1. A ceramic sintering apparatus, comprising:

the closed container is used for containing the ceramic green bodies;

the power supply device is electrically connected with the ceramic green body so as to apply voltage to the ceramic green body for sintering to obtain ceramic; and the dropping device is connected with the closed container and is used for dropping liquid into the ceramic green body.

2. Ceramic sintering device according to claim 1, characterized in that the power supply means comprise voltage measuring means and/or current measuring means.

3. A ceramic sintering device as claimed in claim 1 wherein the droplet means comprises droplet flow control means for controlling the flow of liquid injected into the droplet generation means and droplet generation means connected to the droplet flow control means.

4. The ceramic sintering apparatus according to any one of claims 1 to 3, further comprising a gas transmission device connected to the closed container, wherein the gas transmission device is configured to transmit gas into the closed container, the closed container is opened with a gas outlet, and the gas is discharged through the gas outlet.

5. A method of sintering a ceramic, comprising the steps of:

providing a ceramic green body, connecting the ceramic green body with a power supply device, applying a voltage to the ceramic green body, and gradually increasing the voltage to a target voltage;

and keeping the current density flowing through the ceramic green body constant, dripping liquid into the ceramic green body, and sintering to obtain the ceramic.

6. The method of claim 5, wherein the current density flowing through the ceramic green body is maintained at 10 to 150mA/mm²。

7. The method of claim 5, wherein the ceramic green body is connected to a power supply device in such a manner that: and arranging a first electrode and a second electrode on the ceramic green body, and connecting the first electrode and the second electrode with the power supply device.

8. The ceramic sintering method of claim 7, wherein the first electrode and the second electrode are made of one material selected from gold and conductive silver paste.

9. The method of claim 6, wherein the ceramic has a densification degree of 90% or more.

10. The method of claim 6, wherein the liquid is selected from one of an acid solution, an alkali solution, and a salt solution.

Background

The ceramic material has wide application in the fields of electronics, chemical engineering, aerospace, medical treatment and the like. The long-time high-temperature sintering not only consumes time and energy, but also causes the problem of remarkable growth of ceramic grains, and even the nano-sized powder has the grain size increased to the micron size after sintering. In addition, the temperature of the ceramic after high-temperature sintering is very high, and the ceramic is not effectively utilized at present.

Disclosure of Invention

In view of the above, it is desirable to provide a ceramic sintering apparatus and a ceramic sintering method that can solve the above-mentioned problems.

The present application provides, in a first aspect, a ceramic sintering apparatus comprising:

the closed container is used for containing the ceramic green bodies;

the power supply device is electrically connected with the ceramic green body so as to apply voltage to the ceramic green body for sintering to obtain ceramic;

and the dropping device is connected with the closed container and is used for dropping liquid into the ceramic green body.

The ceramic sintering device that this application embodiment provided utilizes power supply unit to exert voltage to ceramic unburned bricks for ceramic unburned bricks forms the pottery that has certain density through the sintering of dodging under the effect of voltage and electric current, has avoided the drawback that the tradition needs long-time high temperature sintering. When using this ceramic sintering device, the ceramic unburned bricks in the sintering have higher temperature, utilize the dropping liquid device dropwise add liquid on the ceramic unburned bricks that have higher temperature in the sintering process, the high temperature on ceramic unburned bricks surface is as high temperature reaction platform in utilizing the sintering, liquid takes place solid-liquid reaction with the ceramic unburned bricks of high temperature under the condition of strong electric field, thereby make the ceramic surface property after the sintering shaping obtain the adjustment, the surface property of pottery has been changed, and adjust and control different ions of doping in the ceramic of sintering shaping through the different liquid of dropwise add, the high temperature on ceramic unburned bricks surface has been used as high temperature reaction platform in the sintering effectively simultaneously. The ceramic sintering device provided by the application can realize the effects of ceramic sintering and surface performance adjustment at the same time, and the process and the operation are simple, so that the ceramic sintering device has a good application prospect.

According to some embodiments of the present application, a dropping device is used to drop a liquid to a ceramic green body during sintering. The dropping device is controlled to drop liquid in the process of forming ceramic by sintering the ceramic green body, so that the surface modification of the ceramic is facilitated.

According to some embodiments of the present application, the power supply device is a high voltage ac power supply, and can supply currents of different magnitudes according to requirements.

According to some embodiments of the application, the power supply device comprises a voltage measuring device and/or a current measuring device. The power supply device of the present application may use only the voltage measuring device, only the current measuring device, or both the voltage measuring device and the current measuring device. The voltage measuring device is exemplified by a voltmeter, and the current measuring device is exemplified by an ammeter, by which the voltage and current applied to the ceramic green sheet can be measured and controlled.

