Integrated crucible preform based on multilayer structure

Abstract

The utility model relates to an integrated crucible preform based on a multilayer structure, and belongs to the technical field of thermal field components for monocrystalline silicon. The prefabricated body comprises a pure net tire needling laying layer and an alternate superposition structure which is formed on the outer surface of the pure net tire needling laying layer and comprises a carbon cloth / net tire laminated needling laying layer and a carbon fiber winding layer, and the carbon fiber winding layer is arranged on the outermost layer of the prefabricated body. According to the prefabricated body, the isotropic pure net tire needling laying layer is adopted as an inner surface layer combined with a subsequent functional coating, and the combination effect with the subsequent functional coating can be improved; an alternate laminated structure composed of a carbon cloth / net tire laminated needling paving layer and a carbon fiber winding layer is adopted as an external supporting structure to provide mechanical support for the whole preform, so that the service life of an integrated crucible prepared on the basis of the preform can be effectively prolonged on the basis of meeting the mechanical property.

Description

TECHNICAL FIELD

[0001] The utility model relates to a kind of integrated crucible preform based on multilayer structure, belong to single crystal silicon with hot field component technical field. BACKGROUND

[0002] The single crystal silicon pulling furnace used in traditional single crystal silicon pulling is generally composed of carbon / carbon crucible and quartz crucible, i.e. the quartz crucible is nested in the carbon / carbon crucible, the quartz crucible serves to carry the silicon material and ensure the purity of the silicon material, while the carbon / carbon crucible serves to carry the quartz crucible and provide strength support. The temperature in the single crystal silicon pulling furnace is as high as 1500℃, and the quartz crucible containing the silicon material will deform and soften, which needs to be replaced frequently. About 12-18 pieces of quartz crucible will be consumed by one piece of carbon / carbon crucible. In addition, the raw material quartz sand for producing quartz crucible is relatively scarce, and the price of high-purity quartz sand has risen rapidly in recent years and the supply and demand are unbalanced, which leads to high cost of crystal pulling.

[0003] Carbon / carbon composite material is a composite material formed by carbon fiber or various carbon fabrics reinforcing carbon matrix, which has excellent properties such as low density, high specific strength, wear resistance and high temperature resistance, and has been widely used in aerospace, metallurgy and new energy fields. Currently, researchers have proposed to replace the traditional combination of carbon / carbon crucible and quartz crucible with an integrated carbon / carbon composite material crucible, which can avoid the influence of the rapid rise of high-purity quartz sand price and reduce the cost of crystal pulling materials. In addition, the integrated design can combine material and performance into one, maximize the advantages and further reduce product cost.

[0004] Integrated carbon / carbon composite material crucible is obtained by densification treatment of carbon fiber preform and combination of surface high-performance coating. Among them, the carbon fiber preform is the blank of the carbon / carbon composite material 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 net tire and carbon fiber filament, such as patent CN 111002435A discloses a carbon / carbon crucible preform weaving process for single crystal silicon furnace, a layer of plain cloth is first laid on the tool, then a layer of net tire is laid, then the fiber filament is uniformly wound in the transverse and longitudinal directions, then it is needled, and the process is repeated until the preform is completed. Patent CN215250466U discloses a carbon / carbon / silicon carbide composite material crucible preform, which comprises carbon fiber plain cloth, carbon fiber net tire and carbon fiber filament. The carbon fiber net tire is laid on the carbon fiber plain cloth to form a laying unit. The carbon fiber filament is cross-wound on the outer side of each layer of laying unit in the inclined direction. Each laying unit is stacked layer by layer to a predetermined thickness, and needling is 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, the existence of the inner type surface carbon fiber woven cloth has low surface roughness and poor combination with the subsequent functional coating, which greatly affects the service life of the crucible product. Practical new type content

[0005] In view of the poor combination of the preform in the integrated crucible and the subsequent functional coating, the utility model provides a kind of integrated crucible preform based on multilayer structure, the preform uses pure net tire needle laying as the surface layer combined with subsequent functional coating, which can improve the combination effect with subsequent functional layer;Carbon cloth / net tire laminated needle laying combined with carbon fiber winding layer is used as the external support structure of pure net tire needle laying, which provides mechanical support for the whole preform, and 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 purpose of the utility model is realized through the following technical schemes.

