CN112359342B

CN112359342B - Graphite spare surface deposit carborundum equipment

Info

Publication number: CN112359342B
Application number: CN202011063453.0A
Authority: CN
Inventors: 马伟; 张超
Original assignee: Sinosteel New Materials Co Ltd
Current assignee: Symantec Advanced Materials Co ltd
Priority date: 2020-09-30
Filing date: 2020-09-30
Publication date: 2022-11-11
Anticipated expiration: 2040-09-30
Also published as: CN112359342A

Abstract

The invention provides equipment for depositing silicon carbide on the surface of a graphite piece, which comprises a deposition device, a spraying device, a cooling device and a switching device, wherein the deposition device comprises a reaction kettle, a storage table, a vacuumizing pipeline, a raw material gas pipeline, a nitrogen pipeline and a chlorine channel; the spraying device comprises a spraying component and a liquid collecting component; the cooling device comprises a cooling assembly, a drainage assembly and a limiting assembly, wherein a material placing table is arranged in the reaction kettle, a liquid collecting assembly and a spraying assembly capable of covering the liquid collecting assembly are arranged on the material placing table, the cooling assembly communicated with the liquid collecting assembly is arranged in the spraying assembly in a surrounding mode, and the spraying assembly and the cooling assembly alternately and independently work under the action of a switching device, so that the impurity removal and the surface deposition of the surface of the graphite piece are completed in the same reaction kettle, and the technical problem that the deposition effect is influenced due to the fact that the surface deposition of the graphite piece is easy to wear in the transfer process of the graphite piece because the surface deposition of the graphite piece needs to be carried out in two stations in the prior art is solved.

Description

Graphite spare surface deposit carborundum equipment

Technical Field

The invention relates to the field of graphite handicraft production equipment, in particular to equipment for depositing silicon carbide on the surface of a graphite piece.

Background

The graphite is commonly called as 'black gold', has good chemical stability at normal temperature and is not corroded by any strong acid, strong alkali and organic solvent, so the graphite can be made into artware, and the surface of the graphite artware can be effectively protected by covering a silicon carbide coating on the surface of the graphite artware.

The utility model patent of china patent application number CN201621040511.7 discloses a device system of graphite surface deposition carborundum, including purifying first station and the first station of reaction, wherein, it installs graphite purification stove to purify first station, the CVD reacting furnace is installed to the first station of reaction, and graphite purification stove and CVD reacting furnace are fixed knot and construct, promptly graphite purification stove's a stove section of thick bamboo and CVD reacting furnace's a stove section of thick bamboo fix subaerial through the support respectively, and graphite purification stove's furnace chassis and CVD reacting furnace's furnace chassis are located respectively on a elevating platform, and the elevating platform makes a stove section of thick bamboo and furnace chassis closely cooperate through rising.

However, the device is provided with two stations for processing graphite, the graphite workpiece is transferred between the two stations and is grabbed by the grab hand to realize the processing, and the graphite is exposed in the air and is contacted with the grab hand, so that the graphite surface is easily affected, and the deposition effect on the surface of the graphite workpiece is further affected.

Disclosure of Invention

Aiming at the problems, the invention provides equipment for depositing silicon carbide on the surface of a graphite piece, which is characterized in that a placing table is arranged in a reaction kettle, a liquid collecting assembly and a spraying assembly capable of being covered on the placing table are arranged on the placing table, a cooling assembly communicated with the liquid collecting assembly is arranged in the spraying assembly in a surrounding mode, and the spraying assembly and the cooling assembly alternately and independently work under the action of a switching device, so that impurity removal and surface deposition on the surface of the graphite piece are completed in the same reaction kettle, and the technical problem that the surface of the graphite piece is easily abraded in the transfer process of the graphite piece to further influence the deposition effect due to the fact that the surface deposition of the graphite piece needs to be carried out in two stations in the prior art is solved.

