CN109465951B

CN109465951B - Gradient ceramic forming device

Info

Publication number: CN109465951B
Application number: CN201811419796.9A
Authority: CN
Inventors: 吴甲民; 陈安南; 陆路; 汪汝健; 陈双; 刘荣臻; 史玉升; 李晨辉
Original assignee: Huazhong University of Science and Technology
Current assignee: Huazhong University of Science and Technology
Priority date: 2018-11-26
Filing date: 2018-11-26
Publication date: 2020-05-19
Anticipated expiration: 2038-11-26
Also published as: CN109465951A

Abstract

The invention belongs to the field of gradient ceramic forming and discloses a gradient ceramic forming device. The device comprises a non-porous mold and a first support, a second support and a third support which are parallel to each other in the vertical direction and are arranged oppositely, conductive carriers are arranged above the first support and below the third support respectively and are used for forming an even electrostatic field between the first support and the third support, the second support is provided with the non-porous mold coated with a heating pad, after ceramic slurry is injected into the non-porous mold, the heating pad heats the ceramic slurry to enable an ester PH regulator to hydrolyze and release weak acid, the ester PH regulator reacts with a curing agent in the ceramic slurry to release high-valence metal cations, and the metal cations are distributed in the ceramic slurry in a gradient concentration mode under the action of the electrostatic field, so that gradient ceramic is formed. The invention realizes the forming of the gradient ceramics with adjustable and controllable component gradient and continuously changed components, has simple operation and high forming efficiency, and is suitable for the preparation of various structural and functional gradient ceramics.

Description

Gradient ceramic forming device

Technical Field

The invention belongs to the field of gradient ceramic forming, and particularly relates to a gradient ceramic forming device.

Background

Gradient materials are heterogeneous materials whose material composition or structure shows gradient gradually in space, and generally show heterogeneity of macroscopic tissues and continuity of microscopic tissues. The gradient of the components or the structure is generally accompanied with the gradual change of functional characteristics, so that the gradient has a great application prospect in the fields of chemistry and chemical engineering, biomedicine, electronic information, aerospace, aviation and the like.

The gradient ceramic material not only has the characteristics of the gradient material, but also has the advantages of high strength, high temperature resistance and corrosion resistance, so that the gradient ceramic material has wide attention of researchers at home and abroad in recent years. The gradient lead zirconate titanate (PZT) ferroelectric ceramic material is prepared by Zhuyin et al, the phase change region of the PZT ceramic is widened, and a larger dielectric constant can be obtained in a wider temperature region. Jeon J H et al prepared gradient BST ceramics, the better the linear relationship of the dielectric temperature curve with the increase of the number of gradient layers. However, the conventional preparation method of gradient ceramics is to laminate and press sheets with different components after dry pressing, the gradient ceramic material prepared by the method has obvious delamination at the lamination interface, the ingredients at the delamination part are discontinuous, and the mechanical property and functionality of the gradient ceramic are seriously deteriorated due to the problem of mismatch of thermodynamic properties at the interlayer bonding part.

Disclosure of Invention

In view of the above defects or improvement needs of the prior art, the present invention provides a gradient ceramic forming apparatus, which aims to provide a forming apparatus for forming gradient ceramic with continuous components and no layering, wherein through the design of a non-porous mold, the ceramic slurry is heated and applied with an electrostatic field after being injected into the mold, so as to release charged high-valence metal cations and distribute gradient concentration, thereby effectively avoiding the problems of uneven component gradient transition and thermal mismatch caused by interlayer interface combination, and finally preparing the gradient ceramic with excellent mechanical properties and functionality.

To achieve the above object, according to the present invention, there is provided a gradient ceramic device characterized in that the device comprises a first support, a second support, a third support and a non-porous mold, wherein,

the first support, the second support and the third support are arranged in parallel and oppositely in the vertical direction, a conductive carrier is arranged above the first support and below the third support, a uniform electrostatic field is formed between the first support and the third support, the field intensity of the electrostatic field is regulated and controlled by regulating the distance between the first support and the third support, the second support is provided with the non-porous mold, the exterior of the non-porous mold is coated with a heating gasket for heating the ceramic slurry in the non-porous mold, after the ceramic slurry is injected into the non-porous mold, the heating gasket heats the ceramic slurry, so that an ester PH regulator in the ceramic slurry is hydrolyzed to release weak acid, the weak acid reacts with a curing agent in the ceramic slurry to release high-valence metal cations, and the metal cations are distributed in the ceramic slurry in a gradient concentration under the action of the electrostatic field, thereby forming a gradient ceramic.

Further preferably, one end of the heating pad is connected with a temperature monitoring component for monitoring the heating temperature of the heating pad in real time.

Further preferably, the heating temperature range of the heating pad is preferably 40 ℃ to 85 ℃.

