CN112390629A - Device and method for rapidly sintering ceramic - Google Patents

Device and method for rapidly sintering ceramic Download PDF

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CN112390629A
CN112390629A CN202011398857.5A CN202011398857A CN112390629A CN 112390629 A CN112390629 A CN 112390629A CN 202011398857 A CN202011398857 A CN 202011398857A CN 112390629 A CN112390629 A CN 112390629A
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pressure head
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furnace body
stainless steel
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CN112390629B (en
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沈平
郭瑞芬
毛海荣
赵志陶
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Jilin University
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Abstract

The invention relates to a device and a method for rapidly sintering ceramics, which comprises a furnace body, an observation window arranged on one side of the furnace body, a pressurizing assembly and a temperature measuring assembly arranged in the furnace body, an electrifying assembly and an insulating assembly, wherein a graphite mould is arranged at the center of an inner cavity of the furnace body; the rapid sintering method of the ceramic comprises the following steps: pressing, electrifying, heating, powering off and cooling; compared with the traditional sintering method, the method has the advantages that a furnace body is not required to be heated, the heating speed is high, the sintering temperature is high, the period is short, the production efficiency is greatly improved, the energy consumption is reduced, the ceramic sintering technology is enriched, the densification degree of the obtained ceramic is higher, and the applicability is wider.

Description

Device and method for rapidly sintering ceramic
Technical Field
The invention relates to the technical field of ceramic material processing, in particular to a device and a method for rapidly sintering ceramic.
Background
Ceramic materials are widely used in structural and functional fields due to their excellent properties such as high melting point, high strength, high hardness, and high temperature thermal stability. At present, the preparation technology of ceramic materials mainly comprises traditional high-temperature sintering, reaction sintering, hot isostatic pressing sintering and the like, the technologies usually rely on a thermal convection or a thermal radiation mode to heat ceramic green bodies, and the heating rate is low, the sintering period is long, and the energy utilization rate is low. For high temperature volatile ceramics (such as lithium ion battery materials), longer sintering times result in volatilization of components, thereby impairing the performance of the material.
In order to reduce the Sintering energy consumption and shorten the cycle time, Spark Plasma Sintering (SPS) has been proposed. The Chinese patent application number is 201110287859.1, and the inventor proposes a high-pressure sintering combined die and a high-pressure rapid sintering method for preparing nano ceramic by the same to Liugui Wu et al. They put the combined high-pressure sintering die filled with the nano ceramic powder into a plasma sintering furnace for sintering. Sintering the ceramic under the conditions that the heating rate is 100-300 ℃/min, the sintering pressure is 100-1000 MPa, the sintering temperature is 500-800 ℃, and the sintering heat preservation time is 3-10 min. When the conductive sample is sintered, current directly flows through the sample, and joule heat generated by the sample is used for realizing ceramic sintering. While the conductive samples are generally less resistive, which requires a larger (hundreds to thousands of amperes) dc pulse current. When sintering a non-conductive sample, current flows through the graphite mold, and the larger graphite mold heats the sample again by generating joule heat, which undoubtedly greatly reduces the heat utilization efficiency. The Chinese patent application No. 201910233609.6, the inventor proposes a metal oxide ceramic material fast sintering furnace and a sintering process thereof for Hexiangheng et al. The hearth is sequentially provided with a high-temperature chamber, a medium-temperature chamber and a low-temperature chamber which are communicated with each other from top to bottom. During sintering, the green body is sequentially fed into low-temperature, medium-temperature and high-temperature chambers to realize rapid sintering. This technique still requires preheating the chamber. This way of relying on furnace heating to achieve sample heating is inefficient because the rate of furnace heating is slow and the maximum temperature that can be achieved is relatively low (1700 c for a high temperature chamber). In 2010, the university of Colorado Raj invented a new technology, in which a Ceramic green compact with an initial density of 50% was sintered to be dense within 5s at a field strength of 120V/cm and a temperature of 850 ℃, and this technology was called Flash Sintering because of the Flash phenomenon during Sintering (Flash Sintering of Nanograin Zirconia in <5s at 850 ℃, Journal of the