CN113135771B

CN113135771B - Multistage pore structure zirconium dioxide porous ceramic and preparation method thereof

Info

Publication number: CN113135771B
Application number: CN202110526394.4A
Authority: CN
Inventors: 刘玉付; 杨晨晞
Original assignee: Southeast University
Current assignee: Southeast University
Priority date: 2021-05-14
Filing date: 2021-05-14
Publication date: 2022-11-29
Anticipated expiration: 2041-05-14
Also published as: CN113135771A

Abstract

The invention discloses a zirconium dioxide porous ceramic with a hierarchical pore structure and a preparation method thereof, wherein a zirconium dioxide intermediate porous body is prepared by combining a pore-forming agent and a sol-gel method; ball-milling the intermediate porous body to obtain zirconia porous powder; the porous powder is used as a raw material, and the zirconium dioxide porous ceramic block is obtained after gel casting and heat treatment. The invention combines a template method and a sol-gel method to prepare the zirconia porous powder with a hierarchical pore structure. The multi-stage pore powder has the advantage of controllable pore size. And then, gel casting is adopted to successfully prepare the zirconium oxide porous ceramic block with the hierarchical pore structure. Tert-butanol is also a pore former during the gel casting stage, providing another source of pore size for the zirconia porous ceramic monolith. The porosity of the zirconia ceramic block with the multilevel pore structure can reach more than 70 percent, and the zirconia ceramic block can be widely applied to the fields of filtration, membrane separation, high-temperature heat insulation and the like.

Description

Multistage pore structure zirconium dioxide porous ceramic and preparation method thereof

Technical Field

The invention relates to the field of zirconium dioxide porous ceramics and preparation thereof, in particular to a zirconium dioxide porous ceramic with a hierarchical pore structure and a preparation method thereof.

Background

Zirconium dioxide is an important structural functional material, has the characteristics of high temperature resistance, high hardness, good thermal stability and chemical stability and the like, and is widely applied to the fields of fuel cells, heat insulation, information electronics, bionic materials and the like. The porous zirconia blocky ceramic material can not only improve the porosity of the material and reduce the heat insulation coefficient, but also regulate and control the pore wall size and arrangement of the heat insulation material to enhance the mechanical property of the material. Preparation of ZrO ₂ Porous structure of ZrO ₂ The unique chemical properties of the ZrO are combined with the porous space structure to obtain the ZrO with high porosity, high specific surface area, high chemical activity, light weight and high strength ₂ A material.

The porous solid material can be divided into three types of microporous materials with the pore diameter less than 2nm according to the pore diameter; mesoporous material with aperture of 2-50nm and macroporous material with aperture greater than 50 nm. The macroporous-mesoporous material can be widely applied to the fields of filtration, membrane separation, high-temperature heat insulation and the like.

The thermal conductivity of porous materials has a great correlation with their pore structure and porosity. The preparation process is an important means for regulating and controlling the pore structure of the porous ceramic, the requirements on the performance of the porous ceramic in different application fields are different, and the pore structure and the composition of the porous ceramic also determine the performance of the porous ceramic. Therefore, the method has practical significance for the synthesis of the hierarchical porous material and the enhancement of the control on the pore size.

In the prior art, when the zirconium dioxide porous ceramic is prepared, the wet gel is prepared by a sol-gel method, the space occupied by the liquid can be converted into pores by a proper process method, and the wet gel is easy to crack or even break due to capillary force generated by the liquid phase leaving the solid-liquid interface in the evaporation process under normal pressure, so that a block porous material is difficult to prepare. Limited by this, under normal pressure, the sol-gel method is more commonly used in the preparation of non-three-dimensional structural members such as zirconia nanopowders and films, and many studies have been made on the preparation of thermal barrier coatings using sols as precursors.

The porous material with a three-dimensional ordered pore structure can be prepared by combining a sol precursor with a plurality of special pore-forming agents, such as polystyrene microspheres. The self-assembly characteristic of the monodisperse polystyrene microspheres is utilized, the monodisperse polystyrene microspheres are firstly arranged in a face-centered cubic (the bulk density is 0.74), then the liquid-phase precursor is used for filling pores, the thickness of a sample is only a few microns at most, and the method is more suitable for the field of catalysis.