In order to achieve the purpose, the invention provides the following technical scheme:

an apparatus for depositing silicon carbide on the surface of a graphite piece comprises:

the deposition device comprises a reaction kettle, a material placing table arranged in the middle of the bottom surface of the reaction kettle, and a vacuum pumping pipeline, a raw material gas pipeline and a nitrogen pipeline which are respectively arranged in the middle of the material placing table in a penetrating manner; the wall of the reaction kettle is also provided with a chlorine channel;

the spraying device comprises a spraying component which is arranged in the reaction kettle in a vertically sliding mode and can cover the object placing table, and a liquid collecting component which is arranged on the object placing table and can be in linkage fit with the spraying component;

the cooling device comprises a cooling assembly which is arranged on the spraying assembly in a surrounding manner and is communicated with the liquid collecting assembly through a circulating pipeline, a drainage assembly which can be in butt joint with the cooling assembly, and two groups of limiting assemblies which are respectively arranged in the drainage assembly and the cooling assembly and can be in butt joint with each other; the drainage assembly and the liquid collection assembly are arranged at intervals, and

the switching device is arranged at the top of the reaction kettle and drives the liquid collection assembly and the drainage assembly to work alternately.

As an improvement, the spray assembly comprises a working frame arranged on the reaction kettle, a movable column arranged on the reaction kettle in a vertically sliding mode, a sleeve coaxially fixed at the bottom of the movable column, a spray mechanism arranged at the top of the sleeve, a water tank fixed on the working frame, a hose penetrating through the movable column and communicated with the spray mechanism and the water tank, and hydraulic equipment fixedly arranged on the working frame and connected with the movable column in a power mode.

As an improvement, the liquid collecting component comprises a placing disc coaxially fixed on the placing table through a fixing pipe, a rotating disc rotatably installed at the placing table and at the middle position of the placing disc, two limiting rods symmetrically arranged at the edges of the rotating disc, an arc-shaped groove a arranged on the inner wall of the bottom of the sleeve and correspondingly matched with the limiting rods, and a liquid collecting box fixed at the bottom of the placing table and communicated with the circulating pipeline.

As an improvement, the object placing disc and the object placing table are provided with a plurality of through holes a which are aligned up and down, and the rotating disc is provided with a plurality of through holes b which can be aligned with the through holes a.

As an improvement, the cooling assembly comprises a conveying pipeline arranged in the moving column along the length direction of the moving column, a connecting ring communicated with the circulating pipeline and sleeved on the moving column in a sliding manner, a cooling pipeline surrounding the side wall of the sleeve and communicated with the conveying pipeline, and two water outlets symmetrically arranged on two sides of the bottom of the sleeve and communicated with the cooling pipeline; the connecting ring can be communicated with the inlet of the conveying pipeline.

As an improvement, the drainage component comprises a water receiving port which is arranged on the side edge of the object placing table and can be correspondingly matched with the water outlet in an inserted manner, and a water outlet pipe which is arranged in the side walls of the object placing table and the liquid collecting box and is communicated with the water receiving port and an external sewage collecting device.

As an improvement, the limiting component comprises a circular ring arranged in the water outlet and the water receiving port respectively, a moving rod coaxially arranged in the middle of the circular ring in a penetrating manner, a sealing plate coaxially fixed at one end of the moving rod and capable of abutting against the circular ring, a fixing plate coaxially fixed at the other end of the moving rod relative to the sealing plate and elastically connected with the circular ring, and a convex block fixedly arranged on the fixing plate.

As an improvement, the switching device comprises a mounting ring fixed on the top of the reaction kettle and surrounding the movable column, a limiting groove arranged on the inner wall of the mounting ring in the circumferential direction of the mounting ring, and supporting rods symmetrically fixed on the two radial sides of the movable column and moving along the limiting groove.

