Carbon-carbon crucible heightening ring and split type crucible for single crystal furnace comprising same

Abstract

The invention provides a carbon-carbon crucible heightening ring and a split type crucible for a single crystal furnace comprising the same, and relates to the technical field of crucible equipment. The split type crucible mainly comprises a crucible body, a crucible support and a carbon-carbon crucible heightening ring; the carbon-carbon crucible heightening ring is mainly prepared from carbon powder, powder resin and a reinforcing material, and the reinforcing material comprises at least one of carbon nanotubes, single-layer graphene, silicon carbide and aluminum oxide. The carbon-carbon crucible heightening ring prepared from the substances not only has higher hardness and wear resistance, but also has heat-conducting property, can conduct redundant heat to the heightening ring when a single crystal furnace works, and avoids heat accumulation on the bottom surface of the crucible.

Description

Technical Field

[0001] The invention relates to the technical field of crucible equipment, in particular to a carbon-carbon crucible heightening ring and a split crucible for a single crystal furnace comprising the same. Background Art

[0002] The crucible material used in the current single crystal furnace is mainly carbon-carbon composite material, which is an integrated structure. A quartz crucible for holding silicon material is arranged inside the carbon-carbon crucible. The carbon-carbon crucible and the crucible holder in the existing single crystal furnace will rub against each other during operation, which will reduce the life of the crucible and the crucible holder. At the same time, when the carbon-carbon crucible is in operation, heat will accumulate at the bottom of the crucible, causing the local temperature of the crucible to be too high or the heat to be conducted to the inside of the crucible, which will lead to a decrease in the quality of the products produced.

[0003] The existing technology often increases the service life of the crucible by increasing the thickness of the bottom of the crucible. However, after the bottom of the crucible is thickened, the density of the crucible is high locally, and the temperature is different from that of other parts during use, which affects the quality of the product.

[0004] In view of this, the present invention is proposed. Summary of the invention

[0005] The first object of the present invention is to provide a split crucible for a single crystal furnace, wherein the crucible is mainly composed of a crucible body, a crucible support and a crucible heightening ring. Through the arrangement of the crucible heightening ring, the split crucible of the present invention can conduct the excess heat generated during the operation of the single crystal furnace to the crucible heightening ring, thereby preventing the heat on the bottom surface of the crucible from accumulating and conducting to the inside, thereby ensuring product quality.

[0006] A second object of the present invention is to provide a carbon-carbon crucible heightening ring.

[0007] The third object of the present invention is to provide a method for preparing the above-mentioned carbon-carbon crucible heightening ring.

[0008] In order to achieve the above-mentioned purpose of the present invention, the following technical solutions are particularly adopted:

[0009] The present invention provides a split crucible for a single crystal furnace, the crucible comprising a crucible body, a crucible support and a crucible heightening ring;

[0010] The crucible body, the crucible support and the crucible heightening ring are coaxially arranged, the crucible support is placed at the lower end of the crucible body, the crucible heightening ring is placed between the crucible body and the crucible support, and the crucible body, the crucible support and the crucible heightening ring are detachably connected;

[0011] The crucible is a carbon-carbon composite crucible made of a carbon-carbon composite material;

[0012] The crucible heightening ring is a carbon-carbon crucible heightening ring made of a carbon-carbon composite material.

[0013] Furthermore, the crucible body is a cylindrical column structure, and the inner diameter of the upper port of the crucible body is greater than the minimum inner diameter of the lower port;

[0014] The lower end surface of the crucible body is a flat surface.

[0015] Furthermore, the carbon-carbon crucible heightening ring is a cylindrical structure, and the crucible body and the carbon-carbon crucible heightening ring are in contact and connected with each other.

[0016] The present invention provides a carbon-carbon crucible heightening ring, which is mainly made of the following materials: carbon powder, powdered resin and reinforcing material;

[0017] The reinforcing material includes at least one of carbon nanotubes, single-layer graphene, silicon carbide, and aluminum oxide.