American Ceramic Society, Vol. 93 in 2010, No. 11, P3556-P3559). The inventor of Chinese patent application No. 201910058819.6 proposes a method for rapidly sintering NBT piezoelectric ceramics at low temperature by Pu Yong Ping et al, which belongs to the flash firing technology. In the flash burning process, the sample is connected with two ends of a power supply through electrodes, and the sintering is realized by using joule heat generated when current flows through the sample. This requires that the sample have some electrical conductivity. However, most of the ceramic materials are not conductive or have weak conductivity at room temperature, and the ceramic materials need to be heated to a higher temperature to have certain ionic or electronic conductivity. Therefore, in flash firing, it is usually necessary to heat the furnace body to a certain temperature (typically several hundred degrees) to make the sample have a certain conductivity. Furthermore, the greatest disadvantage of flash firing technology is that the sample sintering is not uniform, and the critical conditions under which flash firing occurs are largely dependent on the power supply capability (e.g., extremely high voltages are required to drive the movement of ions or electrons within the ceramic material), which results in a large compromise in its universality and economy. The flash firing technology is only suitable for single-piece production, special requirements are placed on samples, and meanwhile, the traditional electric kiln has the defects of long sintering period, high energy consumption, low energy utilization rate and high cost when being used for preparing ceramic materials, is poor in adaptability and needs to be improved.
Disclosure of Invention
In order to achieve the purpose, the invention provides the following technical scheme:
a rapid ceramic sintering device comprises a furnace body, an observation window arranged on one side of the furnace body, a pressurizing assembly and a temperature measuring assembly which are arranged in the furnace body, an electrifying assembly and an insulating assembly, wherein a graphite mold is arranged at the center of an inner cavity of the furnace body, and a graphite soft felt which is arranged in an S shape and is provided with a sample is arranged in the graphite mold;
the electrifying assembly is arranged above and below the graphite soft felt and matched with the BN side plate and is used for electrifying and heating a sample placed in the graphite soft felt;
the pressurizing assembly is arranged at the upper end and the lower end of the furnace body and is used for pressing and forming a sample;
the insulating assembly is respectively arranged on the graphite soft felt and the graphite die, the pressure head on the stainless steel pressure head of the pressurizing assembly and the pressure head on the graphite, the pressure head under the stainless steel pressure head of the pressurizing assembly and the pressure head under the graphite, the graphite pressure head and the graphite die, and the graphite pressure head and the graphite die are arranged between the pressure head and the graphite die and used for electrical insulation, so that the current is ensured to only flow through the graphite soft felt and not flow through the graphite die, the stainless steel pressure head and the stainless steel pressure head, the current short circuit in the furnace body can not be caused, and the graphite soft felt is ensured to be.
As a further scheme of the invention, the electrifying assembly comprises an upper graphite pressure head, copper electrodes, a power supply and a lower graphite pressure head, wherein the upper graphite pressure head and the lower graphite pressure head are respectively arranged above and below the soft graphite felt and are in contact with the soft graphite felt, the power supply is arranged outside the furnace body, two ends of the power supply are respectively connected with the copper electrodes, the other ends of the two copper electrodes respectively penetrate through the furnace body to be electrically connected with the upper graphite pressure head and the lower graphite pressure head, and the copper electrodes and the furnace body are insulated and sealed by polytetrafluoroethylene.
As a further scheme of the invention, the pressurizing assembly comprises a hydraulic control element, a pressure sensor, a stainless steel upper pressure head and a stainless steel lower pressure head, wherein the stainless steel upper pressure head is arranged at the upper end part of the furnace body, the bottom end of the stainless steel upper pressure head is connected with the upper end surface of the graphite upper pressure head, the stainless steel lower pressure head is arranged at the lower end part of the furnace body, the top end of the stainless steel lower pressure head is fixedly connected with the graphite upper pressure head, the bottom end of the stainless steel lower pressure head is fixedly connected with the output end of the hydraulic control element arranged outside the furnace body, and the pressure sensor is arranged at the connection part of the hydraulic control element and the stainless.
