WO2021258746A1 - Preparation method for concha margaritifera-like layered high-strength super-tough ceramic - Google Patents

Abstract

A preparation method for a concha margaritifera-like layered high-strength super-tough ceramic, comprising the following steps: coating the surface of a multi-sided hollow micro-porous structure of a foam ceramic matrix with a weak interface layer formed by toughening particles; pre-pressing the coated foam ceramic matrix to obtain a ceramic green body having a layered structure; pressing and sintering the pre-pressed foam ceramic to realize a fine combination of the bionic layered structure; and finally hot-pressing and sintering, so as to obtain the concha margaritifera-like layered ceramic, thereby significantly improving the toughness of the structural ceramic on the basis of the strength of the structural ceramic being not impaired.

Description

Preparation method of imitated mother-of-pearl layered high-strength and super-tough ceramics Technical field

The invention belongs to the technical field of structural ceramic materials, and in particular relates to a preparation method of imitated mother-of-pearl layered high-strength and super-tough ceramics.

Background technique

The brittleness of structural ceramic materials is one of the key problems that plague its wide application. In response to this problem, researchers have carried out a large number of studies, and respectively proposed particle dispersion strengthening, fiber or whisker toughening, phase change toughening, and biomimetic structure enhancement. Toughness and other toughening measures. Among them, the bionic structure toughening is inspired by natural biological materials such as shells, mother-of-pearl, coral, bones, bamboo and wood, and achieves a layer similar to the natural biological structure through the fine combination of multiple components.状structural material. The layered bionic structure increases the crack propagation resistance and fracture work when the material is fractured under stress, can significantly improve the fracture toughness of the material, and endow the structural ceramic material with excellent toughness and comprehensive properties.

The fine assembly of the imitated mother-of-pearl layered structure has always been the bottleneck of the preparation process of the layered bionic ceramic material. Early researchers used the method of free settlement of the flake ceramic powder to obtain the layered arrangement. Although this method can obtain the layered structure, There are problems of gradient arrangement and uneven distribution, resulting in a serious decrease in the strength of the structural ceramic block after hot pressing and sintering. Recently, some researchers have proposed the method of freeze-dried ceramic powder dispersion to realize the oriented arrangement of flake ceramic powder. However, this method still has a large layer thickness and foam blank while constructing a layered structure. The body contains organic adhesives that require further debinding, and the sample preparation process is complicated and time-consuming. In addition, the precise controllability of the layer thickness of the biomimetic layered structure is also one of the main factors restricting the high strength and super toughness of the biomimetic layered ceramic material. Pressing and extrusion processes, the ceramic substrate and interface layer sheets are prepared by casting, film rolling, dry pressing and extrusion, respectively, and then the ceramic substrate and the interface layer sheets are stacked in sequence, and finally the bionic layer is obtained by hot pressing and sintering状结构。 Like structure. The layer thickness of the layered structure obtained by this method is relatively large, and the average layer thickness is generally between 0.1 and 2 mm. At the expense of material strength, the toughness of the material is improved to a certain extent.

The preparation method of the imitation mother-of-pearl layered high-strength and super-tough ceramics proposed in the present invention is based on the fact that the foam ceramics with a special honeycomb structure will rupture into a stack of sheets with extremely thin pore walls under pressure, and is realized by impregnating a weak interface layer The fine combination of the biomimetic layered structure, the thickness of the biomimetic layered structure is less than 10μm, and even nanometer-level thickness, so as not to damage the strength of the structured dense ceramics, the toughness of the structured ceramics is greatly improved, and high strength and super toughness are obtained. ceramics.

Summary of the invention

The technical problem to be solved by the invention

The purpose of the present invention is to overcome the complex process, uneven structure distribution and poor interface controllability existing in the existing preparation methods of biomimetic layered ceramic materials, and propose a novel and ingenious preparation of nacre-like layered high-strength and super-tough ceramics method.

Methods for solving technical problems

In view of the above-mentioned problems, the present invention proposes a preparation method of imitating mother-of-pearl layered high-strength and super-tough ceramics.

According to one embodiment of the present invention, there is provided a preparation method of imitating mother-of-pearl layered high-strength and super-tough ceramics, which comprises the following steps: the surface of the multi-faceted hollow sphere of the foam ceramic matrix is coated with a weak interface layer formed by toughening particles; Pre-pressing the coated ceramic foam substrate to obtain a green body with a layered structure; pressurizing and sintering the pre-compressed green body.