[0018] Furthermore, the carbon powder is a carbon powder with a purity of ≥99.99%;

[0019] Preferably, the carbon powder is mainly obtained by crushing discarded carbon-carbon crucibles;

[0020] More preferably, the particle size of the carbon powder is 9 to 20 μm.

[0021] Furthermore, the powdered resin is a powdered phenolic resin;

[0022] Preferably, the powdered phenolic resin is a powdered resin with a particle size of 300 mesh and a carbon residue of 70-75%.

[0023] Further, the reinforcing material is a combination of silicon carbide and aluminum oxide;

[0024] Preferably, in the carbon-carbon crucible heightening ring preparation material, the mass ratio of carbon powder, powdered resin, silicon carbide and aluminum oxide is (2-5): (3-6): 2: 1;

[0025] More preferably, in the carbon-carbon crucible heightening ring preparation material, the mass ratio of carbon powder, powdered resin, silicon carbide and aluminum oxide is 3:4:2:1.

[0026] The present invention provides a method for preparing the above-mentioned carbon-carbon crucible heightening ring, the preparation method comprising:

[0027] S1: mixing carbon powder, powdered resin and reinforcing material, adding solvent and stirring to obtain a mixed powder; then extruding and granulating the mixed powder to obtain particles A;

[0028] S2: placing particles A in a carbon-carbon crucible heightened ring forming mold to obtain a carbon-carbon crucible heightened ring precursor, and sintering to obtain a carbon-carbon crucible heightened ring.

[0029] Furthermore, before the sintering in step S2, the step also includes: pre-sintering the carbon-carbon crucible heightened ring precursor;

[0030] Preferably, the pre-sintering temperature is 160-220°C and the time is 4 hours;

[0031] And / or, the solvent in step S1 is water, and the mass ratio of the powder to water after mixing is 1:3.

[0032] Furthermore, in step S2, the shape of the carbon-carbon crucible heightening ring forming mold is consistent with the shape of the bottom of the crucible to be embedded, and the compression ratio is 1:1.5-3, preferably 1:2.5.

[0033] Compared with the prior art, the present invention has the following beneficial effects:

[0034] The present invention provides a split crucible for a single crystal furnace, wherein the crucible is mainly composed of a crucible body, a crucible support and a crucible heightening ring; wherein: the crucible body, the crucible support and the crucible heightening ring are coaxially arranged, the crucible support is placed at the lower end of the crucible body, the crucible heightening ring is placed between the crucible body and the crucible support, and the crucible body, the crucible support and the crucible heightening ring are detachably connected; the crucible heightening ring is a carbon-carbon crucible heightening ring made of a carbon-carbon composite material. The present invention can conduct the excess heat generated during the operation of the single crystal furnace to the crucible heightening ring through the arrangement of the above-mentioned crucible heightening ring, so that the heat on the bottom surface of the crucible will not accumulate and be conducted to the inside, thereby ensuring product quality.

[0035] The carbon-carbon crucible heightening ring provided by the present invention is mainly made of carbon powder, powdered resin and reinforcing material, and the reinforcing material includes at least one of carbon nanotubes, single-layer graphene, silicon carbide and aluminum oxide. Among them: carbon powder is used as the main component, powdered resin is used as a binder, and reinforcing material is used as a filler and enhanced thermal conductivity material. The carbon-carbon crucible heightening ring prepared from the above-mentioned materials of the present invention not only has high hardness and wear resistance, but also has thermal conductivity, which can conduct excess heat during the operation of the single crystal furnace to the heightening ring, avoiding heat accumulation on the bottom of the crucible.

