Preparation method of integrated crucible preform based on multilayer structure

Abstract

The invention relates to a preparation method of an integrated crucible preform based on a multilayer structure, and belongs to the technical field of thermal field parts for monocrystalline silicon. Laying a carbon fiber net tire on the core mold and needling to form a net tire needling laying layer; a carbon cloth layer is laid on the net tire needling laying layer, then a carbon fiber net tire layer is laid, needling sewing is conducted, and a carbon cloth / net tire laminated needling laying layer is formed; winding carbon fiber yarns on the carbon cloth / net tire laminated needling laying layer to form a carbon fiber winding layer; the carbon cloth / net tire laminated needling paving layer and the carbon fiber winding layer form a paving layer unit, and after a plurality of paving layer units are overlaid on the net tire needling paving layer, heating is performed to achieve a hardening effect, so that preparation of the preform is completed. The preform prepared on the basis of the method not only meets the overall mechanical property requirement of the crucible, but also can improve the combination effect with a subsequent functional coating, so that the service life of the crucible can be effectively prolonged.

Description

Technical Field

[0001] The invention relates to a method for preparing an integrated crucible preform based on a multi-layer structure, and belongs to the technical field of thermal field components for single crystal silicon. Background Art

[0002] The single crystal silicon pulling furnace used in traditional single crystal silicon pulling is usually composed of a carbon / carbon crucible and a quartz crucible, that is, the quartz crucible is nested in the carbon / carbon crucible. The quartz crucible plays the role of carrying silicon materials to ensure the purity of silicon materials, while the carbon / carbon crucible plays the role of carrying the quartz crucible and providing strength support. The temperature inside the single crystal silicon pulling furnace is as high as 1500℃. The quartz crucible holding the silicon materials will have problems such as deformation and softening, and replacement is very frequent. About 1 carbon / carbon crucible will consume 12 to 18 quartz crucibles. In addition, the raw material quartz sand for the production of quartz crucibles is relatively scarce. In recent years, the rapid increase in the price of high-purity quartz sand and the imbalance between supply and demand have led to high crystal pulling costs.

[0003] Carbon / carbon composite materials are composite materials formed by carbon fiber or various carbon fabrics reinforced with carbon matrix. They have excellent properties such as low density, high specific strength, wear resistance, and high temperature resistance. They are currently widely used in aerospace, metallurgy, new energy and other fields. At present, researchers have proposed the use of "integrated carbon / carbon composite crucibles" to replace the traditional "combination of carbon / carbon crucibles and quartz crucibles". On the one hand, it can avoid the impact of the rapid rise in the price of high-purity quartz sand and reduce the material cost of crystal pulling. On the other hand, the integrated design can combine materials and performance into one, maximize its advantages, and further reduce product costs.

[0004] The integrated carbon / carbon composite crucible is obtained by densifying a carbon fiber preform and combining it with a high-performance coating on the surface. Among them, the carbon fiber preform is the blank for preparing the carbon / carbon composite crucible, which directly affects the service life of the crucible product. The carbon fiber preform is usually composed of carbon fiber woven cloth, carbon fiber mesh and carbon fiber filaments. For example, patent CN 111002435A discloses a weaving process for a carbon-carbon crucible preform for a single crystal silicon furnace, first laying a layer of plain cloth on the tooling, then laying a layer of mesh, and then evenly winding with fiber filaments in the horizontal and vertical directions, and then needle punching, and repeating this until the preform is completed; patent CN215250466U discloses a carbon / carbon / silicon carbide composite crucible preform, including carbon fiber plain cloth, carbon fiber mesh and carbon fiber filaments, the carbon fiber mesh is laid on the carbon fiber plain cloth to form a layer unit, the carbon fiber filaments are cross-wound on the outside of each layer of the layer unit along the inclined direction, and each layer unit is stacked layer by layer to a predetermined thickness, and needle punching and stitching are performed in the thickness direction to form a crucible preform. Although the above-mentioned carbon fiber preform has high mechanical strength and good shaping effect, due to the presence of carbon fiber woven cloth on its inner surface, the surface roughness is low and the bonding with subsequent functional coating is poor, which will greatly affect the service life of the crucible product. Summary of the invention

[0005] In view of the problem that the preform in the current integrated crucible has poor bonding with the subsequent functional coating, the present invention provides a method for preparing an integrated crucible preform based on a multi-layer structure. The preform adopts an isotropic pure mesh tire needle-punched layer as the surface layer combined with the subsequent functional coating, which can improve the bonding effect with the subsequent functional layer; a carbon cloth / mesh tire laminated needle-punched layer combined with a carbon fiber winding layer is adopted as the external supporting structure of the pure mesh tire needle-punched layer to provide mechanical support for the preform as a whole. The integrated crucible prepared based on the preform can effectively improve the service life of the crucible product on the basis of meeting the mechanical properties.

[0006] The objectives of the present invention are achieved through the following technical solutions.

