A graphite crucible for combined use

Abstract

The present invention discloses a graphite crucible for combined use, which comprises an inner crucible body and an outer crucible body; a wall groove is formed on the outer wall of the inner crucible body, the wall groove is a blind groove arranged in a spiral shape, a tensile unit is wound around the outer wall of the inner crucible body, and the inner crucible body applies circumferential restraint to the outer wall of the inner crucible body through the tensile unit; the outer crucible body is slightly larger than the outer diameter of the inner crucible body, so that a 5-8 mm accommodation gap is reserved between the inner wall of the outer crucible body and the outer wall of the inner crucible body after the inner crucible body is placed in the outer volume cavity; a through hole is formed on the side wall of the outer crucible body as a pressure relief hole; a bearing surface matching the bottom surface of the inner crucible body is formed on the bottom surface of the outer crucible body in the outer volume cavity, a ring groove connected to the lower part of the accommodation gap is formed at the outer edge of the bearing surface, and a plurality of blind grooves penetrating horizontally are formed on the bearing surface. The graphite crucible of the present invention can effectively improve the quality of the graphite crucible and has a wide application prospect in the field of semiconductor equipment and manufacturing.

Description

Technical Field

[0001] The present invention relates to the technical field of graphite crucibles in graphite products, and particularly to a combined graphite crucible. Background Art

[0002] Graphite, as a kind of material with high temperature resistance and corrosion resistance, has a small coefficient of thermal expansion during high-temperature use, has a certain anti-strain performance against rapid heating and cooling, has a small temperature coefficient of resistance, and has a low thermal inertia, and can be quickly heated and cooled. It is usually used to prepare crucible containers for melting or sintering non-ferrous metals, alloys such as copper, brass, gold, silver, zinc, and lead, and polysilicon materials.

[0003] Generally speaking, graphite crucibles are usually placed in a high-temperature environment during use. The environmental temperature during their working state usually exceeds 1800°C, and sometimes even reaches 3000°C. Being placed in a high-temperature environment for a long time will reduce the strength of the graphite crucible and make its structure loose. Under different process conditions, it is easy to cause cracks or breakage of the graphite crucible, affecting the service performance of the graphite crucible, and may even cause the graphite crucible to be scrapped in advance before its service life expires; in addition, due to the differences in the formulas and structures of graphite crucibles from different manufacturers, there are also differences in the adaptability of graphite crucibles produced by different manufacturers under different heat treatment process conditions; in some vacuum sintering process conditions, this kind of thermal stress shock will also cause cracks or breakage of the graphite crucible to be more obvious; the combination of the above reasons makes it difficult to control the use cost of the graphite crucible. Based on this, there are also methods of using repair agents to repair the cracks and breakages of graphite crucibles. However, although this method of using repair agents can reduce the use cost of graphite crucibles, the graphite crucibles repaired with repair agents are prone to performance defects, affecting the heat treatment effect. With the progress of related metal smelting technologies and the improvement of related market demands, the use conditions of graphite crucibles will become more stringent, and it is more difficult for such repaired defective graphite crucibles to meet high-quality use requirements.

[0004] Therefore, it is necessary to re-design the structure of the graphite crucible and perform overall strengthening treatment so that it can adapt to the impact changes of thermal stress in a high-temperature environment, improve the overall strength of the graphite crucible, and at the same time improve its thermal stability under high temperature or even continuously changing temperature conditions. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a combined graphite crucible to solve the problems of the prior art.

[0006] The technical problem to be solved by the present invention is achieved by the following technical solutions:

[0007] A combined graphite crucible includes an inner crucible body and an outer crucible body. Both the inner crucible body and the outer crucible body are independently formed graphite crucible bodies and are used in combination when in use.

[0008] The inner crucible body is a circular crucible with an inner volume cavity for accommodating the material to be processed. A wall groove is formed on the outer wall of the inner crucible body. The wall groove is a blind groove arranged in a spiral shape. A tensile unit is wrapped around the outer wall of the inner crucible body to apply circumferential restraint to the outer wall of the inner crucible body through the tensile unit.

