CN114993033A

CN114993033A - Vacuum ultrahigh-temperature sintering purification furnace and purification process

Info

Publication number: CN114993033A
Application number: CN202210644276.8A
Authority: CN
Inventors: 高培; 钟明伟; 张伟强
Original assignee: Shanghai Advanced Materials Technology Co ltd
Current assignee: Shanghai Advanced Materials Technology Co ltd
Priority date: 2022-06-09
Filing date: 2022-06-09
Publication date: 2022-09-02

Abstract

The invention discloses a vacuum ultra-high temperature sintering purification furnace and a purification process, which comprise a furnace body frame, a main furnace shell, a cooling water distributor system, a heating system, a heat preservation system, a bottom charging trolley, a lead screw lifting system, a vacuum system, a temperature control system, a process gas system and an equipment electric control system, wherein the furnace body frame is formed by welding sectional materials, and the main furnace shell is arranged at the inner side of the furnace body frame; the main furnace shell is formed by welding stainless steel plates, and a water channel interlayer for cooling the shell is arranged on the inner side of the main furnace shell; the cooling water distributor system is used for providing cooling water for the furnace body equipment, is provided with a water inlet and outlet pipe, a water inlet and outlet branch pipe, a hand valve, a flow switch, a water pressure meter and a water temperature meter, and consists of the water inlet and outlet pipe, the water inlet and outlet branch pipe, the hand valve and the like to form a cooling water distribution loop. The method can meet the sintering or purification processing requirements of large-weight charging materials of 200-5000 kg, and the content of residual ash of the purified formed graphite component is less than or equal to 10 ppm.

Description

Vacuum ultrahigh-temperature sintering purification furnace and purification process

Technical Field

The invention relates to the field of purification or sintering treatment of graphite materials, powder metallurgy ceramic materials and the like, in particular to a vacuum ultrahigh-temperature sintering purification furnace and a purification process.

Background

The unpurified solid carbon material generally contains various impurities such as potassium, sodium, magnesium, calcium, aluminum and the like, chlorine gas is introduced at the temperature of about 2200 ℃ and is calcined at high temperature, so that the chlorine gas can react with the impurities in the solid carbon material, the melting point of chloride generated by the reaction is low, and the chloride can be discharged in a gas form, so that the purity of the carbon material is improved. For a vacuum ultra-high temperature sintering purification furnace with the temperature of more than 2200 ℃, the traditional horizontal structure can not solve the insulation problem of electrode introduction because almost all ceramic insulating materials have high-temperature carbonization reaction, so that the insulation property is failed quickly. The vertical structure can realize the structure without insulation protection of the electrode; meanwhile, the loading mode of bottom loading can replace top loading, and the structural design of loading with heavy weight (more than or equal to 200 kg) is realized.

Disclosure of Invention

The invention aims to provide a vacuum ultrahigh-temperature sintering purification furnace and a purification process, which are used for solving the problems in the background art.