As a further scheme, the insulation assembly comprises a BN side plate, a BN upper plate, a BN lower plate, and a BN upper insulation sleeve and a BN lower insulation sleeve which are arranged on a graphite upper pressure head and a graphite lower pressure head, wherein the BN side plate is arranged at the joint of the inner wall of a graphite die and a graphite soft felt, the BN upper plate and the BN lower plate are respectively laid on the upper end surface and the lower end surface of the graphite die, and central holes matched with the graphite upper pressure head and the graphite lower pressure head are formed in the BN upper plate and the BN lower plate.
As a further scheme of the invention, the ends of the BN upper insulating sleeve and the BN lower insulating sleeve are respectively provided with a thread groove matched with the stainless steel upper pressure head and the stainless steel lower pressure head.
As a further scheme of the invention, the temperature measuring component comprises an infrared thermometer and a thermocouple arranged on the inner wall of the BN side plate, a through hole is arranged at the equal height position of the BN side plate and the graphite mold, the through hole corresponds to the sensing end of the infrared thermometer arranged outside the observation window, and the other end of the infrared thermometer is electrically connected with a computer for obtaining the temperature and time curve of the graphite soft felt in real time.
As a further scheme of the invention, the BN side plate is formed by splicing four petals and encloses a square hole groove for placing the graphite soft felt and the sample.
As a still further aspect of the invention, the sample is made of ceramic powder, and the ceramic powder is one or more of oxide or carbide, nitride, boride and ceramic-metal composite material.
A sintering method of a rapid sintering ceramic device comprises the following steps:
1) pressing ceramic powder into a sample green body with a certain shape under the pressure of 200-500 MPa, then placing the sample green body on a graphite soft felt, wrapping the sample by the graphite soft felt to form an S shape, and placing the sample in a graphite mold;
2) respectively contacting the graphite upper pressure head and the graphite lower pressure head with the graphite soft felt, and connecting the graphite upper pressure head and the graphite lower pressure head with a power supply through copper electrodes;
3) vacuumizing the furnace to below 10Pa, turning on a power switch to electrify the graphite soft felt, and adjusting the current to ensure that the temperature of the graphite soft felt quickly reaches a preset value, wherein the power voltage range is 10-30V, and the current range is 20-50A;
4) after the temperature is constant, keeping electrifying for 5-30 s;
5) in the heat preservation process, 0-50 MPa of pressure is applied, then a power supply is disconnected, and the temperature is reduced at a certain rate.
As a further scheme of the invention, a sample is wrapped between S-shaped stacked graphite soft felts, when the sample to be sintered is conductive or can react with graphite at high temperature, and the sintering temperature is less than or equal to 1200 ℃, 0.5mm of alumina fiber paper is adopted between the sample and the graphite soft felts for insulation, and the sample, the fiber paper and the graphite soft felts are stacked into an S shape and placed in a graphite mold; when the sample to be sintered is conductive or can react with graphite at high temperature, the sintering temperature is higher than 1200 ℃, and BN powder is sprayed on the surface of the sample to insulate the sample from the graphite soft felt.
Compared with the prior art, the invention has the beneficial effects that:
1. compared with the traditional sintering method, the method does not need to heat the furnace body, has high heating speed, high sintering temperature and short period, greatly improves the production efficiency and reduces the energy consumption;
2. compared with SPS technology, the present invention needs no expensive DC pulse power source, and has applied current of several ten amperes far less than that of hundreds to thousands of great current. Meanwhile, the method does not need to heat the die, heat is directly applied to the samples through heat conduction, the heating speed is high, the energy utilization rate is high, a plurality of samples can be sintered simultaneously, high-throughput preparation is realized, the energy consumption is low, and the device is simple.
3. Compared with the flash firing technology, the method has no special selectivity requirement on materials, the sample does not need to be preheated to a certain temperature by a furnace, the sintering period is short, and the simultaneous preparation of multiple samples can be realized.
In a word, the method is simple to operate, efficient, easy to implement and strong in universality, ceramic sintering technologies are enriched, and the obtained ceramic is high in densification degree.