Further preferably, the conductive carrier is connected to a dc power supply, and the intensity of the electrostatic field is adjusted by adjusting the voltage of the dc power supply.

Further preferably, the voltage adjustable range of the direct current power supply is 1V-60V.

Further preferably, the conductive carrier is preferably conductive glass, conductive rubber, or conductive metal.

In general, compared with the prior art, the above technical solution contemplated by the present invention can achieve the following beneficial effects:

1. the device provided by the invention can provide an external electrostatic field to enable charged high-valence counter ions to directionally move in the ceramic slurry so as to generate concentration gradient distribution, and biscuit components after the slurry is cured in situ are continuous and have no layering phenomenon, so that the problems of uneven component gradient transition and thermodynamic mismatching caused by interlayer interface combination can be effectively avoided;

2. the invention can realize the design and regulation of the high-valence counter ion concentration distribution by regulating the intensity of the external electrostatic field, and prepare the gradient ceramic with adjustable component gradient;

3. compared with the gradient ceramic prepared by the traditional forming process, the gradient ceramic prepared by the device provided by the invention has the advantages of no obvious layering phenomenon, excellent mechanical property and gradient functionality, high forming efficiency, low equipment cost, simple operation, suitability for preparation of gradient ceramics with various structures and functions and strong universality.

Drawings

FIG. 1 is a schematic structural view of a gradient ceramic forming apparatus constructed in accordance with a preferred embodiment of the present invention;

FIG. 2 is a side view of a forming platform in a forming apparatus constructed in accordance with a preferred embodiment of the present invention;

FIG. 3 is a top view of a non-porous mold constructed in accordance with a preferred embodiment of the present invention;

fig. 4 is a schematic diagram of a process for preparing a ceramic slurry constructed in accordance with a preferred embodiment of the present invention.

The same reference numbers will be used throughout the drawings to refer to the same or like elements or structures, wherein:

1-direct current power supply, 12-lead, 13-circuit control switch, 2-forming platform, 21-first support, 22-second support, 23-third support, 24-Z axis guide rod, 3-conductive carrier, 4-aporate mould, 5-heating gasket, 6-temperature on-line monitoring component and 7-silica gel heating power supply.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention. In addition, the technical features involved in the embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.

Fig. 1 is a schematic structural view of a gradient ceramic forming apparatus constructed in accordance with a preferred embodiment of the present invention, and as shown in fig. 1, the gradient ceramic forming apparatus includes a dc power supply 1, a forming platform 2, a silica gel heating pad 5, and a silica gel heating power supply 7;

the forming platform 2 comprises a first bracket, a second bracket and a third bracket which are parallel to each other, and the brackets are fixed on a Z-axis guide rod and can move randomly on the guide rod;

conductive carriers 3 are arranged above the first support and below the third support and are connected with a direct current power supply 1 through leads, circuit control switches are arranged on the leads, a non-porous mold 4 for gradient ceramic forming is arranged on the second support, and a silica gel heating gasket 5 is tightly wrapped around the non-porous mold;

the heating pad 5, the silica gel heating pad adopted in this embodiment, is provided with an online temperature monitoring component 6, and is connected with a silica gel heating power supply 7 through a wire.

Preferably, the direct current power supply 1 is a voltage-adjustable power supply, the voltage-adjustable range of the direct current power supply is 1-60V, and the direct current power supply can be used for regulating and controlling the intensity of an electrostatic field of the forming platform;

preferably, the conductive carriers 3 are one or more of conductive glass, conductive rubber and conductive metal, and when the direct current power supply 1 is connected, an electrostatic field can be formed between the conductive carriers, and the field intensity can be regulated and controlled by adjusting the distance between the conductive carriers;

preferably, the temperature online monitoring part 6 is used for heating and online monitoring the temperature of the silica gel gasket, and the heating temperature range is preferably 40-85 ℃.

The invention provides a gradient ceramic forming device, which particularly forms concentration gradient distribution by directionally moving charged high-valence counter ions in ceramic slurry regulated and controlled by an electric field, and obtains gradient ceramic with continuous components and no layering after the slurry is cured and sintered in situ. The gradient ceramic formed by the method has continuous components and no layering phenomenon, can effectively avoid the problems of uneven component gradient transition and thermodynamic mismatching caused by interlayer interface combination, can adjust the voltage of the direct current power supply 1 and the distance between the conductive carriers 3 to realize the design and regulation of high-valence counter ion concentration distribution, and can prepare the gradient ceramic with adjustable component gradient. The method can form the gradient ceramic biscuit with continuous components in one step, has high forming efficiency, low equipment cost and simple operation, is suitable for preparing the gradient ceramics with various structures and functions, and has no obvious layering phenomenon and more excellent mechanical property and gradient functionality compared with the gradient ceramics prepared by the traditional forming process.

