CN110890309B

CN110890309B - Graphite disc repairing method

Info

Publication number: CN110890309B
Application number: CN201811052431.7A
Authority: CN
Inventors: 颜天渊
Original assignee: One World Trade Co ltd
Current assignee: One World Trade Co ltd
Priority date: 2018-09-10
Filing date: 2018-09-10
Publication date: 2023-09-08
Anticipated expiration: 2038-09-10
Also published as: CN110890309A

Abstract

The invention aims to provide a graphite disc repairing method which is low in equipment and material cost and short in repairing time. The repairing method comprises the following steps: removing the decayed holes on the scrapped graphite disc, and judging the damaged range by porous graphite formed by etching with ammonia gas; machining a concave part which can cover the damage range on the scrapped graphite disc through machining; the method comprises the steps of carrying out corresponding filling action on a concave part by using a graphite repairing block formed by processing graphite blocks, and after filling, processing and trimming the concave part until the concave part meets the original shape of a scrapped graphite disc so that the concave part becomes a part of the scrapped graphite disc; and (3) brazing with pure silicon solder, and bonding the graphite repair block and the scrapped graphite disc, wherein silicon carbide grows on the surface of the graphite repair block in a reaction way, and the silicon carbide is combined with the original silicon carbide coating of the scrapped graphite disc into a whole to finish repair, so that the scrapped graphite disc can be reused.

Description

Graphite disc repairing method

Technical Field

The invention relates to a method for repairing a Graphite disc, in particular to a method for repairing a Graphite disc (Graphite Susceptor, graphite Carrier) applied to an organic metal chemical vapor deposition (Metal Organic Chemical Vapor Deposition, MOCVD) epitaxial furnace.

Background

In recent years, gallium nitride (GaN) series compound semiconductor materials have been successfully applied to light emitting diode (Light Emitting Diode, abbreviated as LED) illumination, and will become an indispensable high-frequency and high-power microwave electronic component in a new generation 5G mobile communication system, and in the future, if the gallium nitride (GaN) electronic component can be applied to power conversion equipment in a large amount, the power consumption can be reduced in each power transformation link, which is known as a third generation semiconductor material with the most development potential, and the current commercialized gallium nitride (GaN) is a semiconductor photoelectric component, which is mostly manufactured by MOCVD epitaxy technology.

The yield of the LED chip is determined by the uniformity of the light emitting wavelength, and in order to precisely control the uniformity of the light emitting wavelength of the LED epitaxial wafer, the MOCVD epitaxial furnace needs to be matched with a heater to provide an optimized wafer temperature uniformity so as to deposit a high-quality epitaxial layer, so that the graphite plate is an important component in the MOCVD epitaxial furnace and is one of main consumables of the LED epitaxial factory.

As shown in fig. 1, 2 and 3 and 4, the graphite plate 100, whether in a single-piece or multi-piece form, is generally made of graphite material, and has a corresponding number of pockets 110 on its top surface, see fig. 1 and 3, for carrying wafers 200; the center of the bottom surface has a rotation shaft hole 120, see fig. 2 and 4, for supporting and rotating the graphite disk, and the entire surface is coated with a silicon carbide coating 20 of 100 to 180 μm thickness by CVD, see fig. 5.

The main functions of the silicon carbide coating 20 are as follows:

first point: protecting the graphite substrate 10 from attack by ammonia (NH 3) reactant gases during MOCVD epitaxy; the silicon carbide material has excellent high-temperature chemical stability, and the CVD silicon carbide coating 20 is a compact vapor phase growth polycrystalline film, which can effectively isolate MOCVD process gases after silicon carbide is coated on the surface of the graphite substrate 10.

Second point: the graphite substrate 10 is easily and largely outgassed (outgas) at high temperature, and the released gas can pollute the reaction atmosphere of the MOCVD process, reduce the quality of the epitaxial layer, and effectively prevent the outgassing phenomenon after the graphite plate 100 is coated with the silicon carbide coating 20 for sealing.