At present, the related research for preparing the structural part is less based on the combination of a sol precursor and a pore-forming agent method.

Disclosure of Invention

The purpose of the invention is as follows: in order to solve the problems of the prior art, a first object of the present invention is to provide a hierarchical porous structure zirconium dioxide porous ceramic.

The second purpose of the invention is to provide a preparation method of the multilevel pore structure zirconium dioxide porous ceramic.

The technical scheme is as follows: in order to achieve the purpose, the invention can adopt the following technical scheme:

a zirconium dioxide porous ceramic with a hierarchical pore structure is characterized in that pores in the zirconium dioxide porous ceramic are in a nano-submicron-micron hierarchical composite pore structure, wherein the nano pores are 2-50 nm; the submicron pore is 0.6-0.8 μm; the micron pores are 1-5 microns and are mainly concentrated in 2-3 microns; the pore distribution is locally ordered.

Further, the framework structure comprises one or more of the following features:

the method is characterized in that: the crystal grains forming the framework are irregular, the average size of the crystal grains is 270nm, the maximum particle diameter is 300-400 nm, the minimum particle diameter is not more than 100nm, and the particle size distribution is wide;

and (2) feature: the crystal grains forming the framework are irregular, the average size of the crystal grains is 120nm, the maximum particle diameter is 200-350 nm, the minimum particle diameter is 70-80 nm, and the particle size distribution is wide;

and (3) feature: the crystal grains forming the framework are fine spherical nano particles, and the average size of the crystal grains is 60nm;

and (4) feature: the crystal grains forming the framework are fine spherical nano particles and have a hollow sphere structure.

Further, the skeleton structure comprises the following characteristics 5: the skeleton and pores are distributed locally and orderly.

The skeleton material can form mesopores during lapping due to different length-width ratios of crystal grains, and then is combined with a polystyrene microsphere template to obtain the zirconium dioxide porous body with a hierarchical pore structure after roasting.

The porous body can be used as a raw material for preparing zirconium dioxide porous ceramics by gel casting after ball milling. The tertiary butanol used in the gel injection molding method is used as a solvent and also is a source of micron-sized pores, so that the porosity of the zirconia porous ceramic with the hierarchical pore structure is increased.

The invention discloses a first preparation method of a multilevel pore structure zirconium dioxide porous ceramic, which comprises the following steps:

(1) Dissolving a zirconium-containing precursor in a mixed solution of water and ethanol;

(2) And (3) gelation treatment: adding a pore-forming agent and polyacrylic acid into the mixed solution obtained in the step (1), uniformly stirring, and then adding propylene oxide to obtain blocky gel;

(3) Sealing, aging, drying and roasting the massive gel to obtain a zirconium dioxide porous intermediate with a hierarchical pore structure;

(4) And (3) uniformly mixing an organic monomer, a cross-linking agent and tert-butyl alcohol to prepare a premixed solution, adding a catalyst, the porous powder obtained after ball milling of the zirconium dioxide porous intermediate prepared in the step (3) and a dispersing agent into the premixed solution, uniformly mixing, adding an aqueous solution containing an initiator, quickly stirring, injecting into a mold, curing, demolding, drying and roasting to obtain the zirconium dioxide porous ceramic with the hierarchical pore structure.

Furthermore, the proportion of the pore-forming agent, the zirconium-containing precursor, the absolute ethyl alcohol, the water, the polyacrylic acid and the propylene oxide is (0.9-1.5): (1.8-3.22): (7.0-10.0): (1.0-3.0): (0.5-1.2): 1.0-1.5) by weight.

