阅读说明：本技术 一种碳纤维增韧碳化硅泡沫陶瓷及其制备方法 (Carbon fiber toughened silicon carbide foamed ceramic and preparation method thereof ) 是由 李赛赛 金新新 李明晖 陈若愚 常兵 于 2020-12-09 设计创作，主要内容包括：本发明公开了泡沫陶瓷技术领域的一种碳纤维增韧碳化硅泡沫陶瓷及其制备方法,包括聚氨酯泡沫和碳化硅多孔陶瓷浆料,碳化硅多孔陶瓷浆料包括以下质量份原料：碳化硅微粉50-70份,氧化铝微粉10-20份,二氧化硅微粉2-5份,硅粉1-3份,改性碳纤维0.5-2.5份,聚丙烯酸盐0.2-1.2份,羧甲基纤维素0.05-0.35份,去离子水20-35份；本发明并不涉及二次浸渍技术因此简化了制备工艺,提升了生产效率；本发明通过添加改性碳纤维和金属硅粉显著改善了碳化硅泡沫陶瓷的热震稳定性、断裂韧性和高温机械强度。(The invention discloses a carbon fiber toughened silicon carbide foamed ceramic and a preparation method thereof in the technical field of foamed ceramics, wherein the foamed ceramic comprises polyurethane foam and silicon carbide porous ceramic slurry, and the silicon carbide porous ceramic slurry comprises the following raw materials in parts by mass: 50-70 parts of silicon carbide micro powder, 10-20 parts of alumina micro powder, 2-5 parts of silicon dioxide micro powder, 1-3 parts of silicon powder, 0.5-2.5 parts of modified carbon fiber, 0.2-1.2 parts of polyacrylate, 0.05-0.35 part of carboxymethyl cellulose and 20-35 parts of deionized water; the invention does not relate to a secondary impregnation technology, thereby simplifying the preparation process and improving the production efficiency; the thermal shock stability, the fracture toughness and the high-temperature mechanical strength of the silicon carbide foam ceramic are obviously improved by adding the modified carbon fibers and the metal silicon powder.)

1. The carbon fiber toughened silicon carbide foamed ceramic is characterized by comprising polyurethane foam and silicon carbide porous ceramic slurry, wherein the silicon carbide porous ceramic slurry comprises the following raw materials in parts by mass: 50-70 parts of silicon carbide micro powder, 10-20 parts of alumina micro powder, 2-5 parts of silicon dioxide micro powder, 1-3 parts of silicon powder, 0.5-2.5 parts of modified carbon fiber, 0.2-1.2 parts of polyacrylate, 0.05-0.35 part of carboxymethyl cellulose and 20-35 parts of deionized water.

2. The carbon fiber toughened silicon carbide foamed ceramic according to claim 1, wherein the silicon carbide micro powder comprises 60 parts of aluminum oxide micro powder, 15 parts of silicon dioxide micro powder, 2 parts of silicon metal powder, 1.5 parts of carbon fibers, 1 part of polyacrylate, 0.2 part of carboxymethyl cellulose and 30 parts of deionized water.

3. The carbon fiber-toughened silicon carbide foamed ceramic according to claim 1, wherein the particle size of the fine silicon carbide powder particles is 2 to 4 μm.

4. The carbon fiber toughened silicon carbide foamed ceramic according to claim 1, wherein the alumina micropowder is a bimodal activated alumina micropowder, and the particle size of the alumina micropowder particles is 1-2 μm.

5. The carbon fiber toughened silicon carbide foamed ceramic according to claim 1, wherein the silicon powder is metal silicon powder, and the particle size of the silicon powder particles is 10-40 μm.

6. The carbon fiber-toughened silicon carbide foamed ceramic according to claim 1, wherein the modified carbon fibers have a length of 1-5mm and a diameter of 70 μm.

7. The carbon fiber-toughened silicon carbide foamed ceramic according to claim 1, wherein the modified carbon fibers are prepared by a method comprising, in S1: putting the carbon fiber into an ethanol solution, ultrasonically cleaning, and drying; s2: putting the dried carbon fiber into a nitric acid solution with the mass fraction of 68% and putting the carbon fiber into a water bath kettle, controlling the reaction temperature to be 80-100 ℃ and the reaction time to be 1-1.5 h; s3: and taking out the carbon fiber treated by nitric acid, cleaning and drying to obtain the modified carbon fiber.