In order to achieve the purpose, the invention provides the following technical scheme: a vacuum ultra-high temperature sintering purification furnace and a purification process comprise a furnace body frame, a main furnace shell, a cooling water distributor system, a heating system, a heat preservation system, a bottom charging trolley, a lead screw lifting system, a vacuum system, a temperature control system, a process gas system and an equipment electric control system, wherein the furnace body frame is formed by welding sectional materials, and the main furnace shell is arranged on the inner side of the furnace body frame; the main furnace shell is formed by welding stainless steel plates, and a water channel interlayer for cooling the shell is arranged on the inner side of the shell of the main furnace shell; the cooling water distributor system is used for providing cooling water for furnace body equipment, is provided with a water inlet and outlet pipe, a water inlet and outlet branch pipe, a hand valve, a flow switch, a water pressure gauge and a water temperature gauge, and consists of the water inlet and outlet pipe, the water inlet and outlet branch pipe, the hand valve and the like to form a cooling water distribution loop; the heating system is arranged on the inner side of the main furnace shell and comprises a copper electrode, a graphite heating body and a graphite ring, wherein the graphite heating body is designed in a squirrel-cage structure, the graphite ring is arranged at the upper end and the lower end of the graphite heating body, and the copper electrode is arranged on the graphite ring; the heat preservation system is arranged on the inner side of the main furnace shell and comprises a graphite heat insulation hard felt A, a hard felt fixing rod and a graphite pipe, wherein the graphite heat insulation hard felt A is fixed on the inner side of the main furnace shell and surrounds a graphite heating body on the inner side of the main furnace shell into an independent space so as to block the outward heat transfer loss of the graphite heating body during heating; the bottom charging trolley is arranged on one side of the furnace body frame and comprises a trolley frame, wheels, a walking driving motor, a main furnace bottom cover, a graphite heat-insulating hard felt B, a graphite muffle, a process gas pipe and a ground track, wherein the wheels are arranged at the bottom of the trolley frame, the wheels can be driven by the walking driving motor and move along the pre-buried ground track, the main furnace bottom cover is arranged on the trolley frame, and the graphite heat-insulating hard felt B and the graphite muffle are arranged on the main furnace bottom cover; the lead screw lifting system is arranged on the furnace body frame and used for lifting the bottom charging trolley to a specified position to close the bottom charging trolley and the main furnace shell, and comprises a lead screw lifter, a motor, a coupler and the like, wherein the lead screw lifter is driven by the motor, and the lead screw lifter drives a bearing bracket at the bottom of the lead screw lifter to make the bottom charging trolley perform lifting action and close the main furnace shell by utilizing the lead screw.

Preferably, nine copper electrodes are distributed on the graphite ring, the end part, far away from the graphite ring, of each copper electrode is fixed on the main furnace shell through a flange, and the graphite heating body, the graphite ring and the copper electrodes are connected to form a graphite hot area.

Preferably, the graphite heating body and the graphite ring both adopt high-strength extruded graphite.

Preferably, the graphite pipe is pre-buried in the top of the main furnace shell, the graphite pipe is designed to be a bending structure, and the upper end of the graphite pipe is connected with a vacuum system.

Preferably, the graphite muffle is arranged on the graphite heat insulation hard felt B, the graphite muffle is provided with a graphite cylinder, a graphite base and a graphite top cover, and the graphite base and the graphite top cover are respectively arranged on the top side and the bottom side of the graphite cylinder.

Preferably, the graphite cylinder is provided with a process gas pipe at the bottom side, and the process gas pipe can introduce the process gas into the graphite muffle.

Preferably, the graphite top cover is reserved with vent holes, the vent holes are in butt joint with pre-buried graphite pipes of the heat preservation system, the vacuum system is in butt joint, and the vacuum system is used for pumping out volatilized gas.

Preferably, the invention also provides a purification process of the vacuum ultrahigh-temperature sintering purification furnace, which comprises the following steps:

s1: opening the bottom charging trolley;

s2: placing a graphite product to be purified into a graphite muffle, and driving a bottom charging trolley to ascend by using a lead screw lifting system to close a main furnace shell;

s3: vacuumizing the furnace to below 0.1mbar to remove air and water vapor in the furnace;

s4: vacuumizing the furnace, heating to 1000 ℃, keeping the temperature for 1 hour after the temperature rises at the speed of 5 ℃/min, and maintaining the vacuum in the furnace below 0.2 mbar;

s5: vacuumizing and heating the furnace to 2000 ℃, heating at the speed of 5 ℃/min, keeping the temperature for 1 hour after reaching the temperature, and maintaining the vacuum in the furnace below 0.2 mbar;

s6: heating in vacuum to the purification temperature of 2200-2800 ℃, heating at the speed of 1-10 ℃/min, keeping the temperature and purifying for 50-100 hours, introducing purification process gas R14/CF4 during heating and keeping the temperature, wherein the flow rate of the purification process gas is 2-20 l/min, and the vacuum in the furnace is 10-100 mbar;

