Braided crucible preform, manufacturing method, and carbon / carbon crucible

Abstract

A braided crucible preform, a manufacturing method, and a carbon / carbon crucible. The braided crucible preform comprises: a three-dimensional braided body; a protective layer which is provided on the inner side and / or the outer side of the three-dimensional braided body, is connected to the three-dimensional braided body by means of needling, and comprises web layers and winding layers arranged in a staggered mode, wherein the density of the web layers gradually reduces in a direction away from the three-dimensional braided body, and / or the winding density of the winding layers gradually reduces in the direction away from the three-dimensional braided body. The braided crucible preform comprises the three-dimensional braided body and the protective layer, and the protective layer comprises the web layers and the winding layers, so that circumferential strength and corrosion resistance of the crucible can be ensured. The density of the web layers and / or the winding density of the winding layers gradually reduces in the direction away from the three-dimensional braided body, so that carbon deposition on the three-dimensional braided body layer can be facilitated, the uniformity of carbon deposition is improved, and the overall strength of the crucible is improved.

Description

Braided crucible preform, manufacturing method and carbon / carbon crucible Technical Field

[0001] The present invention belongs to the technical field of semiconductor and solar crystal growth equipment, and in particular relates to a braided crucible preform, a method for manufacturing the braided crucible preform, and a carbon / carbon crucible. Background Art

[0002] The Czochralski (CZ) method, currently widely used in the production of single crystal silicon, involves pulling a single crystal vertically from a melt. Within the manufacturing equipment, a graphite crucible is a component that supports a quartz crucible within it. During use, problems such as cracking and erosion of the graphite crucible can occur due to the different expansion coefficients of the quartz and graphite crucibles, as well as the corrosive reaction between silicon vapor and graphite.

[0003] Carbon / carbon composites (C / C composites) are carbon fiber-reinforced carbon-matrix composites. They offer excellent properties such as low density, high specific strength, high-temperature resistance, low thermal expansion coefficient, good dimensional stability, strong structural designability, and corrosion resistance, making them widely used in both military and civilian applications. In recent years, C / C composites have been widely used in the thermal field components of large-scale single crystal silicon furnaces, owing to their advantages in manufacturing large-scale products and strong structural designability, particularly with technological advances and reduced manufacturing costs. As an alternative to graphite crucibles, C / C composite crucibles are a key component in the thermal field system of single crystal furnaces.

[0004] During single crystal silicon pulling, the carbon / carbon composite crucible is in a mixed atmosphere of silicon vapor and inert gas. Silicon vapor will deposit on the surface of the carbon / carbon composite crucible and partially react with the surface of the carbon / carbon composite to form silicon carbide, or penetrate into pores at a certain depth on the surface to react with carbon to form silicon carbide. Since the thermal expansion coefficients of silicon carbide and carbon / carbon do not match, it is easy to fall off and powder, thereby affecting the further use of the carbon / carbon composite crucible and further affecting the service life of the thermal field components.

[0005] The Chinese invention patent application number CN202111562959.0 discloses a quartz fiber / carbon fiber reinforced carbon-based composite crucible and its preparation method. The middle layer of the crucible preform is carbon fiber, and the inner and outer surface layers are composed of quartz fiber. They are made of carbon fiber plain cloth or twill cloth plus short carbon fiber mesh alternately stacked and needle-punched, or quartz fiber flat cloth + short quartz fiber mesh alternately stacked and needle-punched.

[0006] Although this technical solution improves the strength and service life of the crucible to a certain extent, on the one hand, in this solution, the middle layer is formed by needle-punching carbon fiber plain cloth or twill cloth and short fiber mesh, and the resulting crucible has poor circumferential strength. On the other hand, the inner surface layer and the outer surface layer are both formed by needle-punching quartz fiber flat cloth and short quartz fiber mesh alternately. The crucible preform with this structure is not conducive to deposition to the middle layer during chemical vapor deposition, and the problem of high deposition density in the surface layer of the crucible and low deposition density in the middle layer may occur.

[0007] Therefore, designing a braided crucible preform that can not only ensure the crucible's resistance to silicification corrosion but also improve the crucible's circumferential strength and deposition effect has become a technical problem that needs to be solved urgently by those skilled in the art. Summary of the Invention

[0008] The present invention provides a braided crucible preform. By arranging the braided crucible preform to include a three-dimensional braided body and a protective layer, and arranging the protective layer to include a mesh layer and a winding layer, the circumferential strength and corrosion resistance of the crucible can be ensured. By setting the density of the mesh layer and / or gradually reducing the winding density of each winding layer in a direction away from the three-dimensional braided body, carbon deposition on the three-dimensional braided body layer can be facilitated, thereby solving the problems of poor circumferential strength of existing crucibles with protective layers, high deposition density of the protective layer, and low deposition density of the intermediate layer.

[0009] In order to solve the above technical problems, the basic concept of the technical solution adopted by the present invention is:

[0010] A braided crucible preform comprises: a three-dimensional braided body; and a protective layer, arranged on the inner side and / or outer side of the three-dimensional braided body and connected to the three-dimensional braided body by acupuncture, comprising interlaced mesh layers and winding layers, the density of each mesh layer gradually decreasing in a direction away from the three-dimensional braided body, and / or the winding density of each winding layer gradually decreasing in a direction away from the three-dimensional braided body.

[0011] Furthermore, the winding layer includes: a first winding layer, in which the carbon fiber filaments extend along the circumferential direction of the three-dimensional braid and are arranged along the axial direction of the three-dimensional braid; and a second winding layer, in which the carbon fiber filaments extend along the axial direction of the three-dimensional braid and are arranged along the circumferential direction of the three-dimensional braid.

