WO2022222778A1

WO2022222778A1 - Fine ceramic material formed by means of ceramic precursor framework and preparation method therefor and use thereof

Info

Publication number: WO2022222778A1
Application number: PCT/CN2022/085997
Authority: WO
Inventors: 伍尚华; 吕东霖; 李建斌; 杨平; 孙振飞
Original assignee: 广东工业大学
Priority date: 2021-04-21
Filing date: 2022-04-11
Publication date: 2022-10-27
Also published as: CN113135742A

Abstract

Disclosed are a fine ceramic material formed by means of a ceramic precursor framework and a preparation method therefor and use thereof, which relate to the technical field of ceramics. The preparation method comprises: impregnating porous foam into ceramic precursor slurry to obtain a porous ceramic framework green body; carrying out pyrolysis treatment on the porous ceramic framework green body to obtain a porous ceramic framework; filling the porous ceramic framework with ceramic powder slurry to obtain a high-density ceramic green body; and sintering the high-density ceramic green body into a fine ceramic material by means of a sintering process. The porous foam is used as a template, and the ceramic framework is prepared by a method in which pyrolysis is carried out after the template is impregnated; and matrix ceramic powder is injected into the framework and solidifies, and then is sintered to prepare a sintered composite ceramic body. A reinforced phase of the sintered ceramic body is a ceramic framework with controllable morphology, and the microstructure of the sintered body is regulated and controlled, such that the ceramic performance is improved. The ceramic framework is prepared by pyrolyzing a ceramic precursor, and the matrix ceramic is added in a powder injection manner, such that the composite ceramic is controllable in terms of component and microstructure.

Description

A kind of fine ceramic material formed by ceramic precursor skeleton, its preparation method and application

technical field

The invention relates to the technical field of ceramics, in particular to a fine ceramic material formed by a ceramic precursor skeleton and a preparation method and application thereof.

Background technique

Fine ceramics, mainly including oxide ceramics, nitride ceramics, carbide ceramics and composite ceramics, such as Al ₂ O ₃ , ZrO ₂ , Si ₃ N ₄ , AlN, SiAlON, etc., have high hardness, high strength, high toughness, resistance to Grinding, chemical stability, biocompatibility and other excellent properties, its application is more and more extensive.

The preparation of such high-performance ceramics usually uses high-purity powders as raw materials, and has excellent properties (thermal, electronic, magnetic, optical, chemical, mechanical, etc.) through precise control of chemical composition, microstructure, and grain size. The characteristics of high-performance ceramics are closely related to the microstructure, especially the morphology, size, and arrangement of the grains. There have been many methods to control the microstructure, such as nanoparticle strengthening, whisker strengthening, phase transformation strengthening, texture strengthening, layer strengthening and so on. SiC nanoparticle-enhanced, whisker-enhanced alumina or silicon nitride used in cutting tools, zirconia transformation toughening to obtain high-toughness ceramic materials, long rod-shaped β-Si3N4 grain self-strengthening and toughening silicon nitride ceramic materials, and A textured ceramic material with greatly improved performance in a certain direction is obtained through the oriented arrangement of grains. However, there are still many problems, such as poor ceramic properties and uncontrollable microscopic properties of ceramics.

SUMMARY OF THE INVENTION

The technical problems to be solved by the embodiments of the present invention are the problems of poor performance of the existing fine ceramics and uncontrollable microscopic properties of the ceramics.

In order to solve the above problems, the embodiments of the present invention propose the following technical solutions:

In a first aspect, a method for preparing a fine ceramic material shaped by a ceramic precursor skeleton, comprising:

S1, dipping the porous foam into the ceramic precursor slurry to obtain a porous ceramic skeleton body;

S2, pyrolyzing the porous ceramic skeleton body to obtain the porous ceramic skeleton;

S3, filling the porous ceramic skeleton with ceramic powder slurry to obtain a high-density ceramic body;

S4, sintering the high-density ceramic body into a fine ceramic material through a sintering process.