[0007] The method for preparing an integrated crucible preform based on a multi-layer structure comprises the following steps:

[0008] (1) laying a carbon fiber web on a core mold and performing acupuncture to form a web needle-punched layer;

[0009] (2) first laying a carbon cloth layer on the mesh needle-punched ply formed in step (1), then laying a carbon fiber mesh layer on the carbon cloth layer, and needle-punching and sewing the laid carbon fiber mesh layer and the carbon cloth layer to form a carbon cloth / mesh laminate needle-punched ply; finally, winding carbon fiber filaments on the carbon cloth / mesh laminate needle-punched ply to form a carbon fiber winding layer, and the carbon cloth / mesh laminate needle-punched ply and the carbon fiber winding layer constitute a ply unit;

[0010] (3) Repeating the operation of step (2) multiple times, stacking multiple ply units on the ply unit formed in step (2) until the desired thickness of the preform is reached (i.e., the surface of the carbon fiber winding layer formed in step (2) forms an alternating stacking structure of carbon cloth / net tire stacking needle punching ply and carbon fiber winding layer, until the desired thickness of the preform is reached after the last winding of carbon fiber filaments), then all ply units constitute an external support stack, and a preform precursor is obtained at this time;

[0011] (4) The preform precursor obtained in step (3) is heated to achieve a hardening effect, thereby obtaining an integrated crucible preform based on a multilayer structure.

[0012] Furthermore, the carbon fiber mat is a thin felt made of chopped carbon fiber with a surface density of 50 to 500 g / m 2 .

[0013] Furthermore, the needle-punching density of the web needle-punched layer is 10 to 50 needles / cm 2 The acupuncture depth is 5 to 10 mm.

[0014] Furthermore, the surface density of the carbon cloth used to lay the carbon cloth layer is 200 to 800 g / m 2 .

[0015] Furthermore, the needle-punching density of the carbon cloth / web layer is 10 to 50 needles / cm 2 The acupuncture depth is 5 to 10 mm.

[0016] Furthermore, the thickness of the web needle-punched layer is 100 to 200 mm.

[0017] Furthermore, the thickness of a ply unit is 10-20 mm; in a ply unit, the thickness of the carbon cloth layer is preferably 5-10 mm, the thickness of the carbon fiber mesh layer is preferably 4-8 mm, and the thickness of the carbon fiber winding layer is preferably 1-2 mm.

[0018] Furthermore, the carbon fiber filaments in the carbon fiber winding layer are wound along a direction that is ±45° with respect to the axial direction of the preform.

[0019] Furthermore, according to the structure of the integrated crucible, from the upper part to the lower part of the crucible along its depth direction, it is divided into a crucible straight tube section, a crucible R-angle transition section, and a crucible bottom surface. Then, the thickness of the outer support laminate of the straight tube section of the crucible in the preform is less than the thickness of the outer support laminate of the crucible R-angle transition section, and the thickness of the outer support laminate of the crucible R-angle transition section is less than the thickness of the outer support laminate of the crucible bottom surface.

[0020] Furthermore, the thickness of the outer support stack of the crucible straight tube section, the crucible R angle transition section and the crucible bottom surface in the preform are 100-300 mm, 200-400 mm and 300-600 mm respectively.

[0021] Furthermore, the straight section of the crucible, the R-angle transition section of the crucible and the bottom surface of the crucible adopt laying units of different thicknesses to achieve different thicknesses of the external support stack in different areas. The thicknesses of the laying units adopted in the straight section of the crucible, the R-angle transition section of the crucible and the bottom surface of the crucible are 10-20 mm, 15-30 mm and 20-40 mm respectively, and the difference in thickness of the laying units in different areas is caused by the different thicknesses of the carbon cloth layer, that is, the thickness of the carbon cloth layer laid in the corresponding area of ​​the crucible R-angle transition section and the bottom surface of the crucible is greater than the thickness of the carbon cloth layer laid in the corresponding area of ​​the straight section of the crucible.

[0022] Furthermore, the specific laying operation of the lamination unit in the outer support stack is as follows: first, a whole carbon cloth is laid, and the carbon cloth layer of the straight section of the crucible is formed after the whole carbon cloth is laid, and the R-angle transition section of the crucible and the bottom of the crucible need to be stacked with carbon cloth of the required thickness in their corresponding areas on the basis of the whole carbon cloth laying, thus forming the carbon cloth layer of the R-angle transition section of the crucible and the carbon cloth layer of the bottom of the crucible; then, carbon fiber mesh tires are laid on the carbon cloth layers in three different areas, and needle-punched and sewed to form carbon cloth / mesh tire laminated needle-punched layers in three different areas; finally, carbon fiber filaments are continuously wound on the carbon cloth / mesh tire laminated needle-punched layers in three different areas to form a carbon fiber winding layer.

[0023] Furthermore, in step (4), the heating temperature is 80 to 200° C., and the heating time is 5 to 10 hours.