One embodiment is that the preparation of the foamed ceramic matrix includes adding ceramic powder to deionized water and mixing uniformly to form a ceramic slurry, adding a surfactant to the mixed slurry and adjusting the pH value, and performing the development under vigorous stirring. The foamed ceramic body is obtained by foaming, which is dried and sintered to obtain porous ceramics.

In one embodiment, the ceramic powder includes any one of aluminum oxide, aluminum sol, aluminum powder, zirconia, silicon oxide, silica sol, silicon powder, silicon nitride, boron nitride, silicon carbide, and boron carbide Or multiple mixtures.

One embodiment is that the surfactant is sodium lauryl sulfate, sodium cetyl sulfate or sodium octadecyl sulfate, and the addition amount is 0.01 to 0.40 wt% of the solid content of the slurry.

One embodiment is that the pH value of the slurry is between 3-9, and the reagent used for the adjustment is sodium hydroxide or ammonia water.

One embodiment is that, in terms of weight percentage, the content of ceramic powder in the ceramic slurry is 5-40 wt%, the surfactant is 0.05-16 wt%, and the deionized water is the balance.

One embodiment is that the formation of the weak interface layer includes dipping or vapor deposition on the surface of the substrate to coat the interface layer, and the dipping includes immersing and drying the prepared foam ceramic in a dispersion of toughened particles repeatedly, so that the surface of the cell wall is covered. Cover the weak interface layer.

One embodiment is that the number of immersion-drying repetitions is between 1-8, and the toughening particles of the toughening particle dispersion include alumina, zirconia, silicon carbide, boron carbide, silicon nitride, boron nitride, and aluminum powder. , Nickel powder, silicon powder, graphite, carbon nanotubes, graphene, any one or more of mixtures.

One embodiment is to pre-press the coated ceramic foam matrix to break the pore walls of the multi-faceted hollow spheres in the ceramic foam matrix into sheets and stack them layer by layer, and the pre-compression pressure is 1-20 MPa

One embodiment is that the pressure sintering is a hot pressing sintering method, a spark plasma sintering method or a hot isostatic pressing sintering method.

One embodiment is that the hot-pressing sintering method is to load the pre-pressed porous ceramics into a graphite mold, and heat-press sinter in the graphite mold at a sintering temperature of 500-2000°C, a sintering pressure of 0-100 MPa, and a sintering time of 0.5- 10h, sintering is carried out under vacuum, argon atmosphere or nitrogen atmosphere.

One embodiment is that the hot isostatic pressing method is to load the pre-pressed porous ceramics into a hot isostatic pressing mold, and then vacuum and seal the mold. The sintering temperature is 500-2000°C, the sintering pressure is 0-600 MPa, and the sintering time is 500-2000°C. 0.5-10h, sintering is carried out under vacuum, argon atmosphere or nitrogen atmosphere.

One embodiment is that the spark plasma sintering method is to load the pre-compressed porous ceramics into a sintering mold, apply a pulse current to sinter, the sintering temperature is 300-2000°C, the sintering pressure is 0-600 MPa, and the sintering time is 5-60 min. Sintering is performed under vacuum, argon atmosphere or nitrogen atmosphere.

The beneficial effects of the present invention

The preparation method is environmentally friendly, simple in process, and does not require complicated process equipment and process. The foam ceramic matrix has a special honeycomb structure, and the pore walls are composed of closely arranged particles, which have extremely low thickness and high strength, which can meet the requirements of industrial production. It is required to realize the performance and function control of the biomimetic layered ceramic through the functional adjustment of the interface layer. The prepared biomimetic layered ceramic material has the characteristics of high strength, high toughness and multi-element composite structure, which is of great significance for its application in multiple fields. .

Further features of the present invention will become apparent from the following description of exemplary embodiments.

Description of the drawings

Figure 1 is a process flow diagram of the present invention;

FIG. 2 is an SEM image of the foamed ceramic prepared in Example 1. FIG.

FIG. 3 is an SEM image of the pearl mother-of-pearl layered super-tough ceramic prepared in Example 1. FIG.

detailed description

One embodiment of the present disclosure will be described in detail below, but the present disclosure is not limited to this.

