Prefabricated body, carbon-carbon product and thermal insulation cylinder for single crystal furnace

Abstract

The prefabricated body sequentially comprises the following components: a prefabricated body lower layer; a preform middle layer having a sacrificial layer; the preform lower layer is formed by laminating carbon cloth and a carbon fiber mesh tire and / or a pre-oxidized wire mesh tire; the prefabricated body upper layer is formed by laminating carbon cloth and a carbon fiber net tire and / or a pre-oxidized wire net tire; the prefabricated body middle layer is formed by laminating a sacrificial layer, carbon cloth and a carbon fiber mesh tire and / or a pre-oxidized wire mesh tire. The utility model also relates to a carbon-carbon product and a thermal insulation cylinder for a single crystal furnace.

Description

Technical Field

[0001] The present application relates to the technical field of Czochralski single crystals, and in particular to a carbon fiber preform used in the technical field of Czochralski single crystals, and a carbon-carbon product and a heat preservation tube prepared therefrom. Background Art

[0002] Carbon fiber composite materials are widely used as thermal field materials in single crystal furnaces and polycrystalline furnaces due to their excellent physical and chemical properties such as high temperature resistance, high strength and corrosion resistance.

[0003] As the premise and basis for the preparation of carbon fiber composite materials, the structure of the preform not only affects the various properties of carbon-carbon products, but is also the main source of cost for carbon-carbon products. The existing preforms are prepared by alternating needle-punching of carbon cloth and mesh tires. The preforms prepared are heavy and costly, and the subsequent carbon-carbon products have average thermal insulation properties.

[0004] Therefore, a new preform is urgently needed. Utility Model Content

[0005] In order to solve one of the above problems, the present application relates to a preform and a carbon-carbon product with a specific hollow structure. Specifically, the present application relates to the following solutions:

[0006] A first aspect of the present application relates to a preform, which comprises the following layers in order: a preform lower layer;

[0007] a preform middle layer having a sacrificial layer;

[0008] Prefabricated upper layer,

[0009] The lower layer of the preform is formed by laminating carbon cloth and carbon fiber mesh and / or preoxidized wire mesh;

[0010] The upper layer of the preform is formed by laminating carbon cloth and carbon fiber mesh tire and / or preoxidized wire mesh tire;

[0011] The middle layer of the preform is formed by laminating a sacrificial layer, a carbon cloth and a carbon fiber mesh and / or a preoxidized wire mesh.

[0012] In a specific embodiment, the thickness of the lower layer of the preform is 3 mm-30 mm, preferably 3 mm-20 mm, and more preferably 5 mm-15 mm;

[0013] The thickness of the middle layer of the preform is 3mm-40mm, preferably 3mm-35mm, and more preferably 10mm-20mm;

[0014] The thickness of the upper layer of the preform is 3 mm to 30 mm, preferably 3 mm to 20 mm, and more preferably 5 mm to 15 mm.

[0015] Preferably, the sacrificial layer accounts for 10%-90%, preferably 30%-60% of the total volume of the preform.

[0016] In a specific embodiment, the middle layer includes a peripheral structure and ribs, wherein the ribs divide the peripheral structure into multiple sub-cavities, the sacrificial layer is located in the sub-cavities, and the peripheral structure and ribs are formed by stacking carbon cloth and carbon fiber mesh and / or pre-oxidized wire mesh.

[0017] In a specific embodiment, the preform lower layer, the preform middle layer and the preform upper layer are layer structures with millimeter-scale pores.

[0018] In a specific embodiment, the pores are ≤ 3 mm;

[0019] More preferably, the pores are 50 μm-3 mm.

[0020] In a specific embodiment, the density of the preform is 0.3-0.9 g / cm 3 .

[0021] Preferably, the carbon cloth is selected from any one of plain cloth, twill cloth, unidirectional cloth or non-woven cloth.

[0022] The second aspect of the present application also relates to a carbon-carbon product, which comprises the following layers in sequence:

[0023] Lower level;

[0024] a middle layer with a cavity;

[0025] upper layer,

[0026] The lower layer is formed by laminating carbon cloth and carbon fiber mesh tire and / or pre-oxidized wire mesh tire;

[0027] The upper layer is formed by laminating carbon cloth and carbon fiber mesh tire and / or pre-oxidized wire mesh tire;

[0028] The middle layer is formed by laminating carbon cloth and carbon fiber mesh tire and / or pre-oxidized wire mesh tire.

[0029] In a specific embodiment, the thickness of the lower layer is 3 mm-30 mm, preferably 3 mm-20 mm, and more preferably 5 mm-15 mm;

[0030] The thickness of the middle layer is 3mm-40mm, preferably 3mm-35mm, and more preferably 10mm-20mm;

[0031] The thickness of the upper layer is 3 mm to 30 mm, preferably 3 mm to 20 mm, and more preferably 5 mm to 15 mm.

[0032] Preferably, the cavity accounts for 10%-90% of the total volume of the carbon-carbon article, preferably 30%-60%.

[0033] In a specific embodiment, the cavity in the middle layer of the preform having a cavity is further divided into a plurality of sub-cavities by ribs, wherein the ribs are formed by stacking carbon cloth and carbon fiber mesh and / or preoxidized wire mesh.

[0034] In a specific embodiment, the lower layer, the middle layer and the upper layer are layer structures with millimeter-scale pores, preferably pores ≤ 3 mm, preferably pores of 50 μm-3 mm;

[0035] Preferably, the density of the carbon-carbon product is 0.3-0.9 g / cm 3 .

[0036] In a specific embodiment, the carbon-carbon product is in the shape of a flat plate, a hollow cylinder, a hollow cone or a hollow rotating body;

[0037] Preferably, the carbon cloth is selected from any one of plain cloth, twill cloth, unidirectional cloth or non-woven cloth.