s7: vacuumizing to reduce the temperature to 1000 ℃, reducing the temperature to the temperature and keeping the temperature for 1 hour, introducing over 99.999 percent of high-purity argon during temperature reduction and heat preservation, and keeping the vacuum in the furnace between 10mbar and 100 mbar;

s8: vacuumizing and cooling to be near room temperature, wherein the cooling speed is 10-30 ℃/h or so, more than 99.999 percent of high-purity argon is introduced during cooling, and the vacuum in the furnace is 500mbar-800 mbar;

s9: when the temperature reaches the temperature, introducing high-purity argon with the purity of more than 99.999 percent to repress to one atmosphere, opening the furnace door, taking out the graphite purification product, and finishing the purification processing.

Compared with the prior art, the invention has the beneficial effects that:

1. the invention adopts the full graphite heating element and the heat preservation structure, can realize the vacuum ultra-high temperature sintering (or purification) process with the temperature of more than 2200 ℃ in the application of new materials, and can reach 2800 ℃ at most.

2. The invention adopts a squirrel-cage graphite heating body structure to realize graphite hot-zone power arrangement with heating power of more than 500 KW.

3. According to the invention, the electrode and the insulating layer are in a non-insulating structure, the cold end is connected by adopting the multi-copper electrode in a leading-in mode, so that the traditional structure that the ceramic material is adopted as the insulating material for supporting the insulating layer is abandoned when the graphite hot zone is at the working temperature of over 2200 ℃, and the copper electrode and the integral structure of the high-strength graphite piece keep enough strength.

4. According to the connecting structure of the graphite muffle and the vacuum pipeline, the inner space and the outer space of the muffle are separated; the volatilization generated in the muffle under the high-temperature condition is directly discharged from the vacuum pipeline, and the pollution to the integral hot area outside the muffle is not caused.

5. The heating body and the electrode structure are arranged on a fixed furnace body, the bottom charging furnace door structure is completely independent, the sintering (or purification) processing requirement of large-weight charging materials of 200-5000 kg can be realized by adopting a synchronous lead screw structure, and the content of residual ash in the purified formed graphite component is less than or equal to 10 ppm.

Drawings

FIG. 1 is a schematic view of the overall structure of the present invention;

FIG. 2 is a schematic diagram of the heating system of the present invention;

FIG. 3 is a schematic view of the construction of the insulation system of the present invention;

FIG. 4 is a schematic structural view of the bottom loading trolley of the present invention;

FIG. 5 is a schematic structural view of the graphite muffle of the present invention;

fig. 6 is a schematic structural view of the lead screw lifting system of the present invention.

In the figure: 1. a furnace body frame; 2. a main furnace shell; 3. a cooling water dispenser system; 4. a heating system; 5. a heat preservation system; 6. a bottom charging trolley; 7. a lead screw lifting system; 8. a vacuum system; 9. a temperature control system; 10. a process gas system; 11. an equipment electrical control system; 12. a copper electrode; 13. a graphite heating element; 14. a graphite ring; 15. a flange; 16. a graphite heat insulation hard felt A; 17. a hard felt fixing rod; 18. a graphite tube; 19. a trolley frame; 20. a wheel; 21. a travel driving motor; 22. a main furnace bottom cover; 23. a graphite heat insulation hard felt B; 24. a graphite muffle; 25. a process gas pipe; 26. a ground track; 27. a graphite cylinder; 28. a graphite base; 29. a graphite top cover; 30. a screw elevator; 31. a motor; 32. a coupler is provided.

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.

In the description of the present invention, it should be noted that the terms "vertical", "upper", "lower", "horizontal", and the like indicate orientations or positional relationships based on those shown in the drawings, and are only for convenience of describing the present invention and simplifying the description, but do not indicate or imply that the referred device or element must have a specific orientation, be constructed in a specific orientation, and be operated, and thus, should not be construed as limiting the present invention.