In the embodiment of the invention, the direct current power supply 1 is connected with the conductive carrier 3 through the lead 12 and the circuit control switch 13, the voltage of the direct current power supply 1 is adjustable, the adjustable range of the voltage is 1-60V, when the circuit is connected, a uniform electrostatic field can be formed between the

conductive carriers

31 and 32, and the field intensity can be effectively regulated and controlled by adjusting the voltage. Under a uniform electrostatic field, charged high-valence counter ions in the ceramic slurry in the non-porous mold 4 can move directionally to form concentration gradient distribution in the slurry, and a gradient ceramic biscuit with continuous components and no layering phenomenon can be obtained after the slurry is cured in situ.

Fig. 2 is a side view of a forming platform of a forming apparatus constructed according to a preferred embodiment of the present invention, as shown in fig. 2, a first support 21, a second support 22 and a third support 23 of the forming platform 2 are parallel to each other and connected to a same Z-axis guide rod, a conductive carrier 31 is disposed above the first support 21, a conductive carrier 32 is disposed below the third support 23, when a power supply is connected, a uniform electrostatic field is formed between the

conductive carriers

31 and 32, the field strength of the uniform electrostatic field can be effectively controlled by adjusting the distance between the

conductive carriers

31 and 32, a non-porous mold 4 is disposed above the second support 22, and when the power supply is connected, the curing process of the ceramic slurry can be performed in the uniform electrostatic field.

Fig. 3 is a top view of a non-porous mold constructed according to a preferred embodiment of the present invention, and as shown in fig. 3, a silicone heating pad 5 is tightly wrapped outside the non-porous mold 4 and connected to a temperature on-line monitoring unit 6 and a silicone heating power supply 7. The temperature on-line monitoring part 6 can detect and control the temperature of the silica gel heating gasket 5 in real time, the heating temperature range is preferably 40-85 ℃, and the temperature of the non-porous mold 4 can be close to the real-time temperature of the silica gel heating gasket 5 due to the heat conduction effect. Fig. 4 is a schematic diagram of a process for preparing a ceramic slurry according to a preferred embodiment of the present invention, as shown in fig. 4, during the temperature rising and maintaining process, high-valence counterions in the ceramic slurry are controllably released and directionally move under the action of an electrostatic field to form gradient distribution, the high-valence counterions can compress double electron layers on the surfaces of ceramic particles in the ceramic slurry to cause the ceramic slurry to be cured in situ, and finally, a gradient ceramic biscuit with continuous components and no delamination phenomenon is obtained, and after sintering, gradient ceramics with excellent mechanical properties and functionality can be obtained.

It will be understood by those skilled in the art that the foregoing is merely a preferred embodiment of the present invention, and is not intended to limit the invention, and that any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included within the scope of the present invention.

Claims

1. A gradient ceramic device, characterized in that the device comprises a first holder (21), a second holder (22), a third holder (23) and a non-porous mould (4), wherein,

the first support (21), the second support (22) and the third support (23) are arranged in parallel and oppositely in the vertical direction, a conductive carrier (3) is arranged above the first support (21) and below the third support (23) and used for forming a uniform electrostatic field between the first support (21) and the third support (23), the field intensity of the electrostatic field is regulated and controlled by regulating the distance between the first support (21) and the third support (23), the second support (22) is provided with the non-porous mold (4), the non-porous mold (4) is externally coated with a heating gasket (5) and used for heating ceramic slurry in the non-porous mold, and after the ceramic slurry is injected into the non-porous mold (4), the heating gasket (5) heats the ceramic slurry, so that ester PH regulators in the ceramic slurry are hydrolyzed to release weak acid, the high-valence metal cations are released by the reaction of the high-valence metal cations and a curing agent in the ceramic slurry, and the metal cations are distributed in the ceramic slurry in a gradient concentration manner under the action of the electrostatic field, so that the gradient ceramic is formed.

2. A gradient ceramic device according to claim 1, wherein one end of the heating pad (5) is connected with a temperature monitoring part (6) for real-time monitoring of the heating temperature of the heating pad (5).

3. A gradient ceramic device according to claim 1 or 2, wherein the heating temperature of the heating pad (5) is in the range of 40 ℃ to 85 ℃.

4. A gradient ceramic device according to claim 1, wherein the conductive carrier (3) is connected to a dc power supply (1) and the intensity of the electrostatic field is adjusted by adjusting the voltage of the dc power supply.

5. A gradient ceramic device according to claim 4, wherein the voltage of the DC power supply (1) is adjustable within the range of 1V to 60V.

6. A gradient ceramic device according to claim 1, wherein the conductive carrier (3) is a conductive glass, a conductive rubber or a conductive metal.