According to a further technical solution, the porous foam is an open-cell foam plastic, and the material of the porous foam includes polyethylene, polypropylene, polystyrene and polyurethane.

According to a further technical solution, the shape of the pores of the porous foam includes a circle and a long rod; the porosity of the porous foam is greater than 30%; and the pore size of the porous foam is greater than 10um.

According to a further technical solution thereof, the ceramic precursor slurry includes a ceramic precursor, an organic solvent and a catalyst, wherein the volume percentage of the organic solvent in the ceramic precursor slurry is 0vol%-60vol%.

Its further technical scheme is that the ceramic precursor is at least one of polycarbosilane, polysilazane, polysiloxane and polyzirconoxane; the organic solvent is at least one of ethanol, acetone and xylene; The temperature range of pyrolysis treatment is 200℃-1800℃; the temperature atmosphere of pyrolysis treatment is nitrogen, argon or vacuum.

Its further technical scheme is that the ceramic powder slurry includes ceramic powder and a sintering aid; wherein, the ceramic powder is at least one of Al ₂ O ₃ , ZrO ₂ , Si ₃ N ₄ and AlN; the sintering aid It is at least one of alkaline earth metal oxides, rare earth metal oxides, metal chlorides and metal fluorides.

Its further technical scheme is that the ceramic powder slurry is a slurry with a solidification function; step S3 includes: filling the ceramic powder slurry into the porous ceramic skeleton through a gel injection molding process and solidifying to obtain a high-density ceramic powder. Density ceramic body.

Its further technical scheme is that in step S4, the sintering method is one of normal pressure sintering, hot pressing sintering, air pressure sintering, SPS sintering and microwave sintering, the sintering temperature range is 1400°C-1900°C, and the sintering atmosphere is air, One of nitrogen, argon and vacuum.

In a second aspect, an embodiment of the present invention provides a fine ceramic material prepared by the method described in the first aspect.

In a third aspect, embodiments of the present invention provide the application of the fine ceramic material according to the second aspect in a ceramic cutter and/or a ceramic heat dissipation substrate.

Compared with the prior art, the technical effects that the embodiments of the present invention can achieve include:

In the invention, the shape of the ceramic skeleton is controlled by the easy-to-process and easy-to-produce porous foam as a template, the ceramic skeleton is prepared by a method of impregnating the template with a ceramic precursor and then pyrolyzed, and the matrix ceramic powder is injected into the skeleton to solidify, and then sintered at high temperature to prepare a composite ceramic sintered body. The reinforcing phase of the ceramic sintered body is a ceramic skeleton with a controllable morphology, which regulates the microstructure of the sintered body and improves the performance of the ceramic. The ceramic skeleton is prepared by pyrolysis of a ceramic precursor, and the matrix ceramic is added by powder injection, so that the composition and microstructure of the composite ceramic are controllable.

Description of drawings

In order to explain the technical solutions of the embodiments of the present invention more clearly, the following briefly introduces the accompanying drawings used in the description of the embodiments. Obviously, the drawings in the following description are some embodiments of the present invention, which are of great significance to the art For those of ordinary skill, other drawings can also be obtained from these drawings without any creative effort.

FIG. 1 is a schematic structural diagram of the porous foam used in the embodiment of the present invention.

Detailed ways

The technical solutions in the embodiments will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Similar component numbers in the accompanying drawings represent similar components. Obviously, the embodiments to be described below are only a part of the embodiments of the present invention, but not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

It is to be understood that, when used in this specification and the appended claims, the terms "comprising" and "comprising" indicate the presence of the described features, integers, steps, operations, elements and/or components, but do not exclude one or The presence or addition of a number of other features, integers, steps, operations, elements, components, and/or sets thereof.

It should also be understood that the terms used in the description of the embodiments of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the embodiments of the present invention. As used in the description of the embodiments of the invention and the appended claims, the singular forms "a", "an" and "the" are intended to include the plural forms unless the context clearly dictates otherwise.