In the description of the present invention, it should also be noted that, unless otherwise explicitly specified or limited, the terms "disposed," "mounted," "connected," and "connected" are to be construed broadly and may, for example, be fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.

As shown in fig. 1, the present invention provides a technical solution: a vacuum ultra-high temperature sintering purification furnace comprises a furnace body frame 1, a main furnace shell 2, a cooling water distributor system 3, a heating system 4, a heat preservation system 5, a bottom charging trolley 6, a lead screw lifting system 7, a vacuum system 8, a temperature control system 9, a process gas system 10, an equipment electric control system 11 and the like.

In the present embodiment, the furnace body frame 1 is mainly formed by welding sectional materials, and serves as a support frame, a framework, a panel and the like of the equipment.

In this embodiment, a main furnace casing 2 is installed inside the furnace body frame 1, the main furnace casing 2 is mainly formed by welding stainless steel plates, a water channel interlayer is formed in the casing, and the furnace shell is cooled by cooling water to prevent the furnace shell from overheating.

In this embodiment, the cooling water distributor system 3 is mainly composed of a water inlet and outlet pipe, a water inlet and outlet branch pipe, a hand valve, a flow switch, a water pressure gauge, a water temperature gauge and the like, and is used for providing cooling water for important components needing to be cooled on the equipment, so that the components can work within a reasonable temperature range.

As shown in fig. 2, in the present embodiment, the heating system 4 is installed inside the main furnace shell 2, and the heating system 4 mainly comprises nine copper electrodes 12, a graphite heating element 13, a graphite ring 14, and the like, and forms a graphite hot zone. Nine copper electrodes are fixed on the main furnace shell 2 through flanges 15, the arrangement form of the graphite heating body 13 adopts a squirrel-cage structural design, and the graphite heating body 13 and the graphite ring 14 both adopt high-strength extruded graphite, so that the copper electrodes 12 and the graphite hot zone are kept with enough strength in the integral structure at the working temperature of 2000 ℃, and the structure is stable and reliable.

As shown in fig. 3, in the present embodiment, the heat preservation system 5 is installed inside the main furnace shell 2, the heat preservation system 5 mainly includes a graphite heat insulation hard felt 16, a hard felt fixing rod 17, and the like, the graphite heat heating element 13 is enclosed into an independent space by the graphite heat insulation hard felt 16, unnecessary heat transfer loss to the outside of the graphite heat heating element 13 during heating is blocked, a graphite pipe 18 is embedded in the top of the heat preservation system 5, the graphite pipe 18 is connected with the vacuum system 8, and the embedded graphite pipe 18 adopts a bent structure, so that heat can be effectively prevented from overflowing through the embedded graphite pipe 18, and heat loss is reduced.

As shown in fig. 4, in the present embodiment, the bottom charging carriage 6 is mounted on one side of the furnace body frame 1, and the bottom charging carriage 6 mainly comprises a carriage frame 19, wheels 20, a traveling driving motor 21, a main furnace bottom cover 22, a graphite heat insulation hard felt 23, a graphite muffle 24, a process gas pipe 25, a ground rail 26, and the like;

as shown in fig. 5, the graphite muffle 24 is divided into a graphite cylinder 27, a graphite base 28, and a graphite top cover 29.

In this embodiment, the graphite workpiece may be placed on the graphite base 28 after the graphite bottom cover 29 is removed. When the graphite workpiece is sintered at high temperature, some gas can be volatilized, and the volatilized gas is not easy to diffuse out by utilizing the graphite muffle 24, so that other parts in the furnace are protected from being polluted. The process gas tube 25 is made of molybdenum material and has high temperature resistance, and the process gas can be introduced into the graphite muffle 24 through the process gas tube 25. The graphite top cover 29 is reserved with vent holes and can be butted with the pre-buried graphite pipes 18 in the heat insulation system, so that the vacuum top cover is communicated with a vacuum pipeline, and the vacuum system 8 is utilized to pump out volatilized gas.