Furthermore, the mass ratio of alcohol to water in the mixed solution of water and ethanol is 6; the gelation treatment temperature is 60 ℃, and the pore-forming agent is 10wt.% of polystyrene microspheres; based on the preparation mode of the solvent precursor, different concentrations of zirconium salt and the addition of polyacrylic acid are controlled to obtain different framework structures, and the method specifically comprises the following steps:

when the concentration of zirconium salt is 0.5mol/L and the addition amount of polyacrylic acid is 5wt.%, a skeleton structure containing the feature 1 is obtained;

when the zirconium salt concentration is 0.75mol/L and the polyacrylic acid is added in an amount of 10wt.%, a skeleton structure containing feature 2 is obtained;

when the concentration of zirconium salt is 1.0mol/L and the addition amount of polyacrylic acid is 10wt.%, the skeleton structure including feature 3 is obtained;

when the zirconium salt concentration is 0.75mol/L to 1.0mol/L and the polyacrylic acid is added in an amount of 5wt.%, the skeleton structure as defined to include feature 4 is obtained.

wt.% is calculated relative to the mass of solvent.

Furthermore, in the step (3), the aging temperature is 60 ℃, the aging time is 12 hours, absolute ethyl alcohol is used for replacing for 12 to 24 hours after aging, the drying temperature is 40 ℃, the roasting temperature is 600 ℃ to 700 ℃, the roasting time is 1 to 2 hours, and the temperature rising speed is 2 to 4 ℃/min.

The invention also discloses a second preparation method of the multilevel pore structure zirconium dioxide porous ceramic, which comprises the following steps:

1) Preparing zirconium sol: dissolving a zirconium-containing precursor in an absolute ethyl alcohol solution, adding propylene oxide, adding the solution into a reaction kettle, drying, sealing and aging to obtain zirconium sol;

2) Adding a pore-forming agent into the zirconium sol, ultrasonically dispersing to obtain a suspension, drying, and calcining to obtain a zirconium dioxide porous ceramic intermediate with a hierarchical pore structure and ordered pore arrangement;

3) Uniformly mixing an organic monomer, a cross-linking agent and tert-butyl alcohol to prepare a premixed solution, adding a catalyst, the porous powder obtained after ball milling of the zirconium dioxide porous intermediate prepared in the step 2) and a dispersing agent into the premixed solution, uniformly mixing, adding an aqueous solution containing an initiator, quickly stirring, injecting into a mold, curing, demolding, drying and roasting to obtain the multistage pore structure zirconium dioxide porous ceramic.

Furthermore, in the step 1), the drying temperature is 110 ℃, the drying time is 16h, and the sealing and aging are carried out for 48h.

Furthermore, the weight ratio of the pore-forming agent to the zirconium sol in the step 2) is (1-1.5) to (10-30); drying the suspension at the drying temperature of 40-60 ℃ for 6-8 h, then drying at 150 ℃ for 3h, and raising the temperature to 1000-1200 ℃ at the calcining temperature of 3-4 ℃/min, and carrying out heat preservation and calcination for 1-2 h.

In the two preparation methods, in the last step, the organic monomer is N, N-hydroxymethyl acrylamide, the cross-linking agent is N, N-methylene bisacrylamide, the catalyst is N, N, N ', N' -tetramethyl ethylenediamine, the dispersing agent is polyvinylpyrrolidone, and the initiator is ammonium persulfate; the weight ratio of the organic monomer, the cross-linking agent, the catalyst, the dispersing agent, the zirconium dioxide porous body and the tertiary butanol is (0.9-1.2), (0.09-0.12), (0.20-0.36), (0.09-0.12), (0.30-0.60), (1.5-3.0) and (9.0-11.0).

The synthesis principle is as follows: the method takes inorganic zirconium salt as a raw material, and has the obvious characteristic of controllable hydrolysis rate compared with an expensive zirconium alkoxide raw material; the inorganic zirconium salt is also partially hydrolyzed in the alcohol-water mixed solution, and the propylene oxide is used as a 'proton scavenger' to solvate metal ions in the solution to form [ M (H2O) _m ] ⁿ⁺ Which is sufficiently acidic to donate a proton, propylene oxide undergoes a ring-opening reaction by the aforementioned proton, and [ M (H2O) _m ] ⁿ⁺ A series of hydrolysis and polycondensation reactions are carried out to form a metal oxide gel. On the basis of a dropping propylene oxide method, a small amount of low molecular weight polyacrylic acid is introduced as a dispersing agent and a guiding agent, a gelation mechanism is changed, so that metal hydroxide or oxide preferentially nucleates on carboxyl functional groups of the polyacrylic acid, colloidal groups nucleate along the surface of polyacrylic acid molecular chains, grow restrictively due to space factors and finally grow to be mutually bonded to form gel, the gel has higher formability and strength, and polystyrene microspheres uniformly dispersed in a sol state are cured in situ in a gel state.