Third point: the heat transfer property of the graphite disc 100 is improved, and as the heat conduction and heat radiation coefficients of silicon carbide are higher than those of graphite, a layer of silicon carbide is plated on the surface of the graphite substrate 10, so that better disc surface temperature uniformity can be obtained.

Fourth point: because of the material characteristics of the graphite substrate 10, dust is easily peeled off from the surface, particles (particles) can be polluted on the epitaxial chip, and a high-hardness wear-resistant surface layer is formed after CVD silicon carbide coating, so that particles are not easily generated.

The graphite disc is frequently subjected to external impact during use, which may come from the handling process, loading and unloading or artificial accidental collision, but the most important impact factor is the collision of the Wafer 200, and the current Wafer 200 of the LED epitaxy is a Sapphire Wafer (Al 2O 3) and is very hard; the problem of impact, especially in the high-speed MOCVD epitaxy furnace, is that the rotation speed of the graphite disk 100 is up to 1000 rpm, and the wafer 200 made of hard sapphire is often thrown during the starting and stopping process due to the action of inertia force, and impacts the side wall or edge of the pit (Pocket) 110 of the graphite disk 100, so that some damage occurs to the silicon carbide coating 20, for example: unfilled corners, please refer to fig. 5; more seriously, the outer diameter of the graphite disk 100 of the new generation large-sized epitaxial furnace is about 700mm, and the strong centrifugal force makes the impact force of the wafer 200 larger and the damage force stronger.

The scrapped silicon carbide coated graphite bearing disc is studied for a long time, the damage of the bearing disc is found to be caused by the damage of the graphite disc, and then the bearing disc is scrapped after the graphite substrate is elutriated to form a cavity by the strong gas phase etching effect of high-temperature crack Jie Anqi (NH 3) of the MOCVD epitaxy process.

In order to solve the problem of scrapping the carrier plate, the inventor filed patent document 1, which describes a method of forming a SiC/SiC composite material by Chemical Vapor Infiltration (CVI) of silicon carbide (SiC) at the damaged hole of the scrapped graphite plate, that is, at the wormhole.

Patent document 1 has the following problems:

first point: patent document 1 uses a CVI method to repair the wormholes of a scrapped graphite disc, and requires a large CVD reactor, which has high equipment cost; furthermore, the reaction time required for growing silicon carbide by the CVI method is usually several days, and thus the production cost for repairing the scrapped graphite disc in patent document 1 will be high.

Second point: the uniformity of the temperature of the LED epitaxial wafer affects the uniformity of the epitaxial layer composition, and small temperature differences have a significant effect on the uniformity of the wavelength of the LED chip, generally requiring that the temperature at any point on the surface of the epitaxial wafer is within 1 ℃ of the predetermined growth temperature deviation, so that the graphite disk must provide extremely uniform surface temperature distribution. In reference 1, the damaged holes of the scrapped graphite disc are filled with the CVI SiC/SiC composite material to form a complete repair area, so that the material of the repair area is obviously different from that of the graphite disc, the original surface temperature distribution of the graphite disc can be damaged, the consistency of the luminous wavelength of the grown LED epitaxial wafer is further affected, and the production yield of the LED chips is reduced.

Third point: when the silicon carbide is grown by CVI, the patent document 1 not only deposits silicon carbide in the repair area, but also plates a new CVD silicon carbide film on the surface of the whole graphite disk, namely the thickness of the original silicon carbide coating on the graphite disk is increased, so that all original heat transfer properties of the graphite disk are changed, and the graphite disk which is subjected to precise adjustment on the heat flow of the LED growth temperature can cause trouble, so that the wavelength variability of the grown LED epitaxial wafer is large, and the production yield of the LED chips is reduced.

Patent document 1 is taiwan patent with a patent publication number TWI574336B, and a patent name of recovery and regeneration of a wafer carrier tray and a repair method thereof.

Disclosure of Invention

The invention aims to provide a low-cost graphite disc repairing method which is applied to repairing a scrapped graphite disc, is recycled and can greatly reduce the consumable cost of an LED epitaxial process.