8. The preparation method of the carbon fiber toughened silicon carbide foamed ceramic according to any one of claims 1 to 7, wherein the preparation method comprises the following steps:

(1) carrying out vacuum ball milling on silicon carbide micro powder, alumina micro powder, silica micro powder, silicon powder, modified carbon fiber, polyacrylate, carboxymethyl cellulose and deionized water for 1-3h to obtain silicon carbide porous ceramic slurry;

(2) soaking polyurethane foam in silicon carbide porous ceramic slurry under a vacuum condition, blowing or centrifugally throwing the slurry by compressed air after soaking, naturally drying for 12-24h, and then drying in an oven at the temperature of 100 ℃ for 12-24h to obtain a precursor;

(3) and putting the precursor into a tubular furnace, firstly heating to 1450-1600 ℃ at a heating rate of 2-5 ℃/min under a nitrogen environment, preserving heat for 3-5h, then cooling to 1000 ℃ at 5 ℃/min, preserving heat for 3-5h, and finally cooling to room temperature along with the furnace to obtain the carbon fiber toughened silicon carbide foamed ceramic.

Technical Field

The invention relates to the technical field of foamed ceramics, in particular to carbon fiber toughened silicon carbide foamed ceramics and a preparation method thereof.

Background

The porous ceramic prepared by the organic foam impregnation method has the advantages of high porosity, large specific surface area and the like due to the three-dimensional interpenetrating network structure of the polyurethane foam template, has the characteristics of high temperature resistance, high mechanical strength, chemical corrosion resistance and the like of the ceramic, and is widely applied to the fields of heat exchange materials, high-temperature metal filters, porous burners, chemical catalyst carriers and the like. However, the inherent brittleness of the carbon-silicon covalent bond in the silicon carbide porous ceramic results in the high brittleness of the porous ceramic and the triangular cell ribs generated by the decomposition of the polyurethane foam at the temperature of 600 ℃ at 200-. The carbon fiber has the advantages of small specific gravity, heat resistance, corrosion resistance, high specific strength and specific modulus, excellent high-temperature mechanical property and excellent knittability, so that the carbon fiber reinforced silicon carbide porous ceramic prepared by adopting the carbon fiber reinforced silicon carbide can effectively improve the brittleness of the silicon carbide porous ceramic and improve the high-temperature strength of the silicon carbide porous ceramic.

The patent technology of "preparation method of mullite whisker toughened silicon carbide porous ceramic" (CN110452008A) discloses a mullite whisker reinforced silicon carbide porous ceramic which is prepared by premixing, dissolving, mixing, molding, drying and firing silicon carbide powder and silicon powder which are used as raw materials, aluminum nitrate which is used as an aluminum source, ammonium fluoride which is used as a catalyst, and starch which is used as a bonding agent and a pore-forming agent. Although the method enhances the strength of the silicon carbide porous ceramic to a certain extent, the preparation process is complex, and the prepared silicon carbide ceramic has lower density.

A process for preparing the porous silicon carbide ceramic reinforced by short fibres and nano silicon carbide fibres (CN105859318A) features that the short carbon fibres are used as three-layer skeleton, activated carbon and phenolic resin are used as carbon source, and the short carbon fibres and phenolic resin are heated to a temp higher than the melting point of silicon in argon atmosphere for reaction with silicon powder. Although the bending strength of the porous ceramic is improved by the method, the pore generated by the decomposition of unreacted silicon powder and phenolic resin leads the porous ceramic pore rib interface effect to be obvious and the compactness thereof to be lower.

Therefore, a carbon fiber-toughened silicon carbide ceramic foam is proposed to solve the above problems.

Disclosure of Invention

The invention aims to provide carbon fiber toughened silicon carbide foamed ceramic and a preparation method thereof, and aims to solve the problems of high brittleness and low strength of the silicon carbide foamed ceramic.