[0038] The third aspect of the present application also relates to a heat preservation cylinder for a single crystal furnace, which comprises:

[0039] Carbon felt and the carbon-carbon product disclosed in the second aspect of the present application; wherein,

[0040] The carbon felt is laminated on one side or both sides of the carbon-carbon product;

[0041] Preferably, the density of the carbon-carbon product is 1.0-1.6 g / cm 3 .

[0042] Compared with the prior art, the beneficial effects of this application are as follows:

[0043] (1) The preform prepared in the present application can greatly reduce the input of carbon fiber and the input cost of raw materials.

[0044] (2) The carbon-carbon product prepared in the present application can greatly reduce the input of carbon fiber and reduce the investment cost of carbon fiber; and has a better thermal insulation effect. In addition, the carbon-carbon product is an integral structure with higher strength, which can effectively extend the service life of subsequent carbon-carbon products.

[0045] (3) The insulating tube prepared by the present application has a low proportion of raw materials in the insulating tube, which reduces costs and can significantly improve the insulating performance of the insulating tube, making the insulating tube of the single crystal furnace more energy-saving and environmentally friendly. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 This is a schematic diagram of an exploded view of an embodiment of the preform of the present application.

[0047] Figure 2 This is a cross-sectional view of an embodiment of a carbon-carbon product in a heat-insulating barrel of the present application.

[0048] Figure 3 This is a schematic structural diagram of an embodiment of a carbon-to-carbon product in a heat-insulating barrel of the present application.

[0049] Figure 4 This is a cross-sectional view of the carbon-carbon product in the insulation tube of Comparative Example 1.

[0050] Figure 5A and Figure 5B A schematic cross-sectional view showing a middle layer of an embodiment of a carbon-carbon product of the present application.

[0051] Fig. 6A Schematic diagram of the temperature gradient of the insulation cylinder of comparative example 1 of the present application.

[0052] Figure 6B This is a schematic diagram of the temperature gradient of the insulation cylinder of Example 2 of the present application.

[0053] Fig. 7A This is the isotherm of the insulation cylinder of Example 2 of the present application.

[0054] Figure 7B It is the isotherm of the insulation cylinder of comparative example 1 of the present application.

[0055] Reference numerals

[0056] 1: upper layer of preform; 2: middle layer of preform; 3: sacrificial layer; 4: lower layer of preform; 5: cylinder; 6: cylinder cavity; 10: carbon-carbon product; 20: carbon felt; 30: preform; DETAILED DESCRIPTION

[0057] The following embodiments of the present application are only used to illustrate the specific embodiments of the present application, and these embodiments cannot be understood as limiting the present application. Any other changes, modifications, substitutions, combinations, and simplifications made without departing from the spirit and principle of the present application are deemed to be equivalent replacement methods and fall within the scope of protection of the present application.

[0058] The specific embodiments of the present application will be described in more detail below. However, it should be understood that the present application can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided to enable a more thorough understanding of the present application and to enable the scope of the present application to be fully communicated to those skilled in the art.

[0059] It should be noted that certain words are used in the specification and claims to refer to specific components. Those skilled in the art should understand that technicians may use different nouns to refer to the same component. This specification and claims do not use the difference in nouns as a way to distinguish components, but use the difference in the functions of the components as the criterion for distinction. As mentioned throughout the specification and claims, "including" or "comprising" is an open term, so it should be interpreted as "including but not limited to". The subsequent description of the specification is a preferred embodiment of the implementation of the present application, but the description is based on the general principles of the specification and is not used to limit the scope of the present application. The scope of protection of the present application shall be determined by the attached claims.

[0060] As used in this specification, "a" or "an" may mean one or more. As used in the claims, when used with the word "comprising", the word "a" or "an" may mean one or more than one.

[0061] The term "or" is used in the claims to mean "and / or" unless explicitly stated to refer only to alternatives or the alternatives are mutually exclusive, although the present disclosure supports a definition referring only to alternatives and "and / or." As used herein, "another" may mean at least a second or more.

[0062] The carbon cloth mentioned in this application generally refers to carbon fiber cloth, also known as carbon fiber cloth, carbon fiber cloth, carbon fiber woven cloth, carbon fiber prepreg cloth, carbon fiber reinforced cloth, carbon cloth, carbon fiber fabric, carbon fiber tape, carbon fiber sheet (prepreg cloth), etc.

[0063] The carbon fiber mesh mentioned in the present application is a material used for thermal insulation, especially in medium and high temperature industrial smelting furnaces such as single crystal silicon furnaces, polycrystalline silicon furnaces, and high temperature atmosphere furnaces, and is widely used to make thermal insulation felt products. When preparing the carbon fiber mesh, it is necessary to first widen the long carbon fiber tow to form a widened continuous long carbon fiber, and then cut the widened continuous long carbon fiber to obtain a short carbon fiber mesh, and then use a needle punch or hydroentanglement method to prepare the short carbon fiber mesh into a carbon fiber unit layer, and finally stack multiple unit layers to obtain a carbon fiber mesh finished product. There is no special limitation on the carbon fiber mesh used in this application, and it can be obtained through commercial purchase or prepared by itself, as long as it meets the above definition.

[0064] The pre-oxidized yarn mentioned in this application is an important intermediate product in the process of preparing carbon fiber. It is a partially cyclic black fiber formed by high-temperature pre-oxidation of carbon-containing organic fiber precursors in an air medium. It has the characteristics of fire resistance, flame retardancy, heat insulation, light weight, folding resistance, no shrinkage, and no melt drop. Pre-oxidized yarn has many advantages of carbon fiber products, and the cost is much lower than that of carbon fiber, but the current development and application fields are still relatively small.

[0065] The pre-oxidized wire mesh mat mentioned in this application is usually formed by laying the short-cut pre-oxidized wires into a net through a carding machine and an air-laying machine after opening. There is no particular limitation on the pre-oxidized wire mesh mat used in this application, and it can be obtained commercially or prepared by itself, as long as it meets the above definition.

