith.

Background technology

Ceramic foam has excellent filtration, absorption 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.Characteristics such as its high-specific surface area, low density, fluid permeability, high specific strength, low-k and highly heatproof and shockproof are that many scientific research personnel provide valuable reference.In the last few years, porous ceramic film material had been widely used in ion and heat exchanger, catalysis, transmitter, bio-molecular separation and purification and refractory liner, strainer molten metal and biomedical material.Porous material for remaining silent is mainly used in heat insulating, then is used in strainer and catalyzer etc. for opening and porous material that internal porosity links to each other.It has also contained the problem of the important application of present " heat " and ecological and sustainable energy.The size of hole, shape and distribution are material design and synthetic key character.

Usually gac and zeolite have higher absorption property and catalytic performance, have been widely used as sorbent material, reodorant, SYNTHETIC OPTICAL WHITNER and in various chemistry and foodstuffs industry support of the catalyst or the like at present.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, spreads but help the micropore fluidic less than effect above-mentioned characteristic.On the other hand, the porous material application in a lot of fields with less relatively surface-area constantly increases, like 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 the porous material.Therefore, it is highly important that to possess that bimodal vesicular structure is arranged for the porous material that special purpose is arranged.

Bimodal porous material is meant to have the pore distribution of (generally being divided into micropore and grand hole) of two kinds of different sizes of a kind of successive in the porous material.The performance of bimodal porous material depends mainly on the micropore with huge surface area, and in porous material, has the grand hole that includes considerable quantity, and its function is to improve the diffuse fluid speed that gets into micropore.In other words, the porous material that has two kinds of different apertures has following advantage: has improved in work capacity such as WWT, catalyzed reactions (1); (2) can be according to the differing materials function and flexible design; (3) efficient of raising equipment.In the last few years, have less relatively surface-area and the porous material of pore distribution that two kinds of different sizes are arranged except purposes such as lagging material, use also more and more widely at electrode, artificial skelecton, catalyzer, bio-reactor and the sorbent material etc. of fuel cell.The method for preparing at present porous material is such as transfer printing, sacrifice template and direct foam-forming method etc.Wherein sacrifice template and be meant that precursor and pore-forming material with complex matrix mix, these pore-forming materials can be synthesis of organic substance, natural organic matter, liquid, salt and metal or pottery etc.Carry out drying and sintering then.Thereby obtain porous material.We can obtain the porous material of void content arrival 90% to use this method.Because of its technology simple; And can be through regulating sintering temperature; Soaking time and different size and form pore-forming material come the convenient porous material that is easy to 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 in micropore and grand hole).

Aluminum oxide 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 because of a series of excellent specific properties such as its intensity are high, hardness is big, high temperature resistant, wear-resistant.But its ionic linkage causes the low (Al of its particle spread coefficient more by force ³⁺Spread coefficient only 10 in the time of 1700 ℃ ^-11Cm ²S ^-1) and sintering temperature higher, for example the sintering temperature of 99 alumina-ceramic can be up to nearly 1800 ℃.Through the interpolation of a certain amount of sintering aid, help reducing the sintering temperature of alumina-ceramic, added sintering aid also can play the effect of pore-forming material simultaneously.Through suitable sintering process, can control and obtain needed porous material.Generally, the ceramic foam part can form the densification sintering process.Extra porosity can be degraded fully in heat treatment process through the interpolation pore-forming material and realized.Natural organic, like starch, sugar, timber and fiber etc. is used as pore-forming material usually, because its relatively low cost, and degrades fully with non-toxicity.Through pore-creating perfect combustion, formed the size distribution of sintered compact with bigger hole.Along with 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 all are to be equipped with the aluminum oxide of bimodal pore distribution through sacrificing the template legal system, but do not relate to the void content and the Controlled Pore Structure performance of this porous alumina.

Summary of the invention

In order to overcome the deficiency of above-mentioned 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 for preparing ₂O ₃Stupalith has micron-sized macropore and nano level aperture simultaneously, perhaps the bimodal hole of nanoscale size.

