CN112153764A

CN112153764A - Rapid heating method for preparing ceramic material

Info

Publication number: CN112153764A
Application number: CN202011043207.9A
Authority: CN
Inventors: 才胜; 何志祝; 廖文辉
Original assignee: China Agricultural University
Current assignee: China Agricultural University
Priority date: 2020-09-28
Filing date: 2020-09-28
Publication date: 2020-12-29
Anticipated expiration: 2040-09-28
Also published as: CN112153764B

Abstract

The invention provides a rapid heating method for preparing ceramic materials, which generates current by discharging a power supply (1), leads the current to pass through conductive materials (4) and (5) with high conductivity in a circuit and carries out resistance heating on the conductive materials; the ceramic material (8) positioned in the middle cavity part of the conductive materials (4) and (5) is heated by radiation, the temperature is rapidly increased, and the sintering process is completed in a very short time. After the heating process is finished, the temperature of the ceramic material (8) is rapidly reduced, and the cooling process is finished. The method can realize ultra-rapid heating and cooling process, and the heating rate can reach 10³～10⁴Cooling rate of 10 deg.C/min⁴DEG C/min. The heating temperature reaches 3000 ℃, and the sintering process is completed within about several seconds. The process is simple in operation, simple in equipment structure and uniform in heating.

Description

Rapid heating method for preparing ceramic material

Technical Field

The invention belongs to the field of material preparation and processing, and particularly relates to a rapid heating method based on a Joule heating effect.

Background

The ceramic material has excellent thermodynamic stability, mechanical stability and chemical stability, thereby becoming a class of widely used materials. Conventional ceramic sintering processes typically require several hours of processing time. Because part of elements have volatility, the elements are easy to dissipate in the long-time material sintering process, so that the element components of the prepared ceramic material are difficult to control, and the service performance of the ceramic material is influenced. For example, in the preparation process of the ceramic-based solid electrolyte, because the sintering time of the material is too long, lithium element and sodium element are seriously volatilized in the sintering process, thereby reducing the service performance of the electrolyte material.

In addition to conventional material sintering processes, several other sintering methods have been developed. Such as microwave-assisted sintering, spark plasma sintering, electric field-assisted rapid sintering, and photonic sintering, among others. However, the above sintering methods have great technical limitations. The microwave-assisted sintering process relies on the microwave absorbing properties of the material. The spark plasma sintering process requires the use of molds of compressed ceramic material during sintering and is not suitable for samples having complex three-dimensional geometries. The electric field assisted rapid sintering process requires the use of expensive platinum electrodes, and the rapid sintering conditions are also closely related to the electrical properties of the material. Thus, this method is not a generally applicable ceramic sintering process. For some materials with unknown properties, it is uncertain whether the method can be applied on a large scale. The temperature reached by the photon sintering process is low, and the sintering process of the ceramic material is generally difficult to realize.

Disclosure of Invention

In view of the above, the present invention provides a rapid heating method based on joule heating effect, which is simple in operation, simple in equipment structure, and uniform in heating.

The invention provides a rapid heating method based on joule heating effect, which comprises the following steps:

connecting the material with high conductivity with a power supply to form a current loop; generating a current by a power source, the current flowing through a conductive material in the circuit;

forming a cavity in the middle of the conductive material, and placing the ceramic material to be sintered in the cavity; when current flows through the conductive material in the circuit, the temperature of the conductive material is rapidly increased under the action of joule heating;

under the action of radiation heating, the ceramic material in the cavity inside the conductive material is also heated rapidly, and the sintering process is completed in a very short time; after the heating process is completed, the temperature of the ceramic material is rapidly decreased, and the cooling process is completed.

Preferably, the conductive material is selected from any one of carbon paper and graphene.

Preferably, the carbon paper is of a cutting structure; the graphene is in a strip-shaped or cutting-type structure.

Preferably, the power supply is a direct current power supply or an alternating current power supply, and the current range is 0A-50A.

The invention has the beneficial effects that: ultra-fast heating and cooling process with heating rate up to 10³～10⁴Cooling rate of 10 deg.C/min⁴DEG C/min. The heating temperature reaches 3000 ℃, and the sintering process is completed within about several seconds. The process is simple in operation, simple in equipment structure and uniform in heating.

Drawings

FIG. 1 is a schematic circuit diagram of the present invention, wherein 1. power supply, 2. copper tape, 3. copper tape, 4. first conductive material, 5. second conductive material, 6. first spacer, 7. second spacer, 8. ceramic material;

FIG. 2 is a structural design diagram of the conductive material of the present invention, wherein 9 is a first concentrated heating area, 10 is a second concentrated heating area, and 11 is a third concentrated heating area.

