A molten silicon infiltration device and method for a large-sized thin-walled composite material product

Abstract

The present invention belongs to the technical field of silicon infiltration of composite materials, and specifically relates to a molten silicon infiltration device and method for large-size thin-walled composite material products. The molten silicon infiltration device is assembled in multiple regions, with simple demoulding. By using the upper and lower molds, pressure plates, telescopic structures and rotating tables in cooperation, the silicon powder stays around the product when it is in a high-temperature liquid state, which can effectively prevent the problem of poor gradient uniformity of density in the upper and lower parts caused by the sinking of the silicon powder in a high-temperature liquid state during the process, and effectively improve the porosity and density uniformity of the product.

Description

Technical Field

[0001] The present invention relates to the technical field of silicon infiltration of composite materials, and particularly to a molten silicon infiltration device and method for large-size thin-walled composite material products. Background Art

[0002] Carbon / carbon-silicon carbide (C / C-SiC) is a composite material with carbon fibers as the reinforcement and C and SiC as the matrix. Carbon / carbon-silicon carbide has high specific strength, high specific modulus, excellent high-temperature mechanical properties, low density, good thermal stability, oxidation resistance and low wear properties. It has wide applications in both civilian and military fields. At present, the preparation methods of carbon / carbon-silicon carbide composites mainly include reaction melt infiltration method, chemical vapor infiltration method and precursor pyrolysis method, etc. The chemical vapor infiltration method and the precursor pyrolysis method have slow densification rates, low raw material utilization rates, long preparation cycles and high manufacturing costs, which limit their application ranges; in the reaction melt infiltration method, at high temperatures, a carbon / carbon porous body prepared by a needle punching preform is embedded in silicon powder or silicon particles. When heated above the melting point of silicon, the silicon melts, and the liquid silicon enters the porous body due to capillary action to form a densified material, a method for preparing a densified material. The prepared carbon / carbon-silicon carbide composite material has strong thermal shock resistance, moderate material strength, good oxidation resistance, short preparation cycle, low cost and low residual porosity, and is very competitive in the market. At present, there is still a problem that when the silicon powder is in a liquid state at high temperature during the process of large-size products, it sinks, resulting in poor density gradient uniformity between the upper and lower parts. Summary of the Invention

[0003] To solve the problems existing in the prior art, the main object of the present invention is to propose a molten silicon infiltration device and method for large-size thin-walled composite material products.

[0004] To solve the above technical problems, according to one aspect of the present invention, the following technical solutions are provided:

[0005] A molten silicon infiltration device for large-size thin-walled composite material products, comprising:

[0006] An upper mold, a lower mold, a pressure plate, a side fixing plate, a bottom fixing plate, a rotating table, a telescopic structure;

[0007] The rotating table is located at the bottom of the device, the telescopic structure is located in the middle of the rotating table and is connected to the pressure plate, the lower mold is connected to the pressure plate, the upper mold is located at the top of the device, the side fixing plate is located around the upper mold, and the bottom fixing plate is located around the lower mold.

[0008] As a preferred solution of the molten silicon infiltration device for large-size thin-walled composite material products according to the present invention, wherein: the device further includes a fixing pin located between the upper mold and the side fixing plate.

[0009] As a preferred solution of the molten silicon infiltration device for a large-sized thin-walled composite material product according to the present invention, wherein: the device is made of high-density graphite.

[0010] As a preferred solution of the molten silicon infiltration device for a large-sized thin-walled composite material product according to the present invention, wherein: a feed inlet is provided at the top of the upper mold.

[0011] To solve the above technical problems, according to another aspect of the present invention, the present invention provides the following technical solutions:

[0012] A molten silicon infiltration method for a large-sized thin-walled composite material product, comprising the following steps:

[0013] S1. Prepare a large-sized thin-walled composite material product;

[0014] S2. Place the bottom fixing plate on the pressing plate, install the lower mold, place the large-sized thin-walled composite material product in the lower mold, then place the upper mold to close the mold, and fix the entire device with the side fixing plate.

[0015] S3. Fill the gap between the product and the device with silicon powder, place the device with the product in the silicon infiltration furnace, use the telescopic structure to compress the lower mold through the pressing plate, reduce the gap between the product and the device in the device, so that the melted liquid silicon does not sink, and at the same time, the rotating table rotates the entire device for silicon infiltration to obtain the finished product.

