Carbon / carbon boat body and preparation method

Abstract

The invention discloses a carbon / carbon boat body and a preparation method, the carbon / carbon boat body comprises at least one core layer and a plurality of short fiber reinforcement layers, and the short fiber reinforcement layers are stacked on the surfaces of the two sides of the at least one core layer; the core layer comprises a first reinforced fiber main body layer and matrix carbon distributed in the first reinforced fiber main body layer; the short fiber reinforced layer comprises a second reinforced fiber main body layer and matrix carbon distributed in the second reinforced fiber main body layer, and the second reinforced fiber main body layer comprises short carbon fiber broken filaments distributed in an in-plane staggered mode. In the multi-layer composite structure, the core layer can reinforce the overall strength, the short carbon fiber broken filaments which are in fine filament-shaped mutual loose lap joint arrangement in the short fiber reinforcement layer are uniformly distributed, the space between the short carbon fiber broken filaments is conveniently filled with matrix carbon, and the surface of a single fiber of the short carbon fiber broken filaments is coated with the matrix carbon; the distribution uniformity of fibers and matrix carbon is improved, the conductive uniformity is improved, and the surface smoothness and the finish machining performance can be improved.

Description

Technical Field

[0001] The present application relates to the technical field of composite materials for vacuum coating, and in particular to a carbon / carbon boat and a preparation method thereof. Background Art

[0002] Solar cell coating, plasma-enhanced chemical vapor deposition (PECVD), and high-temperature sintering processes require a boat as a carrier to secure and transport the silicon wafers, ensuring stable formation in high-temperature environments. For example, in the photovoltaic PECVD process, the boat's primary functions include: 1) supporting the silicon wafers: stably supporting the wafers in the high-temperature plasma environment; 2) providing uniform heat transfer: ensuring uniform heating of the wafers to avoid efficiency losses caused by uneven coating; and 3) providing a uniform electric field: applying opposite alternating voltages to two opposing boats to generate a glow discharge and complete the coating. Therefore, the boat must possess excellent high-temperature strength, corrosion resistance, and low contamination properties, as well as good and uniform electrical conductivity. Failure to do so would affect plasma distribution and, consequently, coating uniformity. Furthermore, the boat must be highly machinable and require high precision to ensure a perfect match with the equipment.

[0003] Currently, graphite, especially isostatically pressed graphite, is mostly used as the base material of the boat body on the market. However, the strength of the graphite boat is relatively low. When the thin boat sheets are assembled into the boat body structure, the strength is low. The material is easily damaged during transportation and cleaning, and the service life is short. In addition, with the increase in the number of uses, the inner wall of the graphite boat and the edge of the contact with the silicon wafer wear and become thinner, resulting in uneven conductivity on the surface of the graphite boat, affecting the uniformity of the coating. Moreover, with the development of solar photovoltaic cells, in order to meet the needs of 210mm silicon wafers and thin slices not exceeding 130um, one of the development trends of the boat body is also large size and thinness, requiring the boat body to have higher strength and lower density, but the graphite boat has been unable to meet the development needs of the industry.

[0004] Compared with graphite materials, carbon / carbon composite materials have the advantages of low density, high strength and specific modulus, high thermal shock resistance, high dimensional stability, corrosion resistance and good wear resistance. At the same time, they have good thermal conductivity and electrical conductivity. As a boat material, it can greatly improve its service life and reduce high-temperature bending deformation, fracture damage and wear.

[0005] However, conventional carbon / carbon composite sheets are primarily constructed by needle-punching carbon fibers to obtain a preform, followed by densification of the matrix carbon to create a 2.5D structure, or by densifying carbon fiber cloth prepregs through lamination. Needled preforms, due to their distinct fiber structures—carbon fiber cloth and carbon fiber mesh—exist in numerous pores of varying sizes. During the densification process, the surface pores tend to fill first, making it difficult to densely fill the small pores within. This leads to poor density uniformity, poor electrical conductivity, and poor performance uniformity. Furthermore, the sheet is prone to bending and deformation during long-term use. While the 2D carbon cloth laminates offer high tensile strength, they contain a large number of sized carbon fiber tows within the carbon cloth layers, creating very small interstices within the tows. This makes it difficult for the matrix carbon precursor to fully impregnate and fill the individual fibers within the tows, resulting in poor fiber / matrix interface bonding within the tows. This can lead to small fiber fuzz and holes on the surface of the sheet after processing into the boat, and the machining accuracy falls short of the boat's performance requirements. Summary of the Invention

[0006] In response to the problems existing in the above-mentioned prior art, the present application provides a carbon / carbon boat and a preparation method thereof, and the technical solution is as follows: In one aspect, the present application provides a carbon / carbon boat body, comprising at least one core layer and multiple short fiber reinforcement layers, wherein the short fiber reinforcement layers are stacked on both side surfaces of the at least one core layer; The core layer includes a first reinforcing fiber main body layer and matrix carbon distributed in the first reinforcing fiber main body layer; The short fiber reinforcement layer includes a second reinforcement fiber main body layer and matrix carbon distributed in the second reinforcement fiber main body layer, and the second reinforcement fiber main body layer includes short carbon fiber filaments staggeredly distributed in a plane.

[0007] Furthermore, the multi-layer staple fiber reinforcement layer includes at least one first reinforcement layer and at least one second reinforcement layer, and the at least one first reinforcement layer is located between the at least one core layer and the at least one second reinforcement layer; The first reinforcement layer further includes a conductive carbon matrix distributed in the second reinforcement fiber main layer.

[0008] Further, the conductive carbon matrix includes graphite; In the first reinforcement layer, the mass ratio between the conductive carbon matrix and the second reinforcement fiber main layer is 4:100 to 30:100.

[0009] Furthermore, the carbon / carbon boat satisfies at least one of the following characteristics: The density of the first reinforcing fiber main layer in the core layer is 0.5 g / cm 3 ~1.0g / cm 3 ; The density of the second reinforcing fiber main layer in the short fiber reinforcement layer is 0.4g / cm 3 ~0.9g / cm 3 .

[0010] Furthermore, the carbon / carbon boat body further includes a wear-resistant coating, which covers a surface of the multi-layer short fiber reinforced layer on a side facing away from the core layer, and the material of the wear-resistant coating includes silicon carbide.

[0011] Furthermore, the carbon / carbon boat satisfies at least one of the following characteristics: The density of the carbon / carbon boat is greater than or equal to the preset density, and the preset density is 1.2 g / cm 3 ~2.0g / cm 3 ; The bending strength of the carbon / carbon boat is greater than or equal to a preset bending strength, and the preset bending strength is 120 MPa to 200 MPa; The Shore hardness of the carbon / carbon boat is greater than or equal to a preset Shore hardness, and the preset Shore hardness is 70HSD to 100HSD; The open porosity of the carbon / carbon boat is less than or equal to a preset open porosity, and the preset open porosity is 1.0% to 2.0%.

[0012] On the other hand, the present application also provides a method for preparing a carbon / carbon boat, comprising: The short fiber reinforcement layer prepreg is stacked on both sides of at least one core layer prepreg and hot-pressed to obtain a stacked structure; the core layer prepreg includes a first reinforcing fiber main layer and a phenolic resin distributed in the first reinforcing fiber main layer; the short fiber reinforcement layer prepreg includes a second reinforcing fiber main layer and a phenolic resin distributed in the second reinforcing fiber main layer, and the second reinforcing fiber main layer includes short carbon fiber filaments staggered in the plane; The stacked structure is carbonized to obtain a carbonized embryo; during the carbonization process, the phenolic resins of the core layer prepreg and the short fiber reinforcement layer prepreg undergo a carbonization reaction to generate matrix carbon; The carbonized embryo body is post-processed to obtain a carbon / carbon boat body; the carbon / carbon boat body comprises at least one core layer and multiple short fiber reinforcement layers stacked on both side surfaces of the at least one core layer.