[0024] Furthermore, the preparation step of the inner support layer is also included before the web needle-punched ply, and the preparation step of the inner support layer is the same as the preparation step of a ply unit in step (2), that is, according to the operation of step (2), a ply unit is first formed on the mandrel, i.e., the inner support layer, and then the carbon fiber web is plyed and needle-punched on the inner support layer to form the web needle-punched ply. Accordingly, the thickness of the inner support layer is preferably 10 to 20 mm.

[0025] Furthermore, the density of the integrated crucible preform based on the multi-layer structure without the inner support layer is 0.40-0.50 g / cm 3 , containing an inner support layer with a density of 0.45 to 0.55 g / cm 3 .

[0026] It should be noted that in the subsequent process of preparing a crucible, after the preform containing an inner support layer is densified, the inner support layer must be completely removed to expose the mesh needle-punched layer, and then the required functional coating is prepared on the mesh needle-punched layer. The preform contains an inner support layer because the double-layer preform structure of the mesh needle-punched layer combined with the outer support layer still has the problem of easy deformation of the preform during the chemical vapor deposition densification process, resulting in a decrease in the yield rate and an increase in manufacturing costs; adding an inner support layer can effectively improve the deformation problem of the preform structure and reduce manufacturing costs.

[0027] Beneficial effects:

[0028] (1) The preform described in the present invention uses a pure mesh tire needle-punched ply as the surface layer combined with the subsequent functional coating, because the isotropic structure presented by the pure mesh tire needle-punched ply has a certain roughness and uniform surface quality, which is not only conducive to the preparation of the subsequent functional coating, but also improves the bonding performance between the functional coating and the crucible substrate, thereby effectively improving the service life of the crucible product; the external support structure composed of the carbon cloth / mesh tire laminated needle-punched ply and the carbon fiber winding layer has high strength, low density and thin thickness, and can provide good mechanical support for the preform as a whole. Therefore, when the preform prepared based on the method described in the present invention is used to produce crucible products, it can effectively improve the service life of the crucible products on the basis of meeting the mechanical properties.

[0029] (2) Based on the structural characteristics of the crucible itself, it can be seen that the stress concentration is the greatest at the R corner, which is prone to fatigue cracks. Increasing the thickness here can effectively make the straight tube section transition smoothly to the bottom surface, reducing the stress concentration problem at the R corner; in addition, affected by the actual working conditions, the R corner and the bottom surface are most affected by the gravity of the silicon melt. Increasing the thickness of these two places can effectively prevent the occurrence of "silicon leakage"; and setting different thicknesses for different areas can effectively reduce the overall weight of the preform and reduce the manufacturing cost of the preform while ensuring the mechanical properties of the preform.

[0030] (3) The preform described in the present invention is also provided with an inner support layer. The setting of the inner support layer can effectively improve the deformation problem of the double-layer preform structure of the mesh tire needle-punched layer combined with the outer support layer, and reduce the manufacturing cost; the inner support layer is a carbon cloth / mesh tire laminated needle-punched layer-carbon fiber winding layer structure, and it is still an anisotropic structure after densification treatment, which is not conducive to the preparation of subsequent functional coatings. Therefore, when preparing the crucible product subsequently, it is necessary to first remove the inner support layer after the densification treatment, so that the exposed mesh tire needle-punched layer after the densification treatment is in contact with the subsequent functional coating, which can ensure a good bonding effect of the functional coating. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 Schematic diagram of the structure of the integrated crucible preform based on the multi-layer structure prepared in Example 1.

[0032] Figure 2 Schematic diagram of the structure of the integrated crucible preform based on the multi-layer structure prepared in Example 4.

[0033] Among them, 1-net tire needle punching layer, 2-external support laminate, 3-inner support layer. DETAILED DESCRIPTION

[0034] The present invention is further described below in conjunction with specific embodiments, wherein the methods are conventional methods unless otherwise specified, and the raw materials can be obtained from public commercial channels unless otherwise specified. In addition, in the description of the present invention, it should be understood that the orientations or positional relationships indicated by the terms "upper", "lower", "front", "back", "left", "right", "top", "bottom", "inside", "outside", etc. are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation to the present invention.

[0035] Example 1

[0036] The method for preparing an integrated crucible preform based on a multi-layer structure comprises the following steps:

[0037] (1) The surface density of the coating on the core is 50g / m 2 The carbon fiber web is needle-punched to form a web needle-punched layer 1 with a thickness of 100 mm;

[0038] The acupuncture density is 10 needles / cm 2 , the needle puncture depth is 5mm; the core mold is made according to the inner surface structure and size of the integrated crucible;