[0009] The outer crucible body has an outer volume cavity for accommodating the inner crucible body. The outer volume cavity is slightly larger than the outer diameter of the inner crucible body, so that there is a 5 - 8 mm accommodation gap between the inner wall of the outer crucible body and the outer wall of the inner crucible body after the inner crucible body is placed in the outer volume cavity. A through hole is formed on the side wall of the outer crucible body as a pressure relief hole. The outer crucible body forms a bearing surface on the bottom surface of the outer volume cavity that matches the bottom surface of the inner crucible body, and a ring groove connected to the lower part of the accommodation gap is formed at the outer edge of the bearing surface, and a number of blind grooves penetrating horizontally are formed on the bearing surface.

[0010] As a further limitation, the carbon content of the inner crucible body is 87 - 92%, and it is formed by using natural flake graphite. And the graphite raw material used for forming the inner crucible body includes at least 80% of flake graphite with a mesh size above 100 and 15 - 20% of flake graphite with a mesh size of 50 - 80.

[0011] As a further limitation, the carbon content of the outer crucible body is 85 - 88%, and the outer crucible body is a carbon - bonded crucible with pitch as the binder.

[0012] As a further limitation, the inner crucible body has a spherical bottom surface, and the bearing surface is a concave arc - shaped bearing surface that matches the spherical bottom surface.

[0013] As a further limitation, the outer crucible body forms an annular stepped groove at the upper edge of the outer volume cavity, and the upper edge of the inner crucible body forms a misaligned step that matches the annular stepped groove. When used in combination, the inner crucible body is fixedly placed in the outer volume cavity through the cooperation of the annular stepped groove and the misaligned step.

[0014] As a further limitation, the tensile unit is carbon fiber closely wound and wrapped around the outer surface of the inner crucible body. And the parameter indexes of the carbon fiber are: gram weight: 300 - 500 g / m 2 , modulus: 280 - 330 GPa, strength: 3.5 - 3.8 GPa;

[0015] The number of winding turns of the carbon fiber on the outer surface of the inner crucible body is 2 - 3 turns, and the carbon fiber is adhered to the outer surface of the inner crucible body in the form of asphalt coating or dipping during the forming process of the inner crucible body.

[0016] As a further limitation, the working environment of the combined graphite crucible is an inert atmosphere environment or a vacuum environment, and the temperature range during high-temperature operation is 900°C to 2500°C.

[0017] Beneficial effects: The combined graphite crucible of the present invention uses the combined structure of the inner crucible body and the outer crucible body for sintering operations. It utilizes the structural combination of the outer crucible body and the inner crucible body for thermal stress buffering, thereby improving the deformation resistance performance of the crucible body based on thermal stress; the spiral wall grooves of the inner crucible body itself in combination with the wrapping of carbon fiber can greatly reduce the deformation degree of the graphite crucible during thermal expansion and cooling processes, thereby effectively suppressing the generation and development of cracks / damage in the inner crucible body under thermal stress impact conditions, and maintaining the structural form of the inner crucible body to resist the deformation failure problem caused by thermal stress impact, effectively extending the service life of the inner crucible body as a container for the material to be processed. Description of the Drawings

[0018] Figure 1 It is a schematic diagram of the sectional details of a preferred embodiment of the present invention.

[0019] Wherein: 1, pressure relief hole; 2, crucible lid; 3, inner crucible body; 4, tensile unit; 5, wall groove; 6, accommodation gap; 7, outer crucible body; 8, thickened crucible spherical bottom; 9, bearing surface; 10, annular groove; 11, blind groove; 12, inner volume cavity; 13, outer volume cavity. Detailed Embodiments

[0020] Next, the technical solutions of the present invention will be clearly and completely described in conjunction with the drawings. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0021] In the description of the present invention, it should be noted that the terms used to indicate the orientation or positional relationship in this embodiment are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be construed as a limitation to the present invention.

