CN119684026A

CN119684026A - Method for preparing foamed ceramic by foam impregnation process

Info

Publication number: CN119684026A
Application number: CN202411746202.0A
Authority: CN
Inventors: 李世鹏; 张一帆; 王刚
Original assignee: Sinosteel Luoyang Institute of Refractories Research Co Ltd
Current assignee: Sinosteel Luoyang Institute of Refractories Research Co Ltd
Priority date: 2024-12-02
Filing date: 2024-12-02
Publication date: 2025-03-25

Abstract

The present invention provides a method for preparing foam ceramics by a foam impregnation process. First, the foam matrix is uniformly coated with raw material micropowder, and then slurrying and subsequent drying and sintering processes are carried out. This method does not require alkali solution corrosion or complex surface treatment of the sponge matrix, can maintain the mechanical properties of the foam matrix, and has good shape retention after slurrying and is not easy to deform. The raw material micropowder coats the foam matrix, which increases the surface roughness of the foam matrix and can significantly improve the slurrying effect. In addition, the adaptability range of the ceramic slurry is large, and there is no need to add too much organic matter to the slurry to improve the slurrying effect. The foam matrix is powder-coated in a dynamic process, and the ceramic micropowder is evenly distributed on the surface of the foam matrix, ensuring the uniformity of the slurrying and the open porosity of the foam ceramic.

Description

Method for preparing foamed ceramic by foam impregnation process

Technical Field

The invention belongs to the field of ceramic materials, and particularly relates to a method for preparing foamed ceramics by a foam impregnation process.

Background

The foamed ceramic is a porous ceramic material with three-dimensional network structure and high porosity, and has the characteristics of small density, high porosity, large specific surface area, high thermal shock resistance, high chemical corrosion resistance, high fluid self-interference performance, high filtering adsorptivity and the like due to the special structure of the foamed ceramic, so that the foamed ceramic is widely applied to various aspects such as molten metal, gas-liquid filtration, chemical catalytic carriers, sound absorption and vibration reduction, biological materials, sensors and the like.

Because the foam matrix has poor hydrophilicity, how to improve the slurry coating effect of the foam matrix becomes the key for preparing the foam ceramic, the prior art generally improves the slurry coating effect of the foam matrix through alkali washing treatment and hydrophilic treatment, such as in a patent CN109231995A, the polyurethane foam is subjected to hydrolysis treatment by adopting a sodium hydroxide solution, a diaphragm is removed, the roughness is increased, and a better slurry coating effect is obtained, a patent CN105948804A is firstly respectively immersed with an activating agent, and then the activating agent is mixed and then immersed, so that the slurry coating quality of the foam carrier can be effectively improved, but alkali liquid used in the patent has certain corrosiveness, and the activating agent polyethylenimine has strong toxicity, so that a plurality of limitations are generated on practical operation.

Disclosure of Invention

The invention aims to provide a method for preparing foam ceramic by a foam impregnation process, which can effectively improve the slurry coating amount of a foam matrix without alkali lye corrosion or complex surface treatment on the foam matrix and further prepare the foam ceramic.

The invention adopts the following technical scheme for accomplishing the purposes:

The method for preparing the foam ceramic by using the foam impregnation process specifically comprises the following steps:

1) Dissolving a binder in a solvent to prepare a solution with cohesiveness;

2) Immersing the foam matrix into the solution completely, taking out and removing redundant solution;

3) Placing the immersed foam matrix and the ceramic powder in a closed container together, rolling or rolling the container to drive the foam matrix to roll and enable the ceramic powder to adhere to the foam matrix to form a foam matrix coated by the ceramic powder, and enabling the surface of the foam matrix to be rough;

4) Preparing ceramic slurry, performing slurry coating treatment on a foam matrix coated by ceramic powder, and removing redundant slurry to obtain a foam ceramic blank;

5) And drying the foamed ceramic blank and sintering at high temperature to obtain the foamed ceramic product.