[0039] (2) First, use a sheet with a thickness of 5 mm and a surface density of 200 g / m 2A whole piece of carbon cloth is laid on the mesh tire needle-punched layer 1. After laying a whole piece of carbon cloth, the carbon cloth layer of the straight section of the crucible is formed, and the crucible R angle transition section needs to be superimposed with a layer of small carbon cloth with a thickness of 5mm on the basis of the whole carbon cloth layer to thicken the area to form the carbon cloth layer of the crucible R angle transition section, and the bottom surface of the crucible also needs to be superimposed with two layers of small carbon cloth with a thickness of 5mm on the basis of the whole carbon cloth layer to thicken the area to form the carbon cloth layer of the bottom surface of the crucible; then A carbon fiber mesh is laid on the carbon cloth layer in three different areas of the ferry section and the bottom of the crucible to form a carbon fiber mesh layer with a thickness of 4 mm, and then needle-punched and sewn, so that carbon cloth / mesh laminated needle-punched layers with thicknesses of 9 mm, 14 mm, and 19 mm are formed in the three different areas respectively; finally, carbon fiber filaments are continuously wound on the carbon cloth / mesh laminated needle-punched layers in the three different areas along a direction of ±45° with the axial direction of the preform to form a carbon fiber winding layer, and the thickness of the carbon fiber winding layer is 1 mm;

[0040] Among them, according to the structure of the integrated crucible, from the upper part to the lower part of the crucible along its depth direction, it is divided into a crucible straight section, a crucible R angle transition section, and a crucible bottom surface; the carbon cloth / net tire laminated needle-punched layer and the carbon fiber winding layer form a layer unit, and the thickness of the layer unit of the crucible straight section, the thickness of the layer unit of the crucible R angle transition section, and the thickness of the layer unit of the crucible bottom surface are 10mm, 15mm, and 20mm respectively; the needle density of the carbon cloth / net tire laminated needle-punched layer is 10 needles / cm 2 , the acupuncture depth is 5 mm;

[0041] (3) Repeating the operation of step (2) multiple times, forming an alternating stacking structure of carbon cloth / mesh laminated needle-punched layers followed by carbon fiber winding layers on the surface of the carbon fiber winding layer in step (2) (i.e., stacking multiple layer units on the layer units formed in step (2)), until the desired thickness of the preform is reached after the last winding of the carbon fiber filaments, thereby obtaining a preform precursor;

[0042] Among them, all the ply units stacked in sequence on the mesh needle-punched ply 1 constitute an outer support laminate 2 for supporting the mesh needle-punched ply 1, and the number of ply units laid in different areas is 15 layers. The thickness of the outer support laminate 2 of the straight tube section of the crucible, the thickness of the outer support laminate 2 of the R-angle transition section of the crucible, and the thickness of the outer support laminate 2 of the bottom surface of the crucible are 150 mm, 225 mm, and 300 mm, respectively. It should be noted that a support boss protruding to the outside of the crucible is usually provided in the middle area of ​​the bottom surface of the crucible, such as Figure 1As shown, the support boss is formed by adding an additional number of carbon cloth layers to the support boss area during the layering process of the bottom surface of the crucible. The protruding thickness of the support boss can be in the range of 15 to 30 mm. Since the support boss does not affect the overall mechanical properties of the crucible, the present invention does not limit the support boss and can be set according to needs in practical applications.

[0043] (4) The preform precursor obtained in step (3) is placed at 80° C. for 10 h to achieve a hardening effect, and a density of 0.40 g / cm 3 An integrated crucible preform based on a multi-layer structure.

[0044] Example 2

[0045] The method for preparing an integrated crucible preform based on a multi-layer structure comprises the following steps:

[0046] (1) Lay the surface density on the core mold at 300g / m 2 The carbon fiber web is needle-punched to form a web needle-punched layer 1 with a thickness of 150 mm;

[0047] Among them, the acupuncture density is 30 needles / cm 2 , the needle puncture depth is 8mm; the core mold is made according to the inner surface structure and size of the integrated crucible;

[0048] (2) First, use a sheet with a thickness of 8 mm and a surface density of 500 g / m 2 A whole piece of carbon cloth is laid on the mesh tire needle-punched layer 1. After laying a whole piece of carbon cloth, the carbon cloth layer of the straight section of the crucible is formed, and the crucible R angle transition section needs to be superimposed with a layer of small carbon cloth with a thickness of 8mm on the basis of the whole carbon cloth layer to thicken the area to form the carbon cloth layer of the crucible R angle transition section, and the bottom surface of the crucible also needs to be superimposed with two layers of small carbon cloth with a thickness of 8mm on the basis of the whole carbon cloth layer to thicken the area to form the carbon cloth layer of the bottom surface of the crucible; then A carbon fiber mesh is laid on the carbon cloth layer in three different areas of the ferry section and the bottom of the crucible to form a carbon fiber mesh layer with a thickness of 6 mm, and then needle-punched and sewn, so that carbon cloth / mesh laminated needle-punched layers with thicknesses of 14 mm, 22 mm, and 30 mm are formed in the three different areas respectively; finally, carbon fiber yarns are continuously wound on the carbon cloth / mesh laminated needle-punched layers in the three different areas along a direction of ±45° with the axial direction of the preform to form a carbon fiber winding layer, and the thickness of the carbon fiber winding layer is 1 mm;