[0013] Furthermore, the multi-layer short fiber reinforced layer includes at least one first reinforcement layer and at least one second reinforcement layer, and the short fiber reinforced layer prepreg includes a first reinforcement layer prepreg and a second reinforcement layer prepreg; the short fiber reinforced layer prepreg is prepared by the following steps: Dispersing the short carbon fiber filaments, the conductive carbon matrix, and the phenolic resin in deionized water to obtain a first composite solution, and dispersing the short carbon fiber filaments and the phenolic resin in deionized water to obtain a second composite solution; filtering the first composite solution and the second composite solution respectively to obtain a first fiber layer and a second fiber layer; The first fiber layer and the second fiber layer are respectively immersed in a phenolic resin solution, filtered and dried to obtain the first reinforcement layer prepreg and the second reinforcement layer prepreg.

[0014] Furthermore, the preparation steps of the short fiber reinforced layer prepreg meet at least one of the following characteristics: The particle size of the conductive carbon matrix is less than or equal to a preset particle size, and the preset particle size is 15 μm to 30 μm; In the first composite solution and the second composite solution, the mass ratio of the short carbon fiber filaments to the deionized water is 1:10 to 1:100, and the mass ratio of the phenolic resin to the deionized water is 1:4 to 1:50; The first composite solution and the second composite solution each further include a dispersant, and the mass ratio of the dispersant to the deionized water is 1:50 to 1:250; The thickness of each of the first fiber layer and the second fiber layer is 0.5 mm to 8 mm; The fiber surface density of each of the first fiber layer and the second fiber layer is 30 g / m 2 ~250g / m 2 ; The viscosity of the phenolic resin solution is 300 mPa·s to 2000 mPa·s.

[0015] Furthermore, the short carbon fiber filaments are obtained by the following steps: heat-treating the carbon fiber bundle to obtain desized carbon fiber; The desized carbon fibers are dispersed by air flow to obtain the short carbon fiber filaments; the length of the short carbon fiber filaments is 20 mm to 70 mm.

[0016] Furthermore, the core layer prepreg is obtained by the following steps: A phenolic resin solution is coated on the surface of the first reinforcing fiber main layer and dried to obtain the core layer prepreg; the drying temperature is 60° C. to 90° C. and the drying time is 1 hour to 3 hours.

[0017] Furthermore, after the carbonized embryo is post-processed to obtain a carbon / carbon boat, the method further comprises: A wear-resistant coating is formed on the surface of the carbon / carbon boat; the material of the wear-resistant coating includes silicon carbide.

[0018] Furthermore, the post-processing of the carbonized embryo to obtain a carbon / carbon boat comprises: performing a densification process on the carbonized embryo to obtain a densified carbonized embryo; Purifying the densified carbonized embryo at 2000° C. to 2400° C. to obtain a purified carbonized embryo; The purified carbonized embryo body is machined to obtain the carbon / carbon boat.

[0019] The implementation of this application has the following beneficial effects: The carbon / carbon boat of the present application adopts a multi-layer composite structure, in which the core layer is based on the first reinforcing fiber main layer to strengthen the overall strength of the carbon / carbon boat. The short carbon fiber filaments in the short fiber reinforcement layer are evenly distributed in the form of fine filaments and loosely overlapped with each other, which is convenient for the matrix carbon to be filled between the short carbon fiber filaments and the surface of the single fiber of the short carbon fiber filaments. It is also convenient for the matrix carbon to pass through the short fiber reinforcement layer of the surface layer and be filled into the first reinforcing fiber main layer of the core layer. This not only improves the uniformity of the distribution of fibers and matrix carbon in the entire carbon / carbon boat, which is beneficial to improving the uniformity of the conductivity of the carbon / carbon boat, but also can improve the surface finish and finishing performance of the carbon / carbon boat. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] To more clearly illustrate the technical solution of this application, the following is a brief introduction to the drawings used in the embodiments, wherein identical components are denoted by identical reference numerals. Obviously, the drawings described below are merely some embodiments of this application, and those skilled in the art can derive other drawings based on these drawings without inventive effort.

[0021] Figure 1 A schematic structural diagram of a carbon / carbon boat provided in an embodiment of the present application; Figure 2 A logic diagram of a method for preparing a carbon / carbon boat provided in an embodiment of the present application; Figure 3 A logic diagram of a method for preparing short carbon fiber filaments provided in an embodiment of the present application; Figure 4 A logic diagram of a method for preparing a short fiber reinforced layer prepreg provided in an embodiment of the present application; Figure 5 A logic diagram of a method for preparing a core layer prepreg provided in an embodiment of the present application; Figure 6 A logic diagram of a post-processing method provided in an embodiment of the present application; Figure 7 A logic diagram of a method for preparing a wear-resistant coating provided in an embodiment of the present application.

[0022] Wherein, the reference numerals correspond to: 1-core layer, 2-first reinforcement layer, 3-second reinforcement layer, 4-wear-resistant coating. DETAILED DESCRIPTION

[0023] The following will be combined with the drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are only part of the embodiments of this application, not all of the embodiments, and therefore should not be understood as limiting this application. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0024] It should be noted that in the description of this application, for the following defined terms, these definitions should be applied unless a different definition is given in the claims or elsewhere in this specification. All numerical values, whether or not explicitly indicated, are defined herein as being modified by the term "about". The term "about" generally refers to a numerical range that a person of ordinary skill in the art would consider to be equivalent to the stated value to produce substantially the same properties, functions, results, etc. A numerical range indicated by a low value and a high value is defined to include all numerical values included in the numerical range and all subranges included in the numerical range.

[0025] It should be noted that the terms "first", "second", etc. in the specification, claims, and drawings of the present application are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequential order. It should be understood that the objects used in this way can be interchangeable where appropriate, so that the embodiments of the present application can be implemented in a sequence other than the following diagrams or the following descriptions. In addition, the terms "including" and "having" and any of their variations are intended to cover non-exclusive inclusions, for example, a process, method, system, or product comprising a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or that are inherent to these processes, methods, or products.

[0026] It should be understood that when an element or layer is referred to as being "on," "adjacent to," "connected to," or "coupled to" another element or layer, it may be directly on, adjacent to, connected to, or coupled to the other element or layer, or there may be intervening elements or layers. Conversely, when an element is referred to as being "directly on," "directly adjacent to," "directly connected to," or "directly coupled to" another element or layer, there may be no intervening elements or layers. It should be understood that although the terms first, second, third, etc. may be used to describe various elements, components, regions, layers, and / or parts, these elements, components, regions, layers, and / or parts should not be limited by these terms. These terms are merely used to distinguish one element, component, region, layer, or part from another element, component, region, layer, or part. Therefore, without departing from the teachings of the present application, the first element, component, region, layer, or part discussed below may be represented as a second element, component, region, layer, or part. And when the second element, component, region, layer, or part is discussed, it does not necessarily mean that the first element, component, region, layer, or part is present in the present application.

[0027] The graphite boat components currently used in the PECVD process for photovoltaic cells have relatively low strength, wear resistance, and corrosion resistance, resulting in a short service life and significant degradation in coating performance. This makes it increasingly difficult to meet the demand for larger and thinner photovoltaic crystalline silicon cells. Carbon / carbon composites, as carbon fiber-reinforced carbon matrix composites, offer excellent specific strength, high-temperature strength, and superior corrosion and wear resistance, and have become an alternative to graphite materials in many high-temperature applications. However, traditional carbon / carbon composite materials are mainly composed of two types of composite materials: a 2.5D structure obtained by obtaining a preform by needling carbon fibers and then densifying the matrix carbon; and a 2D structure obtained by stacking and densifying carbon fiber cloth prepregs. Both use reinforcing fibers that contain a large number of large carbon fiber bundles. The gaps inside the bundles are very small, and it is difficult for the precursor of the matrix carbon to completely impregnate and fill in the surface of the single fiber inside the large bundle, resulting in insufficient bonding between the fiber / matrix interface within the large bundle. After the surface of the plate is processed into a boat sheet, small fiber filaments and small holes are prone to appear, resulting in the uniformity and precision processing performance failing to meet the performance requirements of the boat body. At present, it cannot replace the graphite boat and cannot meet the development needs of photovoltaic cells.