[0066] The present application relates to a preform, which comprises the following in sequence: a preform lower layer; a preform middle layer with a sacrificial layer; a preform upper layer, wherein the preform lower layer is formed by stacking carbon cloth and carbon fiber mesh and / or preoxidized wire mesh; the preform upper layer is formed by stacking carbon cloth and carbon fiber mesh and / or preoxidized wire mesh; the preform middle layer is formed by stacking a sacrificial layer, carbon cloth and carbon fiber mesh and / or preoxidized wire mesh.

[0067] The present application relates to a carbon-carbon product, which comprises the following in sequence: a lower layer; a middle layer with a cavity; an upper layer, wherein the lower layer is formed by stacking carbon cloth and carbon fiber mesh tires or by stacking carbon cloth and pre-oxidized wire mesh tires; the upper layer is formed by stacking carbon cloth and carbon fiber mesh tires or by stacking carbon cloth and pre-oxidized wire mesh tires; the middle layer is formed by stacking carbon cloth and carbon fiber mesh tires or by stacking carbon cloth and pre-oxidized wire mesh tires.

[0068] The preform of the present application is used to form the carbon-carbon product of the present application, that is, the sacrificial layer in the preform is removed to form a preform middle layer with a cavity to obtain the carbon-carbon product. Therefore, the description of the preform lower layer, the preform middle layer and the preform upper layer in the present application is also applicable to the lower layer, the middle layer and the upper layer in the carbon-carbon product of the present application. Except that the middle layer of the carbon-carbon product does not have a sacrificial layer and forms a middle layer with a cavity, the rest of the structure is the same as the structure of the preform.

[0069] The preform of the present application has a sacrificial layer in the middle layer of the preform, so that the carbon-carbon product can form a middle layer structure with a cavity.

[0070] The carbon-carbon product of the present application has a cavity and therefore has a better thermal insulation effect than traditional carbon-carbon products. Compared with the thermal insulation tube made of traditional carbon-carbon products, when the thermal insulation tube made of carbon-carbon products is used for thermal insulation, even if the inner wall temperature is the same, for example, 1430°C, the outer wall temperature of the thermal insulation felt is lower. Specifically, the outer wall temperature of the thermal insulation felt of the thermal insulation tube prepared by a specific embodiment of the present application is 135°C, while the outer wall temperature of the thermal insulation felt of the thermal insulation tube prepared by the comparative example is 175°C. It can be seen that the thermal insulation tube formed by the carbon-carbon product with a cavity of the present application has low thermal conductivity and better thermal insulation effect.

[0071] For the preform of the present application, there is no limit to the size of its sacrificial layer as long as it can form a cavity. In the present application, the sacrificial layer accounts for 10%-90% of the total volume of the preform. Preferably, the sacrificial layer accounts for 30%-60% of the total volume of the preform. For example, the sacrificial layer accounts for 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90% of the total volume of the preform. It is worth noting that the total volume of the preform refers to the volume of the preform formed by the upper layer of the preform, the middle layer of the preform and the lower layer of the preform.

[0072] For the carbon-carbon product of the present application, there is no limit to the size of the cavity in the middle layer, as long as it can form a cavity. In the present application, the size of the cavity accounts for 10%-90% of the volume of the entire carbon-carbon product, for example, it can be 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85% or 90%. Preferably, the size of the cavity accounts for 30%-60% of the volume of the entire carbon-carbon product.

[0073] In the present application, the upper layer of the preform may be obtained by alternately laminating and needle-punching carbon cloth and carbon fiber mesh. The upper layer of the preform may be obtained by alternately laminating and needle-punching carbon cloth and preoxidized wire mesh. The middle layer of the preform may be obtained by alternately laminating and needle-punching carbon cloth and carbon fiber mesh. The middle layer of the preform may be obtained by alternately laminating and needle-punching carbon cloth and preoxidized wire mesh. The lower layer of the preform may be obtained by alternately laminating and needle-punching carbon cloth and carbon fiber mesh. The lower layer of the preform may be obtained by alternately laminating and needle-punching carbon cloth and preoxidized wire mesh.

[0074] In the present application, the materials used to form the upper layer of the preform, the middle layer of the preform and the lower layer of the preform can be the same or different. For example, the upper layer of the preform, the middle layer of the preform and the lower layer of the preform are all obtained by alternately plying and needle-punching carbon cloth and carbon fiber mesh tires. For example, the upper layer of the preform, the middle layer of the preform and the lower layer of the preform are all obtained by alternately plying and needle-punching carbon cloth and preoxidized wire mesh tires.

[0075] In one embodiment, the upper layer of the preform and the middle layer of the preform are obtained by alternately laminating and needle-punching carbon cloth and carbon fiber mesh, and the lower layer of the preform is obtained by alternately laminating and needle-punching carbon cloth and preoxidized wire mesh. In one embodiment, the middle layer of the preform and the lower layer of the preform are obtained by alternately laminating and needle-punching carbon cloth and carbon fiber mesh, and the upper layer of the preform is obtained by alternately laminating and needle-punching carbon cloth and preoxidized wire mesh. In one embodiment, the upper layer of the preform and the lower layer of the preform are obtained by alternately laminating and needle-punching carbon cloth and carbon fiber mesh, and the middle layer of the preform is obtained by alternately laminating and needle-punching carbon cloth and preoxidized wire mesh.

[0076] In one embodiment, the upper layer of the preform and the middle layer of the preform are obtained by alternately plying and needle-punching carbon cloth and preoxidized wire mesh tires, and the lower layer of the preform is obtained by alternately plying and needle-punching carbon cloth and carbon fiber mesh tires. In one embodiment, the middle layer of the preform and the lower layer of the preform are obtained by alternately plying and needle-punching carbon cloth and preoxidized wire mesh tires, and the upper layer of the preform is obtained by alternately plying and needle-punching carbon cloth and carbon fiber mesh tires. In one embodiment, the upper layer of the preform and the lower layer of the preform are obtained by alternately plying and needle-punching carbon cloth and preoxidized wire mesh tires, and the middle layer of the preform is obtained by alternately plying and needle-punching carbon cloth and carbon fiber mesh tires.