[0012] Furthermore, the winding layer includes: a first winding layer, in which the carbon fiber filaments extend along the circumference of the three-dimensional braid and are arranged along the axial direction of the three-dimensional braid; or a second winding layer, in which the carbon fiber filaments extend along the axial direction of the three-dimensional braid and are arranged along the circumference of the three-dimensional braid.

[0013] Furthermore, the protective layer includes a first sub-protective layer and a second sub-protective layer arranged in sequence along a direction away from the three-dimensional woven body, the first sub-protective layer includes an alternating mesh layer and a first winding layer, and the second sub-protective layer includes an alternating mesh layer and a second winding layer.

[0014] Furthermore, the first winding layer and the second winding layer respectively include a first sub-winding layer and a second sub-winding layer, and the first sub-winding layer and the second sub-winding layer are staggered in a direction away from the three-dimensional woven body. The winding directions of the carbon fiber filaments of the first sub-winding layer and the second sub-winding layer are opposite and the winding angles are the same. The carbon fiber filaments of the first sub-winding layer and the second sub-winding layer cross each other to form a grid.

[0015] Furthermore, a first web layer is provided between adjacent first or second winding layers, and between the first and second winding layers; and / or a second web layer is provided between the first and second sub-winding layers of the same first and second winding layers.

[0016] Furthermore, the density of each first mesh layer gradually decreases in the direction away from the three-dimensional woven body; the density of each second mesh layer is the same and is less than or equal to the density of the first mesh layer farthest from the three-dimensional woven body; or, the density of each second mesh layer gradually decreases in the direction away from the three-dimensional woven body, and the density of the second mesh layer closest to the three-dimensional woven body is less than or equal to the density of the first mesh layer farthest from the three-dimensional woven body.

[0017] Furthermore, the three-dimensional braided body includes a vertically extending crucible portion and a crucible bottom portion that bends and extends from the lower end of the crucible portion toward the axis of the three-dimensional braided body; the first sub-protective layer is arranged on the crucible portion, and the second sub-protective layer is arranged on the crucible portion and the crucible bottom portion.

[0018] Furthermore, it also includes a filling layer, which is arranged between the second sub-protective layer and the bottom of the three-dimensional braided body, and at the corner between the bottom of the crucible and the crucible joint; the filling layer includes a mesh layer, or includes an alternating mesh layer and a carbon cloth layer; the thickness of the filling layer is greater than or equal to the thickness of the first sub-protective layer.

[0019] Furthermore, the thickness of each web layer gradually decreases in a direction away from the three-dimensional woven structure.

[0020] The present invention also provides a method for manufacturing the braided crucible preform, comprising the following steps:

[0021] S1: First, lay an EVA needle-punched mat on a wooden mold, then place a layer of mesh on the EVA needle-punched mat, and place a staggered winding layer and mesh layer on the outside of the mesh to form an inner protective layer;

[0022] S2: The three-dimensional braided body is placed outside the inner protective layer;

[0023] S3: Arranging staggered winding layers and mesh layers on the outside of the three-dimensional braided body to form an outer protective layer, and arranging a layer of mesh outside the outer protective layer;

[0024] S4: Acupuncture.

[0025] After adopting the above technical solution, the present invention has the following beneficial effects compared with the prior art.

[0026] 1. The present invention provides a braided crucible preform including a three-dimensional braided body and a protective layer, and provides the protective layer including a mesh layer and a winding layer, thereby ensuring the circumferential strength and corrosion resistance of the crucible. By setting the density of the mesh layer, and / or the winding density of each winding layer gradually decreasing in the direction away from the three-dimensional braided body, it is beneficial to carbon deposition on the three-dimensional braided body layer, thereby improving the uniformity of carbon deposition and improving the overall strength of the crucible.

[0027] 2. The present invention provides a mesh layer including a first mesh layer and a second mesh layer, and sets the density of the second mesh layer to be less than or equal to the density of the first mesh layer farthest from the three-dimensional braided body. On the basis of ensuring the deposition effect, the bonding effect between the layers of the protective layer and between the protective layer and the three-dimensional braided body can be improved, thereby further improving the overall strength of the crucible.

[0028] 3. The present invention can enhance the strength of the bottom of the crucible, improve the uniformity of the thickness of the bottom and the top of the crucible, and increase the service life of the crucible by providing a filling layer.

[0029] The specific embodiments of the present invention will be described in further detail below with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The accompanying drawings are part of the present invention and are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention, but do not constitute an undue limitation of the present invention. Obviously, the drawings described below are only some embodiments. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without inventive effort. In the accompanying drawings:

[0031] FIG1 is a schematic structural diagram of a first three-dimensional braided body according to an embodiment of the present invention;

[0032] FIG2 is an interface diagram of a first three-dimensional braided structure according to an embodiment of the present invention;

[0033] FIG3 is a schematic structural diagram of a second three-dimensional braided body according to an embodiment of the present invention;

[0034] FIG4 is a schematic structural diagram of a third three-dimensional braided body according to an embodiment of the present invention;

[0035] FIG5 is a schematic structural diagram of a protective layer according to an embodiment of the present invention;

[0036] FIG6 is a schematic structural diagram of the second winding layer in an embodiment of the present invention.