[0028] In response to the above technical problems, an embodiment of the present application provides a carbon / carbon boat and a preparation method. The preparation method of the carbon / carbon boat is used to prepare the carbon / carbon boat. The carbon / carbon boat adopts a multi-layer composite structure. While enhancing the overall strength of the carbon / carbon boat, it not only improves the distribution uniformity and conductivity uniformity of the fiber and matrix carbon in the entire carbon / carbon boat, but also improves the surface finish and finishing performance of the carbon / carbon boat, meeting the development needs of solar monocrystalline silicon, polycrystalline silicon cell coating, plasma enhanced chemical vapor deposition (PECVD) and high-temperature sintering processes.

[0029] The following is in conjunction with the instructions Figure 1 The carbon / carbon boat of the embodiment of the present application is introduced in detail.

[0030] like Figure 1 As shown, the carbon / carbon boat body includes at least one core layer 1 and multiple short fiber reinforcement layers, and the short fiber reinforcement layers are stacked on the two side surfaces of the at least one core layer 1 to form a multi-layer composite structure; wherein the core layer 1 includes a first reinforcing fiber main layer and a matrix carbon distributed in the first reinforcing fiber main layer, and the first reinforcing fiber main layer includes carbon fiber cloth; the short fiber reinforcement layer includes a second reinforcing fiber main layer and a matrix carbon distributed in the second reinforcing fiber main layer, and the second reinforcing fiber main layer includes short carbon fiber filaments staggered in the plane, and the short carbon fiber filaments are fine filaments, and the short carbon fiber filaments can be randomly overlapped in the plane to form a small wire mesh, and overlapped with each other to form a mesh overlap structure.

[0031] The length of the short carbon fiber filaments is 20mm to 70mm; it can be understood that the length of the short carbon fiber filaments can be any point value between 20mm and 70mm; for example, the length of the short carbon fiber filaments can be 20mm, 25mm, 30mm, 40mm, 50mm, 55mm, 60mm, 70mm, etc.; within this length range, compared with the large carbon fiber tows in the traditional process, the short carbon fiber filaments are dispersed into loosely overlapped small wire meshes with relatively small size, which facilitates the uniform distribution of matrix carbon in the short carbon fiber filaments and wraps the surface of the fiber monofilament to form a good fiber / matrix carbon interface, improve the surface finish and finishing performance, and also improve the distribution uniformity of the short carbon fiber filaments themselves and the matrix carbon, which is beneficial to improving the mechanical properties, electrical conductivity and electrical uniformity of the short fiber reinforcement layer and the carbon / carbon boat.

[0032] In the multi-layer composite structure of the carbon / carbon boat, a carbon / carbon composite material including carbon fiber cloth, matrix carbon, short carbon fiber filaments, etc. is used as the embryonic material of the carbon / carbon boat, which can effectively improve the specific strength, high temperature strength, corrosion resistance and wear resistance of the carbon / carbon boat; wherein, the carbon fiber cloth as the main fiber reinforcement material of the core layer 1 can effectively strengthen the mechanical strength of the core layer 1 and the carbon / carbon boat as a whole; the short fiber reinforcement layer is located on the outside of the core layer 1, that is, the edge of the carbon / carbon boat adopts loose short carbon fiber filaments that are staggered and randomly arranged in the plane. Compared with the traditional carbon fiber tows that are completely dispersed, the dispersed short carbon fiber filaments have good distribution uniformity, which is also convenient for the matrix carbon The filling is wrapped around the surface of the fiber monofilament to strengthen the interface strength between the fiber / matrix carbon, greatly improving the surface smoothness and finishing performance of the short fiber reinforced layer and the carbon / carbon boat as a whole; moreover, the distribution uniformity of the reinforcing fibers and matrix carbon in the entire plane direction of the short fiber reinforced layer can also be greatly improved, which is beneficial to improving the electrical conductivity uniformity, thermal conductivity uniformity and electrical conductivity of the short fiber reinforced layer and the carbon / carbon boat as a whole, thereby greatly improving the performance of the boat and boat assembly in processes such as photovoltaic PECVD, extending the service life, and meeting the development needs of processes such as solar monocrystalline silicon, polycrystalline silicon cell coating, plasma enhanced chemical vapor deposition and high-temperature sintering.

[0033] Specifically, if Figure 1 As shown, the multi-layer short fiber reinforcement layer includes at least one first reinforcement layer 2 and at least one second reinforcement layer 3, and the at least one first reinforcement layer 2 is located between the at least one core layer 1 and the at least one second reinforcement layer 3; the first reinforcement layer 2 also includes a conductive carbon matrix, and the conductive carbon matrix is distributed in the second reinforcement fiber main layer. The conductive carbon matrix can effectively improve the conductivity of the first reinforcement layer 2 and the carbon / carbon boat, and in the preparation process of the carbon / carbon boat, the addition of the conductive carbon matrix can improve the coating efficiency and the initial density of the carbon / carbon boat, and reduce the cycle of the densification treatment in the preparation process; and the conductive carbon matrix is not added to the second reinforcement layer 3 located in the outer layer to avoid the possible decrease in wear resistance of the surface of the second reinforcement layer 3 due to the introduction of the conductive carbon matrix.

[0034] In some exemplary embodiments, multiple layers of staple fiber reinforcement layers are distributed on the same side surface of the core layer 1, and the single-sided multi-layer staple fiber reinforcement layer includes at least one first reinforcement layer 2 and at least one second reinforcement layer 3; optionally, a first reinforcement layer 2 and a second reinforcement layer 3 are distributed on the same side surface of the core layer 1, and the first reinforcement layer 2 is located between the core layer 1 and the second reinforcement layer 3; also optionally, the single-sided multi-layer staple fiber reinforcement layer includes multiple layers of first reinforcement layers 2 and multiple layers of second reinforcement layers 3, and the multiple layers of second reinforcement layers 3 are located as a whole on the outside of the multiple layers of first reinforcement layers as a whole, that is, the surface of a layer of second reinforcement layers 3 close to the core layer 1 in the multiple layers of second reinforcement layers 3 close to the core layer 1 is stacked on the surface of a layer of first reinforcement layers 2 far away from the core layer 1 in the multiple layers of first reinforcement layers 2 far away from the core layer 1

[0035] Specifically, if Figure 1 As shown, in some exemplary embodiments, the multi-layer staple fiber reinforcement layer includes at least two layers of first reinforcement layers 2 and at least two layers of second reinforcement layers 3, and the multi-layer staple fiber reinforcement layer is symmetrically arranged on the two side surfaces of the core layer 1; for example, the multi-layer staple fiber reinforcement layer includes two layers of first reinforcement layers 2 and two layers of second reinforcement layers 3, and on each side surface of the core layer 1, a layer of first reinforcement layer 2 and a layer of second reinforcement layer 3 are distributed outward from the core layer 1.

[0036] In other exemplary embodiments, multiple layers of staple fiber reinforcement layers are asymmetrically arranged on both side surfaces of the core layer 1; for example, on one side surface of the core layer 1, a first reinforcement layer 2 and a second reinforcement layer 3 are distributed outward from the core layer 1, and on the other side surface of the core layer 1, a first reinforcement layer 2, a second first reinforcement layer 2, a second reinforcement layer 3 and a second second reinforcement layer 3 are distributed outward from the core layer 1.

[0037] The multi-layer composite structure of the carbon / carbon boat is arranged in such a way that the first reinforcement layer 2 is located outside the core layer 1 and the second reinforcement layer 3 is located outside the first reinforcement layer 2. The arrangement has good flexibility, can meet the different requirements of various different processes, and has good applicability.