Has the advantages that: the invention has the following advantages:

1) The pore-forming agent is easier to be uniformly dispersed in the liquid phase precursor, and then is cured in situ to form gel, so that the relative position of the dispersed gel can be kept;

2) According to actual needs, the particle size of the pore-forming agent polystyrene microspheres can be selected, and then the multilevel pore structure zirconium dioxide porous ceramic with various pore structures can be obtained through adjustment;

3) The porosity of the zirconium dioxide porous ceramic with the hierarchical pore structure prepared by the invention is 65-75%, and the compressive strength can reach 15MPa.

Drawings

FIG. 1 is a scanning electron micrograph of the pore former (micron-sized polystyrene microspheres) of example 1;

FIG. 2 is a scanning electron micrograph of the zirconium dioxide porous intermediate prepared in example 1;

FIG. 3 is a scanning electron micrograph of a hierarchical pore structure zirconium dioxide porous ceramic prepared in example 1;

FIG. 4 is a scanning electron micrograph of the pore-forming agent (nano-sized polystyrene microspheres) of example 2;

FIG. 5 is a scanning electron micrograph of the zirconium dioxide porous intermediate prepared in example 2;

FIG. 6 is a scanning electron micrograph of the hierarchical pore structure zirconium dioxide porous ceramic prepared in example 2;

fig. 7 is a scanning electron micrograph of the zirconium dioxide porous intermediate prepared in example 3;

FIG. 8 is a scanning electron micrograph of the zirconium dioxide porous intermediate prepared in example 4;

fig. 9 is a scanning electron micrograph of the zirconium dioxide porous intermediate prepared in example 5;

FIG. 10 is a scanning electron micrograph of the zirconium dioxide porous intermediate prepared in example 6;

fig. 11 is a scanning electron micrograph of the zirconium dioxide porous intermediate prepared in comparative example 1.

Detailed Description

Example 1:

(1) Dissolving 3.22g of zirconium oxychloride in a mixed solution of 8.6g of absolute ethyl alcohol and 1.4g of deionized water;

(2) 1.0g of micron-sized polystyrene microspheres were added as shown in FIG. 1. After the mixture is uniformly dispersed by ultrasonic, adding 1.0g of polyacrylic acid, stirring for half an hour, adding 1.0g of propylene oxide, putting the obtained gel into a drying oven, sealing and aging for 12 hours at 60 ℃, adding absolute ethyl alcohol for replacing for 12 hours, then drying at 40 ℃, then putting into a muffle furnace, heating to 700 ℃ at the speed of 2 ℃/min, carrying out heat preservation and roasting for 1 hour, cooling the sample to room temperature along with the furnace, and taking out to obtain ZrO ₂ The morphology of the porous intermediate is shown in figure 2.

(3) Dissolving 1.0gN, N-hydroxymethyl acrylamide in 10g of tertiary butanol, then adding 0.1gN, N-methylene bisacrylamide, 0.1g of polyvinylpyrrolidone, 0.20gN, N' -tetramethylethylenediamine and 2.0g of zirconium dioxide porous intermediate, uniformly mixing, then adding 2mL of ammonium persulfate solution with the concentration of 0.2g/mL, standing for 12h, demoulding, drying at 50 ℃, heating to 100 ℃, continuously drying for 2h, heating to 700 ℃ at the speed of 2 ℃/min, then heating to 1100 ℃ at the speed of 5 ℃/min, insulating, roasting for 1h, furnace-cooling a sample to room temperature, and taking out to obtain the zirconium dioxide porous ceramic with a hierarchical pore structure, wherein the microstructure of the zirconium dioxide porous ceramic is shown in a figure 3, and the framework structure of the zirconium dioxide porous ceramic comprises the following characteristics of 3: the crystal grains are fine spherical nano particles, and the average size of the crystal grains is 60nm.