[0049] Among them, according to the structure of the integrated crucible, from the upper part to the lower part of the crucible along its depth direction, it is divided into a crucible straight section, a crucible R angle transition section, and a crucible bottom surface; the carbon cloth / net tire laminated needle-punched layer and the carbon fiber winding layer form a layer unit, and the thickness of the layer unit of the crucible straight section, the thickness of the layer unit of the crucible R angle transition section, and the thickness of the layer unit of the crucible bottom surface are 15mm, 23mm, and 31mm respectively; the needle density of the carbon cloth / net tire laminated needle-punched layer is 20 needles / cm 2 , the acupuncture depth is 8 mm;

[0050] (3) Repeating the operation of step (2) multiple times, forming an alternating stacking structure of carbon cloth / mesh laminated needle-punched layers followed by carbon fiber winding layers on the surface of the carbon fiber winding layer in step (2) (i.e., stacking multiple layer units on the layer units formed in step (2)), until the desired thickness of the preform is reached after the last winding of the carbon fiber filaments, thereby obtaining a preform precursor;

[0051] Among them, all the ply units stacked in sequence on the mesh needle-punched ply 1 constitute an outer support laminate 2 for supporting the mesh needle-punched ply 1, and the number of ply units laid in different areas is 16 layers. The thickness of the outer support laminate 2 of the straight section of the crucible, the thickness of the outer support laminate 2 of the R-angle transition section of the crucible, and the thickness of the outer support laminate 2 on the bottom of the crucible are 240 mm, 368 mm, and 496 mm, respectively.

[0052] (4) The preform precursor obtained in step (3) was placed at 150° C. for 8 h to achieve a hardening effect, and a density of 0.46 g / cm 3 An integrated crucible preform based on a multi-layer structure.

[0053] Example 3

[0054] The method for preparing an integrated crucible preform based on a multi-layer structure comprises the following steps:

[0055] (1) Lay the surface density on the core mold with 500g / m 2 The carbon fiber web is needle-punched to form a web needle-punched layer 1 with a thickness of 200 mm;

[0056] The acupuncture density is 50 needles / cm 2 , the needle puncture depth is 10mm; the core mold is made according to the inner surface structure and size of the integrated crucible;

[0057] (2) First, use a sheet with a thickness of 10 mm and a surface density of 800 g / m 2The whole carbon cloth is laid on the mesh tire needle-punched layer 1. After laying a whole carbon cloth, the carbon cloth layer of the straight section of the crucible is formed, and the crucible R angle transition section needs to be stacked with a layer of small carbon cloth with a thickness of 10mm on the basis of the whole carbon cloth layer to thicken the area to form the carbon cloth layer of the crucible R angle transition section, and the bottom surface of the crucible also needs to be stacked with two layers of small carbon cloth with a thickness of 10mm on the basis of the whole carbon cloth layer to thicken the area to form the carbon cloth layer of the bottom surface of the crucible; then A carbon fiber mesh is laid on the carbon cloth layer in the transition section and the three different areas of the bottom surface of the crucible to form a carbon fiber mesh layer with a thickness of 8 mm, and then needle-punched and sewn, so that carbon cloth / mesh laminated needle-punched layers with thicknesses of 18 mm, 28 mm, and 38 mm are formed in the three different areas respectively; finally, carbon fiber yarns are continuously wound on the carbon cloth / mesh laminated needle-punched layers in the three different areas along a direction of ±45° with the axial direction of the preform to form a carbon fiber winding layer, and the thickness of the carbon fiber winding layer is 2 mm;

[0058] Among them, according to the structure of the integrated crucible, from the upper part to the lower part of the crucible along its depth direction, it is divided into a crucible straight section, a crucible R angle transition section, and a crucible bottom surface; the carbon cloth / net tire laminated needle-punched layer and the carbon fiber winding layer form a layer unit, and the thickness of the layer unit of the crucible straight section, the thickness of the layer unit of the crucible R angle transition section, and the thickness of the layer unit of the crucible bottom surface are 20mm, 30mm, and 40mm respectively; the needle density of the carbon cloth / net tire laminated needle-punched layer is 50 needles / cm 2 , the acupuncture depth is 10 mm;

[0059] (3) Repeating the operation of step (2) multiple times, forming an alternating stacking structure of carbon cloth / mesh laminated needle-punched layers followed by carbon fiber winding layers on the surface of the carbon fiber winding layer in step (2) (i.e., stacking multiple layer units on the layer units formed in step (2)), until the desired thickness of the preform is reached after the last winding of the carbon fiber filaments, thereby obtaining a preform precursor;

[0060] Among them, all the ply units stacked in sequence on the mesh needle-punched ply 1 constitute an outer support laminate 2 for supporting the mesh needle-punched ply 1, and the number of ply units laid in different areas is 13 layers. The thickness of the outer support laminate 2 of the straight section of the crucible, the thickness of the outer support laminate 2 of the R-angle transition section of the crucible, and the thickness of the outer support laminate 2 on the bottom of the crucible are 260 mm, 390 mm, and 520 mm, respectively.