[0036] The present invention provides a method for preparing a carbon-carbon crucible heightening ring, the method comprising: mixing carbon powder, powdered resin and reinforcing material, adding a solvent and stirring to obtain a mixed powder; then extruding and granulating the mixed powder to obtain particles A; then placing particles A in a carbon-carbon crucible heightening ring forming mold to obtain a carbon-carbon crucible heightening ring precursor and sintering to obtain a carbon-carbon crucible heightening ring. The above-mentioned preparation method has the technical advantages of simple processing technology and easy operation. DETAILED DESCRIPTION

[0037] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0038] According to one aspect of the present invention, a split crucible for a single crystal furnace comprises a crucible body, a crucible support and a crucible heightening ring;

[0039] The crucible body, the crucible support and the crucible heightening ring are coaxially arranged, the crucible support is placed at the lower end of the crucible body, the crucible heightening ring is placed between the crucible body and the crucible support, and the crucible body, the crucible support and the crucible heightening ring are detachably connected;

[0040] The crucible is a carbon-carbon composite crucible made of a carbon-carbon composite material;

[0041] The crucible heightening ring is a carbon-carbon crucible heightening ring made of a carbon-carbon composite material.

[0042] The split crucible for a single crystal furnace provided by the present invention is mainly composed of a crucible body, a crucible support and a crucible heightening ring; wherein: the crucible body, the crucible support and the crucible heightening ring are coaxially arranged, the crucible support is placed at the lower end of the crucible body, the crucible heightening ring is placed between the crucible body and the crucible support, and the crucible body, the crucible support and the crucible heightening ring are detachably connected; the crucible heightening ring is a carbon-carbon crucible heightening ring made of a carbon-carbon composite material. Through the arrangement of the above-mentioned carbon-carbon crucible heightening ring, the present invention can conduct the excess heat generated during the operation of the single crystal furnace to the carbon-carbon crucible heightening ring, so that the heat on the bottom surface of the crucible will not accumulate and be conducted to the inside, thereby ensuring product quality.

[0043] In a preferred embodiment of the present invention, the crucible body is a cylindrical column structure, and the inner diameter of the upper port of the crucible body is greater than the minimum inner diameter of the lower port;

[0044] The lower end surface of the crucible body is a flat surface.

[0045] In a preferred embodiment of the present invention, the carbon-carbon crucible heightening ring is a cylindrical structure, and the crucible body and the carbon-carbon crucible heightening ring are in surface contact and connection.

[0046] According to one aspect of the present invention, a carbon-carbon crucible heightening ring is provided, wherein the carbon-carbon crucible heightening ring is mainly made of the following materials: carbon powder, powdered resin and reinforcing material;

[0047] The reinforcing material includes at least one of carbon nanotubes, single-layer graphene, silicon carbide, and aluminum oxide.

[0048] The carbon-carbon crucible heightening ring provided by the present invention is mainly made of carbon powder, powdered resin and reinforcing material, and the reinforcing material includes at least one of carbon nanotubes, single-layer graphene, silicon carbide and aluminum oxide. Among them: carbon powder is used as the main component, powdered resin is used as a binder, and reinforcing material is used as a filler and enhanced thermal conductivity material. The carbon-carbon crucible heightening ring prepared from the above-mentioned materials of the present invention not only has high hardness and wear resistance, but also has thermal conductivity, which can conduct excess heat during the operation of the single crystal furnace to the heightening ring, avoiding heat accumulation on the bottom of the crucible.

[0049] In a preferred embodiment of the present invention, the carbon powder is a carbon powder with a purity of ≥99.99%;

[0050] As a preferred embodiment, the carbon powder is mainly obtained by crushing discarded carbon-carbon crucibles;

[0051] In the above preferred embodiment, the particle size of the carbon powder is 9 to 20 μm.

[0052] In a preferred embodiment of the present invention, the powdered resin is a powdered phenolic resin;

[0053] Preferably, the powdered phenolic resin is a powdered resin with a particle size of 300 mesh and a carbon residue of 70-75%.

[0054] In a preferred embodiment of the present invention, the reinforcing material is a combination of silicon carbide and aluminum oxide;

[0055] It should be noted that the carbon nanotubes, single-layer graphene, silicon carbide and aluminum oxide in the above-mentioned reinforcing materials of the present invention have the following properties in the carbon-carbon composite material for preparing the crucible heightening ring of the present invention:

[0056] 1. Carbon nanotubes: Carbon nanotubes have excellent conductivity and strength. Adding them to carbon-carbon composite materials can enhance their conductivity, mechanical strength and wear resistance, and improve the wear resistance and thermal conductivity of the material.