The porosity is 66.4%, the compressive strength is 15.17MPa, and the thermal conductivity is 0.362W/(m.k) through tests.

Example 2:

(2) 0.5g each of micron-sized and nano-sized polystyrene microspheres were added, and the nano-microspheres are shown in FIG. 4. After the mixture is uniformly dispersed by ultrasonic, adding 1.2g of polyacrylic acid, stirring for half an hour, adding 1.0g of propylene oxide, putting the obtained gel into an oven, hermetically aging for 12 hours at 60 ℃, adding absolute ethyl alcohol for replacing for 12 hours, then placing the gel into a muffle furnace for drying at 40 ℃, heating to 700 ℃ at the speed of 3 ℃/min, carrying out heat preservation and roasting for 1 hour, cooling the sample to room temperature along with the furnace, taking out and grinding to obtain ZrO ₂ The morphology of the porous intermediate is shown in FIG. 5;

(3) Dissolving 1.0gN, N-hydroxymethyl acrylamide in 10g of tertiary butanol, adding 0.10gN, N-methylene bisacrylamide, 0.10g of polyvinylpyrrolidone, 0.20gN, N' -tetramethylethylenediamine and 1.5g of zirconium dioxide porous intermediate, uniformly mixing, adding 2mL of ammonium persulfate solution with the concentration of 0.4g/mL, standing for 12h, demolding, drying at 50 ℃, heating to 100 ℃, continuously drying for 2h, heating to 700 ℃ at the speed of 2 ℃/min, then heating to 1100 ℃ at the speed of 5 ℃/min, carrying out heat preservation roasting for 1h, cooling a sample to room temperature along with a furnace, and taking out to obtain the formed zirconium dioxide porous ceramic, wherein the microstructure of the formed zirconium dioxide porous ceramic is shown in figure 6, and the skeleton structure of the zirconium dioxide porous ceramic comprises the following characteristics of 3: the crystal grains are fine spherical nano particles, and the average size of the crystal grains is 60nm.

The porosity is 72.3%, the compressive strength is 7.27MPa, and the thermal conductivity is 0.272W/(m.k) through testing.

Example 3:

(1) Dissolving 1.66g of zirconium oxychloride in a mixed solution of 8.6g of absolute ethyl alcohol and 1.4g of deionized water;

(2) 1.0g of micron-sized polystyrene microspheres were added as shown in FIG. 1. After the ultrasonic dispersion is uniform, adding 0.5g of polyacrylic acid, stirring for half an hour, adding 1.0g of propylene oxide, putting the obtained gel into a drying oven, sealing and aging for 12 hours at 60 ℃, adding absolute ethyl alcohol for replacing for 12 hours, drying at 40 ℃, then putting into a muffle furnace,heating to 700 ℃ at the speed of 2 ℃/min, keeping the temperature and roasting for 1h, cooling the sample to room temperature along with the furnace and taking out to obtain ZrO ₂ The morphology of the porous intermediate is shown in FIG. 7;

(3) Dissolving 1.0g of N, N-hydroxymethyl acrylamide in 10g of tertiary butanol, then adding 0.1g of N, N-methylene bisacrylamide, 0.1g of polyvinylpyrrolidone, 0.20g of N, N' -tetramethylethylenediamine and 2.0g of zirconium dioxide porous intermediate, uniformly mixing, then adding 2mL of ammonium persulfate solution with the concentration of 0.2g/mL, standing for 12h, demoulding, drying at 50 ℃, heating to 100 ℃, continuing to dry for 2h, heating to 700 ℃ at the speed of 2 ℃/min, then heating to 1100 ℃ at the speed of 5 ℃/min, insulating and roasting for 1h, cooling the sample to room temperature along with a furnace, and taking out to obtain the zirconium dioxide porous ceramic with a hierarchical pore structure, wherein the framework structure of the zirconium dioxide porous ceramic comprises the following characteristics of 1: the crystal grains forming the framework are irregular, the average size of the crystal grains is 270nm, the maximum particle diameter is 300-400 nm, the minimum particle diameter is not more than 100nm, and the particle size distribution is wide;

example 4:

(1) Dissolving 2.42g of zirconium oxychloride in a mixed solution of 8.6g of absolute ethyl alcohol and 1.4g of deionized water;

(2) 1.0g of micron-sized polystyrene microspheres were added as shown in FIG. 1. After the mixture is uniformly dispersed by ultrasonic, adding 1.0g of polyacrylic acid, stirring for half an hour, adding 1.0g of propylene oxide, putting the obtained gel into a drying oven, sealing and aging for 12 hours at 60 ℃, adding absolute ethyl alcohol for replacing for 12 hours, then drying at 40 ℃, then putting into a muffle furnace, heating to 700 ℃ at the speed of 2 ℃/min, carrying out heat preservation and roasting for 1 hour, cooling the sample to room temperature along with the furnace, and taking out to obtain ZrO ₂ The morphology of the porous intermediate is shown in FIG. 8;

(3) Dissolving 1.0g of N, N-hydroxymethyl acrylamide in 10g of tertiary butanol, then adding 0.1g of N, N-methylene bisacrylamide, 0.1g of polyvinylpyrrolidone, 0.20g of N, N' -tetramethylethylenediamine and 2.0g of zirconium dioxide porous intermediate, uniformly mixing, then adding 2mL of ammonium persulfate solution with the concentration of 0.2g/mL, standing for 12h, demoulding, drying at 50 ℃, heating to 100 ℃, continuing to dry for 2h, heating to 700 ℃ at the speed of 2 ℃/min, then heating to 1100 ℃ at the speed of 5 ℃/min, insulating and roasting for 1h, cooling the sample to room temperature along with a furnace, and taking out to obtain the zirconium dioxide porous ceramic with a hierarchical pore structure, wherein the framework structure of the zirconium dioxide porous ceramic comprises the following characteristics of 2: the crystal grains forming the framework are irregular, the average size of the crystal grains is 120nm, the maximum particle diameter is 200-350 nm, the minimum particle diameter is 70-80 nm, and the particle size distribution is wide.

Example 5:

(2) 1.0g of micron-sized polystyrene microspheres were added as shown in FIG. 1. After the uniform ultrasonic dispersion, adding 0.5g of polyacrylic acid, stirring for half an hour, adding 1.0g of propylene oxide, putting the obtained gel into an oven, hermetically aging for 12 hours at 60 ℃, adding absolute ethyl alcohol for replacing for 12 hours, drying at 40 ℃, then putting into a muffle furnace, heating to 700 ℃ at the speed of 2 ℃/min, carrying out heat preservation and roasting for 1 hour, cooling the sample to room temperature along with the furnace, taking out to obtain ZrO ₂ The morphology of the porous intermediate is shown in FIG. 9;

(3) Dissolving 1.0g of N, N-hydroxymethyl acrylamide in 10g of tert-butyl alcohol, adding 0.1g of N, N-methylene bisacrylamide, 0.1g of polyvinylpyrrolidone, 0.20g of N, N' -tetramethylethylenediamine and 2.0g of zirconium dioxide porous intermediate, uniformly mixing, adding 2mL of ammonium persulfate solution with the concentration of 0.2g/mL, standing for 12h, demolding, drying at 50 ℃, heating to 100 ℃, continuously drying for 2h, heating to 700 ℃ at the speed of 2 ℃/min, then heating to 1100 ℃ at the speed of 5 ℃/min, roasting for 1h, cooling the sample to room temperature along with a furnace, and taking out to obtain the zirconium dioxide porous ceramic with the hierarchical pore structure; its skeleton texture includes feature 4: the crystal grains forming the framework are fine spherical nano particles and have a hollow sphere structure.