As shown in fig. 6, in this embodiment, the screw lifting system 7 mainly includes a screw lifter 30, a motor 31, a coupling 32, and the like, and the screw lifting system 7 is used to lift the bottom loading trolley 6 to a specified position, so that the bottom loading trolley 6 and the main furnace shell 2 are closed. The screw rod lifter 30 has large bearing capacity and stable performance, and can realize the lifting function of loading materials with large weight (more than or equal to 200 kilograms).

In this embodiment, the temperature control system 9 mainly includes a thermocouple, an infrared thermometer, a transformer, and the like. The thermocouple is adopted to measure temperature at low temperature, the infrared thermometer is adopted to measure temperature at high temperature, and the thermometer receives a temperature signal and then controls the output of the transformer, so that the heat productivity of the graphite heating body is controlled, and the function of accurate temperature control is realized.

In the present embodiment, the process gas system 10 is mainly composed of gas pipes, valves, mass flow meters, atmosphere analyzers, and the like. When the graphite sintering process is operated, the process gas system 10 utilizes the process gas pipe 25 to introduce the process gas into the graphite muffle 24 according to the process requirements.

The embodiment of the invention also provides a purification process of the vacuum ultrahigh-temperature sintering purification furnace, which comprises the following steps:

s1: opening the bottom charging trolley 6;

s2: placing a graphite product to be purified into a graphite muffle 24, and driving a bottom loading trolley 6 to ascend by using a lead screw lifting system 7 to close and seal the main furnace shell 2;

s4: vacuumizing and heating the furnace to 1000 ℃, heating at the speed of 5 ℃/min, keeping the temperature for 1 hour after reaching the temperature, and maintaining the vacuum in the furnace below 0.2 mbar;

It is worth noting that: whole purification furnace system realizes control to it through total control button, because the equipment that control button matches is equipment commonly used, belongs to current mature technology, no longer gives unnecessary details its electric connection relation and specific circuit structure here.

Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that changes, modifications, substitutions and alterations can be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.

Claims

1. A vacuum ultra-high temperature sintering purification furnace is characterized by comprising a furnace body frame (1), a main furnace shell (2), a cooling water distributor system (3), a heating system (4), a heat preservation system (5), a bottom charging trolley (6), a lead screw lifting system (7), a vacuum system (8), a temperature control system (9), a process gas system (10) and an equipment electric control system (11), wherein the furnace body frame (1) is formed by welding sectional materials, and the main furnace shell (2) is arranged on the inner side of the furnace body frame (1); the main furnace shell (2) is formed by welding stainless steel plates, and a water channel interlayer for cooling the shell is arranged on the inner side of the main furnace shell (2);

the cooling water distributor system (3) is used for providing cooling water for furnace body equipment, the cooling water distributor system (3) is provided with a water inlet and outlet pipe, a water inlet and outlet branch pipe, a hand valve, a flow switch, a water pressure meter and a water temperature meter, and a cooling water distribution loop is formed by the water inlet and outlet pipe, the water inlet and outlet branch pipe, the hand valve and the like;

the heating system (4) is arranged on the inner side of the main furnace shell (2), the heating system (4) comprises a copper electrode (12), a graphite heating body (13) and a graphite ring (14), wherein the graphite heating body (13) is designed in a squirrel-cage structure, the graphite ring (14) is arranged at the upper end and the lower end of the graphite heating body (13), and the copper electrode (12) is arranged on the graphite ring (14);

the heat preservation system (5) is arranged on the inner side of the main furnace shell (2), the heat preservation system (5) comprises a graphite heat insulation hard felt A (16), a hard felt fixing rod (17) and a graphite pipe (18), wherein the graphite heat insulation hard felt A (16) is fixed on the inner side of the main furnace shell (2), and the graphite heat insulation hard felt A (16) surrounds a graphite heating body (13) on the inner side of the main furnace shell (2) into an independent space so as to block the outward heat transfer loss of the graphite heating body (13) during heating;