To achieve these goals, the technical scheme of the present invention's employing is:

A kind of controlled bimodal vesicular structure Al ₂O ₃The preparation method of stupalith may further comprise the steps:

The first step, the pore-forming material and the alumina powder of two kinds of different shapes differing materials passed through 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; P is the porosity of porous material; V ₁And V ₂Be respectively the design volume of pore-forming material;

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

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

In the 4th step, the powder of acquisition is packed in the pressing mold, places on the die sleeve between two compressing tablets between the push-down head, at the beginning of 20 seconds behind the one-step forming, puts into the isostatic cool pressing appearance again at the 500MPa compacted under in precompressed under the 125MPa through rapidform machine earlier, obtains prefabricated sample;

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

The pore-forming material of said two kinds of different shapes differing materials can for:

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

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

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

In the process; Can also in the original mixed powder of said step 1, add the following sintering aid that accounts for mixed powder total mass 0.5%: any in silicon-dioxide, quicklime, yttrium oxide and the lanthanum trioxide makes reactive behavior improve; The 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 through 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 compares the method for prior art; Can design regulation and control through the pore-forming material of different content and shape and prepare the bimodal porous alumina ceramic material of different porosities and pore structure; Wherein the controllable aperture of macropore is at nano-micro level (about 900nm～300 μ m); (220nm～500nm), and the pore structure of macropore is fibrous, the pore structure of aperture is spherical or flats to the controllable aperture of aperture at nano level.In addition; Raw materials cost required for the present invention is lower; Preparation technology is simple, can a series of materials that satisfy different demands be provided for the application in fields such as electrode, artificial skelecton, catalyzer, bio-reactor and sorbent material, and be easy to large-scale industrial production.

Description of drawings

Fig. 1 for the volume ratio be starch and the thomel of 50vol.% as pore-forming material, the graph of pore diameter distribution of the bimodal porous alumina ceramic that is equipped with through sacrifice template legal system.

Fig. 2 for the volume ratio be starch and the thomel of 50vol.% as pore-forming material, the sem photograph of the bimodal porous alumina ceramic that is equipped with through sacrifice template legal system.

Fig. 3 for the volume ratio be graphite and the thomel (long 90 μ m, diameter 14.5 μ m) of 50vol.% as pore-forming material, the graph of pore diameter distribution of the bimodal porous alumina ceramic that is equipped with through sacrifice template legal system.

Fig. 4 for the volume ratio be graphite and the thomel (long 90 μ m, diameter 14.5 μ m) of 50vol.% as pore-forming material, the sem photograph of the bimodal porous alumina ceramic that is equipped with through sacrifice template legal system.

Embodiment

Below in conjunction with accompanying drawing and embodiment the present invention is explained further details.

Use the bimodal porous alumina ceramic material that the sacrificial mold plate technique prepares different porosities and pore structure.Adopt different pore-forming materials and alumina powder to be mixed with prefabricated powder, just pore-forming material in the starting powder is mixed by a certain percentage, pore-forming material and alumina powder also mix by a certain percentage then, are pressed into behind the base sintering in atmospheric environment.In the whole sintering process pore-forming material through with atmosphere in oxygen reaction burning totally, form difform hole.These pore structures have been duplicated 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 seen table 1.

Table 1

Embodiment 1

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

The first step, the pore-forming material and the alumina powder of two kinds of different shapes differing materials passed through 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; P is the porosity of porous material; V ₁And V ₂Be respectively the volume of pore-forming material;

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

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

In the 4th step, the powder of acquisition is packed in the pressing mold, places on the die sleeve between two compressing tablets between the push-down head, at the beginning of 20 seconds behind the one-step forming, puts into the isostatic cool pressing appearance again at the 500MPa compacted under in precompressed under the 125MPa through rapidform machine earlier, obtains prefabricated sample;

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

Embodiment 2

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

Embodiment 3

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

Embodiment 4

A kind of controlled bimodal vesicular structure Al ₂O ₃Stupalith, aluminum oxide in the 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, the preparation process is consistent with embodiment one.

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 seen table 2.

Table 2

Embodiment 5

A kind of controlled bimodal vesicular structure Al ₂O ₃Stupalith, aluminum oxide in the 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, the preparation process may further comprise the steps:

The first step, the pore-forming material and the alumina powder of two kinds of different shapes differing materials passed through 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; P is the porosity of porous material; V ₁And V ₂Be respectively the design volume of pore-forming material;

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

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

In the 4th step, the powder of acquisition is packed in the pressing mold, places on the die sleeve between two compressing tablets between the push-down head, at the beginning of 20 seconds behind the one-step forming, puts into the isostatic cool pressing appearance again at the 500MPa compacted under in precompressed under the 125MPa through rapidform machine earlier, obtains prefabricated sample;

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

Embodiment 6

A kind of controlled bimodal vesicular structure Al ₂O ₃Stupalith, aluminum oxide in the 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, the preparation process is consistent with embodiment 5.