[0077] In one embodiment, the carbon cloth used in the present application is selected from any one of plain cloth, twill cloth, unidirectional cloth or non-woven cloth.

[0078] In this application, a fabric made of plain weave is called a plain weave. Twill is a cotton fabric with two-up-one-down twill and 45° left-hand slant. Satin is a general term for various specifications of satin weave cotton fabrics, a kind of fabric structure in which the individual weave points on two adjacent warp or weft yarns are evenly distributed but not continuous. Unidirectional fabric generally refers to unidirectional fabric, which refers to a textile with a large amount of textile yarn or untwisted coarse yarn in one direction (usually warp, but also weft unidirectional fabric) and only a small amount of usually fine yarn in the other direction, so that practically all the strength of the cloth is in one direction.

[0079] The plain cloth, twill cloth, satin cloth, unidirectional cloth and non-woven fabric used in this application can be prepared by oneself or purchased from commercial sources, for example, relevant carbon cloth can be purchased from Toray, Toho, Mitsubishi, Hao's, Aksa, Hyosung, Taekwang, Formosa Plastics, Zhongfu Shenying, Jiangsu Hengshen, Guangwei Composites, Jilin Guoxing and other companies.

[0080] The material of the carbon cloth used in the present application can be selected from any of polyacrylonitrile-based carbon fiber, viscose-based carbon fiber, and asphalt-based carbon fiber. For example, polyacrylonitrile-based carbon fiber plain cloth, polyacrylonitrile-based carbon fiber twill cloth, polyacrylonitrile-based carbon fiber satin cloth, and polyacrylonitrile-based carbon fiber unidirectional cloth can be used; or for example, viscose-based carbon fiber plain cloth, viscose-based carbon fiber twill cloth, viscose-based carbon fiber satin cloth, and viscose-based carbon fiber unidirectional cloth can be used; or for example, asphalt-based carbon fiber plain cloth, asphalt-based carbon fiber twill cloth, asphalt-based carbon fiber satin cloth, and asphalt-based carbon fiber unidirectional cloth can be used.

[0081] The present application does not clearly define the thickness of the preform lower layer, the preform middle layer, and the preform upper layer, or the number of layers of the preform lower layer, the preform middle layer, and the preform upper layer, and those skilled in the art can make a selection based on their needs. The thickness or number of layers of the preform lower layer, the preform middle layer, and the preform upper layer can be the same or different.

[0082] In the present application, the number of layers of the preform lower layer, the preform middle layer, and the preform upper layer refers to the number of layer structures formed by laminating carbon cloth and carbon fiber mesh tires or the number of layer structures formed by laminating carbon cloth and preoxidized wire mesh tires.

[0083] In a specific embodiment, the thickness of the lower layer of the preform is 3 mm to 30 mm, preferably 3 mm to 20 mm, and more preferably 5 mm to 15 mm. Specifically, the thickness of the lower layer of the preform can be 3 mm, 4 mm, 5 mm, 6 mm, 7 mm, 8 mm, 9 mm, 10 mm, 11 mm, 12 mm, 13 mm, 14 mm, 15 mm, 16 mm, 17 mm, 18 mm, 19 mm, 20 mm, 21 mm, 22 mm, 23 mm, 24 mm, 25 mm, 26 mm, 27 mm, 28 mm, 29 mm or 30 mm.

[0084] In a specific embodiment, the thickness of the middle layer of the preform is 3 mm to 40 mm, preferably 3 mm to 35 mm, and more preferably 10 mm to 20 mm. Specifically, the thickness of the lower layer of the preform can be 3 mm, 4 mm, 5 mm, 6 mm, 7 mm, 8 mm, 9 mm, 10 mm, 11 mm, 12 mm, 13 mm, 14 mm, 15 mm, 16 mm, 17 mm, 18 mm, 19 mm, 20 mm, 21 mm, 22 mm, 23 mm, 24 mm, 25 mm, 26 mm, 27 mm, 28 mm, 29 mm, 30 mm, 31 mm, 32 mm, 33 mm, 34 mm, 35 mm, 36 mm, 37 mm, 38 mm, 39 mm or 40 mm.

[0085] In a specific embodiment, the thickness of the upper layer of the preform is 3 mm to 30 mm, preferably 3 mm to 20 mm, and more preferably 5 mm to 15 mm. Specifically, the thickness of the lower layer of the preform can be 3 mm, 4 mm, 5 mm, 6 mm, 7 mm, 8 mm, 9 mm, 10 mm, 11 mm, 12 mm, 13 mm, 14 mm, 15 mm, 16 mm, 17 mm, 18 mm, 19 mm, 20 mm, 21 mm, 22 mm, 23 mm, 24 mm, 25 mm, 26 mm, 27 mm, 28 mm, 29 mm or 30 mm.

[0086] In the present application, it is preferred that the thickness of the middle layer of the preform is greater than the thickness of the upper layer of the preform or the thickness of the lower layer of the preform.

[0087] In a specific embodiment, the thickness of the lower layer of the preform is 10mm, the thickness of the middle layer of the preform is 15mm, and the thickness of the upper layer of the preform is 10mm. In a specific embodiment, the thickness of the lower layer of the preform is 15mm, the thickness of the middle layer of the preform is 20mm, and the thickness of the upper layer of the preform is 15mm. In a specific embodiment, the thickness of the lower layer of the preform is 20mm, the thickness of the middle layer of the preform is 25mm, and the thickness of the upper layer of the preform is 20mm. In a specific embodiment, the thickness of the lower layer of the preform is 20mm, the thickness of the middle layer of the preform is 30mm, and the thickness of the upper layer of the preform is 20mm. In a specific embodiment, the thickness of the lower layer of the preform is 7mm, the thickness of the middle layer of the preform is 8mm, and the thickness of the upper layer of the preform is 7mm. In a specific embodiment, the thickness of the lower layer of the preform is 10mm, the thickness of the middle layer of the preform is 13mm, and the thickness of the upper layer of the preform is 10mm. In a specific embodiment, the thickness of the lower layer of the preform is 10 mm, the thickness of the middle layer of the preform is 20 mm, and the thickness of the upper layer of the preform is 10 mm.