[0038] Specifically, the conductive carbon matrix includes graphite, which has excellent conductivity and can effectively improve the conductivity of the carbon / carbon boat as a whole; in the first reinforcement layer 2, the mass ratio between the conductive carbon matrix and the second reinforcement fiber main layer is 4:100~30:100; it can be understood that in the first reinforcement layer 2, the mass ratio between the conductive carbon matrix and the second reinforcement fiber main layer can be any point value between 4:100 and 30:100; illustratively, in the first reinforcement layer 2, the mass ratio between the conductive carbon matrix and the second reinforcement fiber main layer can be 4:100, 10:100, 17.5:100, 4:100, 20:100, 25:100, 30:100, etc.; within this mass ratio range, the conductivity of the first reinforcement layer 2 and the carbon / carbon boat as a whole can be effectively improved, the coating efficiency can be improved, and the initial density can be increased to reduce the densification treatment cycle.

[0039] Specifically, the density of the first reinforcing fiber main layer in the core layer 1 is 0.5 g / cm 3 ~1.0g / cm 3 It can be understood that the density of the first reinforcing fiber main layer in the core layer 1 can be 0.5g / cm 3 ~1.0g / cm 3 For example, the density of the first reinforcing fiber main layer in the core layer 1 can be 0.5g / cm 3 , 0.6g / cm 3 , 0.7g / cm 3 , 0.75g / cm 3 , 0.8g / cm 3 , 0.9g / cm 3 , 1.0g / cm 3 In this way, the density of the first reinforcing fiber main layer in the core layer 1 is relatively high, that is, the content of the carbon fiber cloth in the core layer 1 is high and evenly distributed, which can significantly enhance the mechanical properties of the core layer 1 and the carbon / carbon boat as a whole; at the same time, the electrical conductivity of the carbon fiber cloth is significantly higher than that of the matrix carbon, and the higher density of the first reinforcing fiber main layer can also improve the electrical conductivity and electrical uniformity.

[0040] Specifically, the density of the second reinforcing fiber main layer in the short fiber reinforcement layer is 0.4 g / cm 3 ~0.9g / cm 3 It can be understood that the density of the second reinforcing fiber main layer in the short fiber reinforcement layer can be 0.4g / cm 3 ~0.9g / cm 3 For example, the density of the second reinforcing fiber main layer in the short fiber reinforcement layer can be 0.4g / cm 3 , 0.5g / cm 3 , 0.6g / cm3 , 0.7g / cm 3 , 0.75g / cm 3 , 0.8g / cm 3 , 0.9g / cm 3 etc.; in this way, the density of the second reinforcing fiber main layer in the short fiber reinforcement layer is higher, and accordingly, the content of short carbon fiber filaments in the short fiber reinforcement layer is higher, which can significantly enhance the mechanical properties of the short fiber reinforcement layer and the carbon / carbon boat as a whole; at the same time, the electrical conductivity of the short carbon fiber filaments is higher than that of the matrix carbon, and the high content of short carbon fiber filaments can also improve the electrical conductivity and electrical uniformity.

[0041] The overall density of the first reinforcing fiber main layer and the second reinforcing fiber main layer in the carbon / carbon boat is relatively high. Correspondingly, the content of carbon fibers including carbon fiber cloth and short carbon fiber filaments in the carbon / carbon boat is relatively high, which can not only significantly improve the overall strength of the carbon / carbon boat, but also improve the overall conductivity and uniformity of the carbon / carbon boat, which is beneficial to improving the coating efficiency and coating effect.

[0042] Specifically, if Figure 1 As shown, the carbon / carbon boat also includes a wear-resistant coating 4, which covers the surface of the multi-layer short fiber reinforcement layer facing away from the core layer 1. The material of the wear-resistant coating 4 includes silicon carbide. The wear-resistant coating 4 can effectively improve the surface properties of the carbon / carbon boat, such as the smoothness and hardness, and further enhance the wear resistance of the carbon / carbon boat, prevent contact wear and slag and powder falling on the surface of the carbon / carbon boat, and reduce volatile matter pollution between the surface of the carbon / carbon boat and the silicon wafer, significantly reduce the performance degradation of the carbon / carbon boat during use, and greatly extend the service life of the carbon / carbon boat.

[0043] Specifically, the thickness of the wear-resistant coating 4 is 5μm to 150μm; it can be understood that the thickness of the wear-resistant coating 4 can be any point value between 5μm and 150μm; illustratively, the thickness of the wear-resistant coating 4 can be 5μm, 10μm, 25μm, 50μm, 75μm, 100μm, 125μm, 150μm, etc.; within this thickness range, the wear-resistant coating 4 can effectively cover the surface of the second reinforcement layer 3 away from the core layer 1, prevent uneven surface quality caused by local coating loss, and improve surface smoothness and hardness, enhance wear resistance, reduce performance degradation of the carbon / carbon boat during use, and extend service life.

[0044] The carbon / carbon boat as a whole is a carbon / carbon composite material, including matrix carbon formed by a precursor (phenolic resin) of matrix carbon, carbon fiber cloth of the first reinforcing fiber main layer, short carbon fiber filaments of the second reinforcing fiber main layer, matrix carbon added during the densification process of the subsequent preparation method, and graphite conductive carbon matrix in the second reinforcing layer 3, which can significantly improve the overall mechanical properties and wear resistance of the carbon / carbon boat. Among them, the short carbon fiber filaments facilitate the filling of matrix carbon and are wrapped on the surface of the carbon fiber monofilament to strengthen the fiber / matrix carbon interface, which is beneficial to improving the distribution uniformity of carbon fiber and matrix carbon in the carbon / carbon boat, improving the surface smoothness and finishing performance, and the overall density of carbon fiber in the carbon / carbon boat is relatively high, which can greatly improve the conductivity and conductivity uniformity. Combined with the silicon carbide wear-resistant coating 4 on the surface, the surface smoothness and hardness of the carbon / carbon boat can be further improved, which is beneficial to further improve the wear resistance of the carbon / carbon boat and greatly extend the service life of the carbon / carbon boat.

[0045] Specifically, the density of the carbon / carbon boat is greater than or equal to the preset density, which is 1.2 g / cm 3 ~2.0g / cm 3 ; It can be understood that the preset density can be 1.2g / cm 3 ~2.0g / cm 3 For example, the preset density can be 1.2 g / cm 3 , 1.3g / cm 3 , 1.4g / cm 3 , 1.5g / cm 3 , 1.6g / cm 3 , 1.75g / cm 3 , 1.8g / cm 3 , 2.0g / cm 3 etc.; within this density range, the mechanical properties and electrical conductivity of the carbon / carbon boat can be effectively improved; for example, in some specific embodiments, the preset density is 1.5g / cm 3 , that is, the density of the carbon / carbon boat is greater than or equal to 1.5g / cm 3 .

[0046] Specifically, the bending strength of the carbon / carbon boat is greater than or equal to a preset bending strength, and the preset bending strength is 120 MPa to 200 MPa. It can be understood that the preset bending strength can be any point value between 120 MPa and 200 MPa. Exemplarily, the preset bending strength can be 120 MPa, 130 MPa, 140 MPa, 150 MPa, 160 MPa, 170 MPa, 180 MPa, 190 MPa, 200 MPa, etc. For example, in some specific embodiments, the preset bending strength is 155 MPa, that is, the bending strength of the carbon / carbon boat is greater than or equal to 155 MPa. In this way, the carbon / carbon boat can have good mechanical properties.

[0047] Specifically, the Shore hardness of the carbon / carbon boat is greater than or equal to the preset Shore hardness, and the preset Shore hardness is 70HSD~100HSD; it can be understood that the preset Shore hardness can be any point value between 70HSD and 100HSD; illustratively, the preset Shore hardness can be 70HSD, 75HSD, 80HSD, 85HSD, 90HSD, 95HSD, 100HSD, etc.; within the preset Shore hardness range, the carbon / carbon boat has a high hardness, which can effectively improve the wear resistance and extend the service life; for example, in some specific embodiments, the preset Shore hardness is 75HSD, that is, the Shore hardness of the carbon / carbon boat is greater than or equal to 75HSD.