Drawings
FIG. 1 is a schematic diagram of a rapid sintering apparatus for use in the present invention.
FIG. 2 is a graph illustrating temperature versus time in the present invention.
FIG. 3 shows Al obtained in example 1 of the present invention2O3And (4) microstructure topography.
FIG. 4 is a drawing showing a schematic view of an embodiment 4 of the present inventionLa obtained2Zr2O7And (4) microstructure topography.
FIG. 5 shows the high-entropy oxide ceramic (La) obtained in example 5 of the present invention0.2Nd0.2Sm0.2Eu0.2Gd0.2)2Zr2O7And (4) microstructure topography.
FIG. 6 is a TiC microstructure topography obtained in example 6 of the present invention.
In the figure, 1, a stainless steel upper pressure head; 2. BN is provided with an insulating sleeve; 3. pressing a graphite upper pressing head; 4. a copper electrode; 5. BN upper plate; 6. a power source; 7. a graphite mold; 8. BN side plate; 9. a BN lower plate; 10. a graphite lower pressure head; 11. a hydraulic control element; 12. a pressure sensor; 13. a stainless steel lower pressure head; 14. BN lower insulating sleeve; 15. a sample; 16. a thermocouple; 17. an observation window; 18. graphite soft felt; 19. a furnace body; 20. an infrared thermometer.
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.
As shown in figure 1, the invention provides a rapid ceramic sintering device, which comprises a furnace body 19, an observation window 17 arranged on one side of the furnace body 19, a pressurizing assembly and a temperature measuring assembly arranged in the furnace body 19, an electrifying assembly and an insulating assembly, wherein a graphite mold 7 is arranged at the center of an inner cavity of the furnace body 19, and a graphite soft felt 18 which is arranged in an S shape and is provided with a sample 15 is arranged in the graphite mold 7;
the electrifying assembly is arranged above and below the graphite soft felt 18 and matched with the BN side plate 8 and is used for electrifying and heating the sample 15 placed in the graphite soft felt 18;
the pressurizing assembly is arranged at the upper end and the lower end of the furnace body 19 and is used for pressing and forming the sample 15;
the insulating components are respectively arranged between the graphite soft felt 18 and the graphite die 7, between the stainless steel upper pressure head 1 and the graphite upper pressure head 3 of the pressurizing components, between the stainless steel lower pressure head 13 and the graphite lower pressure head 10 of the pressurizing components, between the graphite upper pressure head 3 and the graphite die 7, and between the graphite lower pressure head 10 and the graphite die 7, and are used for electrical insulation, so that the current is ensured to only flow through the graphite soft felt 18, but not flow through the graphite die 7, the stainless steel upper pressure head 1 and the stainless steel lower pressure head 13, and the current short circuit in the furnace body is not caused, and the graphite soft felt 18 is ensured to be only electrified and heated;
the electrifying component comprises a graphite upper pressure head 3, a copper electrode 4, a power supply 6 and a graphite lower pressure head 10, wherein the graphite upper pressure head 3 and the graphite lower pressure head 10 are respectively arranged above and below a graphite soft felt 18 and are in contact with the graphite soft felt 18, the power supply 6 is arranged outside a furnace body 19, two ends of the power supply are respectively connected with the copper electrode 4, the other ends of the two copper electrodes 4 respectively penetrate through the furnace body 19 and the graphite upper pressure head 3 and the graphite lower pressure head 10 to be electrically connected, and the copper electrode and the furnace body are insulated and sealed by polytetrafluoroethylene.