[0061] (4) The preform precursor obtained in step (3) was placed at 200°C for 5 hours to achieve a hardening effect, and a density of 0.50 g / cm 3 An integrated crucible preform based on a multi-layer structure.

[0062] The specific steps of preparing a crucible product based on the integrated crucible preform obtained in step (4) of Example 3 are as follows:

[0063] The density is 0.50g / cm 3 The integrated crucible preform is densified by chemical vapor infiltration combined with resin impregnation and carbonization to obtain a density of 1.60g / cm 3 A carbon / carbon composite crucible body;

[0064] A glassy carbon coating with a thickness of 50 μm was prepared on the surface of the carbon / carbon composite crucible body by using an impregnation curing-carbonization process, namely: first, furfural resin was used for impregnation at an impregnation pressure of 1.0 MPa for 0.5 h, then heated to 100 °C at a heating rate of 1 °C / h and cured at 100 °C for 3 h, then heated to 900 °C at a heating rate of 1 °C / h and carbonized at 900 °C for 5 h;

[0065] Yttrium oxide with a purity of 99.999% and a particle size of 100 μm is used as raw material, and a plasma spraying process is adopted to prepare a yttrium oxide coating with a thickness of 500 μm on the surface of the glassy carbon coating, thereby completing the preparation of the crucible product; wherein, nitrogen is used as a protective gas and hydrogen is used as an anti-oxidation gas in the spraying process, and the nitrogen pressure is 3.0 MPa, and the hydrogen pressure is 2.0 MPa. The voltage of the plasma arc used for spraying is 120 V, the current is 900 A, and the spraying distance is 30 mm.

[0066] The prepared crucible product was subjected to a thermal shock treatment from 1500°C to room temperature, and after 6 cycles, the coating on the carbon / carbon composite crucible body was still intact.

[0067] Example 4

[0068] On the basis of Example 1, step (1) further includes a step of preparing an inner support layer 3 before forming the web needle-punched ply 1, namely:

[0069] First, a sheet with a thickness of 5 mm and a surface density of 200 g / m 2The whole carbon cloth is laid on the core mold to form a carbon cloth layer, and then a carbon fiber mesh is laid on the carbon cloth layer to form a carbon fiber mesh layer with a thickness of 4 mm, and the laid carbon fiber mesh layer and the carbon cloth layer are needle-punched and sewn to form a carbon cloth / mesh laminate needle-punched ply with a thickness of 9 mm; finally, carbon fiber filaments are continuously wound on the carbon cloth / mesh laminate needle-punched ply along the direction of ±45° with the axial direction of the preform to form a carbon fiber winding layer, and the carbon cloth / mesh laminate needle-punched ply and the carbon fiber winding layer constitute an inner support layer 3 with a thickness of 10 mm; then, according to the operating steps and conditions of steps (1) to (3) of Example 1, a mesh needle-punched ply 1 and an outer support laminate 2 are formed on the inner support layer 3 in sequence, and then heat-treated according to the conditions of step (4) of Example 1 to achieve a hardening effect, and a density of 0.41 g / cm 3 An integrated crucible preform based on a multilayer structure, such as Figure 2 shown.

[0070] Compared with Example 1, Example 4 further provides an inner support layer 3 inside the mesh needle-punched layer 1. The mechanical properties of the crucible preforms obtained in Example 1 and Example 4 were tested, that is, 5 test samples were taken from different positions of the outer support laminate 2 area of ​​the crucible preforms in Example 1 and Example 4, each sample having a size of 40 mm×40 mm×50 mm, and then interlayer tensile strength tests were performed on different samples. The average test results of the 5 samples are as follows:

[0071] Prefab Type Tensile strength(MPa) Crucible preform of Example 1 0.40 Crucible preform of Example 4 0.42

[0072] Comparative Example 1

[0073] The method for preparing an integrated crucible preform based on a pure mesh structure comprises the following steps:

[0074] (1) A carbon fiber mesh is laid on a wooden core mold and needle punched, wherein the carbon fiber mesh is made of short-cut carbon fiber with a surface density of 50 g / m 2 The felt has a needle density of 10 needles / cm 2 , the needling depth is 5 mm; the wooden core mold is made based on the inner surface structure and size of the integrated crucible;

[0075] (2) repeating the operation of step (1) multiple times, that is, continuing to lay a carbon fiber web on the web layer obtained in step (1) and performing acupuncture to form a stacked structure of multiple web layers until the desired thickness of the preform is reached, thereby obtaining a preform precursor;

[0076] According to the structure of the integrated crucible, the crucible is divided into a straight section, a R-angle transition section, and a bottom surface of the crucible in sequence from the upper part to the lower part along its depth direction. Different numbers of layering units are used to make the thickness of the straight section, the thickness of the R-angle transition section, and the thickness of the bottom surface of the crucible 250 mm, 325 mm, and 400 mm, respectively.