The embodiment of the present invention proposes a method for preparing a fine ceramic material formed by a ceramic precursor skeleton, and the method includes the following steps S1-S4.

S1, the porous foam is dipped into the ceramic precursor slurry to obtain a porous ceramic skeleton body.

In the specific implementation, in step S1, the shape of the porous foam is used as the shape of the porous ceramic skeleton body, and the internal pore structure of the porous foam is used as the ceramic skeleton template of the porous ceramic skeleton body, and the porous foam is immersed in the ceramic precursor slurry. , the porous ceramic skeleton body was obtained. The structure of the porous foam is shown in Figure 1.

Further, porous foam refers to a porous material with regular pore type and regular arrangement, wherein the shape, size, and direction of the pores can be controlled and designed as needed.

The porous foam is an open-cell foam plastic, and the materials of the porous foam include polyethylene, polypropylene, polystyrene and polyurethane. It should be noted that the material of the porous foam is not limited to the above several types.

Further, the shape of the pores of the porous foam includes a circular shape and a long rod shape; the porosity of the porous foam is greater than 30%; the pore size of the porous foam is greater than 10um. The above features are designed on demand.

Further, the ceramic precursor slurry includes a ceramic precursor, an organic solvent and a catalyst, wherein the volume percentage of the organic solvent in the ceramic precursor slurry is 0vol%-60vol%. Ceramic precursor slurries are slurries that can achieve pyrolysis into ceramic materials.

Further, the ceramic precursor is at least one of polycarbosilane, polysilazane, polysiloxane and polyziroxane, and is not limited to the above.

The organic solvent is at least one of ethanol, acetone and xylene, and is not limited to the above.

S2, the porous ceramic skeleton embryo body is subjected to pyrolysis treatment to obtain a porous ceramic skeleton (ie, a ceramic precursor skeleton).

In a specific implementation, the carbonization of porous foam plastics and the pyrolysis of precursors into ceramics are achieved by high temperature treatment.

Further, the pyrolysis treatment temperature ranges from 200°C to 1800°C, which is determined by the pyrolysis reaction temperature of the ceramic precursor; the pyrolysis treatment temperature atmosphere is nitrogen, argon or vacuum, and is not limited to the above.

S3, filling the ceramic powder slurry in the porous ceramic framework to obtain a high-density ceramic body.

In a specific implementation, the ceramic powder slurry includes ceramic powder and a sintering aid; wherein, the ceramic powder is at least one of Al ₂ O ₃ , ZrO ₂ , Si ₃ N ₄ and AlN.

Sintering aids are alkaline earth metal oxides (MgO, Al ₂ O ₃ , ZrO ₂ , TiO ₂ , CaO, etc.), rare earth metal oxides (Y ₂ O ₃ , Sc ₂ O ₃ , La ₂ O ₃ , Gd ₂ O ₃ , etc.) , Ce ₂ O ₃ , Er ₂ O ₃ , Yb ₂ O ₃ , etc.), at least one of metal chlorides and metal fluorides.

Further, the ceramic powder slurry is a slurry with a solidification function; step S3 includes: filling the ceramic powder slurry into the porous ceramic skeleton through a gel injection molding process and solidifying to obtain a high-density ceramic body .

In a specific implementation, the sintering method is one of normal pressure sintering, hot pressing sintering, gas pressure sintering, SPS sintering and microwave sintering, and is not limited to the above.

The sintering temperature ranges from 1400°C to 1900°C, depending on the sintering and densification temperature of the filled ceramic powder.

The sintering atmosphere is one of air, nitrogen, argon and vacuum, and is not limited to the above.

The embodiment of the present invention also provides a fine ceramic material, which is prepared by the method described in any of the above embodiments.

Embodiments of the present invention also provide applications of the fine ceramic materials provided by the above embodiments in ceramic cutters and/or ceramic heat dissipation substrates.