As an improvement, the limiting groove comprises four sliding grooves which are arranged in a circumferential array mode and are arranged vertically, an arc-shaped groove b which is arranged between every two adjacent sliding grooves and is connected with the sliding grooves end to end, and a one-way rod which is arranged at the tail end of each sliding groove and at the tail end of the arc-shaped groove b in an elastic mode along the moving direction of the supporting rod.

As an improvement, a discharge valve which is opposite to the object placing table is further arranged on the pipe wall of the reaction kettle.

The invention has the beneficial effects that:

(1) According to the invention, the object placing table is arranged in the reaction kettle, the liquid collecting assembly and the sleeve capable of covering the object placing table are arranged on the object placing table, the cooling assembly communicated with the liquid collecting assembly is arranged in the side wall of the sleeve in a surrounding mode, and under the action of the supporting rod and the limiting groove, the sleeve rotates for 90 degrees before moving downwards each time, so that the spraying mechanism and the cooling assembly alternately and independently work, the impurity removal and the surface deposition on the surface of a graphite piece are completed in the same reaction kettle, the movement of the graphite piece is reduced, the surface abrasion of the graphite piece is reduced, and the deposition effect is improved;

(2) According to the invention, the liquid collecting device collects waste liquid in the working process of the spraying mechanism, the deposited graphite piece is cooled through the cooling pipe in the waste liquid discharging process, and the waste liquid can be effectively collected, so that the waste liquid can be reused, the environmental pollution is reduced, unnecessary waste is reduced, and the production cost is reduced;

(3) According to the invention, the impurity removal on the graphite surface and the deposition on the graphite surface are carried out in one reaction kettle, so that the contact between the graphite piece and the outside air is reduced, the impurities in the air are prevented from being attached to the surface of the graphite piece, and the surface deposition effect of the graphite piece is further improved;

(4) The invention reduces the time for transferring the graphite piece between two stations in the traditional equipment, has higher switching efficiency between impurity removal and deposition on the surface of the graphite piece, has higher cooling efficiency after the deposition is finished, and greatly improves the surface deposition efficiency of the graphite piece.

In conclusion, the invention has the advantages of simple structure, ingenious design, good deposition effect, high deposition efficiency and the like, and is particularly suitable for the process of depositing silicon carbide on the surface of the graphite handicraft.

Drawings

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

FIG. 2 is an enlarged view of FIG. 1 at A;

FIG. 3 is a first diagram illustrating the structure of the spray assembly;

FIG. 4 is an enlarged view of FIG. 3 at D;

FIG. 5 is a second schematic view of a spray assembly;

FIG. 6 is an enlarged view of FIG. 5 at B;

FIG. 7 is an enlarged view at C of FIG. 5;

FIG. 8 is a cross-sectional structural view of the rotating ring;

FIG. 9 is a schematic structural diagram of a switching device;

FIG. 10 is an expanded cross-sectional view of the collar;

FIG. 11 is a schematic view of a spacing assembly;

fig. 12 is an enlarged view of fig. 11 at E.

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 is to be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", and the like, indicate orientations and positional relationships based on those shown in the drawings, and are used only for convenience of description and simplicity of description, and do not indicate or imply that the equipment or element being referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus, should not be considered as limiting the present invention.

Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or to implicitly indicate the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of the present invention, "a plurality" means two or more unless specifically defined otherwise.

Example (b):

as shown in fig. 1 to 7, an apparatus for depositing silicon carbide on a surface of a graphite piece includes:

the deposition device 1 comprises a reaction kettle 11, a placing table 12 arranged in the middle of the bottom surface of the reaction kettle 11, and a vacuumizing pipeline 13, a raw material gas pipeline 14 and a nitrogen pipeline 15 which are respectively arranged in the middle of the placing table 12 in a penetrating manner; the wall of the reaction kettle 11 is also provided with a chlorine channel 16;

the spraying device 2 comprises a spraying assembly 21 which is arranged in the reaction kettle 11 in a vertically sliding mode and can cover the object placing table 12, and a liquid collecting assembly 22 which is arranged on the object placing table 12 and can be in linkage fit with the spraying assembly 21;