[0048] Specifically, the porosity of the carbon / carbon boat is less than or equal to the preset porosity, and the preset porosity is 1.0% to 2.0%; it can be understood that the preset porosity can be any point value between 1.0% and 2.0%; illustratively, the preset porosity can be 1.0%, 1.2%, 1.25%, 1.4%, 1.5%, 1.75%, 2.0%, etc.; in this way, the porosity of the carbon / carbon boat is relatively small, which can effectively improve the density and mechanical properties of the carbon / carbon boat, and is also beneficial to the enhancement of the heat resistance of the carbon / carbon boat, greatly extending the service life of the carbon / carbon boat; for example, in some specific embodiments, the preset porosity is 1.5%, that is, the porosity of the carbon / carbon boat is less than or equal to 1.5%.

[0049] During use, the carbon / carbon boat can be assembled into a boat group with spacers, ceramic rods and carbon fasteners. The silicon wafer is inserted in the gap between two adjacent carbon / carbon boats, opposite to the wear-resistant coating 4 on the outermost layer of the carbon / carbon boat, which can effectively reduce contact wear and volatile matter pollution, has high surface finish, good wear resistance, and greatly extends the service life; moreover, the carbon / carbon boat can be widely used in various vacuum coating processes, improves the uniformity of coating, and greatly slows down the attenuation of coating performance, and has good applicability.

[0050] The following is in conjunction with the instructions Figure 2-7 The preparation method of the carbon / carbon boat in the embodiment of the present application is introduced in detail.

[0051] First, if Figure 2 As shown, the short fiber reinforcement layer prepreg is stacked on both sides of at least one layer of core layer prepreg, and hot pressing and curing are performed to obtain a stacked structure.

[0052] Among them, the core layer prepreg includes a first reinforcing fiber main layer and a phenolic resin distributed in the first reinforcing fiber main layer, and the core layer prepreg is used to finally form the core layer of the carbon / carbon boat after subsequent carbonization treatment and post-treatment; the short fiber reinforcement layer prepreg includes a second reinforcing fiber main layer and a phenolic resin distributed in the second reinforcing fiber main layer, and the second reinforcing fiber main layer includes short carbon fiber filaments staggered in the surface, and the short fiber reinforcement layer prepreg is used to finally form the short fiber reinforcement layer of the carbon / carbon boat after subsequent carbonization treatment and post-treatment; the phenolic resin in the core layer prepreg and the short fiber reinforcement layer prepreg serves as a precursor of the matrix carbon, and is used to undergo a carbonization reaction to generate matrix carbon during the subsequent carbonization treatment.

[0053] Specifically, if Figure 3 As shown, in some exemplary embodiments, the short carbon fiber filaments in the short fiber reinforcement layer prepreg are obtained by the following steps: heat-treating the carbon fiber bundle to obtain desized carbon fiber; The desized carbon fibers are dispersed by air flow to obtain the short carbon fiber filaments.

[0054] Among them, the heat treatment is used to desize the surface of the carbon fiber bundle, remove the sizing agent on the surface of the carbon fiber bundle, and then disperse the desized carbon fibers into loosely overlapped and disordered small wire meshes through airflow dispersion, so that the gaps in the carbon fiber bundle that were originally difficult to fill with liquid phase impregnation can be filled with phenolic resin (i.e., a precursor of matrix carbon), so that the subsequently formed matrix carbon is wrapped on the surface of the fiber monofilament to form a good fiber / matrix interface, improve the surface finish and finishing performance, and also improve the distribution uniformity of the short carbon fiber filaments themselves and the matrix carbon, and improve the mechanical properties, electrical conductivity uniformity and thermal conductivity uniformity of the carbon / carbon boat; in addition, in some exemplary embodiments, the carbon fiber bundle can be pre-dispersed by short cutting before heat treatment to improve the dispersion efficiency of the short carbon fiber filaments.

[0055] In some exemplary embodiments, the heat treatment atmosphere is an oxygen-free atmosphere, the temperature is 600°C to 1500°C, and the holding time is 1h to 5h; it can be understood that the temperature can be any point value between 600°C and 1500°C, and the holding time can be any point value between 1h and 5h; exemplarily, the temperature can be 600°C, 700°C, 800°C, 1000°C, 1250°C, 1500°C, etc., and the holding time can be 1h, 2h, 2.5h, 3h, 4h, 5h, etc.; within the range of heat treatment temperature and holding time, the carbon fiber bundles can be quickly and effectively broken up into disordered small, hairy short carbon fiber hairs, with high dispersion efficiency and good dispersion effect.

[0056] Specifically, the multi-layer short fiber reinforced layer includes at least one first reinforcement layer and at least one second reinforcement layer. Accordingly, the short fiber reinforced layer prepreg includes a first reinforcement layer prepreg and a second reinforcement layer prepreg. The first reinforcement layer prepreg is used to finally form a first reinforcement layer after subsequent carbonization treatment and post-processing, and the second reinforcement layer prepreg is used to finally form a second reinforcement layer after subsequent carbonization treatment and post-processing.

[0057] like Figure 4 As shown, the short fiber reinforced layer prepreg is prepared by the following steps: Dispersing the short carbon fiber filaments, the conductive carbon matrix, and the phenolic resin in deionized water to obtain a first composite solution, and dispersing the short carbon fiber filaments and the phenolic resin in deionized water to obtain a second composite solution; filtering the first composite solution and the second composite solution respectively to obtain a first fiber layer and a second fiber layer; The first fiber layer and the second fiber layer are respectively immersed in a phenolic resin solution, filtered and dried to obtain the first reinforcement layer prepreg and the second reinforcement layer prepreg.

[0058] Specifically, in the first composite solution and the second composite solution, the mass ratio of the short carbon fiber filaments to deionized water is 1:10 to 1:100; it can be understood that the mass ratio of the short carbon fiber filaments to deionized water can be any ratio between 1:10 and 1:100; illustratively, the mass ratio of the short carbon fiber filaments to deionized water can be 1:10, 1:20, 1:25, 1:30, 1:50, 1:75, 1:100, etc.; within this mass ratio range, the short carbon fiber filaments have good dispersibility, which is convenient for mixing with the phenolic resin, thereby improving the dispersion uniformity of themselves and the phenolic resin in the short carbon fiber filaments.

[0059] Specifically, in the first composite solution and the second composite solution, the phenolic resin is an aqueous phenolic resin, and the mass ratio of the phenolic resin to deionized water is 1:4 to 1:50; it can be understood that the mass ratio of the phenolic resin to deionized water can be any point value between 1:4 and 1:50; illustratively, the mass ratio of the phenolic resin to deionized water can be 1:4, 1:4, 1:4, 1:4, 1:4, 1:50, etc.; within this mass ratio range, the phenolic resin has good dispersibility and can be easily filled into the short carbon fiber filaments, facilitating the subsequent formation of a good fiber / matrix interface, improving the surface finish and finishing performance of the first reinforcement layer and the second reinforcement layer, and also improving the distribution uniformity, thermal conductivity uniformity and electrical conductivity uniformity of the fibers and carbon matrices in each layer.

[0060] Specifically, the first composite solution and the second composite solution each further include a dispersant, which includes one or more of hydroxypropyl methylcellulose, hydroxyethyl methylcellulose and polyethylene glycol, and has good dispersibility, which is beneficial to improving the dispersion efficiency and uniformity of the short carbon fiber filaments and phenolic resin.

[0061] Specifically, in the first composite solution and the second composite solution, the mass ratio of the dispersant to deionized water is 1:50 to 1:250; it can be understood that the mass ratio of the dispersant to deionized water can be any point value between 1:50 and 1:250; illustratively, the mass ratio of the dispersant to deionized water can be 1:50, 1:75, 1:100, 1:150, 1:200, 1:250, etc.; within this mass ratio range, the amount of dispersant added is small, the utilization rate is high, and the dispersibility of the short carbon fiber filaments and modified silicon carbide is good, which is beneficial to improving the subsequent dispersion uniformity of the short carbon fiber filaments, silicon carbide matrix and carbon matrix in the fiber layer.