The invention combines the preparation of high-porosity foam ceramics with the hot pressing forming technology. Firstly, the prepared ceramic foam body is pre-sintered to obtain a porous ceramic foam with a honeycomb structure. Secondly, an interface layer with a toughening effect is coated on the surface of the cell wall of the foam ceramic matrix by impregnation or deposition process to make the honeycomb structure under pressure. The pore walls of the pores are broken into sheets and form a layered structure of stacked layers. Finally, the preparation of the imitated mother-of-pearl layered high-strength super-tough ceramics is completed by hot pressing and sintering. While the biomimetic layered ceramic material prepared by the invention has extremely high fracture toughness, it does not damage the strength of the compact ceramics. The preparation method proposed by the present invention is simple in process, environmentally friendly, strong in designability of the biomimetic layered structure, and controllable binary phase interface. The pore wall of the foam ceramic matrix is composed of closely arranged particles, and has extremely low thickness and high strength. , By impregnation or vapor deposition on the surface of the substrate to coat the interface layer, the extremely thin pore walls rupture into flakes under pressure, forming a layered layered imitated mother-of-pearl layered structure, which significantly improves the fracture toughness of the material, and can be impregnated Or it can be deposited on the foamed ceramic surface to coat a weak interface layer with special functions to prepare a multifunctional composite ceramic to meet the needs of high performance and multifunctionality of ultra-tough ceramics, which is of great significance for its application in multiple fields.

The toughened particles are added to deionized water and mixed uniformly to form a dispersion of ceramic slurry.

Example

The present invention is described in more detail through examples, but the present invention is not limited to the following examples.

Example 1

In this embodiment, the preparation method of the imitated mother-of-pearl layered high-strength and super-tough alumina ceramic is as follows:

S1. Prepare a uniformly dispersed slurry with 100g of aluminum sol under mechanical stirring, add 0.8g of surfactant sodium lauryl sulfate to the slurry, and adjust the pH to 6 with acid-base reagents, and then send under vigorous stirring. The foamed ceramic body is obtained by sintering at 1200°C for 3 hours to obtain a foamed ceramic with a honeycomb structure; S2, the obtained alumina foamed ceramic is immersed in the zirconia dispersion liquid, taken out and dried, and the above-mentioned dipping-drying process is repeated 3 times , A layer of zirconia weak interface layer is uniformly impregnated on the foam cell wall; S3, the impregnated ceramic foam is pre-compressed under a pressure of 5 MPa to obtain a green body with a layered structure; S4, the pre-compressed The ceramic is placed in a graphite mold, and hot-pressed and sintered for 2 hours at 1550°C, argon atmosphere, and 50 MPa pressure to obtain the imitated mother-of-pearl layered high-strength and super-tough alumina ceramic.

The imitation nacre layered high-strength super-tough alumina ceramic prepared by the above preparation method has a compressive strength of 634Mpa, a fracture toughness of 23.7MPa·m ^1/2 , a work of fracture of 3890J/m ² and a relative density of 99.6%.

Figure 1 is a process flow diagram of preparing the imitation mother-of-pearl layered high-strength and super-tough alumina ceramics.

Figure 2 is a scanning electron micrograph of the cross-section of the foamed ceramic produced. It can be seen from Figure 2 that the foam ceramic micropores are multi-faceted hollow spheres with dense single crystal arrangements on the pore walls, and the thickness of a single crystal is about 0.4um in diameter.

Fig. 3 is a scanning electron microscope photograph of the prepared nacre-like layered high-strength and super-tough alumina ceramic surface. It can be seen from the figure that there are flaky cracks on the surface of the aluminum ceramic.

Example 2

In this embodiment, the preparation method of the imitated mother-of-pearl layered high-strength super-tough zirconia ceramic is as follows:

S1. Add 20g of zirconia ceramic powder with a particle size of 0.3μm into 80g of deionized water and ultrasonically disperse for 2h to prepare a uniformly dispersed ceramic slurry, and add 1.2g of surfactant sodium cetyl sulfate to the zirconia ceramic slurry , Adjust the pH value to 6 by acid-base reagents, foam under vigorous stirring to obtain foam ceramic body, sinter at 1200℃ for 3h to obtain foam ceramic with honeycomb structure; S2, impregnate the obtained zirconia foam ceramic in silicon carbide After taking out the dispersion liquid and drying it, repeat the above-mentioned immersion-drying process three times to evenly impregnate a layer of silicon carbide weak interface layer on the foam cell wall; S3, pre-press the impregnated ceramic foam under a pressure of 8MPa, Obtain a green body with a layered structure; S4. Put the pre-compressed ceramic into a graphite mold and heat-press and sinter it at 1500°C, argon atmosphere, and 40MPa pressure for 1.5h to obtain imitation mother-of-pearl layered high strength Super tough zirconia ceramics.