the cooling device comprises a cooling assembly 32, a drainage assembly 33 and two groups of limit assemblies 34, wherein the cooling assembly 32 is arranged on the spray assembly 21 in a surrounding mode and is communicated with the liquid collecting assembly 22 through a circulating pipeline 31, the drainage assembly 33 can be in butt joint with the cooling assembly 32, and the two groups of limit assemblies 34 are respectively arranged in the drainage assembly 33 and the cooling assembly 32 and can be in butt joint; the drain assembly 33 is spaced apart from the liquid collection assembly 22, and

the switching device 4 is installed on the top of the reaction kettle 11, and drives the liquid collecting assembly 22 and the water discharging assembly 33 to work alternately.

The reaction vessel 11 is connected to a heater.

Further, a discharge valve 17 facing the placing table 12 is further disposed on the tube wall of the reaction kettle 11.

It should be noted that the vacuum-pumping pipeline 13 is communicated with a vacuum-pumping device; the feed gas pipeline 14 is communicated with a feed gas supply device; the nitrogen pipeline 15 is communicated with an external nitrogen supply device; the chlorine channel 16 is communicated with an external chlorine supply device, and the above devices are all in the prior art, and the specific working process and working principle are not described in detail again.

More specifically, the raw material gas is a mixed gas of methyltrichlorosilane, hydrogen and argon, and the volume ratio of the three fluids during deposition is 1.

It is important to note that the reaction vessel 11 is further provided with an exhaust gas duct 18 for discharging the sublimated metal halide.

As shown in fig. 3 to fig. 7, as a preferred embodiment, the spraying assembly 21 includes a working frame 211 disposed on the reaction vessel 11, a moving column 212 disposed on the reaction vessel 11 in a vertically sliding manner, a sleeve 213 coaxially fixed at the bottom of the moving column 212, a spraying mechanism 214 disposed at the top of the sleeve 213, a water tank 215 fixed on the working frame 211, a hose 216 passing through the moving column 212 and communicating the spraying mechanism 214 and the water tank 215, and a hydraulic device 217 fixedly mounted on the working frame 211 and dynamically connected to the moving column 212.

It should be noted that the spraying mechanism 214 and the hydraulic device 217 are the prior art, and the working principle and the working process thereof are not described herein again.

As shown in fig. 3 to 7, as a preferred embodiment, the liquid collecting assembly 22 includes a tray 222 coaxially fixed on the platform 12 through a fixing tube 221, a rotating tray 223 rotatably installed at the middle position between the platform 12 and the tray 222, two limiting rods 224 symmetrically disposed at the edge of the rotating tray 223, an arc-shaped groove a225 opened on the inner wall of the bottom of the sleeve 213 and correspondingly engaged with the limiting rods 224, and a liquid collecting tank 226 fixed at the bottom of the platform 12 and communicating with the circulation pipe 31.

Further, a plurality of through holes a121 aligned up and down are formed in the article placing tray 222 and the article placing table 12, and a plurality of through holes b2231 aligned with the through holes a121 are formed in the rotating tray 223.

It should be noted that, as shown in fig. 5, the sleeve 213 moves downward, the limiting rod 224 is clamped into the arc-shaped groove a225, the limiting rod 224 drives the rotating disc 223 to rotate and align the through hole a121 with the through hole b2231, at this time, the spraying mechanism 214 works, and the washing waste liquid can flow into the liquid collecting tank 226; after spraying, the sleeve 213 moves upwards, the rotating disc 223 rotates and resets, and the reaction kettle 11 still keeps closed.