The pressurizing assembly comprises a hydraulic control element 11, a pressure sensor 12, a stainless steel upper pressure head 1 and a stainless steel lower pressure head 13, the stainless steel upper pressure head 1 is arranged at the upper end part of the furnace body 19, the bottom end of the stainless steel upper pressure head is connected with the upper end surface of the graphite upper pressure head 3, the stainless steel lower pressure head 13 is arranged at the lower end part of the furnace body 19, the top end of the stainless steel lower pressure head 13 is fixedly connected with the graphite upper pressure head 3, the bottom end of the stainless steel lower pressure head 13 is fixedly connected with the output end of the hydraulic control element 11 arranged outside the furnace body 19, and the pressure sensor 12 is arranged at the joint of the hydraulic control element 11 and the stainless steel lower pressure head;
the insulation assembly comprises a BN side plate 8, a BN upper plate 5, a BN lower plate 9, and a BN upper insulation sleeve 2 and a BN lower insulation sleeve 14 which are arranged on the graphite upper pressure head 3 and the graphite lower pressure head 10, wherein the BN side plate 8 is arranged at the joint of the inner wall of the graphite mold 7 and the graphite soft felt 18, the BN upper plate 5 and the BN lower plate 9 are respectively laid on the upper end surface and the lower end surface of the graphite mold 7, and the BN upper plate 5 and the BN lower plate 9 are provided with central holes matched with the graphite upper pressure head 3 and the graphite lower pressure head 10; when the device works, the insulating assembly is used for ensuring that current only flows through the graphite soft felt 18, but not flows through the graphite die 7, the stainless steel upper pressure head 1 and the stainless steel lower pressure head 13, and the current short circuit in the furnace body 19 can not be caused, so that the electrifying assembly is ensured to only electrify and heat the graphite soft felt 18;
the end parts of the BN upper insulating sleeve 2 and the BN lower insulating sleeve 14 are respectively provided with a thread groove matched with the stainless steel upper pressure head 1 and the stainless steel lower pressure head 13;
the temperature measuring component comprises an infrared thermometer 20 and a thermocouple 16 arranged on the inner wall of the BN side plate 8, a through hole is formed at the equal height position of the BN side plate 8 and the graphite mold 7, the through hole corresponds to the sensing end of the infrared thermometer 20 arranged outside the observation window 17, and the other end of the infrared thermometer 20 is electrically connected with a computer for obtaining the temperature and time curve of the graphite soft felt 18 in real time; the temperature in the furnace body 19 is measured by an infrared thermometer 20 and a thermocouple 16 simultaneously, or can be used independently, the temperature range of the infrared thermometer 20 used in the experiment is 1000-3200 ℃, the temperature of the sample 15 is recorded by the thermocouple 16, and the thermocouple 16 is connected with a temperature control meter and transmits data to a computer;
the BN side plate 8 is formed by splicing four petals and encloses a square hole groove for placing the graphite soft felt 18 and the sample 15;
sample 15 was made from ceramic powder; the ceramic powder is one or more of oxide or carbide, nitride, boride and ceramic-metal composite material.
Example 1:
in this embodiment, a rapid high temperature sintering Al2O3The new method is carried out according to the following steps:
a. firstly 30nm of Al2O3The powder was mixed with 3 wt.% aqueous PVA solution and ground to homogeneity and then pressed under a pressure of 400MPa to a size of 20X 4mm3Al of (2)2O3Green compact, initial density of 50%;
b. pre-burning the green body prepared in the step a in the air at 600 ℃ for 1h to remove organic PVA;
c. placing the 5 blanks obtained in the step b between S-shaped stacked graphite soft felts 18 with the length of 150mm, the width of 20mm and the thickness of 3mm, enclosing to form an S shape, and placing the S shape into a square hole groove of a BN side plate 8 in a graphite mold 7; then the furnace is vacuumized to below 10 Pa;
d. electrifying to make current quickly reach 35A, heating the sample to 1800 deg.C at 1000 deg.C/min, keeping the temperature for 20s, and cooling to room temperature at the rate to obtain Al2O3And (5) fast high-temperature sintering.
e. The density of the obtained blank is measured by adopting an Archimedes method, and the density of the blank is calculated to obtain 92%.
The change curve of the temperature with time recorded in example 1 of the present invention is shown in fig. 2; the microstructure is shown in fig. 3.
Example 2:
this example differs from example 1 in that: the initial alumina particles have a size of 500nm, a current of 40A, a sintering temperature of 2000 ℃ and other parameters and steps similar to those of example 1, and the measured density is as high as 95%.