The binder in the step 1 is water-soluble or alcohol-soluble, the water-soluble binder is polyvinyl alcohol solution or cellulose solution, and the alcohol-soluble binder is polyvinyl butyral.

The mass fraction of the polyvinyl alcohol solution is 1-5%.

The cellulose solution is carboxymethyl cellulose solution with the mass fraction of 1-3% or polyvinyl butyral solution with the mass fraction of 1-8%.

In the step 2, the soaking time of the foam matrix is 2-5min, and the redundant solution automatically flows out or is removed by extrusion acceleration.

In the step 3, the impregnated foam matrix and ceramic powder are placed in a V-shaped mixer

The method comprises the steps of overturning a mixer to coat, or placing the soaked foam matrix and ceramic powder in a ball milling tank, rolling on a roller mill to finish coating, adjusting the granularity of the coated ceramic powder according to the aperture of the foam matrix, and correlating the quality of the coated powder with the powder density.

The granularity of the ceramic powder is 1-30 mu m.

In the step 4, the main raw materials of the ceramic slurry are consistent with the components of the ceramic powder in the step 3, so that the coated powder is prevented from becoming an impurity phase, and the step of removing the excessive slurry can adopt a blowing or centrifuging mode.

The preparation method of the foamed ceramic has the advantages that the surface corrosion of the foamed matrix is not needed, the rebound and mechanical properties of the foamed matrix can be kept, the shape retention performance after the slurry coating is good, the foamed matrix is not easy to deform, the raw material micro powder is used for coating the foamed matrix to increase the surface roughness, the slurry coating effect can be obviously improved, the application range of the ceramic slurry is wider, excessive organic matters are not needed to be added into the slurry to improve the slurry coating effect, the foamed matrix is coated in the dynamic process, the ceramic micro powder is uniformly distributed on the surface of the foamed matrix, and the uniformity of slurry coating and the aperture ratio of the foamed ceramic are ensured.

Drawings

FIG. 1 is a photograph of a foam matrix of example 2.

FIG. 2 is a photograph of a foam matrix coated zirconia powder of example 2.

Detailed Description

For a better understanding of the present invention, the present invention will be further described with reference to examples, but the scope of the present invention is not limited to the description of the embodiments.

Example 1:

the embodiment is a preparation process of silicon carbide foam ceramic, which comprises the following specific steps:

1. dissolving a binder PVA (polyvinyl alcohol) in water to prepare a PVA solution with the mass fraction of 5%;

2. immersing a foam matrix of 30PPi into the PVA solution completely, immersing for 3min, taking out, and extruding out redundant solution;

3. placing the impregnated foam matrix and silicon carbide micro powder (3 mu m) into a ball milling tank, rolling on a roller ball mill, wherein the rotating speed of the roller is 120rpm, the time is 3-10 min, taking out the foam matrix coated with powder, and drying at 80-120 ℃ for later use, wherein the mass of the coated silicon carbide powder is 4-5 times that of the foam matrix;

4. Preparing SiC ceramic slurry, namely ball-milling and mixing SiC micro powder (5 mu m), magnesium stabilized zirconia micro powder (1 mu m), water and a dispersing agent (tetramethylammonium hydroxide) on a row of ball mill for 2-4 hours, wherein the ball-milling speed is 200-300 rpm, the SiC micro powder accounts for 95-98% of the total mass of the powder, and the volume and solid phase content of the slurry is 45-50%;

Soaking the foam substrate prepared in the step 3 in the slurry for 30-60 s, and removing the redundant slurry in a centrifugal way to obtain a foam ceramic blank;

5. drying the foamed ceramic blank at 80-120 ℃ for 2-6 hours, and performing heat preservation for 2-4 hours under the protection of Ar gas after drying to obtain the SiC foamed ceramic product.