[0037] Description of the main components in the figure:

[0038] 1. Three-dimensional braid; 11. Crusher part; 12. Crusher bottom; 2. Protective layer; 21. First sub-protective layer; 22. Second sub-protective layer; 23. Filling layer; 3. Carbon fiber filaments; 31. First carbon fiber filaments; 32. Second carbon fiber filaments; 4. Axial strips; 5. Wrapping layer; 51. Second Wrapping layer.

[0039] It should be noted that these drawings and textual descriptions are not intended to limit the conceptual scope of the present invention in any way, but rather to illustrate the concept of the present invention for those skilled in the art by referring to specific embodiments. DETAILED DESCRIPTION

[0040] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. The following embodiments are used to illustrate the present invention but are not used to limit the scope of the present invention.

[0041] In the description of the present invention, it should be noted that the terms "upper", "lower", "front", "back", "left", "right", "vertical", "inside", "outside", etc., indicating directions or positional relationships, are based on the directions or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction. Therefore, they cannot be understood as limiting the present invention.

[0042] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood broadly. For example, they may refer to fixed, detachable, or integral connections; mechanical or electrical connections; and direct or indirect connections through an intermediary. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on the specific circumstances.

[0043] Example 1

[0044] A carbon / carbon composite crucible, or carbon / carbon crucible, is a highly designable, high-performance carbon crucible. Made from a composite material composed of high-strength carbon fiber and a carbon matrix, it offers significant energy and material savings compared to graphite products, while also offering superior performance. It boasts a long lifespan, high specific strength, high-temperature and corrosion resistance, a low thermal expansion coefficient, rapid cooling and heating resistance, and resistance to deformation and cracking. It is an ideal upgrade to replace graphite crucibles in single crystal furnaces. Demand is increasing for carbon / carbon composite crucibles, a key component in the thermal field system of Czochralski single crystal silicon furnaces, supporting the quartz crucibles that hold the silicon material.

[0045] The manufacturing process of carbon / carbon crucible includes: making a carbon / carbon crucible preform, placing the preform in a deposition furnace for carbon deposition, and placing the semi-finished product after deposition in a graphitization furnace for graphitization.

[0046] As shown in FIG. 1 to FIG. 6 , in an embodiment of the present invention, a braided crucible preform is introduced. The braided crucible preform includes a three-dimensional braided body 1 and a protective layer 2 arranged on the inner side and / or the outer side of the three-dimensional braided body 1 .

[0047] Specifically, as shown in Figure 1, the three-dimensional braided body 1 is an annular hollow structure woven from one or more carbon fiber filaments 3. The upper end of the three-dimensional braided body 1 is provided with an opening, the lower end is bowl-shaped, and the middle part of the lower end is provided with a through hole coaxial with the three-dimensional braided body 1. The diameter of the upper end opening of the three-dimensional braided body 1 is larger than the diameter of the through hole at the lower end.

[0048] As shown in Figures 3 and 4, in this embodiment, by setting the axial bars 4 to include at least two weeks arranged radially along the three-dimensional braided body 1, the axial support strength of the braided crucible can be improved, and by setting the first carbon fiber filaments 31 to spirally weave the axial bars 4 on the same circumference, and setting the second carbon fiber filaments 32 to spirally weave the axial bars 4 on the adjacent circumference, and setting the peaks and troughs of the first carbon fiber filaments 31 and the second carbon fiber filaments 32 to cross each other, the axial bars 4 are connected as a whole to form a three-dimensional braided body 1, which can improve the circumferential support strength of the braided crucible, so that the braided crucible preform has a multi-layer carbon fiber composite material arranged radially along the three-dimensional braided body 1, which can improve the overall support strength and service life of the braided crucible.

[0049] In some possible embodiments, the three-dimensional braided body 1 includes a plurality of axial bars 4 arranged at intervals around the axis of the three-dimensional braided body 1 and carbon fiber filaments 3 spirally woven around the axial bars 4, the axial bars 4 including at least two weeks arranged along the radial direction of the preform body, the axial bars 4 on the same circle are connected by first carbon fiber filaments 31, and the axial bars 4 on adjacent circles are connected by second carbon fiber filaments 32, and the peaks and troughs of the first carbon fiber filaments 31 and the second carbon fiber filaments 32 intersect with each other.

[0050] As shown in FIG. 3 , in this embodiment, the axial strips 4 on adjacent circumferences correspond to each other one by one.

[0051] In this embodiment, the peaks and troughs of the first carbon fiber filaments 31 on two adjacent layers of circumference correspond one to one, the peaks of the second carbon fiber filaments 32 simultaneously intersect with the troughs of the first carbon fiber filaments 31 on the inner and outer layers of circumference, and the troughs of the second carbon fiber filaments 32 simultaneously intersect with the peaks of the first carbon fiber filaments 31 on the inner and outer layers of circumference.

[0052] Preferably, in this embodiment, the axial strips 4 on the same circumference are connected by two groups of first carbon fiber filaments 31, and the peaks and troughs of the two groups of first carbon fiber filaments 31 intersect with each other; and / or, the axial strips 4 on adjacent circles are connected by two groups of second carbon fiber filaments 32, and the peaks and troughs of the two groups of second carbon fiber filaments 32 intersect with each other.

[0053] Alternatively, as shown in FIG. 4 , in this embodiment, the axial strips 4 on adjacent circumferences are arranged in a staggered manner.

[0054] In this embodiment, the troughs of the first carbon fiber filaments 31 on the outer circumference intersect with the crests of the second carbon fiber filaments 32 ; the crests of the first carbon fiber filaments 31 on the inner circumference intersect with the troughs of the second carbon fiber filaments 32 .