The invention is developed to solve the above problems, and in order to achieve the purpose of the invention, the technical means of the invention is to provide a method for repairing a graphite disc, which is applied to repairing a recovered scrapped graphite disc, wherein the scrapped graphite disc comprises a graphite substrate with at least one pit concavely arranged on the top surface and a silicon carbide coating coated on the surface of the graphite substrate, and the scrapped graphite disc also has at least one cavity, the cavity is positioned below the silicon carbide coating and is a cavity formed by etching the graphite substrate by ammonia gas, and the method is characterized in that: comprises the following steps: judging: removing the decayed holes on the scrapped graphite disc, and judging the damaged range by porous graphite formed by etching with ammonia gas; the processing steps are as follows: machining a concave part which can cover the damage range on the scrapped graphite disc through machining; filling: the method comprises the steps of carrying out corresponding filling action on a concave part by using a graphite repairing block formed by processing graphite blocks, and after filling, processing and trimming the concave part until the concave part meets the original shape of a scrapped graphite disc so that the concave part becomes a part of the scrapped graphite disc; and (3) repairing: and (3) performing hard welding by using pure silicon solder, jointing the graphite repair block with the scrapped graphite disc, and reacting on the surface of the graphite repair block to grow silicon carbide, so that the silicon carbide is combined with the original silicon carbide coating of the scrapped graphite disc into a whole.

Preferably, the graphite repair block has a cylindrical shape.

Preferably, the diameter size of the graphite patch ranges from 4.0mm to 20.0mm.

Preferably, the graphite repair block has a rectangular parallelepiped shape.

Preferably, in the filling step, when the graphite repair block is used for filling the concave portion, a minimum clearance value of clearance fit between the graphite repair block and the concave portion is 0.001mm, and a maximum clearance value is 0.05mm.

Preferably, the pure silicon solder is pure silicon particles or pure silicon powder; the silicon purity of the pure silicon solder is more than 98%.

Preferably, in the repairing step, the brazing operation of the pure silicon solder adopts a vacuum high-temperature furnace, and the brazing temperature ranges from 1450 ℃ to 1650 ℃.

Preferably, in the repairing step, the brazing operation of the pure silicon solder adopts a vacuum high-temperature furnace, and the vacuum pressure ranges from 0.5torr to 0.001torr.

Compared with the prior art, the invention has the following advantages:

first point: the cost of equipment and materials used in the method for repairing the graphite disk is far lower than that of a large-scale CVD furnace adopted in the patent document 1, and the liquid phase silicon generated in the brazing process of pure silicon solder can react with carbon on the surface layer of a graphite repairing block to grow silicon carbide, so that the required reaction time is very short, and the production cost of the method for repairing the graphite disk is far lower than that of the patent document 1.

Second point: the graphite repairing block is utilized to fill the cavity of the scrapped graphite disc which is originally damaged and empty, and compared with the heat transfer property of filling other materials, the graphite repairing block is closer to the heat transfer property of the original graphite disc, and the temperature uniformity characteristic of the original graphite disc can be restored to the greatest extent.

Third point: the liquid phase silicon generated by the pure silicon solder reacts with carbon to grow silicon carbide, so that the silicon carbide can be locally grown on the surface of the graphite repair block, and the thickness of the silicon carbide coating on the surface of the whole graphite disk can not be increased, so that the original heat transfer characteristic of the graphite disk is not influenced, and the heat flow of the growth temperature of the LED does not need to be readjusted when the repaired graphite disk is put on the machine again.

Drawings

Fig. 1 is a schematic perspective view of a monolithic graphite disk.

Fig. 2 is a perspective schematic view of another view of a monolithic graphite disk.

Fig. 3 is a schematic perspective view of a multi-sheet graphite disk.

Fig. 4 is a schematic perspective view of another view of a multi-sheet graphite disk.

Fig. 5 is a schematic view of the section x-x of fig. 3.

Fig. 6 is a schematic perspective view of a rejected graphite disk.

Fig. 7 is a schematic view of section y-y of fig. 6.

Fig. 8 is a schematic view of the z-z section of fig. 6.

FIG. 9 is a schematic cross-sectional flow chart of the repairing process according to the present invention.