[0022] See Figure 1A preferred embodiment of a graphite crucible for combined use. In this embodiment, it includes an inner crucible body 3 and an outer crucible body 7. The inner crucible body 3 and the outer crucible body 7 are independently formed, and the inner crucible body 3 and the outer crucible body 7 are combined and used together during use. At the same time, the inner crucible body 3 with matching size specifications can be combined with other outer crucible bodies 7 of the same specifications, so that after the single inner crucible body 3 / outer crucible body 7 is damaged, it can still be combined with other outer crucible bodies 7 / inner crucible bodies 3 of the same size, so as to improve the utilization rate of the single inner crucible body 3 and outer crucible body 7 and reduce the use cost of the graphite crucible.

[0023] The material forms of the inner crucible body 3 and the outer crucible body 7 are different. The inner crucible body 3 is a circular crucible, which has an inner volume cavity 12 for accommodating the material to be processed, and a thickened crucible spherical bottom 8 with thickening treatment on the bottom surface of the inner volume cavity 12 to achieve a better heat equalization effect. The inner crucible body 3 has a cylindrical outer wall arranged vertically, and wall grooves 5 are formed on its outer wall. These wall grooves 5 are multiple blind grooves arranged in a spiral shape. At the same time, three circles of carbon fibers are wound around the outer wall of the inner crucible body 3 as a tensile unit 4 to bind the outer wall of the inner crucible body 3. Among them, the wall grooves 5 are formed by tool trimming, and the carbon fibers are formed by infiltrating the carbon fibers with molten asphalt, then extruding the excess asphalt, and then attaching them to the surface of the wall grooves 5, and after close winding, they are formed by high-temperature graphitization treatment.

[0024] As a type of graphite crucible, the carbon content of the inner crucible body 3 in this batch is 90%. It is a clay-type graphite crucible prepared by using natural flake graphite as raw material and clay as binder and then sintered. The natural flake graphite used in the inner crucible body 3 includes 85% of flake graphite above 100 mesh and 18% of flake graphite of 50 - 80 mesh. This inner crucible body 3 has better thermal stability and has better high-temperature treatment performance for polysilicon, precious metals and non-ferrous alloys in a high-temperature environment, and can be used for high-quality heat treatment of the above raw materials. However, the defect is that its thermal stress shock resistance is poor, and it is easy to become loose inside under long-term high-temperature conditions, and then cracks will occur on the outer wall.

[0025] In this embodiment, the setting of the wall grooves 5 can redistribute the thermal stress on the outer wall of the inner crucible body 3 as a whole. The wall bodies between the wall grooves 5 will form a spiral rib structure, so as to regularly discharge the thermal stress obliquely along the spiral ribs on the outer wall of the inner crucible body 3, thereby avoiding the generation of irregular cracks that may be caused by the irregular discharge of thermal stress shock on the smooth surface. At the same time, the setting of the wall grooves 5 can also make the outer wall surface of the inner crucible body 3 have a shrinking space, so that the thermal stress deformation accompanied by the generation of thermal stress can be absorbed by this shrinking space, and it will not cause extrusion shrinkage, and avoid the generation of extrusion cracks on the inner crucible body 3 under the action of the extrusion force generated by the thermal stress deformation.