According to some embodiments of the present application, the droplet device comprises a droplet flow control device for controlling a flow of liquid injected into the droplet generation device and a droplet generation device. In some embodiments, the droplet flow control device is a desktop syringe pump, consisting of a syringe pump, a controller, and a power adapter. The injection pump main part comprises transparent ya keli support and industry aluminium alloy, but the syringe that the centre gripping diameter is suitable, uses the controller to control step motor and carries out high speed or constant velocity motion to the liquid droplet flow of control syringe.

According to some embodiments of the application, the droplet generation device is a syringe.

According to some embodiments of the application, the gas transmission device is connected with the closed container, and is used for inputting gas into the closed container, and the closed container is provided with a gas outlet through which the gas is discharged.

According to some embodiments of the present application, the gas is oxygen, an inert gas, or a reducing gas. In the environment of the sealed container, an inert atmosphere, a reducing atmosphere, and the like can be provided as required, and exhaust gas can be discharged through the gas outlet. When preparing oxide ceramic, oxygen can be introduced to provide oxygen atmosphere, and when preparing carbide ceramic, reducing atmosphere or inert atmosphere can be introduced to prevent the material from being oxidized.

The second aspect of the present application also provides a method for sintering a ceramic, comprising the steps of:

providing a ceramic green body, connecting the ceramic green body with a power supply device, applying a voltage to the ceramic green body, and gradually increasing the voltage to a target voltage;

and keeping the current density flowing through the ceramic green body constant, dripping liquid into the ceramic green body, and sintering to obtain the ceramic.

The application provides a ceramic sintering method, utilize power supply unit to carry out the applied voltage to ceramic green compact, constantly rise voltage makes ceramic green compact take place creeping discharge or internal discharge, dropwise add liquid when keeping the current density of ceramic green compact of flowing through invariable, the surface property after the dropwise add liquid is used for controlling ceramic sintering shaping, finally makes ceramic green compact form the in-process that has higher density pottery and realizes surface modification in the sintering. By utilizing the ceramic sintering method provided by the application, the rapid densification of the ceramic can be realized at a lower furnace temperature, the ceramic sintering temperature can be obviously reduced, the sintering efficiency is improved, and the structure and the performance of the material can be accurately controlled. The ceramic heats up rapidly in the sintering process, and this application utilizes it as good high temperature reaction platform, and dropwise add liquid on ceramic green compact utilizes liquid and the ceramic solid of high temperature to take place solid-liquid reaction under the condition of strong electric field to this regulation and control ceramic surface performance, realizes the doping of different ions through the liquid of control dropwise add, and easy operation utilizes the ceramic sintering method that this application provided to realize ceramic sintering shaping and ceramic surface performance adjustment, has good application prospect.

According to some embodiments of the present application, the current density through the ceramic green body is maintained at 10 to 150mA/mm². Controlling the current density flowing through the ceramic green body to be 10-150 mA/mm²Too low a current density does not guarantee a rapid densification of the ceramic green body, and too high a current may cause the ceramic to shrink sharply, resulting in local overheating and fracture. The current density flowing through the ceramic green body is 10-150 mA/mm²Liquid is dripped during the process, which is beneficial to forming surface modified and high-quality ceramics.

According to some embodiments of the present application, the ceramic green body is connected to a power supply device by: and arranging a first electrode and a second electrode on the ceramic green body, and connecting the first electrode and the second electrode with the power supply device.

According to some embodiments of the present application, the material of the first electrode and the second electrode is independently selected from one of gold and conductive silver paste. Can adopt the mode of spouting gold or scribbling electrically conductive silver thick liquid to form the electrode on ceramic green body to make the follow-up electric connection that can carry out with power supply unit of ceramic green body.

According to some embodiments of the present application, the rate of increasing the voltage is 0.1-5 kV/s. When the boost rate is less than 0.1kV/s, the sintering process is too slow, and is not favorable to the emergence of flashover, when the boost rate is higher than 5kV/s, the too fast boost probably makes the both ends of ceramic unburned bricks direct breakdown arcing to can fuse with the wire that ceramic unburned bricks both ends are connected.

According to some embodiments of the application, the target voltage is 1-20 kV.

According to some embodiments of the application, the ceramic green body has a shape of at least one of a cylinder, a cuboid, and a dog-bone shape.

According to some embodiments of the application, the ceramic has a densification degree of 90% or more. The density of the sintered and formed ceramic is more than or equal to 90 percent by controlling the voltage applied by the power supply device and the current flowing through the ceramic green body.

According to some embodiments of the application, the liquid is selected from one of an acid solution, an alkali solution, a salt solution. Different ions can be doped in the sintered ceramic by dripping liquid drops containing different ions, so that the surface performance of the ceramic is changed, and the ceramic with novel functional characteristics is prepared.