[0088] In a specific embodiment, the number of layers of the lower layer of the preform is 3-15 layers, for example, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14 or 15 layers.

[0089] In a specific embodiment, the number of layers in the preform is 3-15 layers, for example, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14 or 15 layers.

[0090] In a specific embodiment, the number of layers on the preform is 3-30, and can be, for example, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29 or 30 layers.

[0091] In the present application, there is no specific limitation on the material used to form the sacrificial layer, as long as the material can form a cavity after being processed.

[0092] Specifically, the material forming the sacrificial layer is selected from foam, paper, water-soluble fiber, resin, high molecular polymer or ice.

[0093] In a specific embodiment, the material of the sacrificial layer is foam. In a specific embodiment, the material of the sacrificial layer is paper. In a specific embodiment, the material of the sacrificial layer is resin. In a specific embodiment, the material of the sacrificial layer is water-soluble fiber. In a specific embodiment, the material of the sacrificial layer is a high molecular polymer.

[0094] In a specific embodiment, the high molecular polymer is low density polyethylene plastic. In a specific embodiment, the paper is corrugated paper. In a specific embodiment, the foam is PVC board or polystyrene foam.

[0095] In a specific embodiment of the present application, the preform is an integral structure, that is, the upper, middle and lower layers of the preform are an integral whole with the sacrificial layer or cavity, the sacrificial layer or cavity is wrapped inside and cannot be seen from the external structure, and there is no clear dividing line between the upper layer, the middle layer and the lower layer from the appearance, and it is obvious that they are not formed by splicing. Specifically, for example Figure 5A As shown in the figure, the sacrificial layer is wrapped inside the preform; the preform is actually a whole that wraps the sacrificial layer, and the upper, middle and lower layers of the preform are not actually the external sides, and there is actually no clear dividing line. Figure 5A This is just one way that a person skilled in the art can understand what it means that the preform is a unitary structure.

[0096] In a specific embodiment of the present application, the cavity in the middle layer of the preform is further divided into a plurality of sub-cavities by ribs, wherein the ribs are formed by stacking carbon cloth and carbon fiber mesh tires or by stacking carbon cloth and preoxidized wire mesh tires, for example, Figure 5B The structure shown in the figure can be understood by those skilled in the art. Figure 5B The structure shown is only exemplary, and any method known to those skilled in the art can be used to cut the cavity into multiple sub-cavities. In the present application, when there are ribs in the middle layer of the preform, the ribs and the outer layer of the middle layer of the preform together serve as the middle layer, and the total volume of the multiple sub-cavities is the volume of the cavity. The volume of the above-mentioned cavity in the middle layer can refer to the above description. The presence of ribs can further improve the strength of the preform of the present application, and can achieve better load-bearing support performance.

[0097] In a specific embodiment of the present application, the lower layer of the preform, the middle layer of the preform and the upper layer of the preform are layer structures with millimeter-level pores ≤3mm. In the present application, the structure of the preform is complete, and the pores are the overlap pores of the carbon fiber mesh or preoxidized wire mesh and the carbon cloth and the pores left by acupuncture. The greater the density of acupuncture, the more acupuncture pores. In a specific embodiment, the lower layer of the preform, the middle layer of the preform and the upper layer of the preform have pores of 50μm-3mm. The size of the pores can be observed and measured by a microscope. By limiting the pores to the above range, gases and liquids can be effectively seeped out; if the pores are too small, the sacrificial layer cannot be effectively removed to form cavities, and if the pores are too large, the strength and densification efficiency of the preform will be affected.

[0098] In the present application, the preform or carbon-carbon product of the present application can be separate or integral, preferably an integral structure or an integrated structure. In the present application, the integral structure and the integrated structure can be interchangeable, which is intended to indicate that the preform or carbon-carbon product is a complete structure after molding, and is not formed by splicing.

[0099] The density of the carbon-carbon product of the present application is 0.3-0.9 g / cm 3 , for example, 0.4, 0.5, 0.6, 0.7, 0.8 g / cm 3 .

[0100] In the above, the description of the lower layer, middle layer and upper layer of the preform can be applied to the upper layer, middle layer and lower layer of the carbon-carbon product, except that the preform still has the sacrificial layer material, and the carbon-carbon product no longer has the sacrificial layer material but forms a cavity, and there is no other difference.

[0101] like Figure 1 As shown, the present application relates to a method for preparing a carbon-carbon product, which includes: forming a preform lower layer 4; forming a sacrificial layer 3 on the preform lower layer 4; forming a preform middle layer 2 around the sacrificial layer 3; forming a preform upper layer 1 on the preform middle layer 2; and removing the sacrificial layer 3 to form a preform middle layer with a cavity.

[0102] When forming the lower layer 4 of the preform, the carbon cloth and the carbon fiber mesh or the preoxidized wire mesh are alternately layered and needle-punched to form a thickness of 3 mm to 30 mm.

[0103] When the preform middle layer 2 is formed around the sacrificial layer 3, the carbon cloth and the carbon fiber mesh or the preoxidized wire mesh are alternately layered and needle-punched around the sacrificial layer to form a thickness of 3mm-40mm.

[0104] When the preform upper layer 1 is formed on the preform middle layer, the carbon cloth and the carbon fiber mesh or the preoxidized wire mesh are alternately layered and needle-punched to form a thickness of 3 mm to 30 mm.

[0105] In the method of the present application, the descriptions of the materials of the above-mentioned preforms are all applicable to the method for preparing the preforms of the present application.

[0106] In the preform preparation method of the present application, the material forming the sacrificial layer 3 is selected from foam, paper, resin, water-soluble fiber, high molecular polymer or ice. Among them, the foam can be PVC board or polystyrene foam, the paper can be corrugated paper, and the high molecular polymer can be low-density polyethylene plastic.