In order to better illustrate the technical solutions of the present invention, specific embodiments are now provided as follows:

Example 1 Zirconia reinforced and toughened alumina composite ceramics.

An open-cell foam with a pore size greater than 100um and a porosity greater than 60% is selected as the blank template. After the open-cell foam template is dipped in polyziroxane, it is put into a high-temperature furnace for pyrolysis, the atmosphere is flowing nitrogen, the maximum pyrolysis temperature is 1500°C, and the holding time is 1h. A porous zirconia skeleton body is prepared. Alumina slurry was prepared for filling the zirconia ceramic framework. Al ₂ O ₃ and 5wt% Y ₂ O ₃ were added with a certain amount of absolute ethanol, mixed with a planetary ball mill for 12 h, dried and sieved. Add dispersant, deionized water, monomer acrylamide and cross-linking agent N,N'-methylenebisacrylamide (AM:MBAM=9:1) to the powder after preliminary mixing, adjust the pH value to 10 , and the slurry for gel injection molding was obtained after ball milling again for 12 h. The alumina ceramic slurry is defoamed by a vacuum defoamer, and the initiator is added with ammonium persulfate, and the catalyst can be added with tetramethylethylenediamine, which is injected into the zirconia ceramic skeleton. Use a box-type muffle furnace to debond the green body, the debonding temperature is 800°C, and the debonding time is 2h. The debonded green body was sintered at 1600 ℃ for 2 h to prepare zirconia reinforced and toughened alumina composite ceramics. The above composite materials were tested, and their flexural strength and fracture toughness were 850 MPa and 8 MPa·m ^1/2 , respectively. Custom microstructured composite ceramics have excellent mechanical properties and can be used as tools.

Example 2 Silicon carbide reinforced and toughened alumina composite ceramics.

An open-cell foam with a pore size greater than 100um and a porosity greater than 60% is selected as the blank template. The open-cell foam template is impregnated with polycarbosilane, the solvent is ethanol, the catalyst is ferrocene (C ₅ H ₅ ) ₂ Fe, put into a high-temperature furnace for pyrolysis, the atmosphere is flowing nitrogen, the maximum pyrolysis temperature is 1500 ° C, and the temperature is kept warm. The time is 1h. A porous silicon carbide skeleton body is prepared. Alumina slurry was prepared for filling the silicon carbide ceramic framework. Al ₂ O ₃ and 5wt% Y ₂ O ₃ were added with a certain amount of absolute ethanol, mixed with a planetary ball mill for 12 h, dried and sieved. Add dispersant, deionized water, monomer acrylamide and cross-linking agent N,N'-methylenebisacrylamide (AM:MBAM=9:1) to the powder after preliminary mixing, adjust the pH value to 10 , and the slurry for gel injection molding was obtained after ball milling again for 12 h. The alumina ceramic slurry is defoamed by a vacuum defoamer, and the initiator is added with ammonium persulfate, and the catalyst can be added with tetramethylethylenediamine. Use a box-type muffle furnace to debond the green body, the debonding temperature is 800°C, and the debonding time is 2h. The debonded green body was sintered by hot pressing in an argon atmosphere, and sintered at 1700 °C for 2 h to prepare silicon carbide reinforced and toughened alumina composite ceramics. The flexural strength and fracture toughness of the above-mentioned composite materials were tested to be 900 MPa and 8.5 MPa·m ^1/2 , respectively. Custom microstructured composite ceramics have excellent mechanical properties and can be used as tools.

Example 3 Silicon carbide reinforced and toughened silicon nitride composite ceramics.