Drawings

Fig. 1 is a schematic structural diagram of a ceramic sintering apparatus according to an embodiment of the present disclosure;

FIG. 2 is an SEM image of a densified ceramic surface after dropping a copper sulfate solution in an example of the present application;

FIG. 3 is an X-ray energy spectrum corresponding to region 1 of FIG. 2;

FIG. 4 is a graph showing the surface temperature distribution of a ceramic sample before and after applying a voltage and before and after flash firing according to an embodiment of the present invention.

Description of the main elements

Ceramic sintering apparatus 100

Sealed container 110

Air outlet 111

Gas delivery device 120

Dripping device 130

Droplet flow control device 131

Droplet generator 132

Power supply device 140

Voltage measuring device 141

Current measuring device 142

Ceramic green body 150

The following detailed description will further illustrate the invention in conjunction with the above-described figures.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in 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.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used in the description of the invention herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.

Referring to fig. 1, a ceramic sintering apparatus 100 according to an embodiment of the present disclosure includes a sealed container 110, a dropping device 130 connected to the sealed container 110, and a power supply device 140. The closed vessel 110 is used to contain the ceramic green body 150. The dropping device 130 is connected to the closed container 110, and is used for dropping liquid to the ceramic green compact 150 placed in the closed container 110, so as to achieve surface property modulation of the sintered ceramic. The power supply device 140 is used to electrically connect with the ceramic green sheet 150 to apply voltage and current to the ceramic green sheet 150. When the device is used, the power supply device 140 is electrically connected with the ceramic green body 150 and is powered on, the voltage applied to the ceramic green body 150 is gradually increased until the ceramic green body generates surface discharge or internal discharge, the current density flowing through the ceramic green body 150 is controlled, the ceramic with certain density is formed by field sintering by a flash firing method, and liquid is dripped by the dripping device 130 in the field sintering process to regulate and control the surface performance of the ceramic after sintering and forming.

In some embodiments, the power supply device 140 includes a voltage measuring device 141 and a current measuring device 142, the voltage measuring device 141 is used for measuring and controlling the voltage applied to the ceramic green body 150, and the current measuring device 142 is used for measuring the current flowing through the ceramic green body 150, so that the ceramic green body 150 is flash-fired to form ceramic by controlling the applied voltage and the current value passing through the ceramic green body 150, thereby realizing rapid densification of the ceramic, and the density of the prepared ceramic can reach 90% or more.

In some embodiments, the dropping device 130 comprises a droplet flow control device 131 and a droplet generating device 132, the droplet generating device 132 is exemplified by a syringe, the droplet flow control device 131 is exemplified by a desk-top syringe pump, and the desk-top syringe pump is used for controlling the flow rate of the liquid injected into the droplet generating device 132, and further controlling the flow rate of the droplets dropped by the droplet generating device 132, and the flow rate of the droplets dropped is 3 to 8 μ L/s in some embodiments.

In some embodiments, the ceramic sintering apparatus 100 further includes a gas transmission device 120 connected to the closed container 110, the closed container 110 has a gas outlet 111, the gas transmission device 120 is connected to the closed container 110 and is configured to input gas into the closed container 110, the input gas provides a gas atmosphere for subsequent sintering and surface property modulation of the ceramic green sheet 150 placed in the closed container 110, and exhaust gas can be exhausted through the gas outlet 111.

In some embodiments, the gas input by the gas transmission device 120 is oxygen, inert gas or reducing gas, which is used to provide a gas atmosphere for the closed container 110. The gas to be supplied is selected adaptively according to the type of ceramic to be sintered, for example, oxygen may be selectively supplied to provide an oxidizing atmosphere when oxide ceramics are prepared, and an inert gas or a reducing gas may be selectively supplied to prevent oxidation of the ceramics when carbide ceramics are prepared.

In some embodiments, a flow meter is connected to the gas delivery device 120 for controlling the flow rate of the output gas.

In some embodiments, the dripping device 130 of the ceramic sintering device 100 comprises a droplet flow control device 131 and a droplet generating device 132, the droplet generating device 132 is an injector, and the sintering process performed by the ceramic sintering device 100 to prepare the ceramic comprises the following steps:

(1) preparation of the ceramic green body 150: putting the ceramic powder into a mould to be pressed into a shape to form a ceramic green body, then putting the ceramic green body into a heating furnace, heating to 400 ℃ at the heating rate of 2 ℃/min, preserving heat for 2h to decompose and discharge organic glue in the ceramic green body, and respectively forming a first electrode and a second electrode at two ends of the ceramic green body by adopting a method of spraying gold or coating conductive silver paste.