[0016] As a preferred solution of the molten silicon infiltration method for a large-sized thin-walled composite material product according to the present invention, wherein: in the step S1, a carbon fiber raw material is integrally three-dimensionally woven, a 2.5d needle-punched carbon felt is used as the reinforcement to make a carbon fiber reinforcement, and the carbon fiber reinforcement is placed in a CVI furnace for chemical vapor deposition, with the density deposited to 1.1 - 1.3 g / cm 3 , the porosity is 28 - 36%, and the carbon content is 46 - 62 wt% to obtain a C / C composite material, which is machined into a large-sized thin-walled composite material product.

[0017] As a preferred solution of the molten silicon infiltration method for a large-sized thin-walled composite material product according to the present invention, wherein: in the step S2, after fixing with the side fixing plate, a fixing pin is inserted into the gap between the side fixing plate and the upper mold to fix the entire device.

[0018] As a preferred solution of the molten silicon infiltration method for a large-sized thin-walled composite material product according to the present invention, wherein: in the step S3, the particle size of the silicon powder is 200 mesh, and the purity > 99.99%.

[0019] As a preferred solution of the molten silicon infiltration method for a large-sized thin-walled composite material product according to the present invention, wherein: in the step S3, the silicon powder fills the gap between the product and the device through the feed inlet at the top of the upper mold.

[0020] As a preferred embodiment of the molten silicon infiltration method for a large-sized thin-walled composite material product according to the present invention, in which: in step S3, after the device containing the product is placed in the silicon infiltration furnace, it is evacuated to below 200 Pa, the heating time is 120 min to 150 min. When the temperature is raised to 1420 °C, the telescopic structure compresses the lower die through the pressure plate at a speed of 10 km / h, reducing the gap between the product in the device and the device, so that the melted liquid silicon does not sink. At the same time, the rotating table rotates the entire device at a speed of 10 r / min. When the temperature is raised to 1570 - 1630 °C, silicon infiltration is carried out, and the heat preservation time is 15 - 30 min, and the finished product is obtained.

[0021] The beneficial effects of the present invention are as follows:

[0022] The present invention provides a molten silicon infiltration device and method for a large-sized thin-walled composite material product. The molten silicon infiltration device is assembled in multiple regions, and the demoulding is simple. By the combined use of the upper and lower dies, the pressure plate, the telescopic structure and the rotating table, when the silicon powder is in a liquid state at high temperature, it stays around the product, which can effectively prevent the problem of poor gradient uniformity of density in the upper and lower parts caused by the sinking of the silicon powder in a liquid state at high temperature during the process, and effectively improve the porosity and density uniformity of the product. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on the structures shown in these drawings.

[0024] Figure 1 Schematic diagram of the molten silicon infiltration device for the embodiment of the present invention;

[0025] Figure 2 Schematic diagram of the molten silicon infiltration device for Comparative Example 1;

[0026] Figure 3 Schematic diagram of the molten silicon infiltration device for Comparative Example 2.

[0027] Explanation of the reference numerals in the drawings:

[0028] 1 - Feed inlet, 2 - Upper die, 3 - Fixed pin, 4 - Side fixing plate, 5 - Lower die, 6 - Composite material product, 7 - Bottom fixing plate, 8 - Pressure plate, 9 - Rotating table, 10 - Telescopic structure, 11 - Graphite crucible. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0029] The technical solutions in the embodiments will be clearly and completely described below. Apparently, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0030] The present invention provides a molten silicon infiltration device and method for large-sized thin-walled composite products. By using the upper mold, lower mold, pressing plate, telescopic structure and rotating table in cooperation, when the silicon powder is in a high-temperature liquid state, it stays around the product, which can effectively prevent the problem of poor gradient uniformity of density in the upper and lower parts caused by the sinking of the silicon powder in a high-temperature liquid state during the process, and effectively improve the porosity and density uniformity of the product.

[0031] According to one aspect of the present invention, the following technical solutions are provided:

[0032] As Figure 1 shown, a molten silicon infiltration device for a large-sized thin-walled composite product 6 includes:

[0033] an upper mold 2, a lower mold 5, a pressing plate 8, a side fixing plate 4, a bottom fixing plate 7, a rotating table 9, and a telescopic structure 10;

[0034] The rotating table 9 is located at the bottom of the device. The telescopic structure 10 is located in the middle of the rotating table 9 and is connected to the pressing plate 8. The lower mold 5 is connected to the pressing plate 8. The upper mold 2 is located at the top of the device. The side fixing plate 4 is located around the upper mold 2, and the bottom fixing plate 7 is located around the lower mold 5.