FIG. 10 is a schematic diagram of a second cross-sectional flow chart during repair according to the present invention.

FIG. 11 is a schematic flow chart of the present invention.

Fig. 12 is a schematic perspective view of the present invention after repairing a rejected graphite disk having a single wormhole.

FIG. 13 is a schematic perspective view of the present invention after repairing a scrapped graphite disc having a plurality of cavities.

Fig. 14 is a schematic perspective view of the present invention after repairing a rejected graphite disk having pit holes spanning the pits.

Fig. 15 is a schematic perspective view of the present invention when repairing a rejected graphite disk having edge cavities.

Fig. 16 is a schematic perspective view of the invention after repairing a scrapped graphite disc with edge cavities.

Reference numerals illustrate:

1-damaged extent

2-recess

3-graphite repair block

4-pure silicon solder

41-pure silicon particles

42-adhesive

43-silicon clay

10-graphite substrate

110-pit

120-spindle hole

20-silicon carbide coating

30-boreholes

40-porous graphite

100-graphite disk

200-wafer

300-scrapped graphite disc

I-removing porous graphite formed by etching the cavity of the scrapped graphite disc with ammonia gas, and judging the damage range

II-machining a concave part with simple solid geometry and capable of covering damaged area on the scrapped graphite disc

III, using graphite repair blocks processed by graphite blocks to perform corresponding filling action on the concave parts, and after filling, finishing to be in line with the original shape of the scrapped graphite disc so as to enable the scrapped graphite disc to be a part of the scrapped graphite disc

And IV, brazing with pure silicon solder, jointing the graphite repair block with the scrapped graphite disc, reacting on the surface of the graphite repair block to grow silicon carbide, and combining the silicon carbide with the original silicon carbide coating of the scrapped graphite disc into a whole to finish repair, so that the scrapped graphite disc can be reused.

Detailed Description

The following is a detailed description of the embodiments shown in the drawings. It is first noted that in the drawings, identical components or parts are denoted by the same reference numerals as much as possible. In describing the present invention, a specific description of known functions or configurations thereof will be omitted so as not to obscure the gist of the present invention.

In practice, not every pit (pocket) of the graphite disk is in existence and as shown in fig. 6, some pits remain intact when the graphite disk is scrapped, but as long as any pit has a hole, the whole graphite disk must be scrapped. After observing a large number of scrapped graphite disks, common wormholes are found, roughly in two types: round hole shape wormhole, rectangular shape wormhole.

A common hole-shaped cavity, referring to the y-y section in fig. 6 and the schematic diagram in fig. 7, is prone to corner failure at the edge of the pit 110. Since ammonia (NH 3) in the MOCVD epitaxy process of gallium nitride (GaN) semiconductor material is pyrolyzed at high temperature to generate a large amount of atomic hydrogen (H), which is very reactive to the carbon of the graphite phase, when contacting the corner crack, the exposed graphite substrate 10 will strongly etch the graphite, react to generate gaseous hydrocarbons (CHX), and form wormholes 30 in the graphite substrate 10, as shown in fig. 7, resulting in a typical wormhole structure comprising a wormhole area and a porous graphite area.

The hollow area refers to the part of the graphite substrate 10 which is completely eroded and emptied, and the porous graphite area refers to the part of the graphite substrate 10 which is eroded into a porous material. The cavity 30 continuously emits a large amount of hydrocarbon (CHX) gas from the crack during each MOCVD epitaxy process, and mixes the gas into the epitaxy atmosphere, which affects the light emission wavelength and brightness of the LED chip grown in each process, and finally leads to early rejection of the graphite disk.

Referring to the z-z section of fig. 6 and the schematic diagram of fig. 8, a typical elongated cavity is prone to crack at the outer edge of the scrapped graphite disc 300. The ammonia gas in the MOCVD epitaxy process contacts the graphite substrate 10 through crack cracks in the silicon carbide coating 20, rapidly etches the graphite, reacts to form gaseous hydrocarbons (CHX), and is released from the cracks to form elongated cavities in the graphite substrate 10, resulting in a typical cavity structure comprising cavities and porous graphite regions, as shown in fig. 8. The wormholes 30 continuously release a significant amount of hydrocarbon (CHX) gas from the split during each MOCVD epitaxy process, eventually leading to early graphite disk scrapping.