Embodiment 7

A kind of controlled bimodal vesicular structure Al ₂O ₃Stupalith, aluminum oxide in the 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, the preparation process is consistent with embodiment 5.

Embodiment 8

A kind of controlled bimodal vesicular structure Al ₂O ₃Stupalith, aluminum oxide in the 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, the preparation process is consistent with embodiment 5.

Embodiment 9

A kind of controlled bimodal vesicular structure Al ₂O ₃Stupalith; Aluminum oxide in the 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 quicklime of total mass 0.5% in the original mixed powder simultaneously, the preparation process is consistent with embodiment 5.

Embodiment 10

A kind of controlled bimodal vesicular structure Al ₂O ₃Stupalith, aluminum oxide in the 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, the preparation process is consistent with embodiment 5.

Embodiment 11

A kind of controlled bimodal vesicular structure Al ₂O ₃Stupalith, aluminum oxide in the 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, the preparation process is consistent with embodiment 5.

Embodiment 12

A kind of controlled bimodal vesicular structure Al ₂O ₃Stupalith, aluminum oxide in the 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, the preparation process is consistent with embodiment 5.

Embodiment 13

A kind of controlled bimodal vesicular structure Al ₂O ₃Stupalith; Aluminum oxide in the 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 simultaneously, the preparation process is consistent with embodiment 5.

Embodiment 14

A kind of controlled bimodal vesicular structure Al ₂O ₃Stupalith, aluminum oxide in the 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, the preparation process is consistent with embodiment 5.

Embodiment 15

A kind of controlled bimodal vesicular structure Al ₂O ₃Stupalith, aluminum oxide in the 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, the preparation process is consistent with embodiment 5.

Embodiment 16

A kind of controlled bimodal vesicular structure Al ₂O ₃Stupalith, aluminum oxide in the 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, the preparation process is consistent with embodiment 5.

Embodiment 17

A kind of controlled bimodal vesicular structure Al ₂O ₃Stupalith, aluminum oxide in the 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, the preparation process is consistent with embodiment 5.

Embodiment 18

A kind of controlled bimodal vesicular structure Al ₂O ₃Stupalith, aluminum oxide in the 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, the preparation process is consistent with embodiment 5.

Embodiment 19

A kind of controlled bimodal vesicular structure Al ₂O ₃Stupalith, aluminum oxide in the 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, the 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 fiber, and feedstock property is seen table 3.

Table 3

Embodiment 20

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

The first step, the pore-forming material and the alumina powder of two kinds of different shapes differing materials passed through 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; P is the porosity of porous material; V ₁And V ₂Be respectively the volume of pore-forming material;

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

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

In the 4th step, the powder of acquisition is packed in the pressing mold, places on the die sleeve between two compressing tablets between the push-down head, at the beginning of 20 seconds behind the one-step forming, puts into the isostatic cool pressing appearance again at the 500MPa compacted under in precompressed under the 125MPa through rapidform machine earlier, obtains prefabricated sample;