[0007] The integrated crucible preform based on multilayer structure includes pure net tire needle laying and the alternating superposition structure of carbon cloth / net tire laminated needle laying and carbon fiber winding layer formed on the outer surface of pure net tire needle laying, and the outermost layer of the preform is carbon fiber winding layer;

[0008] Among them, the carbon cloth / net tire laminated needle laying is the needle-sewn composite layer of superimposed carbon cloth layer and net tire layer. In addition, the pure net tire needle laying is the net tire layer after needling, and the carbon fiber winding layer is formed by winding carbon fiber filament on the outer surface of carbon cloth / net tire laminated needle laying. The net tire (i.e. carbon fiber net tire) used for laying net tire layer is made of short-cut carbon fiber.

[0009] Further, the thickness of the pure web tire needled layer is 100-200 mm.

[0010] Further, the carbon cloth / web tire stacked needled layer and the carbon fiber wound layer constitute a layer unit, and the thickness of the layer unit is 10-20 mm; in the layer unit, the thickness of the carbon cloth layer is preferably 5-10 mm, the thickness of the carbon fiber web tire layer is preferably 4-8 mm, and the thickness of the carbon fiber wound layer is preferably 1-2 mm.

[0011] Further, all the layer units on the outer surface of the pure web tire needled layer constitute an outer support stacked layer; according to the structure of the integrated crucible, from the upper part to the lower part of the crucible along the depth direction, the crucible is sequentially divided into a crucible straight cylinder section, a crucible R angle transition section, and a crucible bottom surface, and the thickness of the outer support stacked layer of the crucible straight cylinder section in the preform is less than that of the crucible R angle transition section, and the thickness of the outer support stacked layer of the crucible R angle transition section is less than that of the crucible bottom surface.

[0012] Further, the thicknesses of the outer support stacked layers of the crucible straight cylinder 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.

[0013] Further, the crucible straight cylinder section, the crucible R angle transition section, and the crucible bottom surface adopt layer units with different thicknesses to realize different thicknesses of the outer support stacked layers in different regions. More preferably, the thicknesses of the layer units adopted by the crucible straight cylinder section, the crucible R angle transition section, and the crucible bottom surface are 10-20 mm, 15-30 mm, and 20-40 mm, respectively, and the difference in the thicknesses of the layer units in different regions is caused by the difference in the thicknesses of the carbon cloth layers, i.e., the thickness of the carbon cloth layer laid in the corresponding region of the crucible R angle transition section and the crucible bottom surface is greater than that of the carbon cloth layer laid in the corresponding region of the crucible straight cylinder section.

[0014] Further, the preform further comprises an inner support layer arranged on the inner surface of the pure web tire needled layer, the inner support layer is composed of a carbon cloth / web tire stacked needled layer and a carbon fiber wound layer (i.e., the inner support layer is a layer unit in the outer support stacked layer), and the carbon fiber wound layer is wound on the outer surface of the carbon cloth / web tire stacked needled layer and contacts the inner surface of the pure web tire needled layer.

[0015] Further, the thickness of the inner support layer is 10-20 mm.

[0016] It should be noted that the preform containing the inner support layer is first completely removed after densification treatment to expose the pure net tire needled laying layer, and then the functional coating required is prepared on the pure net tire needled laying layer in the subsequent preparation process of the crucible. The preform contains the inner support layer because the preform structure of the pure net tire needled laying layer combined with the outer support stack still has the problem of easy deformation of the preform during the chemical vapor deposition densification treatment, resulting in a low yield and increasing the manufacturing cost; the addition of the inner support layer can effectively improve the deformation problem of the preform structure and reduce the manufacturing cost.

[0017] Advantages:

[0018] (1) The preform disclosed by the utility model adopts the pure net tire needled laying layer as the internal surface layer combined with the subsequent functional coating, and the isotropic structure of the pure net tire needled laying layer has a certain roughness and uniform apparent quality, which is not only beneficial to the preparation of the subsequent functional coating, but also improves the bonding performance of the functional coating and the crucible base, thereby effectively improving the service life of the crucible product; the alternating stack structure composed of the carbon cloth / net tire stack needled laying layer and the carbon fiber winding layer is used as the external support structure, which has high strength, small density and thin thickness, and can provide good mechanical support for the whole preform. Therefore, when the preform disclosed by the utility model is used to produce the crucible product, the service life of the crucible product can be effectively improved on the basis of meeting the mechanical properties.