[0107] In a specific embodiment, the sacrificial layer 3 is a low-density polyethylene plastic. In a specific embodiment, the sacrificial layer is a corrugated paper. In a specific embodiment, the sacrificial layer is a PVC board.

[0108] In the present application, any preform having a cavity can be formed by removing the sacrificial layer 3. Different removal methods can be used for different sacrificial layer materials. For example, when the sacrificial layer material is polystyrene foam, the sacrificial layer can be removed by placing the preform in an organic solvent. The organic solvent can be an acetone solution. When the sacrificial layer material is polystyrene foam, the sacrificial layer can also be removed by heating. In a specific method, the heating temperature is 100-300°C.

[0109] The present application also relates to a heat preservation tube for a single crystal furnace, which comprises: carbon felt and the carbon-carbon product mentioned in the present application as described above; wherein the carbon felt is laminated on one side or both sides of the carbon-carbon product.

[0110] In the present application, the carbon-carbon product can be densified and graphitized after removing the sacrificial layer. The densification and graphitization methods are not limited and can be performed by any method known to those skilled in the art. Specifically, the densification can be performed by chemical vapor deposition, and the graphitization can be performed by high temperature heating to, for example, above 2000°C.

[0111] In a specific embodiment, the density of the carbon-carbon product in the insulation cylinder of the present application is 1.0-1.6 g / cm 3 , for example, 1.1, 1.2, 1.3, 1.4, 1.5 g / cm 3 .

[0112] like Figure 6B As shown, in a specific embodiment, the thermal insulation cylinder of the present application includes a carbon-carbon product 10 and a carbon felt 20 , wherein the thermal insulation carbon felt 20 is laminated on one side or both sides of the carbon-carbon product 10 .

[0113] In a specific embodiment, the heat preservation tube of the present application comprises a carbon-carbon product and a carbon felt located outside the carbon-carbon product. In a specific embodiment, the heat preservation tube of the present application comprises the following laminated structure: a carbon felt, a carbon-carbon product and a carbon felt.

[0114] In a specific embodiment, the carbon-carbon product in the heat preservation tube of the present application is an integral structure or an integrated structure, that is, after the carbon-carbon product is formed, the upper layer, the middle layer and the lower layer are a complete structure and are not formed by splicing.

[0115] For carbon fiber preforms or carbon fiber products, if a cavity needs to be prepared inside them, since carbon fiber preforms or carbon fiber products cannot be hollowed out by machining, they can only be prepared by splicing, that is, preparing a preform flat plate with 6 surfaces, and then splicing to obtain a carbon fiber preform with a cavity. The carbon fiber product finally obtained will have a splicing seam. Since silicon vapor will be generated in the single crystal furnace, this silicon vapor will enter from the splicing seam of the carbon fiber, resulting in a low lifespan of the carbon fiber product with a cavity prepared by splicing.

[0116] In the present application, a preform with a cavity can be directly prepared by preparing a sacrificial layer. The prepared preform is complete and integrated, does not form a joint seam, has a long service life, and the method is simple and feasible, which is conducive to large-scale promotion.

[0117] For the insulation tube, currently, the inner insulation tube is mainly made of graphite and soft felt is wrapped around the outer surface of the insulation tube. Graphite can be machined to prepare a cavity; however, for the insulation tube, due to its thin thickness and cylindrical shape, it is difficult to machine graphite to prepare a cavity, and graphite is relatively brittle, and there may be cracks that affect the strength, and after machining, it also needs to be spliced, and there are splicing seams, which shortens its life. In addition, there is also a method of using solid felt to prepare the inner insulation tube. The strength of the solid felt can be prepared by machining a cavity, but because the solid felt is brittle, there will be cracks that affect the subsequent strength, and even if it is machined, the inlet position of the machine needs to be spliced, and the presence of cracks and splicing seams will lead to its short life.

[0118] In the present application, a preform with a cavity can be directly prepared by preparing a sacrificial layer. The prepared preform is complete and integrated, does not form a splicing seam, has a long service life, and the prepared insulation tube is light in weight, uses less carbon fiber material, and has low cost. The method is simple and feasible, which is conducive to large-scale promotion.

[0119] Example

[0120] The present application provides a general and / or specific description of the materials and test methods used in the experiments. In the following examples, unless otherwise specified, % means wt%, i.e., weight percentage. The reagents or instruments used without indicating the manufacturer are all conventional reagent products that can be obtained commercially.

[0121] Example 1 Preparation of Hollow Flat Plate Preform

[0122] 1) Preparation of the lower structure of the carbon fiber preform: a plain carbon cloth with a width of 500*500 mm and a carbon fiber mesh tire are alternately layered and needle-punched to prepare a 15 mm thick preform flat plate;

[0123] 2) Preparation of “sacrificial layer”: Commercial polystyrene foam from the packaging industry is made into a 440*440*10mm cuboid and embedded in the preform;

[0124] 3) Preparation of the middle layer structure of the carbon fiber preform: 470*30mm plain carbon cloth and mesh tire are alternately layered and needle-punched around the foam, with a preparation height of 10mm;

[0125] 4) Preparation of the upper layer of the carbon fiber preform disc: 500*500 mm plain carbon cloth and mesh tire are alternately layered and needle-punched to prepare a 15 mm thick preform upper layer to obtain a preform;

[0126] 5) Removal of the “sacrificial layer”: the obtained preform is placed in an acetone solution and soaked for 20 minutes to obtain a carbon fiber preform with a cavity;

[0127] 6) Drying: The carbon fiber preform with a cavity obtained in step 5) is placed in an oven for heat treatment at 220° C. for 3 hours to obtain a hollow carbon fiber preform.