Detailed Description

The method provided by the invention connects the conductive material with high conductivity with the power supply to form a current loop, forms a cavity in the middle of the conductive material, and places the ceramic material to be sintered in the cavity. The current generated by the power source passes through the conductive material and resistively heats it, causing the temperature of the conductive material to rise rapidly. Under the action of radiation heating, the ceramic material in the cavity of the conductive material is heated rapidly to complete the rapid sintering process. The process can realize ultra-rapid heating and cooling process, and the heating rate can reach 10³～10⁴Cooling rate of 10 deg.C/min⁴DEG C/min. The heating temperature reaches 3000 ℃, and the sintering process is completed within about several seconds. The process is simple and easy to operate, and the equipment structure is simple, andand the heating is uniform.

The invention and its embodiments will now be further described with reference to the accompanying drawings in which:

as shown in figure 1, copper strips (2) and (3) are respectively connected with a power supply (1), and two ends of conductive materials (4) and (5) are connected with the copper strips (2) and (3) to form a complete loop. When the power source (1) is discharged, the generated current passes through the conductive materials (4) and (5), thereby heating it. The conductivity of the conductive materials (4) and (5) is high and the temperature rises rapidly in a very short time. The ceramic material (8) between the conductive materials (4) and (5) is subject to the radiation heating of the conductive materials (4) and (5), the temperature is rapidly increased, and the sintering process is completed.

One embodiment of the present invention is to use carbon paper or graphene as the conductive materials (4) and (5). Furthermore, the structural design of the electrically conductive materials (4) and (5) has three forms. As shown in fig. 2, the structures of the conductive materials (4) and (5) may be in the form of uniform structures, the widths of which are equal at each position. The conducting materials (4) and (5) can also be cut into a region (9) with a reduced width in the middle, the heating rate of the region is increased due to the increase of the current density of the concentrated heating region (9), and the temperature rising speed of the conducting materials (4) and (5) in the concentrated heating region (9) is increased, so that the ceramic material (8) in the concentrated heating region (9) can reach the sintering temperature more quickly, and the sintering process time is shortened. The conductive materials (4) and (5) can also be cut into two concentrated heating areas (10) and (11) at different positions, and the ceramic materials (8) are respectively placed in the concentrated heating areas (10) and (11). Therefore, after the power supply (1) discharges, the two ceramic materials (8) can be heated and the sintering process can be completed at the same time, and the efficiency of the sintering process is improved. The conductive material with the concentrated heating areas (9), (10) and (11) can improve the resistance heating efficiency, shorten the heating time and the sintering process time of the ceramic material (8), and is beneficial to the control and the stability of the components of the ceramic material.

The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various modifications and decorations can be made without departing from the principle of the present invention, and these modifications and decorations should also be regarded as the protection scope of the present invention.

Claims

1. A rapid heating method based on joule heating effect, characterized in that a rapid temperature rise is achieved by using a resistance heating effect of a conductive material having high conductivity with a power source as an energy source, comprising the steps of:

the power supply (1) discharges to generate a current which flows through the conductive materials (4) and (5) with high conductivity in the circuit;

the generated current causes the temperature of the conductive materials (4) and (5) to rise rapidly in a very short time;

under the action of radiation heating, the conductive materials (4) and (5) heat the ceramic material (8) positioned in the middle cavity of the conductive materials, so that the temperature of the ceramic material (8) reaches the sintering temperature within seconds, and the sintering process is rapidly finished; after the heating process is finished, the temperature of the ceramic material (8) is rapidly reduced, and the cooling process is finished.

2. The rapid heating method according to claim 1, wherein the conductive materials (4) and (5) having high conductivity are selected from any one of carbon paper and graphene.

3. The rapid heating method according to claim 1, characterized in that the geometry of the conductive materials (4) and (5) having high conductivity is a stripe shape having a uniform width and thickness.

4. Rapid heating method according to claim 1, characterized in that the geometry of the conductive materials (4) and (5) with high conductivity is with a concentrated heating zone (9); or a tailored geometry of the two concentrated heating zones (10) and (11);

in the concentrated heating areas (9), (10) and (11), the widths or thicknesses of the conductive materials (4) and (5) are smaller than those of other positions.

5. The rapid heating method according to claim 1, wherein the power source is a dc power source or an ac power source, and the current of the power source is in a range of 0A to 50A.