[0019] (2) Based on the structural characteristics of the crucible, it can be known that the stress concentration at the R corner is the largest and fatigue cracks are easy to occur, and increasing the thickness of the R corner can effectively make the straight cylinder segment smoothly transition to the bottom surface and reduce the stress concentration problem at the R corner. In addition, under the influence of the actual working condition, the R corner and the bottom surface are most affected by the gravity of the silicon melt, and increasing the thickness of the two places can effectively prevent the occurrence of "silicon leakage"; and different thicknesses are set for different regions, which can effectively reduce the overall weight of the preform and reduce the manufacturing cost of the preform on the basis of ensuring the mechanical properties of the preform.

[0020] (3) The preform disclosed by the utility model further comprises an inner support layer, and the setting of the inner support layer can effectively improve the deformation problem of the preform structure of the pure net tire needled laying layer combined with the outer support stack and reduce the manufacturing cost. The inner support layer is a carbon cloth / net tire stack needled laying layer-carbon fiber winding layer structure, which is still an anisotropic structure after densification treatment, which is not conducive to the preparation of the subsequent functional coating. Therefore, the inner support layer after densification treatment needs to be removed first when the crucible product is prepared, so that the exposed pure net tire needled laying layer after densification treatment is in contact with the subsequent functional coating, which can ensure the good bonding effect of the functional coating. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1A schematic view of the structure of the integrated crucible preform based on a multi-layer structure prepared in Example 1.

[0022] Figure 2 A schematic view of the structure of the integrated crucible preform based on a multi-layer structure prepared in Example 4.

[0023] Wherein, 1-pure needled mat layer, 2-outer support layer, 3-inner support layer. DETAILED DESCRIPTION

[0024] The utility model will be further described below in combination with specific embodiments, wherein the method is the conventional method without special instructions, and the raw materials can be obtained from public commercial channels without special instructions. In addition, in the description of the utility model, it should be understood that the terms "upper", "lower", "front", "rear", "left", "right", "top", "bottom", "inner", "outer" and the like indicate the orientation or positional relationship shown in the drawings, which is only for the convenience of describing the utility model and simplifying the description, and does not indicate or imply that the device or element must have a particular orientation, be constructed and operated in a particular orientation, therefore, it should not be understood as a limitation of the utility model.

[0025] Example 1

[0026] The integrated crucible preform based on a multi-layer structure specifically comprises the following preparation steps:

[0027] (1) a carbon fiber mat with an area density of 50 g / m 2 is laid on a core mold and needled to form a pure needled mat layer 1 with a thickness of 100 mm;

[0028] Wherein, the needling density is 10 needles / cm 2 , and the needling depth is 5 mm; the core mold is made according to the inner surface structure and size of the integrated crucible;

[0029] (2) first, a carbon fiber mat with an area density of 200 g / m 2 is laid on the pure needled mat layer 1, and needled to form an outer support layer 2 with a thickness of 5 mm;The whole carbon cloth is laid on the pure net tire needle punching layer 1, and after laying the whole carbon cloth, the carbon cloth layer of the straight cylinder section of the crucible is formed. The R angle transition section of the crucible needs to be overlaid with a layer of small piece of 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 R angle transition section of the crucible, and the bottom surface of the crucible also needs to be overlaid with two layers of small piece of 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, carbon fiber net tires are laid on the carbon cloth layers in the three different areas of the straight cylinder section, the R angle transition section and the bottom surface of the crucible to form carbon fiber net tire layers with a thickness of 4mm, and needle punching is performed, so that carbon cloth / net tire laminated needle punching layers with thicknesses of 9mm, 14mm and 19mm are formed in the three different areas respectively. Finally, carbon fiber filaments are continuously wound in the direction of ±45° with respect to the axial direction of the preform in the carbon cloth / net tire laminated needle punching layers in the three different areas to form carbon fiber winding layers, and the thickness of the carbon fiber winding layers is 1mm.