[0026] In addition, the provision of the wall groove 5 can also enhance the adhesion performance of the tensile unit 4. In this embodiment, the parameters of the carbon fiber used in the tensile unit 4 are as follows: gram weight: 450 g / m 2 , modulus: 320 GPa, strength: 3.8 GPa. The gram weight condition can ensure the adhesion amount to the asphalt mixture while keeping the carbon fiber as thin as possible, thereby ensuring the adhesion performance and heat conduction and heat equalization effects of the tensile unit 4 on the outer wall of the inner crucible body 3; while the modulus and strength parameters are used to ensure the restraint of the tensile unit 4 on the outer wall of the inner crucible body 3. This outer wall restraint can effectively relieve the thermal stress when the inner crucible body 3 undergoes expansion-like deformation and block the expansion of the inner crucible body 3; under such technical characteristic conditions, if the restraint of the tensile unit 4 on the outer wall of the inner crucible body 3 is too large, it is likely to affect the structural strength and structural stability of the inner crucible body 3, and if it is too small, the structural restraint retention effect after the inner crucible body 3 expands due to thermal stress cannot be achieved.

[0027] The outer crucible body 7, as another type of graphite crucible, has a carbon content of 86%. The outer crucible body 7 is a carbonaceous binder type crucible with asphalt as the binder. This type of graphite crucible is superior in terms of strength and thermal shock resistance. When used alone, it is mostly used for melting steel, copper, copper alloys and other non-ferrous metals. However, this type of graphite crucible is not conducive to precise temperature control and thus has relatively poor high-temperature treatment performance. Therefore, in this embodiment, it is used as the outer crucible body 7 so that the inner crucible body 3 placed therein can be buffered by the outer crucible body 7 during high-temperature treatment, making the temperature change curve of the inner crucible body 3 itself relatively lagging and more stable, so as to obtain a better high-temperature heat treatment effect.

[0028] The outer crucible body 7 has an outer volume cavity 13 for accommodating the inner crucible body 3. In this embodiment, in order to facilitate the positioning and placement of the crucible body 3 in the outer volume cavity 13, the outer crucible body 7 is formed with an annular stepped groove at the upper edge of the outer volume cavity 13, and the upper edge of the inner crucible body 3 is formed with a misaligned step matching the annular stepped groove. When used in combination, the inner crucible body 3 is fixedly placed in the outer volume cavity 13 through the cooperation of the annular stepped groove and the misaligned step to achieve positioning placement. At the same time, the cooperation of the annular stepped groove and the misaligned step can also make a relatively closed space be maintained in the gap space at the outer edge of the outer volume cavity 13 after the inner crucible body 3 is placed in the outer volume cavity 13.

[0029] In the embodiment, for more convenient use, the outer crucible body 7 is also combined with a crucible lid 2 through the stepped groove at the upper edge of the outer volume cavity 13; in another embodiment, the combined graphite crucible can also be in a usage form without the crucible lid 2.

[0030] In this embodiment, the size of the outer volume cavity 13 is slightly larger than the outer diameter of the inner crucible body 3, so as to leave a accommodation gap 6 of 5-8 mm between the inner wall of the outer crucible body 7 and the outer wall of the inner crucible body 3 after the inner crucible body 3 is placed in the outer volume cavity 13. And a bearing surface 9 with an inwardly concave arc-shaped upper surface that matches the size of the thickened crucible spherical bottom 8 on the inner crucible body 3 is formed at the bottom of the outer volume cavity 13. This bearing surface 9 can make the heat received by the materials in the inner crucible body 3 with the thickened crucible spherical bottom 8 more uniform and stable.

[0031] A through hole is formed on the side wall of the outer crucible body 13 as a pressure relief hole 1, and a ring groove 10 connected to the lower part of the accommodation gap 6 is formed at the edge of the bearing surface 9, and a number of blind grooves 11 penetrating horizontally are formed on the bearing surface 9; the combination of the pressure relief hole 1, the ring groove 10, the accommodation gap 6 and the blind grooves 11 can effectively relieve most of the thermal stress impact transmitted to the inner crucible body 3 on the inner side through the outer crucible body 13, so as to ensure the structural stability of the inner crucible body 3 and better adapt to frequent thermal stress impact changes, so as to improve the overall strength of the inner crucible body 3 while sacrificing the service life of the use performance of the outer crucible body 13 and improve the thermal stability of the inner crucible body 3 under continuously changing high temperature conditions, thereby meeting the more stringent use performance requirements for graphite crucibles under existing process conditions.