[0055] Specifically, the axial strips 4 on the same circumference are connected by two groups of first carbon fiber filaments 31, and the peaks and troughs of the two groups of first carbon fiber filaments 31 intersect with each other; the two adjacent peaks of the second carbon fiber filaments 32 intersect with the troughs of the two groups of first carbon fiber filaments 31 on the outer circumference; the two adjacent troughs of the second carbon fiber filaments 32 intersect with the peaks of the two groups of first carbon fiber filaments 31 on the inner circumference.

[0056] In this embodiment, by arranging axial strips 4 on the same circumference and connecting them through two groups of first carbon fiber filaments 31, the crests and troughs of the two groups of first carbon fiber filaments 31 intersect with each other, and arranging the first carbon fiber filaments 31 and the second carbon fiber filaments 32 to be staggered along the length direction of the axial strips 4, the circumferential strength of the braided crucible can be further improved, and the service life of the braided crucible can be improved.

[0057] Preferably, in this embodiment, the first carbon fiber filaments 31 and the second carbon fiber filaments 32 are staggered along the length direction of the axial strip 4; the first carbon fiber filaments 31 on adjacent circles correspond one to one along the direction perpendicular to the length of the axial strip 4.

[0058] In some other possible embodiments, the three-dimensional braided body 1 is formed by stacking multiple two-dimensional braided structures.

[0059] As shown in Figures 1 and 2, in this embodiment, the axial bars 4 of the two-dimensional woven body structure are on the same circumference, and have multiple bars arranged at intervals around the axis of the two-dimensional woven body structure. The axial bars 4 are spirally wound by two groups of carbon fiber filaments 3 that are staggered, and the peaks and troughs of the two groups of carbon fiber filaments 3 intersect with each other.

[0060] The two-dimensional braided structure includes multiple layers arranged in a radial direction, and the outer peripheral wall of an inner two-dimensional braided structure is in contact with the inner peripheral wall of an adjacent inner two-dimensional braided structure.

[0061] In this embodiment, the two adjacent layers of the two-dimensional braided structure are connected by needling. Specifically, the braided crucible preform can be needled after a protective layer 2 is placed on the inner side of the innermost two-dimensional braided structure and / or on the outer side of the outermost two-dimensional braided structure. Alternatively, the stacked two-dimensional braided structure can be needled first to form a complete three-dimensional braided structure 1, and then the protective layer 2 can be placed on the inner and / or outer sides.

[0062] Preferably, in this embodiment, a layer of mesh is provided between two adjacent layers of the two-dimensional braided structure to further enhance the stability of the overall structure of the formed three-dimensional braided structure 1 .

[0063] In this embodiment, the protective layer 2 is arranged on the inner side and / or outer side of the three-dimensional braided body 1, and is connected to the three-dimensional braided body 1 by needle puncture. It includes a staggered mesh layer and a winding layer 5, and the density of each mesh layer gradually decreases in the direction away from the three-dimensional braided body 1, and / or the winding density of each winding layer 5 gradually decreases in the direction away from the three-dimensional braided body 1. The staggered arrangement of the mesh layer and the winding layer 5 is specifically a staggered stacking arrangement of the mesh layer and the winding layer 5, that is, one or more winding layers 5 are arranged between two adjacent mesh layers. By arranging the braided crucible preform to include a three-dimensional braided body 1 and a protective layer 2, and arranging the protective layer 2 to include a mesh layer and a winding layer 5, the circumferential strength and corrosion resistance of the crucible can be ensured. By setting the density of the mesh layer, and / or the winding density of each winding layer 5 gradually decreasing in the direction away from the three-dimensional braided body 1, it can be beneficial to carbon deposition on the three-dimensional braided body layer, thereby improving the uniformity of carbon deposition and improving the overall strength of the crucible.

[0064] Specifically, when the woven crucible preform is subjected to chemical vapor deposition, the deposition is carried out from the surface layer of the side wall of the preform to the inner layer of the side wall. By setting the density of the mesh layer and the winding density of each winding layer 5 to gradually decrease in the direction away from the three-dimensional woven body 1, it can be more conducive to the deposition of the carbon-containing gas flow toward the inner layer of the side wall of the preform, so as to ensure the deposition effect on the inner layer of the three-dimensional woven body 1, thereby improving the overall strength of the crucible.

[0065] In this embodiment, the winding layer 5 includes a first winding layer in which carbon fiber filaments 3 extend along the circumferential direction of the three-dimensional braided body 1 and are arranged along the axial direction of the three-dimensional braided body 1, and a second winding layer 51 in which carbon fiber filaments 3 extend along the axial direction of the three-dimensional braided body 1 and are arranged along the circumferential direction of the three-dimensional braided body 1.

[0066] Specifically, during the winding process of the first winding layer of carbon fiber filaments 3, one end of the carbon fiber filaments 3 is first fixed to the first end of the wooden mold, and then the wooden mold is rotated while simultaneously tightening and moving the carbon fiber filaments 3 toward the second end of the wooden mold, so that the carbon fiber filaments 3 are evenly wound around the wooden mold and have a certain tension. Preferably, in this embodiment, the tension of the carbon fiber filaments 3 is controlled by a tensioner.

[0067] As shown in FIG6 , in this embodiment, the carbon fiber filaments 3 of the second winding layer 51 undergo the following winding process:

[0068] First, a circle of support columns is set at the first end and the second end of the wooden mold respectively. The support columns at the first end and the second end of the wooden mold are respectively on the same circumference and evenly arranged along the circumference of the wooden mold. One end of the carbon fiber filament 3 of the second winding layer 51 is fixed on any support column and then wound onto the support column on the other end of the wooden mold.