[0057] 2. Single-layer graphene: Single-layer graphene has extremely high electrical conductivity, thermal conductivity and mechanical strength. Adding it to carbon-carbon composite materials can improve the electrical conductivity, thermal conductivity and mechanical strength of the material while reducing the density of the material.

[0058] 3. Silicon carbide: Silicon carbide has high temperature stability, high hardness and corrosion resistance. Adding it to carbon-carbon composite materials can improve its high temperature resistance, wear resistance and corrosion resistance.

[0059] 4. Alumina: Alumina has excellent insulation properties, wear resistance and high temperature resistance. Adding it to carbon-carbon composite materials can improve their wear resistance, insulation and high temperature stability.

[0060] Through the research of the present invention, it is found that the carbon-carbon composite material prepared by the combination of silicon carbide and aluminum oxide as the reinforcing material has better thermal conductivity than the combination of other materials. Therefore, the present invention preferably selects silicon carbide and aluminum oxide as the combination of reinforcing materials to prepare the crucible heightening ring. It has been verified that the combination of silicon carbide and aluminum oxide as reinforcing materials can not only improve the hardness and wear resistance of the heightening ring, so that it can better reduce the wear of the crucible surface caused by the friction of the carbon-carbon crucible during use, but also, the use of these two substances can make the heightening ring better adjust the thermal conductivity, so that it has better thermal conductivity in the specific environment of the single crystal furnace, ensuring that there will be no heat accumulation at the bottom of the crucible, thereby improving the service life of the crucible.

[0061] In a preferred embodiment of the present invention, in the carbon-carbon crucible heightening ring preparation material, the mass ratio of carbon powder, powdered resin, silicon carbide and aluminum oxide is (2-5): (3-6): 2: 1;

[0062] As a preferred embodiment, the mass ratio of carbon powder, powdered resin, silicon carbide and aluminum oxide in the present invention has a significant effect on the performance of the carbon-carbon crucible heightening ring finally prepared. Experimental verification shows that when the amount of silicon carbide and aluminum oxide added is higher than this ratio, the crucible heightening ring will produce powder shedding; and when the amount of silicon carbide and aluminum oxide added is lower than this ratio, the crucible heightening ring will crack.

[0063] Preferably, in the carbon-carbon crucible heightening ring preparation material, the mass ratio of carbon powder, powdered resin, silicon carbide and aluminum oxide is 3:4:2:1.

[0064] According to one aspect of the present invention, a method for preparing the above-mentioned carbon-carbon crucible heightening ring comprises:

[0065] S1: mixing carbon powder, powdered resin and reinforcing material, adding solvent and stirring to obtain a mixed powder; then extruding and granulating the mixed powder to obtain particles A;

[0066] S2: placing particles A in a carbon-carbon crucible heightened ring forming mold to obtain a carbon-carbon crucible heightened ring precursor, and sintering to obtain a carbon-carbon crucible heightened ring.

[0067] The present invention provides a method for preparing a carbon-carbon crucible heightening ring, the method comprising: mixing carbon powder, powdered resin and reinforcing material, adding a solvent and stirring to obtain a mixed powder; then extruding and granulating the mixed powder to obtain particles A; then placing particles A in a carbon-carbon crucible heightening ring forming mold to obtain a carbon-carbon crucible heightening ring precursor and sintering to obtain a carbon-carbon crucible heightening ring. The above-mentioned preparation method has the technical advantages of simple processing technology and easy operation.

[0068] In a preferred embodiment of the present invention, before the sintering in step S2, the step further includes: pre-sintering the carbon-carbon crucible heightened ring precursor;

[0069] In the above preferred embodiment, the pre-sintering temperature is 160-220°C and the time is 4h;

[0070] In a preferred embodiment of the present invention, the solvent in step S1 is water, and the mass ratio of the powder to water after mixing is 1:3.