In order to achieve the purpose, the invention provides the following scheme to realize the following steps: the carbon fiber toughened silicon carbide foamed ceramic comprises polyurethane foam and silicon carbide porous ceramic slurry, wherein the silicon carbide porous ceramic slurry comprises the following raw materials in parts by mass: 50-70 parts of silicon carbide micro powder, 10-20 parts of alumina micro powder, 2-5 parts of silicon dioxide micro powder, 1-3 parts of silicon powder, 0.5-2.5 parts of modified carbon fiber, 0.2-1.2 parts of polyacrylate, 0.05-0.35 part of carboxymethyl cellulose and 20-35 parts of deionized water.

Preferably, the silicon carbide micro powder comprises 60 parts of silicon carbide micro powder, 15 parts of alumina micro powder, 4 parts of silicon dioxide micro powder, 2 parts of metal silicon powder, 1.5 parts of carbon fiber, 1 part of polyacrylate, 0.2 part of carboxymethyl cellulose and 30 parts of deionized water.

Preferably, the particle size of the silicon carbide micro powder particles is 2-4 μm.

Preferably, the alumina micropowder is bimodal active alumina micropowder, and the particle size of alumina micropowder particles is 1-2 μm.

Preferably, the silicon powder is metal silicon powder, and the particle size of the silicon powder particles is 10-40 μm.

Preferably, the modified carbon fiber has a length of 1-5mm and a diameter of 70 μm.

Preferably, the modified carbon fiber is prepared by the following method, S1: putting the carbon fiber into an ethanol solution, ultrasonically cleaning, and drying; s2: putting the dried carbon fiber into a nitric acid solution with the mass fraction of 68% and putting the carbon fiber into a water bath kettle, controlling the reaction temperature to be 80-100 ℃ and the reaction time to be 1-1.5 h; s3: and taking out the carbon fiber treated by nitric acid, cleaning and drying to obtain the modified carbon fiber.

The invention also provides a preparation method of the carbon fiber toughened silicon carbide foamed ceramic, which comprises the following steps:

(1) carrying out vacuum ball milling on silicon carbide micro powder, alumina micro powder, silica micro powder, silicon powder, modified carbon fiber, polyacrylate, carboxymethyl cellulose and deionized water for 1-3h to obtain silicon carbide porous ceramic slurry;

(2) soaking polyurethane foam in silicon carbide porous ceramic slurry under a vacuum condition, blowing or centrifugally throwing the slurry by compressed air after soaking, naturally drying for 12-24h, and then drying in an oven at the temperature of 100 ℃ for 12-24h to obtain a precursor;

(3) and putting the precursor into a tubular furnace, firstly heating to 1450-1600 ℃ at a heating rate of 2-5 ℃/min under a nitrogen environment, preserving heat for 3-5h, then cooling to 1000 ℃ at 5 ℃/min, preserving heat for 3-5h, and finally cooling to room temperature along with the furnace to obtain the carbon fiber toughened silicon carbide foamed ceramic.

The invention has the beneficial effects that:

according to the invention, the silicon carbide foam ceramic toughened by the modified carbon fibers is added in situ, so that the thermal shock stability and the fracture toughness of the silicon carbide foam ceramic can be improved, and the service life of the silicon carbide foam ceramic is obviously prolonged when the silicon carbide foam ceramic is applied to the metallurgical filtration industry; in addition, the length and the content of the modified carbon fiber can be controlled by adopting the method of adding the modified carbon fiber in situ; the carbon fiber is treated by absolute ethyl alcohol and nitric acid, so that the modified carbon fiber is combined with polyurethane foam, and the strength of the product is improved;

according to the invention, the silicon nitride whisker generated by the reaction of the metal silicon powder added in situ and nitrogen can repair triangular hole ribs generated by the decomposition of polyurethane foam, and can be bridged with the added modified carbon fiber to further improve the thermal shock stability and fracture toughness of the foamed ceramic;

the invention does not relate to a secondary impregnation technology, thereby simplifying the preparation process and improving the production efficiency; the thermal shock stability, the fracture toughness and the high-temperature mechanical strength of the silicon carbide foam ceramic are obviously improved by adding the modified carbon fibers and the metal silicon powder.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Example 1

The carbon fiber toughened silicon carbide foamed ceramic comprises polyurethane foam and silicon carbide porous ceramic slurry, wherein the silicon carbide porous ceramic slurry comprises the following raw materials in parts by mass: 50 parts of silicon carbide micro powder, 10 parts of alumina micro powder, 2 parts of silicon dioxide micro powder, 1 part of silicon powder, 0.5 part of modified carbon fiber, 0.2 part of polyacrylate, 0.05 part of carboxymethyl cellulose and 20 parts of deionized water.