[0128] Example 2 Preparation of thermal insulation cylinder

[0129] 1) Preparation of the lower structure of the carbon fiber preform: a bidirectional plain carbon cloth with a width of 700 mm and a carbon fiber mesh tire are alternately layered and needle-punched to prepare a 7 mm thick cylindrical preform on a mold;

[0130] 2) Preparation of “sacrificial layer”: polystyrene foam with a width of 600 mm was tightly wound around the preform in the center, with a thickness of 8 mm;

[0131] 3) Preparation of the middle layer structure of the carbon fiber preform: Use a bidirectional plain weave with a width of 50 mm and a mesh tire to alternately lay layers on both sides of the foam with a needle punching height of 7 mm;

[0132] 4) Preparation of the upper layer of the carbon fiber preform: a bidirectional plain weave with a width of 700 mm and a mesh tire are alternately layered and needle-punched to obtain a preform;

[0133] 5) Removal of the “sacrificial layer”: the obtained preform is placed in an oven and dried at 270° C. for 3 h to obtain a carbon fiber preform with a cavity;

[0134] 6) The dried hollow carbon fiber preform is placed in a chemical vapor deposition furnace for densification, and the density reaches 1.36 g / cm 3 After that, it was placed in a high temperature furnace for high temperature graphitization treatment at a temperature of 2200°C for 15 hours.

[0135] 7) The high temperature product is machined according to the drawing to obtain a density of 1.32g / cm 3The circular cylindrical product has an inner diameter of 900 mm, an outer diameter of 936 mm, and a height of 690 mm. The structure of the obtained hollow cylinder is shown in Table 1;

[0136] 8) The machined product is put into the chemical vapor deposition furnace again for surface sealing treatment, and the finished product density is 1.37g / cm 3 Carbon-carbon products.

[0137] 9) Wrap the outer ring of the carbon-carbon product with soft felt of 130 mm thickness.

[0138] The temperature distribution curve of the hollow heat preservation cylinder prepared in Example 2 was analyzed by using COMSOL Multiphysics simulation software, and the temperature of the inner wall of the hollow heat preservation cylinder was controlled to be 1430°C. Figure 6B The temperature change from the inner wall of the insulation tube to the outer wall of the insulation felt after the insulation tube is wrapped with the insulation felt is shown. The temperature of the outer wall is 135℃. Fig. 7A The isotherms at this time are shown. The temperature of the hollow part is higher than that of the edge part, proving that the hollow structure has a certain inhibitory effect on heat conduction.

[0139] Embodiment 3-6

[0140] Except for the differences listed in Table 1, the hollow heat-insulating cylinders of Examples 3-6 were prepared in the same manner as in Example 2.

[0141] Example 7

[0142] The hollow insulation cylinder was prepared by repeating the method of Example 3 except that the carbon fiber mesh in Example 3 was replaced with a preoxidized wire mesh. The results showed that the insulation effect was basically the same after the preoxidized wire mesh was used, but the preoxidized wire was low in price and could further save costs.

[0143] Embodiment 8-9

[0144] Except for the differences listed in Table 1, the hollow heat-insulating cylinders of Examples 8-9 were prepared in the same manner as in Example 2.

[0145] Comparative Example 1 Preparation of solid insulation cylinder

[0146] 1) A bidirectional carbon cloth with a width of 700 mm and a web tire are alternately layered and needle-punched to prepare a 17 mm thick cylindrical preform on a mold;

[0147] 2) The high temperature product is machined according to the drawing to obtain a density of 1.32g / cm 3 The structure of the preform cylinder is shown in Table 1;

[0148] 3) The machined product is put into the chemical vapor deposition furnace again for surface sealing treatment, and the finished product density is 1.37g / cm3 Carbon-carbon products.

[0149] 4) Wrap the outer ring of the carbon-carbon product with soft felt of 130 mm thickness.

[0150] The temperature distribution curve of the solid insulation cylinder prepared in Comparative Example 1 was simulated and analyzed using COMSOL Multiphysics simulation software, and the temperature of the inner wall of the solid insulation cylinder was set to 1430°C. Fig. 6A This is a schematic diagram of the temperature gradient of the solid insulation cylinder of Comparative Example 1 of the present application. Figure 6B This is a schematic diagram of the temperature gradient of the hollow heat preservation cylinder of Example 2 of the present application. As can be seen from the figure, Fig. 6A The temperature of the outer wall of the insulation tube is as low as 175℃ and as high as 1427℃; Figure 6B The temperature of the outer wall of the insulation tube is 135℃, and the highest temperature is 1427℃. That is to say, the heat of the single crystal furnace is transferred from the inner wall of the insulation tube to the outer wall of the insulation tube. Figure 6B The heat field transfer of the insulation tube is less, which will lead to Figure 6B The heat ratio of the outer wall of the single crystal furnace Fig. 6A The heat of the outer wall is low. Further, Fig. 7A This is the isotherm of the insulation cylinder of Example 2 of the present application. Figure 7B This is the isotherm of the insulation cylinder of comparative example 1 of this application. As can be seen from the figure, Figure 7B The isotherms of the solid insulation tube are relatively uniform, gradually decreasing from the inside to the outside; the highest temperature of the inner layer is 1349℃, and the lowest temperature of the outer layer is 253℃; Fig. 7A The temperature of the hollow insulation tube is a curve isotherm, with high temperatures at the top and bottom, slightly lower temperatures in the middle, and gradually decreasing temperature differences from the inside to the outside. The highest temperature of the inner layer is 1346°C, the lowest temperature is 1023°C, and the lowest temperature of the outer layer is 216°C. This shows that due to the structure of the hollow insulation tube, the heat transferred out of the hollow insulation tube is less, and the temperatures of the inner and outer walls of the hollow are lower, so that more heat remains in the single crystal furnace. It can be seen that the result of the hollow insulation tube can not only reduce the weight of the insulation tube, reduce the proportion of raw materials, and reduce costs, but also significantly improve the insulation performance of the insulation tube, making the insulation tube of the single crystal furnace more energy-saving and environmentally friendly.

[0151] Table 1 below shows data information of Examples 1-9 and the comparative example. It can be seen from the table that the present application can obtain a preform with a cavity, and the volume of the cavity can reach 10-90%, thereby effectively reducing the amount of raw materials used and reducing costs. For the insulation tube, the hollow insulation tube can further improve its insulation performance.