[0062] Specifically, in the first composite solution, the particle size of the conductive carbon matrix is less than or equal to the preset particle size, and the preset particle size is 15μm to 30μm; it can be understood that the preset particle size can be any point value between 15μm and 30μm; illustratively, the preset particle size can be 15μm, 18μm, 20μm, 22μm, 25μm, 28μm, 30μm, etc.; in this way, the particle size of the conductive carbon matrix is small and can be quickly and evenly dispersed into the short carbon fiber filaments, thereby improving the distribution uniformity and conductivity uniformity of the conductive carbon matrix in the first reinforcement layer prepreg formed after subsequent filtration, thereby improving the coating efficiency; in addition, the addition of the conductive carbon matrix can also increase the initial density of the carbon / carbon boat, reduce the cycle of subsequent densification treatment, and improve preparation efficiency.

[0063] In some exemplary embodiments, the first composite solution and the second composite solution are filtered separately using a filter tank having a filtration hole at the bottom. The filter tank can be a trough-shaped container with a suitable size and shape, and the filtration hole is arranged at the bottom. The filtration hole has a mesh steel plate base. The first composite solution and the second composite solution are filtered separately to form a meshed first fiber layer and a second fiber layer, respectively. The first fiber layer is used to ultimately form a first reinforcement layer, and the second fiber layer is used to ultimately form a second reinforcement layer.

[0064] Specifically, the thickness of each of the first fiber layer and the second fiber layer is 0.5 mm to 8 mm; it can be understood that the thickness of each of the first fiber layer and the second fiber layer can be any point value between 0.5 mm and 8 mm; illustratively, the thickness of each of the first fiber layer and the second fiber layer can be 0.5 mm, 1 mm, 1.5 mm, 2 mm, 3 mm, 5 mm, 7 mm, 8 mm, etc.

[0065] Specifically, the fiber surface density of each of the first fiber layer and the second fiber layer is 30 g / m 2 ~250g / m 2 It can be understood that the fiber surface density of each of the first fiber layer and the second fiber layer can be 30g / m 2 ~250g / m 2 For example, the fiber surface density of each of the first fiber layer and the second fiber layer can be 30g / m 2 , 50g / m 2 , 75g / m 2 , 100g / m 2 , 150g / m 2 , 200g / m 2 , 250g / m 2 wait.

[0066] Thus, within the thickness range and the fiber surface density range, the first fiber layer and the second fiber layer are laid flat in a thin mesh layer, which is beneficial to increasing the fiber content, improving the structural strength of the final carbon / carbon boat, and having good mechanical properties.

[0067] In some exemplary embodiments, during the process of respectively immersing the first fiber layer and the second fiber layer in a phenolic resin solution, filtering and drying, the phenolic resin in the phenolic resin solution used may include one or more of PF8402, PF8218, PF9501, and boron phenolic modified resin. During the filtration process, the phenolic resin in the phenolic resin solution can be fully filled into the first fiber layer and the second fiber layer, especially into the short carbon fiber filaments, thereby greatly improving the dispersion uniformity.

[0068] Specifically, the viscosity of the phenolic resin solution is 300 MPa·s to 2000 MPa·s; it can be understood that the viscosity of the phenolic resin solution can be any point value between 300 MPa·s and 2000 MPa·s; illustratively, the viscosity of the phenolic resin solution can be 300 MPa·s, 400 MPa·s, 500 MPa·s, 800 MPa·s, 1000 MPa·s, 1500 MPa·s, 2000 MPa·s, etc.; within this viscosity range, the phenolic resin solution can effectively penetrate into the first fiber layer and the second fiber layer, fully infiltrate, increase the contact area between the phenolic resin and the short carbon fiber filaments, and increase the bonding tightness between the phenolic resin and the short carbon fiber filaments, thereby increasing the fiber / matrix interface bonding strength, which is convenient for the subsequent conversion of the phenolic resin into matrix carbon and then wrapping the fiber monofilament surface.

[0069] In addition, the phenolic resin solution includes an ethanol solvent, which has good solubility for the phenolic resin, is beneficial to improving the wetting efficiency and effect of the first fiber layer and the second fiber layer, and is also easy to remove during the drying process, reducing residues in the first reinforcement layer prepreg and the second reinforcement layer prepreg.

[0070] In some exemplary embodiments, after the first fiber layer and the second fiber layer are respectively immersed in the phenolic resin solution and filtered, the drying temperature in the drying process is 60°C to 90°C, and the time is 1h to 3h; it can be understood that the drying temperature can be any point value between 60°C and 90°C, and the time can be any point value between 1h and 3h; exemplarily, the drying temperature can be 60°C, 70°C, 75°C, 80°C, 90°C, etc.; the time can be 1h, 1.5h, 2h, 2.5h, 3h, etc.; within this drying temperature and time range, the solvent can be effectively eliminated and the purity of the first reinforcement layer prepreg and the second reinforcement layer prepreg can be improved.

[0071] Specifically, in some exemplary embodiments, Figure 5 As shown, the core layer prepreg is obtained by the following steps: A phenolic resin solution is coated on the surface of the first reinforcing fiber main layer and dried to obtain the core layer prepreg.

[0072] Among them, the first reinforcing fiber main layer includes carbon fiber cloth, the carbon fiber cloth is T700 grade 3K~12K carbon fiber, which has good mechanical strength and can effectively improve the structural strength of the core layer finally formed, thereby improving the overall mechanical properties of the carbon / carbon boat body.

[0073] In addition, during the drying process of the first reinforcing fiber main layer coated with the phenolic resin solution, the drying temperature used is 60°C to 90°C and the time is 1h to 3h. The same drying temperature and drying time can also be used for the drying treatment of the first fiber layer and the second fiber layer after being soaked in the phenolic resin solution and filtered. No further details will be given here.

[0074] After obtaining the first reinforcement layer prepreg, the second reinforcement layer prepreg and the core layer prepreg, according to the desired number of layers, at least one first reinforcement layer prepreg, at least one second reinforcement layer prepreg and at least one core layer prepreg are stacked layer by layer with the core layer prepreg on the innermost side and the second reinforcement layer prepreg on the outer side, and placed in a hot pressing mold, and placed together with the mold on a hot press for hot pressing and curing to obtain a stacked structure; wherein the hot pressing curing temperature is 180°C to 300°C, the heat preservation time is 2h to 5h, and the hydraulic press is used for the hot pressing. The force is a variable hydraulic pressure, and the hydraulic pressure is 1MPa~12MPa; it can be understood that the temperature of hot pressing curing can be any point value between 180℃~300℃, the holding time can be any point value between 2h~5h, the hydraulic pressure is a variable hydraulic pressure, and the hydraulic pressure can be any point value between 1MPa~12MPa, which are not enumerated here; for example, in an exemplary specific embodiment, the temperature of hot pressing curing is 200℃, the holding time is 3h, and the hydraulic pressure is gradually increased from 1MPa to 12MPa for maintenance.

[0075] Then, if Figure 2 As shown, the stacked structure is carbonized to obtain a carbonized embryonic body.

[0076] During the carbonization process, the phenolic resins in the core layer prepreg and the short fiber reinforcement layer prepreg undergo carbonization reaction to generate matrix carbon. That is, at least part of the matrix carbon in the final carbon / carbon boat is converted from the phenolic resin, which is beneficial to improving the distribution uniformity of the matrix carbon.

[0077] Among them, the temperature of the carbonization treatment is 650℃~950℃; it can be understood that the temperature of the carbonization treatment can be any point value between 650℃~950℃; illustratively, the temperature of the carbonization treatment can be 650℃, 700℃, 750℃, 800℃, 850℃, 900℃, 950℃, etc.; within this carbonization treatment temperature range, phenolic resin can be effectively converted into matrix carbon, thereby improving the interface bonding strength between the matrix carbon and the carbon fiber.

[0078] Then, if Figure 2 As shown, the carbonized embryo is post-processed to obtain a carbon / carbon boat; the carbon / carbon boat includes at least one core layer and multiple short fiber reinforcement layers stacked on both side surfaces of the at least one core layer.