The imitation nacre layered high-strength super-tough zirconia ceramic prepared by the above preparation method has a compressive strength of 762Mpa, a fracture toughness of 21.4MPa·m ^1/2 , a work of fracture of 2692J/m ² and a relative density of 99.6%.

Example 3

In this embodiment, the preparation method of the imitated mother-of-pearl layered high-strength and super-tough alumina ceramic is as follows:

S1. Add 15g of alumina ceramic powder with a particle size of 0.5μm into 85g of deionized water and ball mill for 2h to prepare a uniformly dispersed ceramic slurry. Add 1.0g of surfactant sodium octadecyl sulfate to the alumina ceramic slurry. , Adjust the pH value to 7 through acid-base reagents, foam under vigorous stirring to obtain foam ceramic body, sinter at 1100 ℃ for 4h to obtain foam ceramic with honeycomb structure; S2, impregnate the obtained alumina foam ceramic in silicon powder After taking out the dispersion liquid and drying it, repeat the above-mentioned impregnation-drying process three times, and evenly impregnate a layer of weak interface layer of silicon powder on the cell walls of the foam ceramic; S3, pre-compress the impregnated ceramic foam under a pressure of 6MPa, Obtain a green body with a layered structure; S4, put the pre-compressed ceramic into a hot isostatic pressing mold, and heat-press and sinter it at 1600°C, an argon atmosphere, and a pressure of 30 MPa for 2 hours to obtain an imitation mother-of-pearl layer Shaped high-strength super-tough zirconia ceramics.

The imitation nacre layered high-strength super-tough alumina ceramic prepared by the above preparation method has a compressive strength of 899Mpa, a fracture toughness of 19.8MPa·m ^1/2 , a work of fracture of 3628J/m ² and a relative density of 99.2%.

Example 4

In this embodiment, the preparation method of the imitated mother-of-pearl layered high-strength super-tough silicon carbide ceramic is: (silicon powder)

S1. Add 20g of silicon powder with a particle size of 0.1μm to 80g of deionized water and ultrasonically disperse for 2h to prepare a uniformly dispersed silicon powder slurry. Add 0.8g of surfactant sodium lauryl sulfate to the silicon powder slurry and pass the acid Alkaline reagent adjusts the pH to 6, foamed under vigorous stirring to obtain a foamed ceramic body, which is embedded in a graphite mold, and sintered in an argon atmosphere at 1200°C for 3 hours to obtain a carbonized honeycomb structure. Silicon foam ceramics; S2. Repeat the immersion-drying process of the obtained silicon carbide foam ceramics in the graphite dispersion liquid for 6 times, and evenly impregnate a layer of graphite weak interface layer on the foam ceramic cell walls; S3, the impregnated foam ceramics Pre-compressed at 3MPa pressure to obtain a green body with a layered structure; S4. Put the pre-compressed ceramic into a graphite mold, and heat-press and sinter for 2h under the conditions of 1600°C, argon atmosphere and 50MPa pressure to obtain the imitation Mother-of-pearl layered high-strength super-tough zirconia ceramics.

The imitation nacre layered high-strength super-tough silicon nitride ceramic prepared by the above preparation method has a compressive strength of 585Mpa, a fracture toughness of 16.2MPa·m ^1/2 , a work of fracture of 3320J/m ² , and a relative density of 99.2%.