[0069] Specifically, the support column can be a nail, and the nail provided at the first end of the wooden mold is spaced apart from the upper opening of the three-dimensional braided body 1, or is fitted between the upper opening of the three-dimensional braided body 1, and the nail provided at the second end of the wooden mold is spaced apart from the lower through hole of the three-dimensional braided body 1, or is fitted between the lower through hole of the three-dimensional braided body 1.

[0070] One end of the carbon fiber filament 3 is fixed on any nail provided at the first end of the wooden mold, and then wrapped around the nail on the second end, and wrapped around once in sequence to form a second winding layer 51 extending along the axial direction of the three-dimensional braided body 1 and arranged along the circumferential direction of the three-dimensional braided body 1.

[0071] In this embodiment, the tension of the carbon fiber filaments 3 of the second winding layer 51 is controlled by a tensioner.

[0072] In this embodiment, the carbon fiber filaments 3 are flat filaments. During the winding process of the carbon fiber filaments 3, the carbon fiber filaments 3 are parallel to the peripheral wall of the wooden mold.

[0073] In this embodiment, the angle between the carbon fiber filaments 3 of the first and second winding layers 51 and the axis of the three-dimensional braid 1 is greater than 0° and less than 90°. In this embodiment, wrapping the three-dimensional braid 1 with the carbon fiber filaments 3 ensures the integrity of the carbon fiber filaments 3, thereby further improving the strength of the protective layer 2.

[0074] Preferably, as shown in FIG5 , in this embodiment, the protective layer 2 includes a first sub-protective layer 21 and a second sub-protective layer 22, sequentially arranged in a direction away from the three-dimensional braid 1. The first sub-protective layer 21 includes a staggered mesh layer and a first winding layer, and the second sub-protective layer 22 includes a staggered mesh layer and a second winding layer 51. Thus, the second winding layer 51, which has a lower density, is arranged on the side away from the three-dimensional braid 1, while the first winding layer, which has a higher density, is arranged on the side closer to the three-dimensional braid 1. This facilitates inward deposition of carbon during carbon deposition on the braided crucible preform, improving deposition uniformity.

[0075] In this embodiment, the first winding layer and the second winding layer 51 respectively include a first sub-winding layer and a second sub-winding layer, and the first sub-winding layer and the second sub-winding layer are staggered in a direction away from the three-dimensional braided body 1. The winding directions of the carbon fiber filaments 3 of the first sub-winding layer and the second sub-winding layer are opposite and the winding angles are the same. The carbon fiber filaments 3 of the first sub-winding layer and the second sub-winding layer cross each other to form a grid.

[0076] Specifically, the carbon fiber filaments of one of the first and second sub-wrap layers are wound clockwise from the first end to the second end of the three-dimensional braid, and the carbon fiber filaments of the other of the first and second sub-wrap layers are wound counterclockwise from the first end to the second end of the three-dimensional braid. That is, the carbon fiber filaments of the first and second sub-wrap layers are arranged crosswise, and the carbon fiber filaments of the first and second sub-wrap layers are interlaced to form a grid, which can improve the winding effect on the mesh layer, thereby facilitating an increase in the angle between the carbon fiber filaments 3 of the first and second sub-wrap layers and the axis of the three-dimensional braid 1, that is, facilitating an increase in the spacing between each loop of the carbon fiber filaments 3 of the first and second sub-wrap layers, that is, ensuring the winding effect on the mesh layer while increasing the density of the winding layer 5.

[0077] Preferably, in this embodiment, the first sub-wound layer and the second sub-wound layer are arranged alternately; the carbon fiber filaments 3 of the first sub-wound layer and the second sub-wound layer have the same angle with the axis of the three-dimensional braided body 1 .

[0078] Preferably, in this embodiment, a first web layer is provided between adjacent first winding layers or second winding layers 51, and between the first winding layer and the second winding layer 51; and / or a second web layer is provided between the first sub-winding layer and the second sub-winding layer of the same first winding layer and the second winding layer 51.

[0079] Preferably, in this embodiment, the web layer includes a first web layer and a second web layer, and the density of each of the first web layers gradually decreases in a direction away from the three-dimensional braided body 1 .

[0080] In this embodiment, the density of each second mesh layer is the same and is less than or equal to the density of the first mesh layer farthest from the three-dimensional braided body 1; or, the density of each second mesh layer gradually decreases in the direction away from the three-dimensional braided body 1, and the density of the second mesh layer closest to the three-dimensional braided body 1 is less than or equal to the density of the first mesh layer farthest from the three-dimensional braided body 1.

[0081] In this embodiment, by setting the mesh layer to include a first mesh layer and a second mesh layer, and setting the density of the second mesh layer to be less than or equal to the density of the first mesh layer farthest from the three-dimensional braided body 1, it is possible to improve the bonding effect between the layers of the protective layer 2 and between the protective layer 2 and the three-dimensional braided body 1 on the basis of ensuring the deposition effect, thereby further improving the overall strength of the crucible.

[0082] Preferably, in this embodiment, the thickness of each web layer gradually decreases in a direction away from the three-dimensional braided body 1 .

[0083] Further preferably, in this embodiment, the thickness of each of the first mesh layers gradually decreases in the direction away from the three-dimensional braided body 1, and the thickness of each of the second mesh layers is the same and is less than or equal to the thickness of the first mesh layer farthest from the three-dimensional braided body 1; or, the thickness of each of the second mesh layers gradually decreases in the direction away from the three-dimensional braided body 1, and the thickness of the second mesh layer closest to the three-dimensional braided body 1 is less than or equal to the thickness of the first mesh layer farthest from the three-dimensional braided body 1.