[0035] Preferably, the device further includes a fixing pin 3 located between the upper mold 2 and the side fixing plate 4.

[0036] Preferably, the device is made of high-density graphite.

[0037] Preferably, a feed port 1 is provided at the top of the upper mold 2.

[0038] According to another aspect of the present invention, the following technical solutions are provided:

[0039] A molten silicon infiltration method for a large-sized thin-walled composite product includes the following steps:

[0040] S1. Prepare a large-sized thin-walled composite product;

[0041] S2. Place the bottom fixing plate on the pressing plate, install the lower mold, place the large-sized thin-walled composite product into the lower mold, then place the upper mold to close the mold, and fix the whole device with the side fixing plate;

[0042] S3. Fill the gap between the product and the device with silicon powder, place the device with the product into the silicon infiltration furnace. The telescopic structure compresses the lower mold through the pressing plate, reducing the gap between the product and the device in the device, so that the melted liquid silicon does not sink. At the same time, the rotating table rotates the entire device for silicon infiltration to obtain the finished product.

[0043] Preferably, in the step S1, the carbon fiber raw material is integrally three-dimensionally woven, and a 2.5d needle-punched carbon felt is used as the reinforcing body to make a carbon fiber reinforcing body. The carbon fiber reinforcing body is placed in a CVI furnace for chemical vapor deposition. The density is deposited to 1.1 - 1.3 g / cm 3 , the porosity is 28 - 36%, and the carbon content is 46 - 62 wt% to obtain a C / C composite material, which is machined into a large-size thin-walled composite material product.

[0044] Preferably, in the step S2, after being fixed with the side fixing plate, the fixing pin is inserted into the gap between the side fixing plate and the upper mold to fix the entire device.

[0045] Preferably, in the step S3, the particle size of the silicon powder is 200 mesh, and the purity > 99.99%.

[0046] Preferably, in the step S3, the silicon powder fills the gap between the product and the device through the top feed port of the upper mold.

[0047] Preferably, in the step S3, after the device with the product is placed in the silicon infiltration furnace, it is evacuated to below 200 Pa. The heating time is 120 - 150 min. When the temperature is raised to 1420 °C, the telescopic structure compresses the lower mold through the pressing plate at a speed of 10 km / h, reducing the gap between the product and the device in the device, so that the melted liquid silicon does not sink. At the same time, the rotating table rotates the entire device at a speed of 10 r / min. When the temperature is raised to 1570 - 1630 °C for silicon infiltration, the holding time is 15 - 30 min to obtain the finished product.

[0048] The technical solution of the present invention will be further described below in conjunction with specific embodiments.

[0049] The molten silicon infiltration devices used in each embodiment include:

[0050] Upper mold 2, lower mold 5, pressing plate 8, side fixing plate 4, bottom fixing plate 7, rotating table 9, telescopic structure 10; the rotating table 9 is located at the bottom of the device, the telescopic structure 10 is located in the middle of the rotating table 9 and is connected to the pressing plate 8, the lower mold 5 is connected to the pressing plate 8, the upper mold 2 is located at the top of the device, the side fixing plate 4 is located around the upper mold 2, and the bottom fixing plate 7 is located around the lower mold 5; the device further includes a fixing pin 3 located between the upper mold 2 and the side fixing plate 4. The devices are all made of high-density graphite. There is a feed port 1 provided at the top of the upper mold 2.

[0051] Example 1

[0052] A molten silicon infiltration method for large-sized thin-walled composite products, comprising the following steps:

[0053] S1. Prepare large-sized thin-walled composite products:

[0054] Using carbon fiber raw materials for integral three-dimensional weaving, a carbon fiber reinforcement is made with 2.5D needled carbon felt as the reinforcement. The carbon fiber reinforcement is placed in a CVI furnace for chemical vapor deposition to obtain a C / C composite with a density of 1.1 g / cm 3 , an open porosity of 28%, and a carbon content of 46 wt%. It is machined into a large-sized thin-walled composite product.