The grain diameter of the silicon carbide micro powder particles is 2-4 mu m; the alumina micropowder is bimodal active alumina micropowder, and the particle size of alumina micropowder particles is 1-2 μm; the silicon powder is metal silicon powder, and the particle size of the silicon powder particles is 10-40 μm; the length of the modified carbon fiber is 1-5mm, and the diameter is 70 μm; the preparation method of the modified carbon fiber is as follows, S1: putting the carbon fiber into an ethanol solution, ultrasonically cleaning, and drying; s2: putting the dried carbon fiber into a nitric acid solution with the mass fraction of 68% and putting the carbon fiber into a water bath kettle, controlling the reaction temperature to be 80 ℃, and controlling the reaction time to be 1 h; s3: and taking out the carbon fiber treated by nitric acid, cleaning and drying to obtain the modified carbon fiber.

The preparation method of the carbon fiber toughened silicon carbide foamed ceramic specifically comprises the following steps:

(1) carrying out vacuum ball milling on silicon carbide micro powder, alumina micro powder, silica micro powder, silicon powder, modified carbon fiber, polyacrylate, carboxymethyl cellulose and deionized water for 1h to obtain silicon carbide porous ceramic slurry;

(2) soaking polyurethane foam in silicon carbide porous ceramic slurry under a vacuum condition, blowing or centrifugally throwing the slurry by compressed air after soaking, naturally drying for 12h, and then drying in an oven at the temperature of 100 ℃ for 12h to obtain a precursor;

(3) and (3) putting the precursor into a tube furnace, firstly heating to 1450 ℃ at a heating rate of 2 ℃/min in a nitrogen environment, preserving heat for 3h, then cooling to 1000 ℃ at a temperature of 5 ℃/min, preserving heat for 3h, and finally cooling to room temperature along with the furnace to obtain the carbon fiber toughened silicon carbide foamed ceramic.

Example 2

The carbon fiber toughened silicon carbide foamed ceramic comprises polyurethane foam and silicon carbide porous ceramic slurry, wherein the silicon carbide porous ceramic slurry comprises the following raw materials in parts by mass: 55 parts of silicon carbide micro powder, 12 parts of alumina micro powder, 2 parts of silicon dioxide micro powder, 1 part of silicon powder, 1 part of modified carbon fiber, 0.5 part of polyacrylate, 0.1 part of carboxymethyl cellulose and 25 parts of deionized water.

The grain diameter of the silicon carbide micro powder particles is 2-4 mu m; the alumina micropowder is bimodal active alumina micropowder, and the particle size of alumina micropowder particles is 1-2 μm; the silicon powder is metal silicon powder, and the particle size of the silicon powder particles is 10-40 μm; the length of the modified carbon fiber is 1-5mm, and the diameter is 70 μm; the preparation method of the modified carbon fiber is as follows, S1: putting the carbon fiber into an ethanol solution, ultrasonically cleaning, and drying; s2: putting the dried carbon fiber into a nitric acid solution with the mass fraction of 68% and putting the carbon fiber into a water bath kettle, controlling the reaction temperature to be 85 ℃ and the reaction time to be 1.2 h; s3: and taking out the carbon fiber treated by nitric acid, cleaning and drying to obtain the modified carbon fiber.