[0030] According to the structure of the integrated crucible, the crucible is sequentially divided into a straight cylinder section, an R angle transition section and a bottom surface along the depth direction from the upper part to the lower part of the crucible. The carbon cloth / net tire laminated needle punching layer and the carbon fiber winding layer form a layer unit, and the thickness of the layer unit of the straight cylinder section, the thickness of the layer unit of the R angle transition section and the thickness of the layer unit of the bottom surface are 10mm, 15mm and 20mm respectively. The needle punching density of the carbon cloth / net tire laminated needle punching layer is 10 needles / cm 2 , and the needle punching depth is 5mm.

[0031] (3) repeatedly performing the operation of step (2) to form an alternating superposition structure of carbon cloth / net tire laminated needle punching layer first and carbon fiber winding layer second on the surface of the carbon fiber winding layer formed in step (2) (i.e. superimposing multiple layer units on the layer unit formed in step (2)), until the last winding of carbon fiber filaments reaches the required thickness of the preform, and then a preform precursor is obtained.

[0032] All the layer units sequentially superimposed on the pure net tire needle punching layer 1 form an outer support layer 2 for supporting the pure net tire needle punching layer 1, and the number of layer units laid in different areas is 15 layers. The thickness of the outer support layer 2 of the straight cylinder section, the thickness of the outer support layer 2 of the R angle transition section and the thickness of the outer support layer 2 of the bottom surface are 150mm, 225mm and 300mm respectively. It should be noted that the middle area of the bottom surface of the crucible is usually provided with a support boss protruding outwardly from the crucible, such as Figure 1As shown, the support boss is formed by additionally increasing the number of carbon cloth layers in the support boss area during the bottom surface layering process of the crucible, and the protruding thickness of the support boss can be in the range of 15-30mm, since the support boss does not affect the overall mechanical properties of the crucible, the support boss is not limited in the present application, and can be set according to requirements in actual application.

[0033] (4) The preform precursor obtained in step (3) is treated at 80℃ for 10h to achieve hardening effect, and then a multi-layer structure-based integrated crucible preform with a density of 0.40g / cm 3 is obtained; it should be noted that the purpose of heating treatment at low temperature is to harden the preform and further improve the overall mechanical properties of the preform, so that the preform is not easy to deform during subsequent storage and transportation.

[0034] Example 2

[0035] The multi-layer structure-based integrated crucible preform specifically comprises the following preparation steps:

[0036] (1) A carbon fiber web with an areal density of 300g / m 2 is laid on a core mold and needled to form a pure web needle-punched layer 1 with a thickness of 150mm;

[0037] wherein the needle density is 30 needles / cm 2 , and the needle depth is 8mm; the core mold is made according to the inner surface structure and size of the integrated crucible;

[0038] (2) First, a whole carbon cloth with a thickness of 8mm and an areal density of 500g / m 2 is laid on the pure web needle-punched layer 1, and after laying the whole carbon cloth, the carbon cloth layer of the straight cylinder section of the crucible is formed, while the carbon cloth layer of the R-angle transition section of the crucible needs to be thickened by adding one more layer of small piece of carbon cloth with a thickness of 8mm on the basis of the whole carbon cloth layer to form the carbon cloth layer of the R-angle transition section of the crucible, and the carbon cloth layer of the bottom surface of the crucible also needs to be thickened by adding two more layers of small piece of carbon cloth with a thickness of 8mm on the basis of the whole carbon cloth layer to form the carbon cloth layer of the bottom surface of the crucible; then carbon fiber webs are laid on the carbon cloth layers in the three different areas of the straight cylinder section, the R-angle transition section and the bottom surface of the crucible to form carbon fiber web layers with a thickness of 6mm, and are needled and stitched, so that carbon cloth / web laminated needle-punched layers with a thickness of 14mm, 22mm and 30mm are formed in the three different areas respectively; finally, carbon fiber filaments are continuously wound in the direction of ±45° to the axial direction of the preform on the carbon cloth / web laminated needle-punched layers in the three different areas to form a carbon fiber wound layer with a thickness of 1mm;