Referring to the section y-y in fig. 6, a in fig. 9, and fig. 11, the repairing method of the present invention is described by taking a round hole shape cavity at the edge of the pit 110 as an example, and the steps are as follows:

firstly, judging the step I: as shown in a of fig. 9, the damaged area 1 is determined by removing the porous graphite 40 formed by etching the cavity 30 of the scrapped graphite disc 300 with ammonia gas.

The method of removing the porous graphite 40 is not limited, and for example, the silicon carbide coating 20 above the wormholes 30 is manually crushed by a sharp-cone tool, and then the loose porous graphite 40 in the wormholes 30 is excavated to judge the damaged area 1, as shown in b of fig. 9.

Subsequently, processing step ii: as shown in fig. 9 c, a recess 2 having a simple solid geometry, which covers the damaged area 1, is machined on the rejected graphite disk 300 by machining.

The method for machining the concave portion 2 is not limited, for example, a Computer Numerical Control (CNC) machine tool, a milling machine, a drilling machine and the like, but the simple solid geometry can be cylindrical, square, cuboid, triangular prism and the like, and the cylindrical concave portion 2 is preferably applied, and the diameter size of the concave portion 2 ranges from 4.0mm to 20.0mm.

Then filling step III: as shown in d of fig. 9 and e and f of fig. 10, the concave portion 2 is correspondingly filled with the graphite repair block 3 processed from the graphite block material, and after filling, the concave portion is processed and trimmed to conform to the original shape of the scrapped graphite disc 300, so that the concave portion becomes a part of the scrapped graphite disc 300.

As a material of the graphite block, high-strength isotropic graphite (Isotropic graphite), for example: SGL Carbonn model R8500 or R8510, chengdu Carbon model CDI-1B or Toyo Tanso model IG-56, etc.; the graphite repair block 3 can fill the concave part 2 correspondingly, so the shape can be cylindrical, square, cuboid, triangular prism and the like, the graphite repair block 3 is preferably used as the cylindrical graphite repair block 3, and the diameter size range of the graphite repair block 3 is also 4.0mm to 20.0mm; the gap value between the concave part 2 and the graphite repair block 3 is 0.00mm in an ideal state, the maximum allowable gap value is 0.05mm, the preferred minimum gap value is 0.001mm, and the preferred maximum gap value is 0.01mm; after the graphite repair block 3 fills the recess 2, the machining method is not limited, for example, CNC machining center, milling machine and the like are adopted, the machining precision of the external dimension can reach +/-0.01 mm, and the engraving machining can be performed to restore to meet the original various external designs of the scrapped graphite disc 300.

Finally, repairing step IV: as shown in fig. 10, the graphite repair block 3 and the scrapped graphite disc 300 are joined by brazing with pure silicon solder 4, silicon carbide grows on the surface of the graphite repair block 3 by reaction, and the silicon carbide is integrated with the original silicon carbide coating 20 of the scrapped graphite disc 300, so that the scrapped graphite disc 300 can be reused.

The pure silicon solder 4 forms liquid phase silicon at the high temperature of brazing, and capillary penetration enters a gap between the graphite repair block 3 and the concave part 2 to react with carbon to grow silicon carbide, and the following basic chemical reaction is shown: si (l) +C(s) →SiC(s).

Wherein, the carbon comes from the carbon on the surface layers of the graphite repair block 3 and the concave part 2, silicon carbide grows in a reaction way, the gap is filled, and the graphite repair block 3 and the scrapped graphite disc 300 are welded together.