The preparation method of the carbon fiber toughened silicon carbide foamed ceramic specifically comprises the following steps:

(1) carrying out vacuum ball milling on silicon carbide micro powder, alumina micro powder, silica micro powder, silicon powder, modified carbon fiber, polyacrylate, carboxymethyl cellulose and deionized water for 1h to obtain silicon carbide porous ceramic slurry;

(2) soaking polyurethane foam in silicon carbide porous ceramic slurry under a vacuum condition, blowing or centrifugally throwing the slurry by compressed air after soaking, naturally drying for 15h, and then drying in an oven at the temperature of 100 ℃ for 12h to obtain a precursor;

(3) and (3) putting the precursor into a tube furnace, firstly heating to 1450 ℃ at a heating rate of 3 ℃/min in a nitrogen environment, preserving heat for 3h, then cooling to 1000 ℃ at a temperature of 5 ℃/min, preserving heat for 3.5h, and finally cooling to room temperature along with the furnace to obtain the carbon fiber toughened silicon carbide foamed ceramic.

Example 3

The carbon fiber toughened silicon carbide foamed ceramic comprises polyurethane foam and silicon carbide porous ceramic slurry, wherein the silicon carbide porous ceramic slurry comprises the following raw materials in parts by mass: 60 parts of silicon carbide micro powder, 15 parts of alumina micro powder, 3 parts of silicon dioxide micro powder, 1.5 parts of silicon powder, 1.5 parts of modified carbon fiber, 0.8 part of polyacrylate, 0.2 part of carboxymethyl cellulose and 25 parts of deionized water.

The grain diameter of the silicon carbide micro powder particles is 2-4 mu m; the alumina micropowder is bimodal active alumina micropowder, and the particle size of alumina micropowder particles is 1-2 μm; the silicon powder is metal silicon powder, and the particle size of the silicon powder particles is 10-40 μm; the length of the modified carbon fiber is 1-5mm, and the diameter is 70 μm; the preparation method of the modified carbon fiber is as follows, S1: putting the carbon fiber into an ethanol solution, ultrasonically cleaning, and drying; s2: putting the dried carbon fiber into a nitric acid solution with the mass fraction of 68% and putting the carbon fiber into a water bath kettle, controlling the reaction temperature to be 85 ℃ and the reaction time to be 1.5 h; s3: and taking out the carbon fiber treated by nitric acid, cleaning and drying to obtain the modified carbon fiber.

The preparation method of the carbon fiber toughened silicon carbide foamed ceramic specifically comprises the following steps:

(1) carrying out vacuum ball milling on silicon carbide micro powder, alumina micro powder, silica micro powder, silicon powder, modified carbon fiber, polyacrylate, carboxymethyl cellulose and deionized water for 2 hours to obtain silicon carbide porous ceramic slurry;

(2) soaking polyurethane foam in silicon carbide porous ceramic slurry under a vacuum condition, blowing or centrifugally throwing the slurry by compressed air after soaking, naturally drying for 18h, and then drying in an oven at the temperature of 100 ℃ for 18h to obtain a precursor;

(3) and (3) putting the precursor into a tube furnace, firstly heating to 1500 ℃ at the heating rate of 4 ℃/min under the nitrogen environment, preserving the heat for 4h, then cooling to 1000 ℃ at the temperature of 5 ℃/min, preserving the heat for 3.5h, and finally cooling to room temperature along with the furnace to obtain the carbon fiber toughened silicon carbide foamed ceramic.

Example 4

The carbon fiber toughened silicon carbide foamed ceramic comprises polyurethane foam and silicon carbide porous ceramic slurry, wherein the silicon carbide porous ceramic slurry comprises the following raw materials in parts by mass: 65 parts of silicon carbide micro powder, 18 parts of alumina micro powder, 4 parts of silicon dioxide micro powder, 2 parts of silicon powder, 2 parts of modified carbon fiber, 1 part of polyacrylate, 0.3 part of carboxymethyl cellulose and 30 parts of deionized water.

The grain diameter of the silicon carbide micro powder particles is 2-4 mu m; the alumina micropowder is bimodal active alumina micropowder, and the particle size of alumina micropowder particles is 1-2 μm; the silicon powder is metal silicon powder, and the particle size of the silicon powder particles is 10-40 μm; the length of the modified carbon fiber is 1-5mm, and the diameter is 70 μm; the preparation method of the modified carbon fiber is as follows, S1: putting the carbon fiber into an ethanol solution, ultrasonically cleaning, and drying; s2: putting the dried carbon fiber into a nitric acid solution with the mass fraction of 68% and putting the carbon fiber into a water bath kettle, controlling the reaction temperature to be 90 ℃ and the reaction time to be 1.5 h; s3: and taking out the carbon fiber treated by nitric acid, cleaning and drying to obtain the modified carbon fiber.