[0152] Table 1 Data information of Examples 1-9 and Comparative Example 1

[0153]

[0154]

[0155] Although the embodiments of the present application are described above, the present application is not limited to the above specific embodiments and application fields, and the above specific embodiments are merely illustrative and instructive, rather than restrictive. A person of ordinary skill in the art can make many forms under the guidance of this specification and without departing from the scope of protection of the claims of the present application, all of which belong to the protection of the present application.

Claims

1. A preform, characterized in that: They include the following in order: Preform lower layer; a preform middle layer having a sacrificial layer; Prefabricated upper layer, The lower layer of the preform is formed by laminating carbon cloth and carbon fiber mesh and / or preoxidized wire mesh; The upper layer of the preform is formed by laminating carbon cloth and carbon fiber mesh tire and / or preoxidized wire mesh tire; The middle layer of the preform is formed by laminating a sacrificial layer, a carbon cloth and a carbon fiber mesh and / or a preoxidized wire mesh.

2. The preform according to claim 1, wherein: The thickness of the lower layer of the preform is 3mm-30mm; The thickness of the middle layer of the preform is 3mm-40mm; The thickness of the upper layer of the preform is 3mm-30mm.

3. The preform according to claim 2, wherein: The thickness of the lower layer of the preform is 3mm-20mm.

4. The preform according to claim 2, wherein: The thickness of the lower layer of the preform is 5mm-15mm.

5. The preform according to claim 2, wherein: The thickness of the middle layer of the preform is 3mm-35mm.

6. The preform according to claim 2, wherein: The thickness of the middle layer of the preform is 10mm-20mm.

7. The preform according to claim 2, wherein: The thickness of the upper layer of the preform is 3mm-20mm.

8. The preform according to claim 2, wherein: The thickness of the upper layer of the preform is 5mm-15mm.

9. The preform according to claim 2, wherein: The sacrificial layer accounts for 10%-90% of the total volume of the preform.

10. The preform according to claim 2, wherein: The sacrificial layer accounts for 30%-60% of the total volume of the preform.

11. The preform according to claim 1, wherein: The middle layer includes a peripheral structure and ribs, wherein the ribs divide the peripheral structure into a plurality of sub-cavities, the sacrificial layer is located in the sub-cavities, and the peripheral structure and ribs are formed by stacking carbon cloth and carbon fiber mesh and / or pre-oxidized wire mesh.

12. The preform according to any one of claims 1 to 11, wherein: The preform lower layer, the preform middle layer and the preform upper layer are layer structures with millimeter-level pores.

13. The preform according to claim 12, wherein: The pores of the preform lower layer, the preform middle layer and the preform upper layer are ≤3 mm.

14. The preform according to claim 12, wherein: The pores of the preform lower layer, the preform middle layer and the preform upper layer are 50 μm-3 mm.

15. The preform according to claim 12, wherein: The density of the preform is 0.3-0.9 g / cm 3 .

16. A carbon-carbon product, characterized in that: It includes the following layers in order: Lower level; a middle layer with a cavity; upper layer, The lower layer is formed by laminating carbon cloth and carbon fiber mesh tire and / or pre-oxidized wire mesh tire; The upper layer is formed by laminating carbon cloth and carbon fiber mesh tire and / or pre-oxidized wire mesh tire; The middle layer is formed by laminating carbon cloth and carbon fiber mesh tire and / or pre-oxidized wire mesh tire.

17. The carbon-carbon product according to claim 16, wherein: The thickness of the lower layer is 3mm-30mm; The thickness of the middle layer is 3mm-40mm; The thickness of the upper layer is 3mm-30mm.

18. The carbon-carbon product according to claim 17, wherein: The thickness of the lower layer is 3mm-20mm.

19. The carbon-carbon product according to claim 17, wherein: The thickness of the lower layer is 5mm-15mm.

20. The carbon-carbon product according to claim 17, wherein: The thickness of the middle layer is 3mm-35mm.

21. The carbon-carbon product according to claim 17, wherein: The thickness of the middle layer is 10mm-20mm.

22. The carbon-carbon product according to claim 17, wherein: The thickness of the upper layer is 3mm-20mm.

23. The carbon-carbon product according to claim 17, wherein: The thickness of the upper layer is 5mm-15mm.

24. The carbon-carbon product according to claim 17, wherein: The cavity accounts for 10%-90% of the total volume of the carbon-carbon product.

25. The carbon-carbon product according to claim 17, wherein: The cavity accounts for 30%-60% of the total volume of the carbon-carbon product.

26. The carbon-carbon product according to claim 16, wherein: The cavity of the middle layer having the cavity is further divided into a plurality of sub-cavities by ribs, wherein the ribs are formed by stacking carbon cloth and carbon fiber mesh and / or pre-oxidized wire mesh.

27. The carbon-carbon product according to claim 16, wherein: The lower layer, the middle layer and the upper layer are layer structures with millimeter-scale pores.

28. The carbon-carbon product according to claim 16, wherein: The pores of the lower layer, the middle layer and the upper layer are ≤3mm.

29. The carbon-carbon product according to claim 16, wherein: The pores of the lower layer, the middle layer and the upper layer are 50 μm-3 mm.

30. The carbon-carbon product according to claim 16, wherein: The density of the carbon-carbon product is 0.3-0.9 g / cm 3 .

31. The carbon-carbon product according to claim 16, wherein: The carbon-carbon product is in the shape of a flat plate, a hollow cylinder, a hollow cone or a hollow rotating body.

32. A heat preservation cylinder for a single crystal furnace, characterized in that: It includes: Carbon felt and the carbon-carbon product according to any one of claims 16 to 31; wherein, The carbon felt is laminated on one side or both sides of the carbon-carbon product.

33. The heat preservation cylinder according to claim 32, wherein: The density of the carbon-carbon product is 1.0-1.6 g / cm 3 .

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