[0055] S2. Place the bottom fixing plate 7 on the pressing plate 8, install the lower mold 5, place the large-sized thin-walled composite product 6 in the lower mold 5, then place the upper mold 2 to close the mold. After fixing with the side fixing plate 4, the fixing pin 3 is inserted into the gap between the side fixing plate 4 and the upper mold 2 to fix the entire device;

[0056] S3. Fill the gap between the product and the device with silicon powder having a particle size of 200 mesh and a purity > 99.99% through the top feed port 1 of the upper mold 2. After the device with the product is placed in the silicon infiltration furnace, evacuate to below 200 Pa. The heating-up time is 120 min. When the temperature is raised to 1420 °C, the telescopic structure 10 compresses the lower mold 5 through the pressing plate 8 at a speed of 10 km / h to reduce the gap between the product and the device in the device, so that the melted liquid silicon does not sink. At the same time, the rotating table 9 rotates the entire device at a speed of 10 r / min. When the temperature is raised to 1570 °C, silicon infiltration is carried out, and the holding time is 15 min to obtain finished product A. When the temperature drops below 100 °C, open the furnace and open the device mold. When the temperature drops to room temperature, take out the product and clean it.

[0057] Example 2

[0058] A molten silicon infiltration method for large-sized thin-walled composite products, comprising the following steps:

[0059] S1. Prepare large-sized thin-walled composite products:

[0060] Using carbon fiber raw materials for integral three-dimensional weaving, a carbon fiber reinforcement is made with 2.5D needled carbon felt as the reinforcement. The carbon fiber reinforcement is placed in a CVI furnace for chemical vapor deposition to obtain a C / C composite with a density of 1.2 g / cm 3 , an open porosity of 32%, and a carbon content of 53 wt%. It is machined into a large-sized thin-walled composite product.

[0061] S2. Place the bottom fixing plate 7 on the pressure plate 8, load the lower die 5, load the large-size thin-walled composite material product 6 into the lower die 5, then place the upper die 2 for clamping. After fixing with the side fixing plate 4, insert the fixing pin 3 into the gap between the side fixing plate 4 and the upper die 2 to fix the whole device;

[0062] S3. Fill the gap between the product and the device with silicon powder with a particle size of 200 mesh and a purity > 99.99% through the top feed port 1 of the upper die 2. After placing the device with the product in the silicon infiltration furnace, evacuate to below 200 Pa, and the heating-up time is 135 min. When the temperature is raised to 1420 °C, the telescopic structure 10 compresses the lower die 5 through the pressure plate 8 at a speed of 10 km / h, reducing the gap between the product and the device in the device, so that the melted liquid silicon does not sink. At the same time, the turntable 9 rotates the whole device at a speed of 10 r / min. When the temperature is raised to 1600 °C, perform silicon infiltration, and the holding time is 22 min to obtain the finished product B. When the temperature drops below 100 °C, open the furnace and open the device mold. When the temperature drops to room temperature, take out the product and clean it.

[0063] Example 3

[0064] A method for melt infiltration of silicon into a large-size thin-walled composite material product, comprising the following steps:

[0065] S1. Prepare a large-size thin-walled composite material product:

[0066] Adopt integral three-dimensional weaving of carbon fiber raw materials, use 2.5D needle-punched carbon felt as the reinforcement to make a carbon fiber reinforcement, place the carbon fiber reinforcement in a CVI furnace, and perform chemical vapor deposition to obtain a C / C composite material with a density of 1.3 g / cm 3 , an open porosity of 36%, and a carbon content of 62 wt%, and machine-process it into a large-size thin-walled composite material product.

[0067] S2. Place the bottom fixing plate 7 on the pressure plate 8, load the lower die 5, load the large-size thin-walled composite material product 6 into the lower die 5, then place the upper die 2 for clamping. After fixing with the side fixing plate 4, insert the fixing pin 3 into the gap between the side fixing plate 4 and the upper die 2 to fix the whole device;

[0068] S3. Fill the gap between the product and the device with silicon powder having a particle size of 200 mesh and a purity > 99.99%. After placing the device with the product into the silicon infiltration furnace, evacuate to below 200 Pa. The heating-up time is 150 min. When the temperature is raised to 1420 °C, the telescopic structure 10 compresses the lower mold 5 through the pressing plate 8 at a speed of 10 km / h, reducing the gap between the product and the device in the device, so that the melted liquid silicon does not sink. At the same time, the turntable rotates the entire device at a speed of 10 r / min. When the temperature is raised to 1630 °C, perform silicon infiltration, and the heat preservation time is 30 min to obtain the finished product C. When the temperature drops below 100 °C, open the furnace and open the device mold. When the temperature drops to room temperature, take out the product and clean it up.