The preparation method of the carbon fiber toughened silicon carbide foamed ceramic specifically comprises the following steps:

(1) carrying out vacuum ball milling on silicon carbide micro powder, alumina micro powder, silica micro powder, silicon powder, modified carbon fiber, polyacrylate, carboxymethyl cellulose and deionized water for 2.5 hours to obtain silicon carbide porous ceramic slurry;

(2) soaking polyurethane foam in silicon carbide porous ceramic slurry under a vacuum condition, blowing or centrifugally throwing the slurry by compressed air after soaking, naturally drying for 20h, and then drying in an oven at the temperature of 100 ℃ for 20h to obtain a precursor;

(3) and (3) putting the precursor into a tube furnace, firstly heating to 1500 ℃ at the heating rate of 4 ℃/min in a nitrogen environment, preserving heat for 4h, then cooling to 1000 ℃ at the temperature of 5 ℃/min, preserving heat for 4h, and finally cooling to room temperature along with the furnace to obtain the carbon fiber toughened silicon carbide foamed ceramic.

Example 5

The carbon fiber toughened silicon carbide foamed ceramic comprises polyurethane foam and silicon carbide porous ceramic slurry, wherein the silicon carbide porous ceramic slurry comprises the following raw materials in parts by mass: 70 parts of silicon carbide micro powder, 20 parts of alumina micro powder, 5 parts of silicon dioxide micro powder, 3 parts of silicon powder, 2.5 parts of modified carbon fiber, 1.2 parts of polyacrylate, 0.35 part of carboxymethyl cellulose and 35 parts of deionized water.

The grain diameter of the silicon carbide micro powder particles is 2-4 mu m; the alumina micropowder is bimodal active alumina micropowder, and the particle size of alumina micropowder particles is 1-2 μm; the silicon powder is metal silicon powder, and the particle size of the silicon powder particles is 10-40 μm; the length of the modified carbon fiber is 1-5mm, and the diameter is 70 μm; the preparation method of the modified carbon fiber is as follows, S1: putting the carbon fiber into an ethanol solution, ultrasonically cleaning, and drying; s2: putting the dried carbon fiber into a nitric acid solution with the mass fraction of 68% and putting the carbon fiber into a water bath kettle, controlling the reaction temperature to be 100 ℃ and the reaction time to be 1.5 h; s3: and taking out the carbon fiber treated by nitric acid, cleaning and drying to obtain the modified carbon fiber.

The preparation method of the carbon fiber toughened silicon carbide foamed ceramic specifically comprises the following steps:

(1) carrying out vacuum ball milling on silicon carbide micro powder, alumina micro powder, silica micro powder, silicon powder, modified carbon fiber, polyacrylate, carboxymethyl cellulose and deionized water for 3 hours to obtain silicon carbide porous ceramic slurry;

(2) soaking polyurethane foam in silicon carbide porous ceramic slurry under a vacuum condition, blowing or centrifugally throwing the slurry by compressed air after soaking, naturally drying for 24 hours, and then drying in an oven at the temperature of 100 ℃ for 24 hours to obtain a precursor;

(3) and (3) putting the precursor into a tube furnace, firstly heating to 1600 ℃ at a heating rate of 5 ℃/min under a nitrogen environment, preserving heat for 5h, then cooling to 1000 ℃ at 5 ℃/min, preserving heat for 5h, and finally cooling to room temperature along with the furnace to obtain the carbon fiber toughened silicon carbide foamed ceramic.

In the description herein, references to the description of "one embodiment," "an example," "a specific example" or the like are intended to mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

The preferred embodiments of the invention disclosed above are intended to be illustrative only. The preferred embodiments are not exhaustive and do not limit the method of making the high strength carbon fiber reinforced porous ceramic to the specific embodiments described. Obviously, many modifications and variations are possible in light of the above teaching. The embodiments were chosen and described in order to best explain the principles of the invention and the practical application, to thereby enable others skilled in the art to best utilize the invention. The invention is limited only by the claims and their full scope and equivalents.