Example 6:

(1) Dissolving 1.6g of zirconium oxychloride in 70mL of absolute ethanol, adding 5.8g of propylene oxide, adding the solution into a reaction kettle, drying for 16h at 110 ℃, and then sealing and aging for 48h to obtain zirconium sol;

(2) 1.0g of micron-sized polystyrene microspheres were added as shown in FIG. 1. Uniformly dispersing in 3.0g of absolute ethyl alcohol, adding 10.0g of the prepared zirconium sol, ultrasonically dispersing for 10min, drying the obtained suspension at 60 ℃ for 7h, drying at 150 ℃ for 3h, taking out a sample, heating to 1100 ℃ at 3 ℃, preserving heat, calcining for 1h, cooling the sample to room temperature along with a furnace, and taking out to obtain ZrO with slightly-ordered pore arrangement ₂ An intermediate porous material, as shown in fig. 10;

(3) Dissolving 1.0g of N, N-hydroxymethyl acrylamide in 10g of tert-butyl alcohol, adding 0.1g of N, N-methylene bisacrylamide, 0.1g of polyvinylpyrrolidone, 0.20g of N, N' -tetramethylethylenediamine and 2.0g of zirconium dioxide porous intermediate, uniformly mixing, adding 2mL of ammonium persulfate solution with the concentration of 0.2g/mL, standing for 12h, demolding, drying at 50 ℃, heating to 100 ℃, continuously drying for 2h, heating to 700 ℃ at the speed of 2 ℃/min, then heating to 1100 ℃ at the speed of 5 ℃/min, roasting for 1h, cooling a sample to room temperature along with a furnace, and taking out to obtain the zirconium dioxide porous ceramic with the hierarchical pore structure, wherein the framework structure of the zirconium dioxide porous ceramic comprises the following characteristics of 5: the skeleton and pores are distributed locally and orderly.

Comparative example 1:

(2) Adding 0.5g of polyacrylic acid into a liquid-phase precursor of zirconium without adding any pore-forming agent, stirring for half an hour, adding 1.0g of propylene oxide, putting the obtained gel into an oven, hermetically aging at 60 ℃ for 12h, adding absolute ethyl alcohol for replacing for 12h, drying at 40 ℃, then putting into a muffle furnace, heating to 700 ℃ at the speed of 2 ℃/min, carrying out heat preservation and roasting for 1h, cooling the sample to room temperature along with the furnace, and taking out to obtain ZrO ₂ A porous intermediate;

(3) 1.0g of N, N-hydroxymethyl acrylamide is dissolved in 10g of tertiary butanol, then 0.1g of N, N-methylene bisacrylamide, 0.1g of polyvinylpyrrolidone, 0.20g of N, N' -tetramethylethylenediamine and 2.0g of zirconium dioxide porous intermediate are added, after uniform mixing, 2mL of ammonium persulfate solution with the concentration of 0.2g/mL is added, the mixture is kept stand for 12h, after demoulding and drying at 50 ℃, the temperature is raised to 100 ℃, drying is continued for 2h, after the temperature is raised to 700 ℃ at the speed of 2 ℃/min, the temperature is raised to 1100 ℃ at the speed of 5 ℃/min, the mixture is kept stand for 1h, and after a sample is cooled to room temperature along with a furnace, the sample is taken out, so that the zirconium oxide porous ceramic with the hierarchical pore structure is obtained, the appearance of the zirconium oxide porous ceramic is shown in a graph 11, the distribution of the pore structure is disordered, only pores with the sizes of micrometer are present, the multilevel pore structure cannot be obtained, and through holes with the size of more than 20 micrometers exist, so that the mechanical property of the porous ceramic block body is influenced.

Claims

1. A preparation method of a zirconium dioxide porous ceramic with a hierarchical pore structure is characterized in that pores in the zirconium dioxide porous ceramic are in a nano-submicron-micron hierarchical composite pore structure, wherein the nano pores are 2 nm-50 nm; the submicron pore is 0.6-0.8 μm; the micron pore size is 1-5 μm; the pore distribution is locally ordered;

the preparation method comprises the following steps:

(1) Dissolving a zirconium-containing precursor into a mixed solution of water and ethanol;

2. The method according to claim 1, wherein the hierarchical structure zirconium dioxide porous ceramic has a skeleton structure comprising one or more of the following features:

3. The method for preparing a hierarchical porous zirconium dioxide porous ceramic according to claim 1, wherein: the weight ratio of the pore-forming agent, the zirconium-containing precursor, the absolute ethyl alcohol, the water, the polyacrylic acid and the epoxypropane is (0.9-1.5), (1.8-3.22), (7.0-10.0), (1.0-3.0), (0.5-1.2) and (1.0-1.5).