According to the embodiment, the foam substrate is coated with the SiC micro powder with the thickness of 3 mu m, so that uniform slurry coating of the foam ceramic is realized, the slurry coating amount can reach 20 times of the mass of the foam substrate, and the powder coating effect can be seen in the attached drawing of the specification.

Example 2:

the embodiment is a preparation process of zirconia foam ceramic, which specifically comprises the following steps:

1. Dissolving a binder PVB (polyvinyl butyral) in absolute ethyl alcohol to prepare PVB solution with the mass fraction of 3%;

2. immersing a 40PPi foam matrix into the PVB solution completely, immersing for 3min, taking out, and extruding out redundant solution;

3. Placing the immersed foam matrix and magnesium stabilized zirconia micro powder (1 mu m) into a V-shaped mixer, wherein the rotation speed is 60rpm for 5min, taking out the foam matrix coated with the powder, and drying the foam matrix at 60-110 ℃ for standby, wherein the mass of the coated zirconia powder is 10-12 times that of the foam matrix;

4. Preparing zirconia ceramic slurry, namely ball-milling and mixing magnesium stabilized zirconia micro powder (1 mu m), water and a dispersing agent (ammonium polyacrylate) on a row of ball mill for 1-2 hours at a ball milling rotating speed of 200-300 rpm, wherein the volume solid phase content of the slurry is 40-45%;

Soaking the foam substrate prepared in the step 3 in the slurry for 30-60 s, and blowing out the redundant slurry by using a powerful fan to obtain a foam ceramic blank.

5. And drying the foamed ceramic blank at 80-120 ℃ for 2-6 hours, and performing high-temperature sintering at 1600-1700 ℃ for 2-4 hours after drying to obtain the magnesium-stabilized zirconia foamed ceramic product.

In the embodiment, the foam substrate is coated with zirconia micro powder with the diameter of 1 mu m, so that the foam ceramic is uniformly coated with slurry, and the slurry coating amount can reach 35 times of the quality of the foam substrate.

Claims

1. A method for preparing foamed ceramics by a foam impregnation process is characterized by comprising the following steps:

1) Dissolving a binder in a solvent to prepare a solution with cohesiveness;

2. The method for preparing foamed ceramic by using the foam impregnation process as set forth in claim 1, wherein the binder in the step 1 is water-soluble or alcohol-soluble, the water-soluble binder is a polyvinyl alcohol solution or a cellulose solution, and the alcohol-soluble binder is polyvinyl butyral.

3. The method for preparing foam ceramic by using the foam impregnation process as claimed in claim 2, wherein the mass fraction of the polyvinyl alcohol solution is 1-5%.

4. The method for preparing foam ceramic by using the foam impregnation process as claimed in claim 2, wherein the cellulose solution is 1-3% by mass of carboxymethyl cellulose solution or 1-8% by mass of polyvinyl butyral solution.

5. The method for preparing foam ceramic by using the foam impregnation process as claimed in claim 1, wherein in the step 2, the soaking time of the foam matrix is 2-5min, and the redundant solution automatically flows out or is removed by extrusion acceleration.

6. The method for preparing foam ceramic by using the foam impregnation process according to claim 1, wherein in the step 3, the impregnated foam matrix and ceramic powder are placed in a V-shaped mixer, the mixer is turned over to coat, or the impregnated foam matrix and ceramic powder are placed in a ball milling tank to roll on a roller mill to complete coating, the granularity of the coated ceramic powder is adjusted according to the pore diameter of the foam matrix, and the quality of the coated powder is related to the powder density.

7. The method for preparing foam ceramic by using the foam impregnation process as claimed in claim 6, wherein the granularity of the ceramic powder is 1-30 μm.

8. The method for preparing foamed ceramic by using the foam impregnation process as set forth in claim 1, wherein in the step 4, the main raw material of the ceramic slurry is consistent with the ceramic powder component in the step 3, so as to avoid the coated powder becoming an impurity phase, and in the step, the superfluous slurry is removed by adopting a blowing or centrifuging mode.