[0071] In a preferred embodiment of the present invention, in step S2, the shape of the carbon-carbon crucible heightening ring forming mold is consistent with the shape of the bottom of the crucible to be embedded, and the compression ratio is 1:1.5-3, preferably 1:2.5.

[0072] The technical solution of the present invention will be further described below in conjunction with embodiments.

[0073] Note: The following examples and test examples of this application use the composite crucible prepared in Example 3 of CN117088703A as an example to illustrate the performance of the carbon-carbon crucible heightening ring of this application. The carbon-carbon crucible heightening ring prepared in each of the examples is compatible with the composite crucible prepared in Example 3 of CN117088703A.

[0074] Example 1

[0075] A method for preparing a carbon-carbon crucible heightening ring, the method comprising:

[0076] 1. Use a crusher to crush the discarded carbon-carbon crucible into powder with a particle size of 13 μm.

[0077] 2. Put the crushed carbon-carbon crucible powder, 300 mesh powder resin (75% residual carbon), silicon carbide and alumina into a stirrer and stir and mix them. The weight ratio of the four powders is 3:4:2:1.

[0078] 3. After the powder is stirred for 10 minutes, slowly add water in a weight ratio of 1:3 to the powder into the stirring container. After all the water is added, stir for another 5 minutes to obtain a mixed powder.

[0079] 4. Place the mixed powder in a sieve mold with a pore size of 3 mm and press it at a pressure of 0.5 MPa to obtain particles with a particle size of 3 mm.

[0080] 5. Place the prepared particles in a molding mold. The shape of the mold is consistent with the shape of the bottom of the crucible to be embedded. The compression ratio is 1:2.5, and it is heated to 200°C for 4 hours to obtain a product with a thickness of 30 mm after molding.

[0081] 6. The product is subjected to high temperature graphitization treatment at 1800°C to obtain a finished height-enhancing ring.

[0082] Example 2

[0083] This embodiment is the same as Example 1 except that in step 2, "the weight ratio of the crushed carbon-carbon crucible powder, 300 mesh powder resin (residual carbon 75%), silicon carbide, and aluminum oxide is 2:3:2:1."

[0084] Example 3

[0085] This embodiment is the same as Example 1 except that in step 2, "the weight ratio of the crushed carbon-carbon crucible powder, 300 mesh powder resin (residual carbon 75%), silicon carbide, and aluminum oxide is 5:6:2:1."

[0086] Example 4

[0087] This embodiment is the same as Example 1 except that in step 2, "the weight ratio of the crushed carbon-carbon crucible powder, 300 mesh powder resin (residual carbon 75%), silicon carbide, and aluminum oxide is 3:4:3:3."

[0088] Example 5

[0089] This embodiment is the same as Example 1 except that in step 2, "the weight ratio of the crushed carbon-carbon crucible powder, 300 mesh powder resin (residual carbon 75%), silicon carbide, and aluminum oxide is 3:4:1:1."

[0090] Example 6

[0091] This embodiment is the same as Embodiment 1 except that Step 1 is "crushing the discarded carbon-carbon crucible into powder with a particle size of 20 μm by a pulverizer".

[0092] Example 7

[0093] This embodiment is the same as Embodiment 1 except that Step 1 is "crushing the discarded carbon-carbon crucible into powder with a particle size of 9 μm by a pulverizer".

[0094] Example 8

[0095] This embodiment is the same as Embodiment 1 except that step 3 is "after stirring the powder for 10 minutes, slowly adding water in a weight ratio of 1:5 to the powder into the stirring container, and stirring for another 5 minutes after all the water has been added to obtain a mixed powder."

[0096] Example 9

[0097] This embodiment is the same as Embodiment 1 except that step 3 is "after stirring the powder for 10 minutes, slowly adding water in a weight ratio of 1:1 to the powder into the stirring container, and stirring for another 5 minutes after all the water has been added to obtain a mixed powder."