[0077] (3) The preform precursor obtained in step (2) was placed at 80° C. for 10 h to obtain a preform with a density of 0.30 g / cm based on a pure web structure. 3 An integrated crucible preform.

[0078] Compared with Example 1, Comparative Example 1 only has a mesh needle-punched layer 1, and no outer support laminate 2. The mechanical properties of the crucible preforms obtained in Example 1 and Comparative Example 1 were tested, that is, 5 test samples were taken from different positions of the outer support laminate 2 region of the crucible preform described in Example 1, and 5 test samples were taken from different regions of the crucible preform described in Comparative Example 1, each sample having a size of 40 mm × 40 mm × 50 mm, and then the interlayer tensile strength test was performed on different samples, and the average test results of the 5 samples were as follows:

[0079] Prefab Type Tensile strength(MPa) Crucible preform of Example 1 0.40 Crucible preform of Comparative Example 1 0.04

[0080] Comparative Example 2

[0081] On the basis of Example 2, except that the operation of preparing the web needle-punched layer 1 on the mandrel in step (1) of Example 2 is omitted, the outer support laminate 2 is directly prepared on the mandrel according to the operation steps and conditions of steps (2) to (3) of Example 2, and then the outer support laminate 2 is heat-treated according to the conditions of step (4) of Example 2, and the density is correspondingly obtained. 0.45 g / cm 3 An integrated crucible preform.

[0082] Compared with Example 2, Comparative Example 2 does not have a mesh needle-punched layer 1, but only an outer support laminate 2. The mechanical properties of the crucible preforms obtained in Example 2 and Comparative Example 2 were tested, that is, 5 test samples were taken from different positions of the outer support laminate 2 region of the crucible preforms described in Example 2 and Comparative Example 2, each sample having a size of 40 mm×40 mm×50 mm, and then the interlayer tensile strength test was performed on the different samples, and the average test results of the 5 samples were as follows:

[0083] Prefab Type Tensile strength(MPa) Crucible preform of Example 2 0.52 Crucible preform of comparative example 2 0.50

[0084] The specific steps of preparing a crucible product based on the integrated crucible preform obtained in Example 2 and Comparative Example 2 are as follows:

[0085] The density of the prepared sample in Example 2 is 0.46 g / cm3 The density of the integrated crucible preform prepared in Example 2 is 0.45 g / cm 3 The integrated crucible preforms were densified by chemical vapor infiltration combined with resin impregnation and carbonization, and the density was 1.60 g / cm 3 A carbon / carbon composite crucible body;

[0086] The glassy carbon coating with a thickness of 50 μm was prepared on the surface of the two carbon / carbon composite crucible bodies obtained above by the impregnation curing-carbonization process, namely: first, furfural resin was used for impregnation at an impregnation pressure of 1.0 MPa for 0.5 h, then heated to 100°C at a heating rate of 1°C / h and cured at 100°C for 3 h, and then heated to 900°C at a heating rate of 1°C / h and carbonized at 900°C for 5 h;

[0087] Using yttrium oxide with a purity of 99.999% and a particle size of 100μm as raw material, a plasma spraying process was adopted to prepare a yttrium oxide coating with a thickness of 500μm on the surface of the above-mentioned glassy carbon coating, thereby completing the preparation of two crucible products; wherein, nitrogen was used as a protective gas and hydrogen as an anti-oxidation gas in the spraying process, and the nitrogen pressure was 3.0MPa, the hydrogen pressure was 2.0MPa, the voltage of the plasma arc used for spraying was 120V, the current was 900A, and the spraying distance was 30mm.

[0088] The two prepared crucible products were subjected to a thermal shock treatment from 1500°C to room temperature. For the crucible product prepared based on the integrated crucible preform described in Example 2, the coating on the carbon / carbon composite material crucible body was still intact after 5 cycles; while for the crucible product prepared based on the integrated crucible preform described in Comparative Example 2, the coating on the carbon / carbon composite material crucible body fell off after 2 cycles.

[0089] In summary, the above are only preferred embodiments of the present invention and are not intended to limit the protection scope of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing an integrated crucible preform based on a multi-layer structure, characterized in that: The following steps are involved: (1) laying a carbon fiber web on a core mold and performing acupuncture to form a web needle-punched layer; (2) first laying a carbon cloth layer on the mesh needle-punched ply formed in step (1), then laying a carbon fiber mesh layer on the carbon cloth layer, and needle-punching and sewing the laid carbon fiber mesh layer and the carbon cloth layer to form a carbon cloth / mesh laminate needle-punched ply; finally, winding carbon fiber filaments on the carbon cloth / mesh laminate needle-punched ply to form a carbon fiber winding layer, and the carbon cloth / mesh laminate needle-punched ply and the carbon fiber winding layer constitute a ply unit; (3) Repeating the operation of step (2) multiple times, stacking multiple ply units on the ply unit formed in step (2) until the required thickness of the preform is reached, and all the ply units constitute an external support stack, thereby obtaining a preform precursor; (4) The preform precursor obtained in step (3) is heated to achieve a hardening effect, thereby obtaining an integrated crucible preform based on a multilayer structure.