[0084] In this embodiment, the three-dimensional braided body 1 includes a vertically extending crucible portion 11 and a crucible bottom portion 12 that curves and extends from the lower end of the crucible portion 11 toward the axis of the three-dimensional braided body 1. The first sub-protective layer 21 is disposed on the crucible portion 11, and the second sub-protective layer 22 is disposed on both the crucible portion 11 and the crucible bottom portion 12. This facilitates winding of the wrapping layer 5 and improves the overall stability of the protective layer 2. Furthermore, because the density of the second wrapping layer 51 gradually increases along the direction extending from the crucible portion 11 toward the crucible bottom portion 12, disposing the first wrapping layer only on the crucible portion 11 facilitates uniformity in the overall density of the wrapping layer 5, thereby improving the deposition efficiency of the braided crucible preform.

[0085] Preferably, in this embodiment, the density of the first winding layer is set to gradually decrease in the direction close to the bottom 12 of the crucible, that is, the angle between the carbon fiber filaments 3 of the first winding layer and the axis of the three-dimensional braided body 1 is set to gradually increase in the direction close to the bottom 12 of the crucible, so as to further improve the uniformity of the overall density of the winding layer 5 of the protective layer 2 and further improve the deposition effect of the braided crucible preform.

[0086] Preferably, in this embodiment, the protective layer 2 further includes a filling layer 23. Specifically, the filling layer 23 is disposed between the second sub-protective layer 22 and the crucible bottom 12 of the three-dimensional braided body 1, and between the crucible bottom 12 and the crucible closure 11. This ensures, on the one hand, a uniform thickness of the crucible bottom 12 and the crucible closure 11, and, on the other hand, further strengthens the bottom strength of the crucible, thereby increasing the service life of the crucible.

[0087] Preferably, in this embodiment, the filling layer 23 includes a mesh layer, or includes a mesh layer and a carbon cloth layer that are alternately arranged.

[0088] Further preferably, in this embodiment, the thickness of the filling layer 23 is greater than or equal to the thickness of the first sub-protective layer 21 .

[0089] Preferably, in this embodiment, the innermost layer of the protective layer 2 on the inner side of the three-dimensional braided body 1 and the outermost layer of the protective layer 2 on the outer side of the three-dimensional braided body 1 are respectively provided with a layer of mesh and then needle-punched, so that the second winding layer 51 can be stably maintained on the preform.

[0090] Example 2

[0091] In this embodiment, a method for manufacturing the braided crucible preform is provided. The method for manufacturing the braided crucible preform is as follows:

[0092] S1: Set up inner protective layer;

[0093] First, an EVA needle-punched mat is laid on a wooden mold. A layer of mesh is then placed on the EVA needle-punched mat. Finally, a wrapping layer 5 and a mesh-tightening layer are sequentially placed to form an alternating stack of mesh-tightening layers and wrapping layers 5. Specifically, a second sub-protective layer 22, a filling layer 23, and a first sub-protective layer 21 are sequentially placed around the periphery of the EVA needle-punched mat, so that the outer shape of the resulting inner protective layer matches the inner shape of the three-dimensional braided body 1.

[0094] Preferably, in this embodiment, a second wrapping layer 51 is provided on the outermost portion of the inner protective layer to stably maintain the filling layer 23 on the wooden mold.

[0095] S2: The three-dimensional braided body 1 is placed outside the inner protective layer;

[0096] S3: Setting an outer protective layer;

[0097] A first sub-protective layer 21 , a filling layer 23 and a second sub-protective layer 22 are sequentially arranged on the outside of the three-dimensional braided body 1 , and then a layer of mesh is arranged on the outermost layer of the outer protective layer.

[0098] S4: Acupuncture.

[0099] After the inner protective layer, the three-dimensional braided body 1 and the outer protective layer are set at one time, the braided crucible preform is needle-punched as a whole to connect the layers of the protective layer 2 and the protective layer 2 with the three-dimensional braided body 1 to form a stable braided crucible preform, which is then demoulded.

[0100] In this embodiment, after the braided crucible preform is manufactured, chemical vapor deposition and graphitization processes are sequentially performed to obtain a crucible.

[0101] The chemical vapor deposition process includes: using natural gas as a carbon source gas, nitrogen as a carrier gas, the reaction temperature of the vapor deposition process is 800-1100°C, the natural gas flow rate is 40-110L / min, and the deposition time is 100-200h.

[0102] The graphitization process includes: placing the crucible blank after chemical vapor deposition in a graphitization furnace with a temperature of about 2000° C. and keeping the temperature in the vacuum environment of the graphitization furnace for 5-10 hours.

[0103] In the following embodiment, the inner and outer sides of the three-dimensional braided body 1 of the crucible preform are respectively set to have an apparent density of 0.42 to 0.5 g / cm 3 The thickness of the three-dimensional braided body 1 is 8-16 mm, and the density is 0.5-0.6 g / cm 3 The thickness of the protective layer is 2 to 6 mm, and the weight ratio of the web layer to the winding layer of the protective layer is 1:5.