Example 3:
this example differs from example 1 in that: sample 15 dimensions phi 12X 4mm2The graphite soft felt 18 has the dimensions of 150mm multiplied by 20mm multiplied by 5mm, the current is 35A, the sintering temperature is 1800 ℃, other parameters and steps are the same as the example 1, and the measured density is up to 95%.
Example 4:
the composite oxide ceramic La with the ceramic powder of 30nm selected in the example2Zr2O7Sample size of phi 6X 4mm2The number of the samples is 10, and the size of the graphite soft felt is 100 multiplied by 15 multiplied by 4mm3The applied current is 40A, the temperature is 1900 ℃, the heat preservation time is 22s, and the heating and cooling rate is 750 ℃/min. Other parameters and procedures were the same as in example 1, with a ceramic densification of up to 97%, the microstructure of which is shown in FIG. 4.
Example 5:
the ceramic powder selected in the example is a high-entropy oxide ceramic (La) with the grain size of 30nm0.2Nd0.2Sm0.2Eu0.2Gd0.2)2Zr2O7Sample size of phi 6X 4mm2The graphite soft felt has the size of 120 multiplied by 15 multiplied by 4mm3The number of samples was 6, the applied current was 35A, and the temperature was 1800The heating and cooling rate is 400 ℃/min. Other parameters and procedures were the same as in example 1, with a ceramic densification of up to 98%, the microstructure being shown in FIG. 5.
Example 6:
the ceramic powder selected in this example was 1 μm TiC, which is different from example 1 in that the ceramic powder was not mixed with PVA aqueous solution and it was not calcined at 600 ℃ to remove organic matter. And (3) spraying BN insulation on the surface of the TiC blank to ensure that the graphite soft felt generates enough joule heat. The sample size is phi 12 multiplied by 4mm2The graphite soft felt has the size of 150 multiplied by 20 multiplied by 3mm3The number of the heating elements is 5, the magnitude of applied current is 48A, the temperature is 2300 ℃, the heating and cooling rate is 1500 ℃/min, and the magnitude of applied pressure is 27 MPa. The ceramic density was as high as 94% and the microstructure is shown in figure 6.
Example 7:
the ceramic powder selected in this example was 1 μm Si3N4Except that the ceramic powder is not required to be mixed with the PVA water solution and is not required to be pre-sintered at 600 ℃ to remove organic matters. The sample size is 20mm multiplied by 3mm, the number is 4, the graphite soft felt size is 150mm multiplied by 20mm multiplied by 3mm3The applied current is 35A, the temperature is 1800 ℃, the heating and cooling rate is 1000 ℃/min, the applied pressure is 30MPa, and the ceramic density is up to 95%.
Example 8:
the ceramic powder selected in this example was 1 μm TiB2Unlike example 1, the ceramic powder was not mixed with the aqueous PVA solution nor calcined at 600 ℃ to remove the organic matter. TiB2The surface of the blank is sprayed with BN insulation to ensure that the graphite soft felt generates enough joule heat. The graphite soft felt has the size of 160 multiplied by 20 multiplied by 3mm3The size of the sample is 10mm multiplied by 3mm, the number of the samples is 5, the magnitude of the applied current is 45A, the temperature is 2200 ℃, the heating and cooling rate is 1500 ℃/min, the magnitude of the applied pressure is 28MPa, and the density of the ceramic is as high as 94%.
Example 9:
the ceramic powder selected in this example was 1 μm Li1.5Al0.5Ge1.5(PO4)3(LAGP), in contrast to example 1, LAGP bodies with graphiteThe soft felts are isolated by alumina fiber paper. The fiber paper and the graphite soft felt are closely contacted and arranged in an S-shaped lamination. The graphite soft felt has the size of 150 multiplied by 20 multiplied by 2mm3The applied current is 20A, the temperature is 1000 ℃, the heating and cooling rate is 2000 ℃/min, no pressure is required to be applied, and the ceramic density is as high as 94%.