Example 5

In this embodiment, the preparation method of a mother-of-pearl-like layered high-strength and super-tough boron nitride ceramic is: (boron nitride)

S1. Add 30g of boron nitride ceramic powder with a particle size of 0.7μm into 70g of deionized water and ultrasonically disperse for 2h to prepare a uniformly dispersed ceramic slurry, and add 1.2g of surfactant dodecyl to the boron nitride ceramic slurry Sodium sulfate, adjust the pH value to 6 with acid-base reagents, foam ceramic bodies under vigorous stirring, and sinter them at 1100°C for 3 hours to prepare foam ceramics with honeycomb structure; S2, the silicon carbide foam ceramics obtained in nickel The powder dispersion was repeated 6 times with the impregnation-drying process, and a weak interface layer of metallic nickel was evenly impregnated on the cell walls of the foam ceramic; S3, the impregnated ceramic foam was pre-compressed under a pressure of 10 MPa to obtain a layered structure Green body; S4. Put the pre-compressed ceramic into a graphite mold and heat-press and sinter it at 1500°C, argon atmosphere, and 40MPa pressure for 1.5h to obtain imitation pearl-like layered high-strength and super-tough boron nitride ceramics .

The imitation nacre layered high-strength super-tough silicon nitride ceramic prepared by the above preparation method has a compressive strength of 585Mpa, a fracture toughness of 16.2MPa·m ^1/2 , a work of fracture of 2980J/m ² and a relative density of 99.2%.

Performance Testing:

To	Flexural strength MPa	Fracture toughness MPa·m 1/2	Break work J/m 2	Relative density%
Example 1	634	23.7	3890	99.6
Example 2	762	21.4	2692	99.4
Example 3	899	19.8	3628	99.2
Example 4	585	16.2	3320	99.2
Example 5	629	20.6	2980	99.5

Industrial applicability

The preparation method of the present invention is environmentally friendly and simple in process. The prepared biomimetic layered ceramic material has the characteristics of high strength, high toughness and multi-element composite structure, which is of great significance for its application in multiple fields.

This embodiment is only a preferred embodiment 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 changes or substitutions within the technical scope disclosed by the present invention. , 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 (10)

1. A preparation method of imitating mother-of-pearl layered high-strength and super-tough ceramics is characterized in that it comprises the following steps:

   The surface of the multi-faceted hollow sphere of the foam ceramic matrix is covered with a weak interface layer formed by toughened particles;

   Pre-press the coated ceramic foam substrate to obtain a green body with a layered structure;

   Press and sinter the pre-compressed body.
2. The preparation method according to claim 1, wherein the preparation of the foamed ceramic matrix comprises adding the ceramic powder to deionized water and mixing uniformly to form a ceramic slurry, adding a surfactant to the mixed slurry and adjusting the pH value, Foaming is carried out under vigorous stirring to obtain a foamed ceramic body, which is dried and sintered to obtain porous ceramics.
3. The preparation method according to claim 2, wherein the ceramic powder comprises aluminum oxide, aluminum sol, aluminum powder, zirconia, silicon oxide, silica sol, silicon powder, silicon nitride, boron nitride, silicon carbide, Any one or more mixtures of boron carbide.
4. The preparation method according to claim 2, wherein the surfactant is sodium lauryl sulfate, sodium cetyl sulfate or sodium octadecyl sulfate, and the addition amount is 0.01-0.40 of the solid content of the slurry. wt%.
5. The preparation method according to claim 2, wherein the pH value of the slurry is between 3-9, and the reagent used for the adjustment is sodium hydroxide or ammonia water.
6. The production method according to claim 2, wherein, by weight percent, of the ceramic slurry content of the ceramic powder is 5-40wt%, surface active agent is 0.05-16wt%, balance deionized water .
7. The preparation method according to claim 1, wherein forming the weak interface layer comprises repeatedly immersing and drying the prepared foam ceramic in the toughened particle dispersion for multiple times, and the cell wall surface is covered with the weak interface layer.
8. The preparation method according to claim 1, wherein the number of repetitions of immersion-drying is between 1-8, and the toughening particles of the toughening particle dispersion include alumina, zirconia, silicon carbide, boron carbide, silicon nitride, Any one or a mixture of boron nitride, aluminum powder, nickel powder, silicon powder, graphite, carbon nanotubes, and graphene.
9. The preparation method according to claim 1, wherein the coated ceramic foam matrix is pre-pressed to break the pore walls of the multi-faceted hollow spheres in the ceramic foam matrix into sheets and stacked layer by layer, and the pre-compression pressure is 1- 20MPa.
10. The preparation method according to claim 1, wherein the pressure sintering is a hot pressing sintering method, a spark plasma sintering method, or a hot isostatic pressing sintering method.

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