4. The method for preparing a hierarchical porous zirconium dioxide porous ceramic according to claim 2, wherein: the mass ratio of alcohol to water in the mixed solution of water and ethanol is 6; the gelation treatment temperature is 60 ℃, and the pore-forming agent is 10wt.% of polystyrene microspheres; the zirconium-containing precursor is zirconium salt;

when the concentration of zirconium salt is 0.75mol/L and the addition amount of polyacrylic acid is 10wt.%, a skeleton structure containing the feature 2 is obtained;

when the concentration of zirconium salt is 1.0mol/L and the addition amount of polyacrylic acid is 10wt.%, a skeleton structure containing the feature 3 is obtained;

when the concentration of the zirconium salt is 0.75mol/L to 1.0mol/L and the addition amount of the polyacrylic acid is 5wt.%, the skeleton structure containing the feature 4 is obtained.

5. The method for preparing the hierarchical porous structure zirconium dioxide porous ceramic according to claim 1, wherein: in the step (3), the aging temperature is 60 ℃, the aging time is 12 hours, the anhydrous ethanol is used for replacing for 12 to 24 hours after aging, the drying temperature is 40 ℃, the roasting temperature is 600 ℃ to 700 ℃, the roasting time is 1 to 2 hours, and the heating speed is 2 to 4 ℃/min.

6. A preparation method of a zirconium dioxide porous ceramic with a hierarchical pore structure is characterized in that pores in the zirconium dioxide porous ceramic are in a nano-submicron-micron hierarchical composite pore structure, wherein the nano pores are 2 nm-50 nm; the submicron pore is 0.6-0.8 μm; the micron pore size is 1-5 μm; the pore distribution is locally ordered;

the preparation method comprises the following steps:

1) Preparing zirconium sol: dissolving a zirconium-containing precursor in an absolute ethyl alcohol solution, adding epoxypropane, adding the solution into a reaction kettle, drying, sealing and aging to obtain zirconium sol;

2) Adding a pore-forming agent into the zirconium sol, performing ultrasonic dispersion to obtain a suspension, drying and calcining to obtain a zirconium dioxide porous ceramic intermediate with a hierarchical pore structure and ordered pore arrangement;

3) Uniformly mixing an organic monomer, a cross-linking agent and tert-butyl alcohol to prepare a premixed solution, adding a catalyst and the porous powder obtained after ball-milling of the zirconium dioxide porous intermediate prepared in the step 2) and a dispersing agent into the premixed solution, uniformly mixing, adding an aqueous solution containing an initiator, quickly stirring, injecting into a mold, curing, demolding, drying and roasting to obtain the zirconium dioxide porous ceramic with the hierarchical pore structure.

7. The method according to claim 6, wherein the hierarchical porous structure of the zirconium dioxide porous ceramic comprises a characteristic 5: the skeleton and pores are distributed locally and orderly.

8. The method for preparing the hierarchical porous structure zirconium dioxide porous ceramic according to claim 6, wherein: in the step 1), the drying temperature is 110 ℃, the drying time is 16h, and the sealing and aging are carried out for 48h.

9. The method for preparing a hierarchical porous zirconium dioxide porous ceramic according to claim 6, wherein: in the step 2), the weight ratio of the pore-forming agent to the zirconium sol is (1-1.5) to (10-30); drying the suspension at the drying temperature of 40-60 ℃ for 6-8 h, then drying at 150 ℃ for 3h, and raising the temperature to 1000-1200 ℃ at the calcining temperature of 3-4 ℃/min, and carrying out heat preservation and calcination for 1-2 h.