[0032] In addition, as a limitation, in this embodiment, considering the use environment of the carbon fiber as the tensile unit 4, the working environment of the combined graphite crucible is an inert gas environment or a vacuum environment, and the temperature range during its high-temperature operation is 900°C to 2500°C.

[0033] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art of this industry should understand that the uses of these embodiments are only for illustrating the present invention rather than intending to limit the protection scope of the present invention. In addition, it should also be understood that after reading the technical content of the present invention, those skilled in the art can make various changes, modifications and / or variations to the present invention, and all these equivalent forms also fall within the protection scope defined by the appended claims of this application.

Claims

1. A graphite crucible for combined use, characterized in that, It includes an inner crucible body and an outer crucible body. Both the inner crucible body and the outer crucible body are independently formed graphite crucible bodies and are used in combination when in use; The inner crucible body is a circular crucible with an inner volume cavity for accommodating the material to be processed. A wall groove is formed on the outer wall of the inner crucible body. The wall groove is a blind groove arranged in a spiral shape. A tensile unit is wound around the outer wall of the inner crucible body to apply circumferential restraint to the outer wall of the inner crucible body through the tensile unit; The outer crucible body has an outer volume cavity for accommodating the inner crucible body. The outer volume cavity is slightly larger than the outer diameter of the inner crucible body, so that a 5 - 8 mm accommodation gap is reserved between the inner wall of the outer crucible body and the outer wall of the inner crucible body after the inner crucible body is placed in the outer volume cavity; A through hole is formed on the side wall of the outer crucible body as a pressure relief hole; The outer crucible body forms a bearing surface matching the bottom surface of the inner crucible body on the bottom surface of the outer volume cavity, and a ring groove connected to the lower part of the accommodation gap is formed at the outer edge of the bearing surface, and several blind grooves penetrating horizontally are formed on the bearing surface.

2. The graphite crucible for combined use according to claim 1, wherein The carbon content of the inner crucible body is 87 - 92%, and it is formed by using natural flake graphite. And the graphite raw material used for forming the inner crucible body includes at least 80% of flake graphite with a mesh size of more than 100 meshes and 15 - 20% of flake graphite with a mesh size of 50 - 80 meshes.

3. The graphite crucible used in combination according to claim 1, characterized in that, The carbon content of the outer crucible body is 85 - 88%, and the outer crucible body is a carbon - bonded type crucible with pitch as the binder.

4. The graphite crucible for combined use according to claim 1, characterized in that, The inner crucible body has a spherical bottom surface, and the bearing surface is an inner concave arc - shaped bearing surface matching the spherical bottom surface.

5. The graphite crucible used in combination according to claim 1, characterized in that, The outer crucible body forms an annular stepped groove at the upper edge of the outer volume cavity, and the upper edge of the inner crucible body forms a misaligned step matching the annular stepped groove. When used in combination, the inner crucible body is fixedly placed in the outer volume cavity through the cooperation of the annular stepped groove and the misaligned step.

6. The graphite crucible used in combination according to claim 1, characterized in that, The tensile unit is carbon fiber closely wound around the outer surface of the inner crucible; and the parameter indexes of the carbon fiber are: gram weight: 300-500 g / m 2 , modulus: 280-330 GPa, strength: 3.5-3.8 GPa.

7. The graphite crucible used in combination according to claim 6, characterized in that, The number of winding turns of the carbon fiber on the outer surface of the inner crucible body is 2 - 3 turns, and the carbon fiber is adhered to the outer surface of the inner crucible body in the form of pitch coating or dipping during the forming process of the inner crucible body.

8. The graphite crucible for combined use according to claim 1, characterized in that, The working environment of the graphite crucible used in combination is an inert gas environment or a vacuum environment, and the temperature range during its high - temperature operation is 900°C - 2500°C.

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