[0104] Experimental Example 1:

[0105] This experimental example tests the performance of a carbon / carbon crucible prepared from a braided crucible preform of Example 1 through deposition and graphitization. The preparation method of the carbon / carbon crucible includes the following steps:

[0106] S01: Deposition: The braided crucible preform of Example 1 is placed in a deposition furnace for chemical vapor deposition. The inner and outer sides of the three-dimensional braided body 1 of the crucible preform are respectively set to have an apparent density of 0.45 g / cm 3 The thickness of the inner and outer protective layers is 4 mm, and the weight ratio of the protective layer to the winding layer is 1:5. The thickness of the three-dimensional braided body 1 is 10 mm and the density is 0.6 g / cm 3 .

[0107] During the vapor deposition process, natural gas (methane volume content 85%) is used as the carbon source gas and nitrogen is used as the carrier gas. Nitrogen is introduced into the furnace through the bottom of the deposition furnace at a flow rate of 5 L / min and natural gas is introduced into the furnace at a flow rate of 80 L / min. The temperature of the vapor deposition process is about 900°C and the deposition time is 200 hours.

[0108] S02: Graphitization: The crucible blank obtained in step S01 is placed in a graphitization furnace for graphitization. The graphitization treatment temperature is about 2000° C. and the holding time is 8 hours to obtain a carbon / carbon crucible.

[0109] The prepared carbon / carbon crucible was tested: the density of the inner and outer surface layers was 1.55 g / cm 3 The density of the middle layer is 1.50g / cm 3 , the flexural strength is 179MPa, and the service life of the carbon / carbon crucible is 200 days.

[0110] Comparative Example 1:

[0111] The method for preparing the crucible preform in this comparative example is different from that in Experimental Example 1.

[0112] The needle punching density on the inner and outer sides of the three-dimensional braided body 1 is 0.45 g / cm 3 The mesh layer forms a protective layer with a thickness of 4mm; the thickness of the three-dimensional braided body is 10mm and the density is 0.6g / cm 3 .

[0113] The crucible preform was subjected to vapor deposition and graphitization treatment using the process method and parameters of Experimental Example 1 to obtain a carbon / carbon crucible.

[0114] Comparative Example 2:

[0115] The method for preparing the crucible preform in this comparative example is different from that in Experimental Example 1.

[0116] A protective layer consisting of alternately stacked mesh layers and carbon cloth layers is needle-punched on both the inner and outer sides of the three-dimensional braided body 1. The apparent density of the protective layer is 0.45 g / cm 3 The thickness of the protective layer is 4mm, the weight ratio of the mesh and carbon cloth is 1:5, the thickness of the three-dimensional braid is 10mm, and the density is 0.6g / cm 3 .

[0117] The crucible preform was subjected to vapor deposition and graphitization treatment using the process method and parameters of Experimental Example 1 to obtain a carbon / carbon crucible.

[0118] Comparative Example 3:

[0119] The preparation method of the intermediate layer of this comparative example is different from that of Experimental Example 1.

[0120] The carbon cloth and mesh tire are needle-punched into a whole to form an intermediate layer with a thickness of 10 mm and a density of 0.6 g / cm 3 ;

[0121] A protective layer is provided on both the inner and outer sides of the middle layer. The structure and preparation method of the protective layer are the same as those of the inner and outer protective layers of the three-dimensional braided body 1 in Experimental Example 1. The apparent density of the protective layer is 0.45 g / cm 3 The thickness of the protective layer is 4mm, and the weight ratio of the protective layer to the winding layer is 1:5.

[0122] The crucible preform was subjected to vapor deposition and graphitization treatment using the process method and parameters of Experimental Example 1 to obtain a carbon / carbon crucible.

[0123] The performance of the carbon / carbon crucibles prepared in Experimental Example 1 and Comparative Examples 1-3 was tested, and the results are shown in the following table.

[0124] The life of the crucible in the present invention refers to the total time used to straighten the single crystal, from the beginning of use until the first crack appears on the surface of the crucible.

[0125] The bulk density is tested in accordance with GB / T2997-2015 “Test method for bulk density, apparent porosity and true porosity of dense shaped refractory products”.

[0126] The flexural strength is determined in accordance with GB / T3001-2007 (normal temperature flexural strength test method).

[0127] The above description is merely a preferred embodiment of the present invention and does not constitute any form of limitation to the present invention. Although the present invention has been disclosed as above in terms of a preferred embodiment, it is not intended to limit the present invention. Any technician familiar with the present invention can make some changes or modifications to equivalent embodiments using the above-mentioned technical contents without departing from the scope of the technical solution of the present invention. The implementation schemes in the above-mentioned embodiments can be further combined or replaced. However, any simple modifications, equivalent changes and modifications made to the above-mentioned embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention are still within the scope of the solution of the present invention.

Claims

1. A braided crucible preform, characterized in that: include: Three-dimensional braided body (1); and, The protective layer (2) is arranged on the inner side and / or the outer side of the three-dimensional braided body (1) and is connected to the three-dimensional braided body (1) by needle puncture. The protective layer (2) comprises alternately arranged web layers and winding layers (5), wherein the winding density of each winding layer (5) gradually decreases in a direction away from the three-dimensional braided body (1).

2. The braided crucible preform according to claim 1, characterized in that: The winding layer (5) comprises: In a first winding layer, the carbon fiber filaments extend along the circumferential direction of the three-dimensional braided body (1) and are arranged along the axial direction of the three-dimensional braided body (1); In the second winding layer (51), the carbon fiber filaments extend along the axial direction of the three-dimensional braided body (1) and are arranged along the circumferential direction of the three-dimensional braided body (1).