An open-cell foam with a pore size greater than 100um and a porosity greater than 60% is selected as the blank template. The open-cell foam template is impregnated with polycarbosilane, the solvent is ethanol, the catalyst is ferrocene (C ₅ H ₅ ) ₂ Fe, put into a high-temperature furnace for pyrolysis, the atmosphere is flowing nitrogen, the maximum pyrolysis temperature is 1500 ° C, and the temperature is kept warm. The time is 1h. A porous silicon carbide skeleton body is prepared. A silicon nitride slurry was prepared for filling the silicon carbide ceramic framework. Si ₃ N ₄ , 5 wt% Al ₂ O ₃ and 5 wt % Y ₂ O ₃ were added with a certain amount of absolute ethanol, mixed with a planetary ball mill for 12 hours, dried and sieved. Add dispersant, deionized water, monomer acrylamide and cross-linking agent N,N'-methylenebisacrylamide (AM:MBAM=9:1) to the powder after preliminary mixing, adjust the pH value to 10 , and the slurry for gel injection molding was obtained after ball milling again for 12 h. The silicon nitride ceramic slurry is defoamed by a vacuum defoamer, and the initiator is added with ammonium persulfate, and the catalyst can be added with tetramethylethylenediamine. . Use a box-type muffle furnace to debond the green body, the debonding temperature is 800°C, and the debonding time is 2h. The debonded green body was sintered by hot pressing in nitrogen atmosphere, and sintered at 1800 ℃ for 2 h to prepare silicon carbide reinforced and toughened silicon nitride composite ceramics. The above composite materials were tested, and their flexural strength and fracture toughness were 1000 MPa and 7 MPa·m ^1/2 , respectively. Custom microstructured composite ceramics have excellent mechanical properties and can be used as tools.

Example 4 Zirconia reinforced and toughened aluminum nitride composite ceramics.

An open-cell foam with a pore size greater than 100um and a porosity greater than 60% is selected as the blank template. After the open-cell foam template is dipped in polyziroxane, it is put into a high-temperature furnace for pyrolysis, the atmosphere is flowing nitrogen, the maximum pyrolysis temperature is 1500°C, and the holding time is 1h. A porous zirconia skeleton body is prepared. An aluminum nitride slurry was prepared for filling the zirconia ceramic framework. AlN, 5wt% MgO and 5wt% Y ₂ O ₃ were added with a certain amount of absolute ethanol, mixed with a planetary ball mill for 12 h, dried and sieved. Add dispersant, deionized water, monomer acrylamide and crosslinking agent N,N'-methylenebisacrylamide (AM:MBAM=9:1) to the powder after preliminary mixing, adjust the pH value to 10 , and the slurry for gel injection molding was obtained after ball milling again for 12 h. The aluminum nitride ceramic slurry is defoamed by a vacuum defoamer, and the initiator is added with ammonium persulfate, and the catalyst can be added with tetramethylethylenediamine. . Use a vacuum tube furnace to debond the green body, the debonding temperature is 800°C, and the debonding time is 2h. The debonded green body was sintered at 1850 ℃ for 4 h to prepare zirconia reinforced and toughened aluminum nitride composite ceramics. The above composite materials were tested, and their flexural strength and fracture toughness were 600 MPa and 7 MPa·m ^1/2 , respectively, and their thermal conductivity was 120 W·m ^-1 ·K ^-1 . The composite ceramics with customized microstructures have excellent mechanical properties, and at the same time, due to the high thermal conductivity of aluminum nitride, the prepared composite ceramics can be used for insulating and heat-dissipating substrates.

Comparative example Silicon carbide reinforced alumina composite ceramics.

80wt% Al ₂ O ₃ , 15wt% SiC and 5wt% Y ₂ O ₃ were added to a certain amount of absolute ethanol, mixed with a planetary ball mill for 12 hours, dried and sieved. Silicon carbide reinforced alumina composite ceramics were prepared by hot pressing sintering at 1800 ℃ for 2 h in nitrogen atmosphere. The above composite materials were tested, and their flexural strength and fracture toughness were 650 MPa and 7 MPa·m ^1/2 , respectively.