The working principle of the invention is as follows: when the device works, ceramic powder is pressed into a sample 15 green body with a certain size under a certain pressure, the sample 15 is placed between the graphite soft felts 18 which are stacked in an S shape in a furnace body 19, a power supply 6 is started, direct current is applied to the graphite soft felts 18 through a copper electrode 4, after the temperature is stable, a pressurizing assembly applies pressure, the sample 15 is rapidly sintered within a plurality of seconds under the action of Joule heat conduction and pressure, and the sample 15 is rapidly cooled to room temperature after power failure; the ceramic adopts current thermal effect and heat conduction to realize faster heating rate and simultaneously avoid large heat loss; sample 15 bypasses the low temperature slow heating stage at an ultra-fast heating rate, thereby reducing particle growth, maintaining a higher sintering driving force, and increasing densification rate; the method has the advantages of simple operation, high efficiency, easy implementation, strong universality, enrichment of ceramic sintering technology, higher densification degree of the obtained ceramic and wider applicability. It will be evident to those skilled in the art that the invention is not limited to the details of the foregoing illustrative embodiments, and that the present invention may be embodied in other specific forms without departing from the spirit or essential attributes thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein. Any reference sign in a claim should not be construed as limiting the claim concerned.
Furthermore, it should be understood that although the present description refers to embodiments, not every embodiment may contain only a single embodiment, and such description is for clarity only, and those skilled in the art should integrate the description, and the embodiments may be combined as appropriate to form other embodiments understood by those skilled in the art.

Claims (10)

1. The utility model provides a quick sintering ceramic device, includes furnace body (19), set up observation window (17) in furnace body (19) one side and set up pressurization subassembly and the temperature measuring subassembly in furnace body (19), its characterized in that: the device is characterized by also comprising a power-on assembly and an insulating assembly, wherein a graphite mold (7) is arranged in the center of the inner cavity of the furnace body (19), and a graphite soft felt (18) which is arranged in an S shape and is used for placing a sample (15) is arranged in the graphite mold (7);
the electrifying assembly is arranged above and below the graphite soft felt (18), is matched with the BN side plate (8) and is used for electrifying and heating the sample (15) placed in the graphite soft felt (18);
the pressurizing assemblies are arranged at the upper end and the lower end of the furnace body (19) and are used for pressing and molding the sample (15);
the insulating assembly is respectively arranged on the graphite soft felt (18) and the graphite mold (7), the pressure head (3) is arranged on the pressure head (1) and the graphite on the stainless steel of the pressurizing assembly, the pressure head (13) is arranged on the stainless steel of the pressurizing assembly and the pressure head (10) is arranged on the graphite, the pressure head (3) and the graphite mold (7) are arranged on the graphite, the graphite is arranged between the pressure head (10) and the graphite mold (7) and is used for electrical insulation, so that the current only flows through the graphite soft felt (18), the current does not flow through the pressure head (1) and the stainless steel pressure head (13) on the graphite mold (7) and the stainless steel, the current short circuit in the furnace body can not be caused, and the graphite soft felt (18).
2. The rapid sintering ceramic device of claim 1, wherein: the circular telegram subassembly includes pressure head (3), copper electrode (4), power (6) and graphite lower pressure head (10) on the graphite, pressure head (3) and graphite lower pressure head (10) set up respectively on graphite soft felt (18) below and contact with graphite soft felt (18) on the graphite, power (6) set up outside furnace body (19), and its both ends are connected with copper electrode (4), two on furnace body (19) and graphite pressure head (3) and graphite lower pressure head (10) electric connection are passed respectively to copper electrode (4) other end, it is insulating and sealed with polytetrafluoroethylene between copper electrode (4) and furnace body (19).
3. The rapid sintering ceramic device of claim 1, wherein: the pressurizing assembly comprises a hydraulic control element (11), a pressure sensor (12), a stainless steel upper pressure head (1) and a stainless steel lower pressure head (13), the stainless steel upper pressure head (1) is arranged at the upper end of a furnace body (19), the bottom end of the stainless steel upper pressure head is connected with the upper end face of a graphite upper pressure head (3), the stainless steel lower pressure head (13) is arranged at the lower end of the furnace body (19), the top end of the stainless steel upper pressure head is fixedly connected with the graphite upper pressure head (3), the bottom end of the stainless steel lower pressure head (13) is fixedly connected with the output end of the hydraulic control element (11) arranged outside the furnace body (19), and the pressure sensor (12) is arranged at the joint of the hydraulic control element (11) and the stainless steel lower pressure head (13) and used for detecting the pressure applied to the hydraulic control element (11.