the bottom charging trolley (6) is arranged on one side of the furnace body frame (1), the bottom charging trolley (6) comprises a trolley frame (19), wheels (20), a walking driving motor (21), a main furnace bottom cover (22), a graphite heat-insulating hard felt B (23), a graphite muffle (24), a process gas pipe (25) and a ground track (26), wherein the wheels (20) are arranged at the bottom of the trolley frame (19), the wheels (20) can be driven by the walking driving motor (21) and move along the pre-buried ground track (26), the main furnace bottom cover (22) is arranged on the trolley frame (19), and the graphite heat-insulating hard felt B (23) and the graphite muffle (24) are arranged on the main furnace bottom cover (22);

the lead screw lifting system (7) is arranged on the furnace body frame (1) and used for lifting the bottom loading trolley (6) to a specified position to enable the bottom loading trolley (6) to be closed with the main furnace shell (2), the lead screw lifting system (7) comprises a lead screw lifter (30) and a motor (31), wherein the lead screw lifter (30) is driven by the motor (31), and the lead screw lifter (30) drives a bearing bracket at the bottom of the lead screw lifter to enable the bottom loading trolley (6) to do lifting action and be closed with the main furnace shell (2) by utilizing the lead screw.

2. The vacuum ultrahigh temperature sintering purification furnace as claimed in claim 1, wherein: nine copper electrodes (12) are distributed on the graphite circular ring (14), the end part, far away from the graphite circular ring (14), of each copper electrode (12) is fixed on the main furnace shell (2) through a flange (15), and the graphite heating body (13), the graphite circular ring (14) and the copper electrodes (12) are connected to form a graphite hot area.

3. The vacuum ultrahigh temperature sintering purification furnace as claimed in claim 2, wherein: the graphite heating body (13) and the graphite ring (14) both adopt high-strength extruded graphite.

4. The vacuum ultrahigh-temperature sintering purification furnace as claimed in claim 1, wherein: graphite pipe (18) pre-buried in main furnace shell (2) top, graphite pipe (18) are bending structure design, and graphite pipe (18) upper end meets with vacuum system (8).

5. The vacuum ultrahigh-temperature sintering purification furnace as claimed in claim 1, wherein: the graphite muffle (24) is arranged on the graphite heat insulation hard felt B (23), the graphite muffle (24) is provided with a graphite cylinder (27), a graphite base (28) and a graphite top cover (29), and the graphite base (28) and the graphite top cover (29) are respectively arranged on the top side and the bottom side of the graphite cylinder (27).

6. The vacuum ultrahigh-temperature sintering purification furnace as claimed in claim 5, wherein: the bottom side of the graphite cylinder (27) is provided with a process gas pipe (25), and the process gas pipe (25) can introduce process gas into the graphite muffle (24).

7. The vacuum ultrahigh-temperature sintering purification furnace as claimed in claim 5, wherein: and vent holes are reserved in the graphite top cover (29), are in butt joint with the embedded graphite pipes (18) of the heat insulation system (5), are in butt joint with the vacuum system (8), and are used for pumping out volatilized gas by the vacuum system (8).

8. The purification process of the vacuum ultra-high temperature sintering purification furnace as claimed in any one of claims 1 to 7, wherein: the method comprises the following steps:

s1: opening the bottom charging trolley (6);

s2: placing a graphite product to be purified into a graphite muffle (24), and driving a bottom loading trolley (6) to ascend by using a lead screw lifting system (7) to close a sealed main furnace shell (2);

s6: heating in vacuum to the purification temperature of 2200-2800 deg.C at a heating rate of 1-10 deg.C/min, maintaining the temperature for 50-100 hr, introducing purification process gas R14/CF4 at the time of heating and maintaining the temperature, with the flow rate of purification process gas being 2-20L/min, and the vacuum in the furnace being 10-100 mbar;