As shown in fig. 1, 2 and 8, as a preferred embodiment, the cooling assembly 32 includes a delivery pipe 321 opened in the moving column 212 along the length direction of the moving column 212, a connection ring 322 connected to the circulation pipe 31 and slidably sleeved on the moving column 212, a cooling pipe 323 surrounding the sidewall of the sleeve 213 and connected to the delivery pipe 321, and two water outlets 324 symmetrically disposed at two sides of the bottom of the sleeve 213 and connected to the cooling pipe 323; the connection ring 322 may be provided in communication with an inlet of the delivery pipe 321.

It should be noted that a pumping device is disposed on the conveying pipeline 321.

Further, the drainage component 33 includes a water receiving port 331 disposed at a side of the object placing table 12 and corresponding to the water outlet 324 for inserting and matching, and a water outlet pipe 332 disposed in the side walls of the object placing table 12 and the liquid collecting tank 226 and communicating the water receiving port 331 with an external sewage collecting device.

Still further, the limiting component 34 includes a circular ring 341 disposed in the water outlet 324 and the water receiving port 331, a moving rod 342 coaxially penetrating the middle of the circular ring 341, a sealing plate 343 coaxially fixed at one end of the moving rod 342 and capable of abutting against the circular ring 341, a fixing plate 344 coaxially fixed at the other end of the moving rod 342 relative to the sealing plate 343 and elastically connected to the circular ring 341, and a protrusion 345 fixedly mounted on the fixing plate 344.

It should be noted that, as shown in fig. 11 and 12, when the water outlet 324 is abutted to the water receiving opening 331, the upper and lower bumps 345 abut against each other, so that the cooling pipeline 323 and the water outlet pipe 332 can be communicated with each other.

More specifically, when the water outlet 324 is separated from the water throttle 331, the sealing plate 343 seals the middle position of the circular ring 341, so that a closed space is formed in the reaction vessel 11.

As shown in fig. 9, as a preferred embodiment, the switching device 4 includes a mounting ring 41 fixed on the top of the reaction vessel 11 and surrounding the moving column 212, a limiting groove 42 opened on the inner wall of the mounting ring 41 along the circumferential direction of the mounting ring 41, and struts 43 symmetrically fixed on the two longitudinal sides of the moving column 212 and moving along the limiting groove 42.

Further, the limiting groove 42 includes four sliding grooves 421 which are arranged in a circumferential array and are arranged vertically, an arc-shaped groove b422 which is arranged between two adjacent sliding grooves 421 and is connected with the sliding grooves 421 end to end, and a one-way rod 423 which is respectively and elastically installed at the tail end of the sliding groove 421 and the tail end of the arc-shaped groove b422 along the moving direction of the supporting rod 43.

It should be noted that, as shown in fig. 10, when the supporting rod 43 moves in the arc-shaped groove b422, the sleeve 213 is driven to rotate 90 °, that is, the engagement between the arc-shaped groove a225 and the limiting rod 224 and the engagement between the water outlet 324 and the water receiving opening 331 are performed alternately.

More specifically, the one-way lever 423 moves the rod 43 in one direction, that is, the sleeve 213 rotates in one direction.

The working process is as follows:

in the invention, a worker opens the discharge valve 17 to place a graphite piece on the placing disc 222, then closes the discharge valve 17, the vacuumizing device vacuumizes through the vacuumizing pipeline 13 until the vacuum degree in the reactor is 0.5mbar, then the heater heats the reaction kettle 11 to 700 ℃, the nitrogen supply device fills nitrogen into the reaction kettle 11 through the nitrogen pipeline 15 to change the vacuum degree to 60mbar, then the reaction kettle 11 is continuously heated to 1600 ℃, chlorine is filled through the chlorine channel 16 to the vacuum degree of 1.2bar, and the temperature of 1600 ℃ is maintained for five minutes, then the temperature is continuously raised to 2000 mbar, the temperature is maintained to 2000 ℃ for seven hours of purification, then the temperature is slowly reduced, the chlorine is stopped being filled for five minutes, then the nitrogen is kept filled and the vacuum degree is continuously reduced until the temperature is reduced to 600 ℃ and the vacuum degree is reduced to 60, then the nitrogen filling is stopped, then, the reaction kettle 11 is vacuumized to 0.8mbar, nitrogen is then introduced to 1.0bar, the hydraulic device 217 pushes the sleeve 213 to move downwards, the support rod 43 moves in the chute 421, the limiting rod 224 is clamped in the arc-shaped groove a225, the limiting rod 224 drives the rotating disc 223 to rotate, the through hole a121 is aligned with the through hole b2231, the spraying mechanism 214 sprays the graphite piece, waste liquid flows into the liquid collecting tank 226 to be collected, then, the hydraulic device 217 drives the sleeve 213 to move upwards, the support rod 43 moves along the arc-shaped groove b422 under the action of the one-way rod 423, the sleeve 213 rotates 90 degrees, the rotating disc 223 rotates to reset, then, the heater heats the reaction kettle 11 to 200 ℃ to dry the graphite piece, and then, the vacuumizing device vacuumizes the reaction kettle 11 through the vacuumizing pipeline 13 until the vacuum degree is 0.8mbar, then, the heater heats the reaction kettle 11 and introduces nitrogen gas until the vacuum degree is 160mbar, the reaction kettle 11 heats up to 800 ℃ and starts to introduce hydrogen gas through the raw material gas pipeline 14 until the vacuum degree is 0.9bar and continuously heats up to 1500 ℃, after maintaining the temperature for a period of time, the raw material gas is introduced and maintained in this state for six hours, then the introduction of argon gas and methyltrichlorosilane in the raw material gas is stopped, meanwhile, the hydraulic equipment 217 drives the sleeve 213 to move down, under the action of the one-way rod 423, the support rod 43 moves down along the chute 423, the water outlet 324 and the water inlet 331 are butted, the two bumps 345 are butted against each other, the cooling pipeline 323 is communicated with the water outlet pipe 332, the pumping device enables the waste liquid in the liquid collecting tank 226 to sequentially pass through the circulating pipeline 31, the cooling pipeline 323 and the water outlet pipe 332, at this time, the temperature is reduced and the temperature reduction rate is 2 ℃/min, when the vacuum degree in the sleeve 213 is 160mbar, the introduction of hydrogen gas is stopped, the period of time is maintained, when the temperature is 200 ℃, the nitrogen gas introduction is stopped, then the vacuum degree is reduced to 0.6mbar, the pressure is consistent with the pressure in the sleeve 213, and the graphite kettle is pumped up, and the graphite discharging piece is taken out, and the graphite kettle is taken out, and the graphite discharging piece is completely taken out, and the graphite discharging piece is taken out.

Claims

1. An apparatus for depositing silicon carbide on the surface of a graphite piece, which is characterized by comprising:

the deposition device (1) comprises a reaction kettle (11), a storage table (12) arranged in the middle of the bottom surface of the reaction kettle (11), and a vacuumizing pipeline (13), a raw material gas pipeline (14) and a nitrogen pipeline (15) which are respectively arranged in the middle of the storage table (12) in a penetrating manner; the wall of the reaction kettle (11) is also provided with a chlorine channel (16);

the spraying device (2) comprises a spraying assembly (21) which is arranged in the reaction kettle (11) in a vertically sliding mode and can cover the object placing table (12), and a liquid collecting assembly (22) which is arranged on the object placing table (12) and can be in linkage fit with the spraying assembly (21);

the cooling device comprises a cooling component (32) which is arranged on the spray component (21) in a surrounding manner and communicated with the liquid collecting component (22) through a circulating pipeline (31), and a drainage component (33) which can be butted with the cooling component (32), wherein the drainage component (33) comprises a water receiving port (331) which is arranged at the side edge of the object placing table (12) and can be correspondingly inserted and matched with water outlets (324) symmetrically arranged at two sides of the bottom of the sleeve (213), a water outlet pipe (332) which is arranged in the side walls of the object placing table (12) and the liquid collecting tank (226) and is communicated with the water receiving port (331) and an external sewage collecting device, and two groups of limiting components (34) which are respectively arranged in the drainage component (33) and the cooling component (32) and can be butted; the drain assembly (33) is spaced from the liquid collection assembly (22), an