[0039] Wherein, according to the structure of the integrated crucible, from the upper part to the lower part of the crucible along its depth direction is sequentially divided into a crucible straight cylinder section, a crucible R angle transition section, and a crucible bottom surface; the carbon cloth / net tire laminated needled layer and the carbon fiber winding layer form a laying unit, and the thickness of the laying unit of the crucible straight cylinder section, the thickness of the laying unit of the crucible R angle transition section, and the thickness of the laying unit of the crucible bottom surface are 15 mm, 23 mm, and 31 mm respectively; the needling density of the carbon cloth / net tire laminated needled layer is 20 needles / cm 2 , and the needling depth is 8 mm;

[0040] (3) repeatedly the operation of step (2) to form an alternating superposition structure of the carbon cloth / net tire laminated needled layer first and the carbon fiber winding layer second on the surface of the carbon fiber winding layer of step (2) (i.e. superimposing multiple laying units on the laying unit formed in step (2)), until the last winding of the carbon fiber filament reaches the required thickness of the preform, and then a preform precursor is obtained;

[0041] Wherein, all the laying unit groups sequentially superimposed on the pure net tire needled layer 1 form an outer support layer 2 for supporting the pure net tire needled layer 1, and the number of laying units laid in different areas is 16 layers, and the thickness of the outer support layer 2 of the crucible straight cylinder section, the thickness of the outer support layer 2 of the crucible R angle transition section, and the thickness of the outer support layer 2 of the crucible bottom surface are 240 mm, 368 mm, and 496 mm respectively;

[0042] (4) placing the preform precursor obtained in step (3) at 150℃ for 8h to achieve a hardening effect, and obtaining a multi-layer structure-based integrated crucible preform with a density of 0.46g / cm 3 .

[0043] Example 3

[0044] The multi-layer structure-based integrated crucible preform specifically comprises the following preparation steps:

[0045] (1) laying a carbon fiber net tire with an area density of 500g / m 2 on a core mold and needling to form a pure net tire needled layer 1 with a thickness of 200mm;

[0046] Wherein, the needling density is 50 needles / cm 2 , and the needling depth is 10 mm; the core mold is made according to the inner surface structure and size of the integrated crucible;

[0047] (2) first using a carbon fiber net tire with a thickness of 10mm and an area density of 800g / m 2The whole carbon cloth is laid on the pure net tire needle-punched layer 1, and after laying the whole carbon cloth, the carbon cloth layer of the straight cylinder section of the crucible is formed. The R angle transition section of the crucible needs to be thickened by stacking a layer of small piece of carbon cloth with a thickness of 10 mm on the basis of the whole carbon cloth layer to form the carbon cloth layer of the R angle transition section of the crucible, and the bottom surface of the crucible also needs to be thickened by stacking two layers of small piece of carbon cloth with a thickness of 10 mm on the basis of the whole carbon cloth layer to form the carbon cloth layer of the bottom surface of the crucible. Then, carbon fiber nets are laid on the carbon cloth layers in the three different areas of the straight cylinder section, the R angle transition section and the bottom surface of the crucible to form carbon fiber net layers with a thickness of 8 mm, and needle-punched stitching is performed, so that carbon cloth / net stacked needle-punched layers with thicknesses of 18 mm, 28 mm and 38 mm are formed in the three different areas respectively. Finally, carbon fiber filaments are continuously wound in the direction of ±45° with respect to the axial direction of the preform in the carbon cloth / net stacked needle-punched layers in the three different areas to form a carbon fiber winding layer, and the thickness of the carbon fiber winding layer is 2 mm.

[0048] According to the structure of the integrated crucible, from the upper part to the lower part of the crucible along the depth direction, the straight cylinder section, the R angle transition section and the bottom surface of the crucible are sequentially formed. The carbon cloth / net stacked needle-punched layer and the carbon fiber winding layer form a layer unit, and the thickness of the layer unit of the straight cylinder section, the thickness of the layer unit of the R angle transition section and the thickness of the layer unit of the bottom surface are 20 mm, 30 mm and 40 mm respectively. The needle-punching density of the carbon cloth / net stacked needle-punched layer is 50 needles / cm 2 , and the needle-punching depth is 10 mm.

[0049] (3) Repeat the operation of step (2) multiple times to form an alternating stacked structure of carbon cloth / net stacked needle-punched layer first and carbon fiber winding layer second on the surface of the carbon fiber winding layer of step (2) (i.e. stack multiple layer units on the layer unit formed in step (2)), until the last winding of carbon fiber filaments reaches the required thickness of the preform, and then a preform precursor is obtained.