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

Embodiment 21

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

Embodiment 22

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

Embodiment 23

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

Embodiment 24

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

Embodiment 1～24 porous alumina ceramic material that the present invention prepares is respectively at analytical balance, D8 Discover type XRD diffraction analysis appearance, LEO 1530 type ESEMs and AutoPore IV 9500 V1.04 type mercury injection apparatuses void content, cross section pattern, specific surface area, pore volume and the pore size distribution of test sample 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.Can find out from table 4; Use different pore-forming materials (thomel and starch, Mierocrystalline cellulose and graphite or polymethylmethacrylate and nylon-66 fiber) and different length-to-diameter ratio Mierocrystalline celluloses as the different proportionings of pore-forming material to preparing to such an extent that the pore structure and the form of porous alumina ceramic material has very big influence.Because Mierocrystalline cellulose is unfavorable for base compactness just as pore-forming material, the raising of cellulosic volume content and length-to-diameter ratio has increased the void content and the pore size of sintered sample.As pore-forming material, is 20vol.% in the volume(tric)fraction of pore-forming material in raw mix for thomel and starch, and when 30vol.% and 50vol.%, the porous alumina ceramic sample is bimodal.As pore-forming material, when the length-to-diameter ratio of thomel is 6.21 and the volume(tric)fraction of pore-forming material in raw mix when being 50vol.%, porous alumina ceramic sample pore size distribution is bimodal for Mierocrystalline cellulose and graphite.Because Mierocrystalline cellulose and polymethylmethacrylate take fire about 160 ℃; The nylon-66 fiber takes fire about 253 ℃, and starch takes fire about 350 ℃, and graphite takes fire about 1000 ℃; Starch when sintering temperature is 1550 ℃; Mierocrystalline cellulose, the pore structure and the form of polymethylmethacrylate and nylon-66 fiber can not be kept, and thomel and graphite can be kept its pore structure and form.

Table 4

The above is merely one embodiment of the present invention; It or not whole or unique embodiment; The conversion of any equivalence that those of ordinary skills take technical scheme of the present invention through reading specification sheets of the present invention is claim of the present invention and contains.

Claims (10)

1. controlled bimodal vesicular structure Al ₂O ₃The preparation method of stupalith is characterized in that, may further comprise the steps:

The first step, the pore-forming material and the alumina powder of two kinds of different shapes differing materials passed through 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; P is the porosity of porous material; V ₁And V ₂Be respectively the design volume of pore-forming material;

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

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

In the 4th step, the powder of acquisition is packed in the pressing mold, places on the die sleeve between two compressing tablets between the push-down head, at the beginning of 20 seconds behind the one-step forming, puts into the isostatic cool pressing appearance again at the 500MPa compacted under in precompressed under the 125MPa through rapidform machine earlier, obtains prefabricated sample;

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

2. controlled bimodal vesicular structure Al according to claim 1 ₂O ₃The preparation method of stupalith is characterized in that, the pore-forming material of said two kinds of different shapes differing materials is spherical starch and fibrous carbon fiber, and the volume ratio of pore-forming material and aluminum oxide is 1～4: 4.

3. controlled bimodal vesicular structure Al according to claim 2 ₂O ₃The preparation method of stupalith is characterized in that, the mean diameter 7.00 μ m of said fibrous carbon fiber, length 50～150 μ m.

4. controlled bimodal vesicular structure Al according to claim 1 ₂O ₃The preparation method of stupalith is characterized in that, the pore-forming material of said two kinds of different shapes differing materials is flats graphite and fibrous cellulose, and the volume ratio of pore-forming material and aluminum oxide is 3～7: 7.

5. controlled bimodal vesicular structure Al according to claim 4 ₂O ₃The preparation method of stupalith is characterized in that, the mean diameter 14.5 μ m of said fibrous cellulose, length 90 μ m.

6. controlled bimodal vesicular structure Al according to claim 4 ₂O ₃The preparation method of stupalith is characterized in that, the mean diameter 14.5 μ m of said fibrous cellulose, length 150 μ m.

7. controlled bimodal vesicular structure Al according to claim 4 ₂O ₃The preparation method of stupalith is characterized in that, the mean diameter 14.5 μ m of said fibrous cellulose, length 200 μ m.

8. controlled bimodal vesicular structure Al according to claim 1 ₂O ₃The preparation method of stupalith is characterized in that, the pore-forming material of said two kinds of different shapes differing materials is particulate state polymethylmethacrylate and fibrous nylon-66 fiber, and the volume ratio of pore-forming material and aluminum oxide is 1～4: 4.

9. controlled bimodal vesicular structure Al according to claim 8 ₂O ₃The preparation method of stupalith is characterized in that, the mean diameter 19 μ m of said fibrous nylon-66 fiber, length 800 μ m.

10. according to the described controlled bimodal vesicular structure Al of the arbitrary claim of claim 1 to 9 ₂O ₃The preparation method of stupalith is characterized in that, in the original mixed powder of said step 1, adds the following sintering aid that accounts for mixed powder total mass 0.5%: any in silicon-dioxide, quicklime, yttrium oxide and the lanthanum trioxide.

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