The switching device (4) is installed at the top of the reaction kettle (11) and drives the liquid collecting assembly (22) and the water draining assembly (33) to work alternately;

the spraying assembly (21) comprises a working frame (211) arranged on the reaction kettle (11), a moving column (212) arranged on the reaction kettle (11) in a vertically sliding mode, a sleeve (213) coaxially fixed at the bottom of the moving column (212), a spraying mechanism (214) arranged at the top of the sleeve (213), a water tank (215) fixed on the working frame (211), a hose (216) penetrating through the moving column (212) and communicating the spraying mechanism (214) with the water tank (215), and a hydraulic device (217) fixedly arranged on the working frame (211) and in power connection with the moving column (212);

the liquid collecting assembly (22) comprises a storage tray (222) coaxially fixed on the storage table (12) through a fixing pipe (221), a rotating tray (223) rotatably installed at the middle positions of the storage table (12) and the storage tray (222), two limiting rods (224) symmetrically arranged at the edges of the rotating tray (223), an arc-shaped groove a (225) arranged on the inner wall of the bottom of the sleeve (213) and correspondingly matched with the limiting rods (224), and a liquid collecting box (226) fixed at the bottom of the storage table (12) and communicated with the circulating pipeline (31);

a plurality of through holes a (121) which are aligned up and down are formed in the object placing disc (222) and the object placing table (12), and a plurality of through holes b (2231) which can be aligned with the through holes a (121) are formed in the rotating disc (223);

the switching device (4) comprises a mounting ring (41) which is fixed on the top of the reaction kettle (11) and surrounds the moving column (212), a limiting groove (42) which is formed in the inner wall of the mounting ring (41) along the circumferential direction of the mounting ring (41), and supporting rods (43) which are symmetrically fixed on the two radial sides of the moving column (212) and move along the limiting groove (42);

the limiting groove (42) comprises four sliding grooves (421) which are arranged in a circumferential array and are vertically arranged, arc-shaped grooves b (422) which are arranged between every two adjacent sliding grooves (421) and are connected end to end with the sliding grooves (421), and one-way rods (423) which are elastically installed at the tail ends of the sliding grooves (421) and the tail ends of the arc-shaped grooves b (422) respectively along the moving direction of the supporting rods (43).

2. The apparatus for depositing SiC on the surface of a graphite piece according to claim 1, wherein the cooling assembly (32) comprises a conveying pipe (321) which is arranged in the moving column (212) along the length direction of the moving column (212), a connecting ring (322) which is communicated with the circulating pipe (31) and is slidably sleeved on the moving column (212), and a cooling pipe (323) which is surrounded in the side wall of the sleeve (213) and is communicated with the conveying pipe (321); the two water outlets (324) are communicated with the cooling pipeline (323), and the connecting ring (322) can be communicated with the inlet of the conveying pipeline (321).

3. The apparatus of claim 1, wherein the position-limiting assembly (34) comprises a ring (341) disposed in the water outlet (324) and the water inlet (331), a moving rod (342) coaxially disposed through a middle portion of the ring (341), a sealing plate (343) coaxially fixed at one end of the moving rod (342) and capable of abutting against the ring (341), a fixing plate (344) coaxially fixed at the other end of the moving rod (342) relative to the sealing plate (343) and elastically connected to the ring (341), and a protrusion (345) fixedly mounted on the fixing plate (344).

4. The equipment for depositing the silicon carbide on the surface of the graphite piece according to claim 1, wherein a discharge valve (17) which is opposite to the object placing table (12) is further arranged on the pipe wall of the reaction kettle (11).