Referring to fig. 10 g, pure silicon solder 4 may be provided in the form of pure silicon particles 41, the purity of the pure silicon particles 41 being above 98%, the particle size range of the particles being smaller than 4 mesh and larger than 18 mesh of the us screen. Firstly, smearing an adhesive 42 on the surface of a graphite repair block 3 and the joint gap between the adhesive and a concave part 2 by using a water color pen or a writing brush, and then adhering pure silicon particles 41 to the whole surface of the graphite repair block 3 and the joint gap between the pure silicon particles and the concave part 2; the adhesive 42 to be used is not particularly limited as long as the adhesive 42 can temporarily bond and fix the pure silicon particles 41; however, for convenience of operation, pressure sensitive adhesives may be preferably used, and suitable ones may be selected from: such as acrylate pressure sensitive adhesive, neoprene pressure sensitive adhesive, or polyurethane pressure sensitive adhesive.

Referring to g' of fig. 10, the pure silicon solder 4 may be silicon clay 43 made of pure silicon powder with purity of 98% or more and particle size of powder in the range of 270 mesh smaller than us mesh and 1250 mesh larger than us mesh; the silicon clay 43 is directly pressed on the surface of the graphite repair block 3 and the joint gap between the graphite repair block and the concave part 2, and the preparation method of the silicon clay 43 is preferably as follows: 100 parts by weight of pure silicon powder and 100 to 120 parts by weight of binder are mixed and stirred into a silicon clay 25, and the binder can be polyvinyl alcohol, polyvinyl acetate or methyl cellulose.

As shown in g and g' of fig. 10, the scrapped graphite plate 300 to which the pure silicon solder 4 has been attached is placed in a vacuum high temperature furnace to perform the hard welding of the graphite repair block 3 and the scrapped graphite plate 300. The brazing temperature can be selected to be above the melting point of silicon, a preferred brazing temperature range is 1450 ℃ to 1650 ℃, and a preferred vacuum pressure range for the vacuum high temperature furnace during the brazing step is 0.5torr to 0.001torr. The constant temperature holding time of the hard soldering is preferably 1to 2 hours, and the pure silicon solder 4 is melted to form liquid phase silicon to be infiltrated into the gap between the graphite repair block 3 and the concave part 2 in a capillary way, so that silicon carbide is grown in a reaction way; and a silicon liquid phase film is formed to cover the outer surface of the graphite repair block 3 and react with carbon on the surface layer to grow silicon carbide.

As shown in h of fig. 10, liquid silicon enters into the gap between the graphite repair block 3 and the concave part 2 by capillary infiltration, silicon carbide grows to fill the gap, the graphite repair block 3 and the scrapped graphite disc 300 are hard welded, a continuous and compact silicon carbide film is grown on the outer surface of the graphite repair block 3 by reaction, the film thickness is about 10 μm to 50 μm, the film is connected with the original CVD silicon carbide coating 20 on the surface of the scrapped graphite disc 300 into a whole, the original graphite disc surface silicon carbide coating 20 is restored, and the graphite substrate 10 is protected from being corroded by the MOCVD epitaxial process Cheng Anqi.

As shown in fig. 12, the graphite repair block 3 fills the concave portion 2 of the scrapped graphite disc 300 through the above repair steps, fills each of the cavities 30 to perform the subsequent repair steps, and allows the scrapped graphite disc 300 to recover the normal function for recycling.

In the repairing method, although silicon carbide is produced by the entire reaction of liquid phase silicon formed by melting pure silicon solder 4 on the surface of the graphite plate in principle, if there is an excessive amount of pure silicon solder 4, the silicon carbide remains after the high temperature reaction, and an acid washing or high temperature evaporation step may be added to the repairing method to remove the excessive pure silicon solder 4. In the pickling step, the pickling solution used can be selected from mixed solution of hydrofluoric acid HF and nitric acid HNO 3; in the high temperature evaporation step, the graphite plate may be placed again in a vacuum high temperature furnace and heated to a temperature of 1450 ℃ to 1650 ℃ and maintained at constant temperature for 1to 2 hours, preferably at a vacuum pressure in the range of 0.5torr to 0.001torr.

As shown in fig. 13, in another embodiment, two pits 110 of the scrapped graphite disc 300 are provided with three cavities 30 with different sizes to form three concave portions 2 with different sizes, so that the following repairing steps are performed by matching with three graphite repairing blocks 3 with different diameters.