[0050] All the layer units sequentially stacked on the pure net tire needle-punched layer 1 form an outer support layer 2 for supporting the pure net tire needle-punched layer 1, and the number of layer units laid in different areas is 13 layers. The thickness of the outer support layer 2 of the straight cylinder section, the thickness of the outer support layer 2 of the R angle transition section and the thickness of the outer support layer 2 of the bottom surface are 260 mm, 390 mm and 520 mm respectively.

[0051] (4) The preform precursor obtained in step (3) is treated at 200°C for 5h to achieve a hardening effect, and a multi-layer structure-based integrated crucible preform with a density of 0.50 g / cm 3 is obtained.

[0052] The specific steps for preparing the crucible product from the integrated crucible preform obtained in step (4) of Example 3 are as follows:

[0053] The integrated crucible preform with a density of 0.50 g / cm 3 is densified by a chemical vapor infiltration process combined with a resin impregnation carbonization process to obtain a carbon / carbon composite crucible body with a density of 1.60 g / cm 3 ;

[0054] A glassy carbon coating with a thickness of 50 μm is prepared on the surface of the carbon / carbon composite crucible body by an impregnation-curing-carbonization process, i.e. first impregnating with furfuryl alcohol resin at an impregnation pressure of 1.0 MPa for 0.5 h, then heating at a rate of 1°C / h to 100°C and curing at 100°C for 3 h, and then heating at a rate of 1°C / h to 900°C and carbonizing at 900°C for 5 h.

[0055] A yttria coating with a thickness of 500 μm is prepared on the surface of the glassy carbon coating by a plasma spraying process using yttria with a purity of 99.999% and a particle size of 100 μm as raw material, i.e. the preparation of the crucible product is completed; wherein, nitrogen is used as the protective gas and hydrogen is used as the anti-oxidation gas in the spraying process, the nitrogen pressure is 3.0 MPa, the hydrogen pressure is 2.0 MPa, the voltage of the plasma arc used in the spraying is 120 V, the current is 900 A, and the spraying distance is 30 mm.

[0056] The prepared crucible product is subjected to thermal shock treatment at 1500°C - room temperature, and after 6 cycles the coating on the carbon / carbon composite crucible body is still intact.

[0057] Example 4

[0058] On the basis of Example 1, the preform further comprises an inner support layer 3 arranged on the inner surface of the pure mesh needle-punched layer 1, and correspondingly, the preparation of the inner support layer 3 is further included before the pure mesh needle-punched layer 1 is formed in step (1) of Example 1, i.e.

[0059] First, a piece of 5 mm thick, 200 g / m 2carbon cloth layer, and then carbon fiber mesh tire layer with a thickness of 4 mm is formed on the carbon cloth layer by laying carbon fiber mesh tire on the carbon cloth layer, and the laid carbon fiber mesh tire layer and the carbon cloth layer are needled and stitched to form a carbon cloth / mesh tire laminated needled laying layer with a thickness of 9 mm; finally, carbon fiber filaments are continuously wound on the carbon cloth / mesh tire laminated needled laying layer in the direction of ±45° with respect to the axial direction of the preform to form a carbon fiber wound layer, and the carbon cloth / mesh tire laminated needled laying layer and the carbon fiber wound layer form an inner support layer 3 with a thickness of 10 mm; then, the pure mesh tire needled laying layer 1 and the outer support layer 2 are sequentially formed on the inner support layer 3 according to the operation steps and conditions of steps (1)-(3) of Example 1, and the heating treatment is performed according to the conditions of step (4) of Example 1 to achieve the hardening effect, and then a preform with a density of 0.41 g / cm 3 The integrated crucible preform based on the multi-layer structure is shown in Figure 2

[0060] Compared with Example 1, Example 4 further has an inner support layer 3 arranged inside the pure mesh tire needled laying layer 1. The mechanical property test is performed on the crucible preforms obtained in Example 1 and Example 4, that is, five test samples are taken from different positions of the outer support layer 2 of the crucible preforms in Example 1 and Example 4, each sample has a size of 40 mm x 40 mm x 50 mm, and then the interlayer tensile strength test is performed on different samples, and the average value of the test results of the five samples is as follows:

[0061]

[0062] Comparative Example 1

[0063] The integrated crucible preform based on the pure mesh tire structure comprises the following preparation steps:

[0064] (1) carbon fiber mesh tire is laid on a wooden core mold and needled, wherein the carbon fiber mesh tire is a thin felt made of chopped carbon fibers with an area density of 50 g / m 2 , the needling density is 10 needles / cm 2 , and the needling depth is 5 mm; the wooden core mold is made based on the inner surface structure and size of the integrated crucible;

[0065] (2) the operation of step (1) is repeated multiple times, that is, the carbon fiber mesh tire is continuously laid and needled on the mesh tire layer obtained in step (1) to form a superposition structure of multiple mesh tire layers until the required thickness of the preform is reached, and a preform precursor is obtained;

[0066] ​In the integrated crucible, from the upper part to the lower part of the crucible along the depth direction, the crucible is sequentially divided into a straight cylinder section, a crucible R corner transition section, and a crucible bottom surface. Different numbers of laying units (i.e., different numbers of net tire layers) are used to make the thickness of the straight cylinder section, the thickness of the crucible R corner transition section, and the thickness of the crucible bottom surface 250 mm, 325 mm, and 400 mm, respectively.

[0067] (3) The preform precursor obtained in step (2) is treated at 80°C for 10h to obtain an integrated crucible preform with a density of 0.30g / cm 3 .

[0068] Comparative Example 1 has only a pure net tire needling layer 1 without an outer support layer 2. The mechanical properties of the crucible preforms obtained in Example 1 and Comparative Example 1 are tested, i.e., 5 test samples are taken from different positions in the outer support layer 2 region of the crucible preform described in Example 1, and 5 test samples are taken from different regions of the crucible preform described in Comparative Example 1, each sample having a size of 40mm×40mm×50mm. The interlayer tensile strength of different samples is then tested, and the average of the test results of the 5 samples is as follows:

[0069]

[0070] Comparative Example 2

[0071] Based on Example 2, only the operation of preparing a pure net tire needling layer 1 on the mandrel in step (1) of Example 2 is not performed, but an outer support layer 2 is directly prepared on the mandrel according to the operation steps and conditions of steps (2)-(3) of Example 2. Then, the outer support layer 2 is heat treated according to the conditions of step (4) of Example 2, and an integrated crucible preform with a density of 0.45g / cm 3 is obtained accordingly.

[0072] Comparative Example 2 has only an outer support layer 2 without a pure net tire needling layer 1. The mechanical properties of the crucible preforms obtained in Example 2 and Comparative Example 2 are tested, i.e., 5 test samples are taken from different positions in the outer support layer 2 region of the crucible preforms described in Example 2 and Comparative Example 2, each sample having a size of 40mm×40mm×50mm. The interlayer tensile strength of different samples is then tested, and the average of the test results of the 5 samples is as follows:

[0073]

[0074] The specific steps for preparing a crucible product based on the integrated crucible preforms obtained in Example 2 and Comparative Example 2 are as follows:

[0075] The integrated crucible preform prepared in Example 2 with a density of 0.46 g / cm 3 and the integrated crucible preform prepared in Comparative Example 2 with a density of 0.45 g / cm 3 were densified by a chemical vapor infiltration process combined with a resin impregnation carbonization process, and both obtained carbon / carbon composite material crucible bodies with a density of 1.60 g / cm 3 ;

[0076] Two glassy carbon coating layers with a thickness of 50 μm were prepared on the surfaces of the above two carbon / carbon composite material crucible bodies by an impregnation-curing-carbonization process, i.e. first impregnating with furfuryl alcohol resin at an impregnation pressure of 1.0 MPa for 0.5 h, then heating to 100℃ at a heating rate of 1℃ / h and curing at 100℃ for 3 h, and then heating to 900℃ at a heating rate of 1℃ / h and carbonizing at 900℃ for 5 h;

[0077] A yttria coating layer with a thickness of 500 μm was prepared on the surface of each glassy carbon coating layer by a plasma spraying process using yttria with a purity of 99.999% and a particle size of 100 μm as raw material, i.e. two crucible products were completed; in the spraying process, nitrogen was used as a protective gas and hydrogen was used as an anti-oxidation gas, the nitrogen pressure was 3.0 MPa, the hydrogen pressure was 2.0 MPa, the voltage of the plasma arc used in the spraying was 120 V, the current was 900 A, and the spraying distance was 30 mm.