[0079] Specifically, if Figure 6 As shown, in some exemplary embodiments, the post-processing of the carbonized embryo to obtain a carbon / carbon boat includes: performing a densification process on the carbonized embryo to obtain a densified carbonized embryo; Purifying the densified carbonized embryo at 2000° C. to 2400° C. to obtain a purified carbonized embryo; The purified carbonized embryo body is machined to obtain the carbon / carbon boat.

[0080] Among them, the densification treatment increases the density of the carbonized embryo by adding matrix carbon into the carbonized embryo. Accordingly, the matrix carbon in the final carbon / carbon boat includes the matrix carbon generated by the carbonization reaction of the phenolic resin and the matrix carbon added during the densification treatment. The densification treatment can increase the density of the densified carbonized embryo so that the density is greater than or equal to the preset density, effectively increasing the density of the final carbon / carbon boat and improving the mechanical properties of the carbon / carbon boat.

[0081] In addition, the densification treatment can be carried out after the carbonization treatment or before the carbonization treatment, and the densification treatment includes at least one of vapor deposition densification and liquid phase densification; wherein, in the process of densification by vapor deposition, the matrix carbon added by the densification treatment includes at least one of carbon sources such as natural gas and methane; wherein, in the process of densification by liquid phase, the matrix carbon added by the densification treatment includes at least one of carbon sources such as phenolic resin, furan resin and asphalt.

[0082] The purification treatment can effectively reduce the ash impurities in the carbon / carbon boat and improve the purity, while also increasing the graphitization degree of the matrix carbon, which is beneficial to improving the mechanical properties, electrical conductivity and finishing properties of the carbon / carbon boat.

[0083] The temperature of the purification treatment is 1800°C to 2400°C; it can be understood that the temperature of the purification treatment can be any point value between 1800°C and 2400°C; illustratively, the temperature of the purification treatment can be 1800°C, 1900°C, 2000°C, 2100°C, 2200°C, 2300°C, 2400°C, etc.; within this purification treatment temperature range, the ash impurities are removed efficiently and at a high removal rate, which can greatly improve the purity of the carbon / carbon-silicon carbide composite material and enhance the graphitization degree of the matrix carbon.

[0084] Machining steps are performed after the densification and purification processes to form the carbon / carbon boat into a composite material having desired dimensions.

[0085] Specifically, if Figure 7 As shown, after the carbonized embryo body is post-processed to obtain a carbon / carbon boat, the method further includes: A wear-resistant coating is formed on the surface of the carbon / carbon boat; the material of the wear-resistant coating includes silicon carbide.

[0086] The wear-resistant coating can be formed by physical vapor deposition, chemical vapor deposition, coating and spraying processes, and can effectively cover the surface of the short fiber reinforcement layer. The coating has good uniformity, greatly improving the wear resistance of the carbon / carbon boat surface, reducing performance degradation during use, and extending service life.

[0087] Finally, the carbon / carbon boats with wear-resistant coatings are assembled into a boat group. The gap between two adjacent carbon / carbon boats is used to place silicon wafers, thereby playing the role of transporting silicon wafers. It has good support stability, good thermal conductivity and electrical conductivity uniformity, and excellent precision processing performance. It can flexibly and reliably meet the development needs of solar monocrystalline silicon, polycrystalline silicon cell coating, plasma-enhanced chemical vapor deposition and high-temperature sintering processes, and is widely used in various vacuum coating processes to improve the coating effect and slow down the degradation of coating performance.

[0088] The following describes the embodiments of the present application in combination with the above technical solutions.

[0089] The carbon / carbon boats in Examples 1-8 were prepared by the following steps: 1. Heat-treating the carbon fiber bundle at 600°C to 1500°C for 1h to 5h to obtain desizing carbon fiber, and then air-dispersing the desizing carbon fiber to obtain short carbon fiber filaments with a length of 20mm to 70mm and in the form of fine filaments; 2. Dispersing short carbon fiber filaments, a dispersant, a conductive carbon matrix and a phenolic resin in deionized water to obtain a first composite solution, and dispersing the short carbon fiber filaments, a dispersant and a phenolic resin in deionized water to obtain a second composite solution; wherein the mass ratio of the short carbon fiber filaments, the dispersant, the phenolic resin and the deionized water is a first preset mass ratio; the conductive carbon matrix in the first composite solution is graphite, and the mass ratio of the graphite to the short carbon fiber filaments is a second preset mass ratio.

[0090] 3. The first composite solution and the second composite solution are respectively poured into a filter tank with a suction filtration hole at the bottom for suction filtration to obtain a first fiber layer and a second fiber layer.

[0091] 4. Immerse the first fiber layer and the second fiber layer in a phenolic resin solution respectively, filter and dry at 60°C to 90°C for 1 hour to 3 hours to remove the solvent to obtain a first reinforcement layer prepreg and a second reinforcement layer prepreg; the phenolic resin solution includes phenolic resin and ethanol solvent, and has a viscosity of 300 MPa·s to 2000 MPa·s.

[0092] 5. A phenolic resin solution is coated on the surface of the first reinforcing fiber main layer and dried at 60°C to 90°C for 1h to 3h to obtain a core layer prepreg; the carbon fiber cloth carbon filaments in the first reinforcing fiber main layer are T700 grade 3K to 12K carbon filaments.

[0093] 6. According to the preset layer ratio between the core layer, the first reinforcement layer and the second reinforcement layer, the core layer prepreg, the first reinforcement layer prepreg and the second reinforcement layer prepreg are stacked and aligned edge by edge in a mold, and the first reinforcement layer prepreg and the second reinforcement layer prepreg are symmetrically distributed with the core layer prepreg as the symmetry plane. They are placed in a hot press together with the mold and hot-pressed and cured at 150°C to 200°C. The temperature is kept for 2h to 4h, and the hydraulic pressure is gradually increased from 1MPa to 12MPa to obtain a stacked structure.

[0094] 7. Carbonizing the stacked structure at 650° C. to 950° C. to form matrix carbon from the phenolic resin, thereby obtaining a carbonized embryonic body.

[0095] 8. Performing a densification treatment on the carbonized embryo to obtain a densified carbonized embryo with a desired density.

[0096] 9. Purifying the densified carbonized body at 1800° C. to 2400° C. to reduce ash impurities in the material and increase the graphitization degree of the matrix carbon to obtain a purified carbonized body; 10. Machining the purified carbonized body to obtain a carbon / carbon boat.

[0097] 11. Forming a wear-resistant coating on the surface of the carbon / carbon boat; the material of the wear-resistant coating includes silicon carbide.

[0098] 12. Assemble the carbon / carbon boat body with wear-resistant coating into a boat group.

[0099] The carbon / carbon boat in each embodiment is tested using the following parameter method: 1) The bending strength test adopts a universal testing machine and the test standard is GB / T 1449-2005.

[0100] 2) The Shore hardness test standard adopts GB / T 39535-2020.

[0101] 3) The volume density test is performed by measuring the length, width and thickness to calculate the product volume, controlling the machining accuracy of the finished product to +0.1mm, and weighing the product to calculate the volume density.

[0102] 4) The porosity is tested using the boiling method in accordance with GB / T 24529-2009.

[0103] 5) The resistivity test uses a DC low resistance tester to measure the resistance value at both ends of a sample of specific size (500*25*2) and calculate the resistivity value of the material.

[0104] The test results are shown in Table 1 below.

[0105] Table 1 Test results of carbon / carbon boats of Examples 1-8

[0106] Comparative Example Conventional isostatically pressed graphite boats on the market are not coated and have a density of 1.80 g / cm 3 , Shore hardness 74HSD, open porosity 15.26%, resistivity 23x10 -6 Ω·m; There is currently no conventional carbon / carbon boat on the market. A conventional 2.5D needle-punched preform densified sheet was selected as the carbon / carbon boat material to measure relevant properties. Its density is 1.52g / cm 3 , Shore hardness 65HSD, open porosity 11.24%, resistivity 23x10 -6 Ω·m.