[0098] Example 10

[0099] This embodiment is the same as Embodiment 1 except that step 4 is "placing the mixed powder in a sieve mold with a pore size of 3 mm, pressing it at a pressure of 0.5 MPa to obtain particles with a particle size of 5 mm".

[0100] Embodiment 11

[0101] This embodiment is the same as Embodiment 1 except that step 4 is "placing the mixed powder in a sieve mold with a pore size of 3 mm, pressing it at a pressure of 0.5 MPa to obtain particles with a particle size of 2 mm".

[0102] Example 12

[0103] This embodiment is the same as Embodiment 1 except that in step 2, "silicon carbide is replaced by an equal amount of single-layer graphene, and aluminum oxide is replaced by an equal amount of carbon nanotubes."

[0104] Embodiment 13

[0105] This embodiment is the same as Embodiment 1 except that in step 2, "silicon carbide is replaced by an equal amount of single-layer graphene, and aluminum oxide is replaced by an equal amount of silicon carbide".

[0106] Embodiment 14

[0107] This embodiment is the same as Embodiment 1 except that the aluminum oxide in step 2 is replaced by an equal amount of carbon nanotubes.

[0108] Embodiment 15

[0109] This embodiment is the same as Embodiment 1 except that in step 2, "silicon carbide is replaced by an equal amount of aluminum oxide, and aluminum oxide is replaced by an equal amount of carbon nanotubes."

[0110] Example 16

[0111] This embodiment is the same as Embodiment 1 except that in step 2, “silicon carbide is replaced by an equal amount of single-layer graphene”.

[0112] Comparative Example 1

[0113] This example is the same as Example 1 except that step 2 is: "Put the crushed carbon-carbon crucible powder and 300 mesh powder resin (75% residual carbon) into a stirrer for stirring and mixing, and the weight ratio of the carbon-carbon crucible powder to the powder resin is 5:5". This comparative example does not contain a reinforcing material.

[0114] Experimental Example 1

[0115] The carbon-carbon crucible heightening rings prepared in the above-mentioned Examples 1 to 16 and Comparative Example 1 were matched with the crucible prepared in Example 3 in CN117088703A, and were placed in the use environment of a single crystal furnace for testing to observe the service life and use of the crucible.

[0116] The specific test data are as follows:

[0117]

[0118]

[0119] From the above, it can be seen that the carbon-carbon crucible heightening ring prepared in Examples 1 to 3 of the present application can effectively increase the service life of the crucible after being applied to a single crystal furnace.

[0120] Compared with Examples 1 to 3, in Example 4, due to the excessive amount of silicon carbide and aluminum oxide added, the binder cannot completely bond and solidify the silicon carbide and aluminum oxide, resulting in powder falling; in Example 5, compared with Examples 1 to 3, due to the excessive amount of silicon carbide and aluminum oxide added, the carbon-carbon crucible does not have high hardness and wear resistance, resulting in cracking;

[0121] Compared with Examples 1 to 3, Example 6 has a larger particle size of 20 μm for the carbon powder used, which results in an inability to achieve an ideal service life; Compared with Examples 1 to 3, Example 7 has a larger particle size of 9 μm for the carbon powder used, which results in a carbon crucible that is not as hard and wear-resistant as the crucible is, resulting in cracking;

[0122] Compared with Examples 1 to 3, in Example 8, since the mass ratio of raw material powder to water is 1:5, the carbon crucible does not have high hardness and wear resistance, and cracking occurs; in Example 9, compared with Examples 1 to 3, since the mass ratio of raw material powder to water is 1:1, powder falling occurs at high temperature and pollutes the furnace;

[0123] Compared with Examples 1 to 3, Example 10 cannot achieve an ideal service life because the particle size of the carbon-carbon crucible heightening ring prepared by sintering is 5 mm; Example 11 cannot achieve an ideal service life because the particle size of the carbon-carbon crucible heightening ring prepared by sintering is 2 mm;

[0124] Examples 12 to 16 are carbon-carbon crucible heightening rings made of reinforcing materials other than the combination of "silicon carbide and aluminum oxide", and cannot achieve an ideal service life;

[0125] Comparative Example 1 is a carbon-carbon crucible heightening ring that does not include a reinforcing material, does not have high hardness and wear resistance, and cracks occur, while having a poor service life.