4. The rapid sintering ceramic device of claim 1, wherein: the insulation assembly comprises a BN side plate (8), a BN upper plate (5), a BN lower plate (9) and a BN upper insulation sleeve (2) and a BN lower insulation sleeve (14) which are arranged on graphite lower pressure heads (3) and graphite lower pressure heads (10), wherein the BN side plate (8) is arranged at the joint of the inner wall of a graphite mold (7) and a graphite soft felt (18), the BN upper plate (5) and the BN lower plate (9) are respectively laid on the graphite mold (7) to form upper and lower end faces, and the BN upper plate (5) and the BN lower plate (9) are provided with center holes matched with the graphite upper pressure heads (3) and the graphite lower pressure heads (10).
5. The rapid sintering ceramic device of claim 1, wherein: the BN upper insulation sleeve (2) and the BN lower insulation sleeve (14) are respectively provided with a thread groove matched with the stainless steel upper pressure head (1) and the stainless steel lower pressure head (13).
6. The rapid sintering ceramic device of claim 1, wherein: the temperature measuring assembly comprises an infrared thermometer (20) and a thermocouple (16) arranged on the inner wall of the BN side plate (8), a through hole is formed in the position with the same height as the graphite mold (7) of the BN side plate (8), the through hole corresponds to the sensing end of the infrared thermometer (20) arranged outside the observation window (17), and the other end of the infrared thermometer (20) is electrically connected with a computer and used for obtaining the temperature and time curve of the graphite soft felt (18) in real time.
7. The rapid sintering ceramic device of claim 1, wherein: the BN side plate (8) is formed by splicing four petals and encloses a square hole groove for placing the graphite soft felt (18) and the sample (15).
8. The rapid sintering ceramic device of claim 1, wherein: the sample (15) is made of ceramic powder compounded with one or more of oxides, carbides, nitrides, borides, and ceramic-metal composites.
9. The sintering method of a rapid sintering ceramic device according to any one of claims 1 to 8, comprising the steps of;
1) the ceramic powder is pressed into a sample (15) green compact with a certain shape under the pressure of 200-500 MPa, then the sample (15) green compact is placed on a graphite soft felt (18), and the graphite soft felt (18) wraps the sample (15) to form an S shape and is placed in a graphite mold (7).
2) Respectively contacting the graphite upper pressure head (3) and the graphite lower pressure head (10) with a graphite soft felt (18), and connecting the graphite upper pressure head and the graphite lower pressure head with a power supply (6) through a copper electrode (4);
3) the furnace is vacuumized to below 10Pa, then a power supply (6) switch is turned on to electrify the graphite soft felt (18), the current is adjusted to enable the temperature of the graphite soft felt (18) to quickly reach a preset value, the voltage range of the power supply (6) is 10-30V, and the current range is 20-50A;
4) after the temperature is constant, keeping electrifying for 5-30 s;
5) in the heat preservation process, 0-50 MPa of pressure is applied, then the power supply (6) is disconnected, and the temperature is reduced at a certain rate.
10. The sintering method of a rapid sintering ceramic device according to claim 9, wherein: in the step 1), a sample (15) is wrapped between S-shaped stacked graphite soft felts (18), when the sample (15) to be sintered is conductive or can react with graphite at high temperature, and the sintering temperature is less than or equal to 1200 ℃, 0.5mm alumina fiber paper is adopted between the sample (15) and the graphite soft felts (18) for insulation, and the sample (15), the fiber paper and the graphite soft felts (18) are stacked into an S shape and placed in a graphite mold (7); when the sample (15) to be sintered is conductive or can react with graphite at high temperature, and the sintering temperature is higher than 1200 ℃, BN powder is sprayed on the surface of the sample (15) to insulate the sample from the graphite soft felt (18).
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