[0107] Referring to the test results in Table 1, and comparing with the comparative examples, it can be seen that the density of the carbon / carbon boats prepared in Examples 1-8 is all within 1.5 g / cm 3 The Shore hardness is above 76HSD and the porosity is below 1.5%. It can effectively enhance the density, uniformity and mechanical properties of the carbon / carbon boat, improve the surface finish, wear resistance and finishing performance, and is also beneficial to the uniformity of thermal conductivity of the carbon / carbon boat, reduce performance loss during use, and extend the service life of the carbon / carbon boat. In addition, the resistivity is above 18 x10 -6 Ω·m or less, indicating that the conductivity and uniformity of the carbon / carbon boat have also been effectively improved, which is beneficial to improving the coating effect.

[0108] It should be noted that the various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same and similar parts between the various embodiments can be referenced to each other.

[0109] What is described above are only some embodiments of the present application and are not intended to limit the present application. Those skilled in the art should understand that the present application may be subject to various changes and improvements, and any modifications, equivalent substitutions, and improvements made in accordance with the present application shall fall within the scope of protection required by the present application.

Claims

1. A carbon / carbon boat, characterized in that: It comprises at least one core layer (1) and multiple short fiber reinforcement layers, wherein the short fiber reinforcement layers are stacked on both side surfaces of the at least one core layer (1); The core layer (1) comprises a first reinforcing fiber main body layer and matrix carbon distributed in the first reinforcing fiber main body layer; The short fiber reinforcement layer includes a second reinforcement fiber main layer and matrix carbon distributed in the second reinforcement fiber main layer, and the second reinforcement fiber main layer includes short carbon fiber filaments staggeredly distributed in a plane.

2. The carbon / carbon boat according to claim 1, characterized in that: The multi-layer staple fiber reinforcement layer comprises at least one first reinforcement layer (2) and at least one second reinforcement layer (3), wherein the at least one first reinforcement layer (2) is located between the at least one core layer (1) and the at least one second reinforcement layer (3); The first reinforcement layer (2) further comprises a conductive carbon matrix, and the conductive carbon matrix is distributed in the second reinforcement fiber main layer.

3. The carbon / carbon boat according to claim 2, characterized in that: The conductive carbon matrix includes graphite; In the first reinforcement layer (2), the mass ratio between the conductive carbon matrix and the second reinforcement fiber main layer is 4:100 to 30:

100.

4. The carbon / carbon boat according to claim 1, characterized in that: The carbon / carbon boat satisfies at least one of the following characteristics: The density of the first reinforcing fiber main layer in the core layer (1) is 0.5 g / cm 3 ~1.0g / cm 3 ; The density of the second reinforcing fiber main layer in the short fiber reinforcement layer is 0.4g / cm 3 ~0.9g / cm 3 .

5. The carbon / carbon boat according to any one of claims 1 to 4, characterized in that: The carbon / carbon boat body further comprises a wear-resistant coating (4), the wear-resistant coating (4) covering the surface of the multi-layer short fiber reinforcement layer facing away from the core layer (1), and the material of the wear-resistant coating (4) comprises silicon carbide.

6. The carbon / carbon boat according to any one of claims 1 to 4, characterized in that: The carbon / carbon boat satisfies at least one of the following characteristics: The density of the carbon / carbon boat is greater than or equal to the preset density, and the preset density is 1.2 g / cm 3 ~2.0g / cm 3 ; The bending strength of the carbon / carbon boat is greater than or equal to a preset bending strength, and the preset bending strength is 120 MPa to 200 MPa; The Shore hardness of the carbon / carbon boat is greater than or equal to a preset Shore hardness, and the preset Shore hardness is 70HSD to 100HSD; The open porosity of the carbon / carbon boat is less than or equal to a preset open porosity, and the preset open porosity is 1.0% to 2.0%.

7. A method for preparing a carbon / carbon boat, characterized in that: include: The short fiber reinforcement layer prepreg is stacked on both sides of at least one core layer prepreg and hot-pressed to obtain a stacked structure; the core layer prepreg includes a first reinforcing fiber main layer and a phenolic resin distributed in the first reinforcing fiber main layer; the short fiber reinforcement layer prepreg includes a second reinforcing fiber main layer and a phenolic resin distributed in the second reinforcing fiber main layer, and the second reinforcing fiber main layer includes short carbon fiber filaments staggered in the plane; performing carbonization treatment on the stacked structure to obtain a carbonized embryonic body; During the carbonization process, the phenolic resins of the core layer prepreg and the short fiber reinforcement layer prepreg undergo carbonization reaction to generate matrix carbon; The carbonized embryo body is post-processed to obtain a carbon / carbon boat body; the carbon / carbon boat body comprises at least one core layer and multiple short fiber reinforcement layers stacked on both side surfaces of the at least one core layer.

8. The method for preparing a carbon / carbon boat according to claim 7, wherein: The multi-layer short fiber reinforced layer includes at least one first reinforcement layer and at least one second reinforcement layer, and the short fiber reinforced layer prepreg includes a first reinforcement layer prepreg and a second reinforcement layer prepreg; the short fiber reinforced layer prepreg is prepared by the following steps: Dispersing the short carbon fiber filaments, the conductive carbon matrix, and the phenolic resin in deionized water to obtain a first composite solution, and dispersing the short carbon fiber filaments and the phenolic resin in deionized water to obtain a second composite solution; filtering the first composite solution and the second composite solution respectively to obtain a first fiber layer and a second fiber layer; The first fiber layer and the second fiber layer are respectively immersed in a phenolic resin solution, filtered and dried to obtain the first reinforcement layer prepreg and the second reinforcement layer prepreg.

9. The method for preparing a carbon / carbon boat according to claim 8, wherein: The preparation steps of the short fiber reinforced layer prepreg meet at least one of the following characteristics: The particle size of the conductive carbon matrix is less than or equal to a preset particle size, and the preset particle size is 15 μm to 30 μm; In the first composite solution and the second composite solution, the mass ratio of the short carbon fiber filaments to the deionized water is 1:10 to 1:100, and the mass ratio of the phenolic resin to the deionized water is 1:4 to 1:50; The first composite solution and the second composite solution each further include a dispersant, and the mass ratio of the dispersant to the deionized water is 1:50 to 1:250; The thickness of each of the first fiber layer and the second fiber layer is 0.5 mm to 8 mm; The fiber surface density of each of the first fiber layer and the second fiber layer is 30 g / m 2 ~250g / m 2 ; The viscosity of the phenolic resin solution is 300 mPa·s to 2000 mPa·s.

10. The method for preparing a carbon / carbon boat according to claim 8, wherein: The short carbon fiber filaments are obtained by the following steps: heat-treating the carbon fiber bundle to obtain desized carbon fiber; performing air flow dispersion on the desized carbon fibers to obtain the short carbon fiber filaments; The length of the short carbon fiber filaments is 20 mm to 70 mm.

11. The method for preparing a carbon / carbon boat according to any one of claims 7 to 10, characterized in that: The core layer prepreg is obtained by the following steps: A phenolic resin solution is coated on the surface of the first reinforcing fiber main layer and dried to obtain the core layer prepreg; the drying temperature is 60° C. to 90° C. and the drying time is 1 hour to 3 hours.

12. The method for preparing a carbon / carbon boat according to any one of claims 7 to 10, characterized in that: After the carbonized embryo is post-processed to obtain a carbon / carbon boat, the method further includes: A wear-resistant coating is formed on the surface of the carbon / carbon boat; the material of the wear-resistant coating includes silicon carbide.

13. The method for preparing a carbon / carbon boat according to any one of claims 7 to 10, characterized in that: The post-processing of the carbonized embryo to obtain a carbon / carbon boat comprises: performing a densification process on the carbonized embryo to obtain a densified carbonized embryo; Purifying the densified carbonized embryo at 2000° C. to 2400° C. to obtain a purified carbonized embryo; The purified carbonized embryo body is machined to obtain the carbon / carbon boat.

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