The above examples all show that the composite ceramic can be prepared by using the porous foam as the template to obtain the ceramic skeleton, and the performance of the composite ceramic has the potential of excellent performance. Firstly, by controlling the pore type, pore size and porosity of the porous foam to control the morphology of the ceramic skeleton, the ceramic skeleton is obtained by pyrolysis of the ceramic precursor. Then, after injecting the base ceramic powder, a dense sintered body is prepared by high temperature sintering. The microstructure of the sintered body is that the ceramic skeleton is embedded in the ceramic matrix, and the performance of the final sintered body is high.

In the above-mentioned embodiments, the description of each embodiment has its own emphasis. For parts that are not described in detail in a certain embodiment, reference may be made to related descriptions of other embodiments.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit and scope of the invention. Thus, even if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

The above are the specific embodiments of the present invention, but the protection scope of the present invention is not limited to this. Any person skilled in the art can easily think of various equivalent modifications within the technical scope disclosed by the present invention. or replacement, these modifications or replacements should be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention should be subject to the protection scope of the claims.

Claims

A method for preparing a fine ceramic material shaped by a ceramic precursor skeleton, characterized in that it comprises:

S1, dipping the porous foam into the ceramic precursor slurry to obtain a porous ceramic skeleton body;

S2, pyrolyzing the porous ceramic skeleton body to obtain the porous ceramic skeleton;

S3, filling the porous ceramic skeleton with ceramic powder slurry to obtain a high-density ceramic body;

S4, sintering the high-density ceramic body into a fine ceramic material through a sintering process.
The method for preparing a fine ceramic material formed by a ceramic precursor skeleton according to claim 1, wherein the porous foam is an open-cell foamed plastic, and the material of the porous foam comprises polyethylene, polypropylene, polyethylene Styrene and Polyurethane.
The method for preparing a fine ceramic material shaped by a ceramic precursor skeleton according to claim 2, wherein the shape of the pores of the porous foam includes a circle and a long rod; the porosity of the porous foam is greater than 30% ; The pore size of the porous foam is greater than 10um.
The method for preparing a fine ceramic material shaped by a ceramic precursor skeleton according to claim 3, wherein the ceramic precursor slurry comprises a ceramic precursor, an organic solvent and a catalyst, wherein the organic solvent accounts for the ceramic precursor slurry The volume percentage is 0vol%-60vol%.
The method for preparing a fine ceramic material shaped by a ceramic precursor skeleton according to claim 4, wherein the ceramic precursor is at least one of polycarbosilane, polysilazane, polysiloxane and polyziroxane One; the organic solvent is at least one of ethanol, acetone and xylene; the pyrolysis treatment temperature range is 200°C-1800°C; the pyrolysis treatment temperature atmosphere is nitrogen, argon or vacuum.
The method for preparing a fine ceramic material shaped by a ceramic precursor skeleton according to claim 1, wherein the ceramic powder slurry comprises ceramic powder and a sintering aid; wherein the ceramic powder is Al 2 O 3 , At least one of ZrO 2 , Si 3 N 4 and AlN; the sintering aid is at least one of alkaline earth metal oxide, rare earth metal oxide, metal chloride and metal fluoride.
The method for preparing a fine ceramic material formed by a ceramic precursor skeleton according to claim 6, wherein the ceramic powder slurry is a slurry with a solidification function; step S3 comprises: through gel injection molding The molding process fills the ceramic powder slurry into the porous ceramic framework and solidifies to obtain a high-density ceramic body.
The method for preparing a fine ceramic material shaped by a ceramic precursor skeleton according to claim 1, wherein in step S4, the sintering method is normal pressure sintering, hot pressing sintering, gas pressure sintering, SPS sintering and microwave sintering. One, the sintering temperature range is 1400°C-1900°C, and the sintering atmosphere is one of air, nitrogen, argon and vacuum.
A fine ceramic material, characterized in that it is prepared by the method of any one of claims 1-8.
Application of the fine ceramic material as claimed in claim 9 in a ceramic cutter and/or a ceramic heat dissipation substrate.