3. The braided crucible preform according to claim 1, characterized in that: The winding layer (5) comprises: In the first winding layer, the carbon fiber filaments extend along the circumferential direction of the three-dimensional braided body (1) and are arranged along the axial direction of the three-dimensional braided body (1); or In the second winding layer (51), the carbon fiber filaments extend along the axial direction of the three-dimensional braided body (1) and are arranged along the circumferential direction of the three-dimensional braided body (1).

4. The braided crucible preform according to claim 2 or 3, characterized in that: The first winding layer and the second winding layer (51) respectively comprise a first sub-winding layer and a second sub-winding layer, the first sub-winding layer and the second sub-winding layer are arranged alternately in a direction away from the three-dimensional braided body (1), the carbon fiber filaments of the first sub-winding layer and the second sub-winding layer have opposite winding directions and the same winding angles, and the carbon fiber filaments of the first sub-winding layer and the second sub-winding layer cross each other to form a grid.

5. The braided crucible preform according to claim 4, characterized in that: A first web layer is provided between adjacent first winding layers or second winding layers (51), and between the first winding layer and the second winding layer (51); and / or, A second web layer is arranged between the first sub-wrap layer and the second sub-wrap layer of the same first and second wrap layers (51).

6. The braided crucible preform according to claim 5, characterized in that: The density of each web layer gradually decreases in a direction away from the three-dimensional woven body (1); or, The density of each first web layer gradually decreases in a direction away from the three-dimensional woven body (1); the density of each second web layer is the same and is less than or equal to the density of the first web layer farthest from the three-dimensional woven body (1); or, The density of each second web layer gradually decreases in the direction away from the three-dimensional woven body (1), and the density of the second web layer closest to the three-dimensional woven body (1) is less than or equal to the density of the first web layer farthest from the three-dimensional woven body (1).

7. The braided crucible preform according to claim 3, characterized in that: The web layer and the first winding layer are arranged alternately to form a first sub-protective layer (21), and the web layer and the second winding layer (51) are arranged alternately to form a second sub-protective layer (22); The first sub-protective layer (21) and the second sub-protective layer (22) are arranged in sequence along a direction away from the three-dimensional braided body (1).

8. The braided crucible preform according to claim 7, characterized in that: The three-dimensional braided body (1) comprises a vertically extending crucible portion (11) and a crucible bottom portion (12) which bends and extends from the lower end of the crucible portion (11) toward the direction close to the axis of the three-dimensional braided body (1); a first sub-protective layer (21) is arranged on the crucible portion (11), and a second sub-protective layer (22) is arranged on the crucible portion (11) and the crucible bottom portion (12).

9. The braided crucible preform according to claim 8, characterized in that: It also includes a filling layer (23) which is arranged between the second sub-protection layer (22) and the crucible bottom (12) of the three-dimensional braided body (1), and between the crucible bottom (12) and the crucible joint (11); The filling layer (23) includes a web layer, or the filling layer (23) includes a web layer and a carbon cloth layer arranged alternately; Preferably, the thickness of the filling layer (23) is greater than or equal to the thickness of the first sub-protective layer (21).

10. The braided crucible preform according to claim 5, characterized in that: The thickness of each web layer gradually decreases in a direction away from the three-dimensional woven body (1); or, The thickness of each first web layer gradually decreases in a direction away from the three-dimensional woven body (1), and the thickness of each second web layer is the same and is less than or equal to the thickness of the first web layer farthest from the three-dimensional woven body (1); or, The thickness of each second web layer gradually decreases in a direction away from the three-dimensional woven body (1), and the thickness of the second web layer closest to the three-dimensional woven body (1) is less than or equal to the thickness of the first web layer farthest from the three-dimensional woven body (1).

11. The braided crucible preform according to any one of claims 1 to 3, characterized in that: The three-dimensional braided body (1) comprises: Axial bars (4), comprising a plurality of bars arranged at intervals around the axis of the three-dimensional braided body (1), wherein the axial bars (4) comprise at least two axial bars arranged along the radial direction of the three-dimensional braided body (1); first carbon fiber filaments (31) for helically weaving axial strips (4) on the same circumference; The second carbon fiber filaments (32) are used to helically weave the axial strips (4) on adjacent circumferences, and the wave crests and wave troughs of the first carbon fiber filaments (31) and the second carbon fiber filaments (32) intersect with each other.

12. The braided crucible preform according to any one of claims 1 to 3, characterized in that: The three-dimensional braid (1) comprises a plurality of two-dimensional braid structures arranged in a radial direction, wherein the outer peripheral wall of an inner two-dimensional braid structure is in contact with the inner peripheral wall of an adjacent inner two-dimensional braid structure; and the two adjacent two-dimensional braid structures are connected by needle punching. Preferably, a layer of mesh is provided between two adjacent layers of the two-dimensional woven structure.

13. A method for manufacturing the braided crucible preform according to any one of claims 1 to 12, characterized in that: The following steps are involved: S1: firstly laying an EVA needle-punched mat on a wooden mold, then arranging a layer of mesh on the EVA needle-punched mat, and arranging a staggered winding layer (5) and a mesh layer on the outside of the mesh to form an inner protective layer; S2: placing the three-dimensional braided body (1) on the outside of the inner protective layer; S3: arranging a winding layer (5) and a mesh layer in staggered layers outside the three-dimensional braided body (1) to form an outer protective layer, and arranging a layer of mesh outside the outer protective layer; S4: Acupuncture.

14. A carbon / carbon crucible, characterized in that: The braided crucible preform is prepared by sequentially subjecting the braided crucible preform as claimed in any one of claims 1 to 12 to chemical vapor deposition and graphitization treatment.

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