(2) Placing the ceramic green body 150 into the closed container 110, winding wires around the first electrode and the second electrode at two ends of the ceramic green body 150, electrically connecting the ceramic green body 150 with the power supply device 140 through the wires, and fixing the wires on the fixing bracket to suspend the ceramic green body 150, wherein the ceramic green body 150 is illustrated by taking a zinc oxide ceramic green body in a dog bone shape as an example, and the power supply device 140 is a high-voltage alternating-current power supply;

(3) inputting gas into the closed container 110 by using the gas transmission device 120, and discharging the gas from the gas outlet 111, so that the ceramic green body 150 in the closed container 110 is in a gas atmosphere;

(4) the power supply device 140 is switched on, and then the voltage is increased at the speed of 400V/s until the voltage at two ends of the ceramic green body 150 is suddenly reduced and the passing current is suddenly increased, so that the ceramic green body generates surface discharge or internal discharge;

(5) by adjusting the voltage, the current flowing through the ceramic green body 150 is controlled to be 10-150 mA/mm²The flow rate of the liquid injected into the droplet forming device 132 was controlled by the droplet flow rate control device 131, 50. mu.L of a copper sulfate solution having a concentration of 1mol/L was added dropwise to the ceramic green sheet 150 via a syringe at a flow rate of 5. mu.L/s, the voltage and current were kept constant, and after 1 minute, the power supply device 140 was turned off to complete the sintering.

The above sintering process is described by taking dropping 1mol/L copper sulfate solution as an example, and it can be understood that different ions can be doped in the sintered ceramic by replacing the dropped liquid, and the liquid can be one of an acid solution, an alkali solution and a salt solution.

In some embodiments, the voltage increase rate during the sintering process is 0.1 to 5kV/s, the ceramics with different densities can be formed by flash firing by adjusting the voltage increase rate and controlling the current density passing through the ceramic green body 150, and the surface modification can be realized during the sintering process for forming the ceramics with higher densities by dropping the liquid under the condition of keeping the current density flowing through the ceramic green body 150 constant. Taking the dropping of a copper sulfate solution for surface modification as an example, the ceramic with the modified surface is characterized by using a scanning electron microscope and X-ray energy spectrum analysis (EDS), FIG. 2 shows an SEM image of the ceramic surface after the surface modification by dropping the copper sulfate solution, FIG. 3 shows the result of real-time collection of EDS spectral lines in the area of the frame line 1 in FIG. 2, the ordinate is the counting rate CPS of X-ray photons, and the abscissa is the energy value (KeV) of elements. Table 1 is an elemental analysis of the X-ray energy spectrum of fig. 3. As can be seen from fig. 2-3 and table 1, the presence of copper ions was detected on the densified ceramic surface formed after sintering, indicating that the modification of the ceramic surface was achieved by adding a copper sulfate solution dropwise.

TABLE 1 elemental analysis of the X-ray energy spectrum of FIG. 3

In the ceramic sintering method provided by the application, the ceramic green body is sintered by applying voltage, the surface discharge or the internal discharge of the ceramic green body is caused by continuously increasing the voltage to a target voltage in the initial sintering stage, flash firing is caused, then the current density flowing through the ceramic green body is maintained, the flash firing sintering is carried out, the surface temperature distribution of the ceramic sample before and after the voltage application and before and after the flash firing is as shown in figure 4, when no voltage is applied (figure 4 (a)), the temperature of the surface of the sample is close to the room temperature, when the voltage is applied for 2s (figure 4 (b)), the local temperature in the middle of the sample is continuously increased, and the temperature-increased area is diffused to the periphery. This non-uniform distribution is mainly caused by the random and non-uniform distribution of the partial discharge points. The first to begin the hot start area marks where the partial discharge is most intense. The high temperature region distribution at the moment of flash-over (fig. 4 (c)) is in a sputtering state, because a large amount of heat is generated at the moment of electric breakdown, releasing a large amount of energy. In the flash-firing process (fig. 4 (d)), the surface temperature of the sample tends to be stable, and the overall temperature distribution is 970-1100 ℃. If the dropping is performed before the voltage is applied, the occurrence of the flash firing is promoted mainly by increasing the water content of the ceramic green body. Compared with the mode of dripping before voltage is applied, the method has the advantages that dripping is carried out in the flash process, water in dripping liquid is rapidly evaporated on the surface of the high-temperature ceramic at 1100 ℃, ions in acid, alkali and salt solution are left on the surface of the high-temperature ceramic and are subjected to solid-liquid reaction with the high-temperature ceramic under a strong electric field, and then surface modification can be realized.

Although the present invention has been described with reference to the above preferred embodiments, it should be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the invention as defined by the appended claims.