[0126] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A split crucible for a single crystal furnace, characterized in that: The crucible comprises a crucible body, a crucible support and a crucible heightening ring; The crucible body, the crucible support and the crucible heightening ring are coaxially arranged, the crucible support is placed at the lower end of the crucible body, the crucible heightening ring is placed between the crucible body and the crucible support, and the crucible body, the crucible support and the crucible heightening ring are detachably connected; The crucible is a carbon-carbon composite crucible made of a carbon-carbon composite material; The crucible heightening ring is a carbon-carbon crucible heightening ring made of a carbon-carbon composite material.

2. The split carbon-carbon crucible for a single crystal furnace according to claim 1, characterized in that: The crucible body is a cylindrical column structure, and the inner diameter of the upper port of the crucible body is larger than the minimum inner diameter of the lower port; The lower end surface of the crucible body is a flat surface.

3. The split carbon-carbon crucible for a single crystal furnace according to claim 1, characterized in that: The carbon-carbon crucible heightening ring is a cylindrical structure, and the crucible body and the carbon-carbon crucible heightening ring are in contact and connected with each other.

4. A carbon-carbon crucible heightening ring, characterized in that: The carbon-carbon crucible heightening ring is mainly made of the following materials: carbon powder, powdered resin and reinforcing material; The reinforcing material includes at least one of carbon nanotubes, single-layer graphene, silicon carbide, and aluminum oxide.

5. The carbon-carbon crucible heightening ring according to claim 4, characterized in that: The carbon powder is a carbon powder with a purity of ≥99.99%; Preferably, the carbon powder is mainly obtained by crushing discarded carbon-carbon crucibles; More preferably, the particle size of the carbon powder is 9 to 20 μm.

6. The carbon-carbon crucible heightening ring according to claim 4, characterized in that: The powdered resin is a powdered phenolic resin; Preferably, the powdered phenolic resin is a powdered resin with a particle size of 300 mesh and a carbon residue of 70-75%.

7. The carbon-carbon crucible heightening ring according to claim 4, characterized in that: The reinforcing material is a combination of silicon carbide and aluminum oxide; Preferably, in the carbon-carbon crucible heightening ring preparation material, the mass ratio of carbon powder, powdered resin, silicon carbide and aluminum oxide is (2-5): (3-6): 2: 1; More preferably, in the carbon-carbon crucible heightening ring preparation material, the mass ratio of carbon powder, powdered resin, silicon carbide and aluminum oxide is 3:4:2:

1.

8. A method for preparing a carbon-carbon crucible heightening ring according to any one of claims 4 to 7, characterized in that: The preparation method comprises: S1: mixing carbon powder, powdered resin and reinforcing material, adding solvent and stirring to obtain a mixed powder; then extruding and granulating the mixed powder to obtain particles A; S2: placing particles A in a carbon-carbon crucible heightened ring forming mold to obtain a carbon-carbon crucible heightened ring precursor, and sintering to obtain a carbon-carbon crucible heightened ring.

9. The method for preparing a carbon-carbon crucible heightening ring according to claim 8, characterized in that: Before the sintering step S2, the process further comprises: The step of pre-sintering the carbon-carbon crucible heightened ring precursor; Preferably, the pre-sintering temperature is 160-220°C and the time is 4 hours; And / or, the solvent in step S1 is water, and the mass ratio of the powder to water after mixing is 1:

3.

10. The method for preparing a carbon-carbon crucible heightening ring according to claim 8, characterized in that: In the step S2, the shape of the carbon-carbon crucible heightening ring forming mold is consistent with the shape of the bottom of the crucible to be embedded, and the compression ratio is 1:1.5-3, preferably 1:2.5.

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