As shown in fig. 14, another example is shown in which the scrapped graphite disc 300 has two cavities 30 of different sizes and spans two pits 110, two recesses 2 of different sizes are formed, a corresponding graphite repair block 3 is used in cooperation with the scrapped graphite disc, a single graphite repair block 3 is used for the small recesses 2, and three graphite repair blocks 3 are used for the large recesses 2, so as to perform the subsequent repairing steps, and the embodiment is the same as described above.

The cavity 30 at the edge is generally elongated, and the embodiment is the same as described above with reference to the z-z section in fig. 6 and fig. 8, except that the cavity 30 is a rectangular recess 2 formed during machining, and the graphite repair block 3 is also formed into a rectangular parallelepiped shape as shown in fig. 15.

As shown in fig. 16, the rectangular graphite repair block 3 fills the corresponding rectangular recess 2 to perform the subsequent repair step, and the embodiment is the same as the above, so that the scrapped graphite disc 300 can be recovered to normal function and recycled.

While the construction, features and effects of the present invention have been described in detail with reference to the embodiments shown in the drawings, the above description is only a preferred embodiment of the present invention, but the present invention is not limited to the embodiments shown in the drawings, and all changes made according to the concepts of the present invention or modifications as equivalent embodiments are within the scope of the present invention without departing from the spirit covered by the specification and drawings.

Claims

1. The method for repairing the graphite disc is applied to repairing the recovered scrapped graphite disc (300), wherein the scrapped graphite disc (300) comprises a graphite substrate (10) with at least one pit (110) concavely arranged on the top surface and a silicon carbide coating (20) coated outside the surface of the graphite substrate (10), the scrapped graphite disc (300) also has at least one cavity (30), and the cavity (30) is positioned below the silicon carbide coating (20) and is an empty hole formed by etching the graphite substrate (10) by ammonia gas, and the method is characterized by comprising the following steps:

judging step (I): removing porous graphite (40) formed by etching the decayed holes (30) on the scrapped graphite disc (300) by ammonia gas, and judging a damaged range (1);

and (2) a processing step (II): machining a concave part (2) which can cover the damaged range (1) on the scrapped graphite disc (300) through machining;

filling step (III): a graphite repair block (3) formed by processing graphite blocks is used for carrying out corresponding filling action on the concave part (2), and after filling is finished, the concave part is processed and trimmed to be in line with the original shape of the scrapped graphite disc (300) so as to form a part of the scrapped graphite disc (300); and

repairing step (IV): and (3) brazing is carried out by using pure silicon solder (4), the graphite repair block (3) and the scrapped graphite disc (300) are joined, silicon carbide grows on the surface of the graphite repair block (3) through reaction, and the silicon carbide and the original silicon carbide coating (20) of the scrapped graphite disc (300) are combined into a whole.

2. The method for repairing a graphite disk according to claim 1, wherein: the graphite repair block (3) is cylindrical.

3. The method for repairing a graphite disk according to claim 2, wherein: the diameter size of the graphite repair block (3) ranges from 4.0mm to 20.0mm.

4. The method for repairing a graphite disk according to claim 1, wherein: the graphite repair block (3) is cuboid.

5. The method for repairing a graphite disk according to claim 1, wherein: in the filling step (III), when the graphite repair block (3) is used for filling the concave part (2), the minimum clearance value of clearance fit between the graphite repair block and the concave part is 0.001mm, and the maximum clearance value is 0.05mm.

6. The method for repairing a graphite disk as defined in claim 5, wherein: the pure silicon solder (4) is pure silicon particles or pure silicon powder;

the pure silicon solder (4) has a silicon purity of at least 98%.

7. The method for repairing a graphite disk as defined in claim 6, wherein: in the repairing step (IV), the brazing operation of the pure silicon solder (4) adopts a vacuum high-temperature furnace, and the brazing temperature range is 1450-1650 ℃.

8. The method for repairing a graphite disk as defined in claim 7, wherein: in the repairing step (IV), the brazing operation of the pure silicon solder (4) adopts a vacuum high-temperature furnace, and the vacuum pressure range is 0.5torr to 0.001torr.