2. The method for preparing an integrated crucible preform based on a multi-layer structure according to claim 1, characterized in that: The carbon fiber mat is a thin felt made of chopped carbon fiber with a surface density of 50 to 500 g / m 2 ; or / and, the surface density of the carbon cloth used for laying the carbon cloth layer is 200 to 800 g / m 2 ; Or / and, the needle-punching density of the web needle-punched layer is 10 to 50 needles / cm 2 , the acupuncture depth is 5 to 10 mm; Or / and, the needle-punching density of the carbon cloth / net tire laminated needle-punching layer is 10 to 50 needles / cm 2 The acupuncture depth is 5 to 10 mm.

3. The method for preparing an integrated crucible preform based on a multilayer structure according to claim 1 or 2, characterized in that: The thickness of the web needle-punched layer is 100 to 200 mm; Or / and, the density of the integrated crucible preform based on the multilayer structure is 0.40-0.50 g / cm 3 .

4. The method for preparing an integrated crucible preform based on a multilayer structure according to claim 1 or 2, characterized in that: The thickness of one ply unit is 10-20 mm; in one ply unit, the thickness of the carbon cloth layer is 5-10 mm, the thickness of the carbon fiber mesh layer is 4-8 mm, and the thickness of the carbon fiber winding layer is 1-2 mm.

5. The method for preparing an integrated crucible preform based on a multi-layer structure according to claim 1 or 2, characterized in that: According to the structure of the integrated crucible, the crucible is divided into a straight section of the crucible, a R-angle transition section of the crucible, and a bottom surface of the crucible in sequence along its depth direction from the upper part to the lower part. The thickness of the outer support laminate of the straight section of the crucible in the preform is less than the thickness of the outer support laminate of the R-angle transition section of the crucible, and the thickness of the outer support laminate of the R-angle transition section of the crucible is less than the thickness of the outer support laminate of the bottom surface of the crucible.

6. The method for preparing an integrated crucible preform based on a multi-layer structure according to claim 5, characterized in that: The thicknesses of the outer support stacking layer of the crucible straight tube section, the crucible R angle transition section and the crucible bottom surface in the preform are 100-300mm, 200-400mm and 300-600mm respectively.

7. The method for preparing an integrated crucible preform based on a multi-layer structure according to claim 6, characterized in that: The crucible straight section, crucible R angle transition section and crucible bottom surface use ply units of different thicknesses to achieve different thicknesses of the external support stack in different areas. The thicknesses of the ply units used in the crucible straight section, crucible R angle transition section and crucible bottom surface are 10-20 mm, 15-30 mm and 20-40 mm respectively, and the difference in thickness of the ply units in different areas is caused by the different thicknesses of the carbon cloth layer. Or / and, the thickness of the mesh needle-punched layer is 100-200 mm; Or / and, the density of the integrated crucible preform based on the multilayer structure is 0.40-0.50 g / cm 3 .

8. The method for preparing an integrated crucible preform based on a multi-layer structure according to claim 1, characterized in that: The heating temperature in step (4) is 80 to 200° C. and the heating time is 5 to 10 hours.

9. The method for preparing an integrated crucible preform based on a multi-layer structure according to claim 1 or 2, characterized in that: The preparation step of the inner support layer is also included before the mesh needle-punched ply, and the preparation step of the inner support layer is the same as the preparation step of a ply unit in step (2), that is, according to the operation of step (2), a ply unit is first formed on the core mold, which is the inner support layer, and then the carbon fiber mesh is laid on the inner support layer and needle-punched to form a mesh needle-punched ply.

10. The method for preparing an integrated crucible preform based on a multi-layer structure according to claim 9, characterized in that: The thickness of the inner support layer is 10 to 20 mm; Or / and, the thickness of the mesh needle-punched layer is 100-200 mm; Or / and, according to the structure of the integrated crucible, the crucible is divided into a straight section of the crucible, a R-angle transition section of the crucible, and a bottom surface of the crucible in sequence from the upper part to the lower part along its depth direction, then the thickness of the outer support laminate of the straight section of the crucible in the preform is less than the thickness of the outer support laminate of the R-angle transition section of the crucible, the thickness of the outer support laminate of the R-angle transition section of the crucible is less than the thickness of the outer support laminate of the bottom surface of the crucible, and the thickness of the outer support laminate of the straight section of the crucible, the R-angle transition section of the crucible, and the bottom surface of the crucible are 100-300 mm, 200-400 mm, and 300-600 mm, respectively; Or / and, an integrated crucible preform based on a multilayer structure, containing an inner support layer with a density of 0.45 to 0.55 g / cm 3 .

Images