[0078] The two prepared crucible products were subjected to thermal shock treatment at 1500℃-room temperature, and the coating layer on the carbon / carbon composite material crucible body of the crucible product prepared based on the integrated crucible preform described in Example 2 was still intact after 5 cycles; while the coating layer on the carbon / carbon composite material crucible body of the crucible product prepared based on the integrated crucible preform described in Comparative Example 2 fell off after 2 cycles.

[0079] In conclusion, the above is only a preferred embodiment of the present application, and is not used to limit the protection scope of the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. An integrated crucible preform based on a multi-layer structure, characterized in that: It includes a pure mesh needle-punched layup and an alternating superposition structure formed on the outer surface of the pure mesh needle-punched layup, consisting of a carbon cloth / mesh laminate needle-punched layup followed by a carbon fiber winding layer, and the outermost layer of the preform is a carbon fiber winding layer. The carbon cloth / mesh tire laminate needle-punched layup is a composite layer of stacked carbon cloth layers and mesh tire layers needle-punched and stitched together.

2. The integrated crucible preform based on a multi-layer structure according to claim 1, characterized in that: The thickness of the needle-punched ply in pure mesh tires is 100-200 mm.

3. The integrated crucible preform based on a multi-layer structure according to claim 1, characterized in that: A carbon cloth / mesh laminate needle-punched layup and a carbon fiber winding layer form a layup unit, and the thickness of a layup unit is 10-20 mm.

4. The integrated crucible preform based on a multi-layer structure according to claim 3, characterized in that: In a single layup unit, the carbon cloth layer has a thickness of 5–10 mm, the carbon fiber mesh layer has a thickness of 4–8 mm, and the carbon fiber winding layer has a thickness of 1–2 mm.

5. The integrated crucible preform based on a multi-layer structure according to claim 1, characterized in that: The carbon cloth / mesh tire laminate needle-punched layup and the carbon fiber winding layer form a layup unit, and all the layup units on the outer surface of the pure mesh tire needle-punched layup form an outer support laminate. Based on the structure of the integrated crucible, the crucible is divided into a straight cylindrical section, a radius transition section, and a bottom surface along its depth direction from the top to the bottom. The thickness of the outer support layer of the straight cylindrical section is less than that of the radius transition section, and the thickness of the outer support layer of the radius transition section is less than that of the bottom surface.

6. The integrated crucible preform based on a multi-layer structure according to claim 5, characterized in that: The thicknesses of the straight cylindrical section of the crucible, the transition section of the crucible's radius (R-angle), and the outer support layer on the bottom surface of the crucible in the preform are 100–300 mm, 200–400 mm, and 300–600 mm, respectively.

7. The integrated crucible preform based on a multi-layer structure according to claim 5 or 6, characterized in that: Different thicknesses of plywood units are used in the straight cylindrical section of the crucible, the R-angle transition section of the crucible, and the bottom surface of the crucible to achieve different thicknesses of external support layers in different areas.

8. The integrated crucible preform based on a multi-layer structure according to claim 7, characterized in that: The thicknesses of the layup units used in the straight cylindrical section of the crucible, the transition section of the crucible's R-angle, and the bottom surface of the crucible are 10–20 mm, 15–30 mm, and 20–40 mm, respectively. The difference in the thickness of the layup units in different areas is caused by the different thicknesses of the carbon cloth layer.

9. The integrated crucible preform based on a multi-layer structure according to any one of claims 1-6, characterized in that: The preform also includes an inner support layer disposed on the inner surface of the pure mesh tire needle-punched ply. The inner support layer is composed of a carbon cloth / mesh tire laminate needle-punched ply and a carbon fiber winding layer, while the carbon fiber winding layer is wound around the outer surface of the carbon cloth / mesh tire laminate needle-punched ply and in contact with the inner surface of the pure mesh tire needle-punched ply.

10. The integrated crucible preform based on a multi-layer structure according to claim 9, characterized in that: The thickness of the inner support layer is 10-20 mm.

Images