[0069] Comparative Example 1

[0070] A melting silicon infiltration method for a large-size thin-walled composite material product, and the melting silicon infiltration device used includes:

[0071] The upper mold 2, the lower mold 5, and the side fixing plate 4; the upper mold 2 is located at the top of the device, the side fixing plate 4 is located around the upper mold 2, and the device further includes a fixing pin 3 located between the upper mold 2 and the side fixing plate 4; the method includes the following steps:

[0072] S1. Prepare a large-size thin-walled composite material product:

[0073] Adopt integral three-dimensional weaving of carbon fiber raw materials, use 2.5d needle-punched carbon felt as the reinforcement to make a carbon fiber reinforcement, place the carbon fiber reinforcement into a CVI furnace, and perform chemical vapor deposition to obtain a C / C composite material with a density of 1.1 g / cm 3 , an open porosity of 28%, and a carbon content of 46 wt%, and machine-process it into a large-size thin-walled composite material product.

[0074] S2. Place the large-size thin-walled composite material product 6 into the lower mold 5, then put the upper mold 2 on to close the mold. After fixing with the side fixing plate 4, insert the fixing pin 3 into the gap between the side fixing plate 4 and the upper mold 2 to fix the whole device;

[0075] S3. Fill the gap between the product and the device with silicon powder having a particle size of 200 mesh and a purity > 99.99%. After placing the device with the product into the silicon infiltration furnace, evacuate to below 200 Pa. The heating-up time is 135 min. When the temperature is raised to 1600 °C, perform silicon infiltration, and the heat preservation time is 30 min to obtain the finished product D. When the temperature drops below 100 °C, open the furnace and open the device mold. When the temperature drops to room temperature, take out the product and clean it up.

[0076] Comparative Example 2

[0077] A melting silicon infiltration method for a large-size thin-walled composite material product, and the melting silicon infiltration device used includes: a graphite crucible 11; the method includes the following steps:

[0078] S1. Prepare large-sized thin-walled composite products:

[0079] Use the overall three-dimensional weaving of carbon fiber raw materials, and use 2.5D needled carbon felt as the reinforcement to make a carbon fiber reinforcement. Put the carbon fiber reinforcement into a CVI furnace and carry out chemical vapor deposition to obtain a C / C composite material with a density of 1.3 g / cm 3 , an open porosity of 36%, and a carbon content of 62 wt%. Machine-process it into a large-sized thin-walled composite product.

[0080] S2. Load the large-sized thin-walled composite product 6 into the graphite crucible 11;

[0081] Cover the product with silicon powder with a particle size of 200 mesh and a purity > 99.99% through the top feed port. After putting the graphite crucible containing the product into the silicon infiltration furnace, evacuate to below 200 Pa, with a heating-up time of 135 min, heat up to 1600 °C for silicon infiltration, and a holding time of 30 min to prepare the finished product E. When the temperature drops below 100 °C, open the furnace and open the device mold, and take out the product and clean it when the temperature drops to room temperature.

[0082] After cutting samples of the finished products A / B / C / D / E, conduct density and porosity tests. The results are shown in the following table:

[0083]

[0084] It can be seen from the above embodiments and comparative examples that by using the pressing plate, telescopic structure and rotating table of the device of the present invention in combination, the silicon powder stays around the product when it is in a high-temperature liquid state, which can effectively prevent the problem of poor density gradient uniformity caused by the sinking of the silicon powder in a high-temperature liquid state during the process, effectively improve the density uniformity problem of the product, and is used for silicon infiltration of large-sized thin-walled composite products, and a composite product with uniform overall density, uniform porosity, and reduced porosity can be obtained.

[0085] The above are only the preferred embodiments of the present invention, and do not limit the patent scope of the present invention accordingly. Any equivalent structural transformation made using the content of the specification of the present invention under the inventive concept of the present invention, or direct / indirect application in other related technical fields, is included in the patent protection scope of the present invention.

Claims

1. A method for silicon infiltration by melting of a large-size thin-walled composite material product, characterized in that, The molten silicon infiltration device adopted includes: an upper mold, a lower mold, a pressing plate, side fixing plates, a bottom fixing plate, a rotating table, and a telescopic structure; the rotating table is located at the bottom of the device, the telescopic structure is located in the middle of the rotating table and is connected to the pressing plate, the lower mold is connected to the pressing plate, the upper mold is located at the top of the device, the side fixing plates are located around the upper mold, and the bottom fixing plate is located around the lower mold; the following steps are included: S1. Prepare a large-size thin-walled composite material product; S2. Place the bottom fixing plate on the pressing plate, install the lower mold, load the large-size thin-walled composite material product into the lower mold, then place the upper mold to close the mold, and fix the whole device with the side fixing plates; S3. Fill the gap between the product and the device with silicon powder. After the device with the product is placed in the silicon infiltration furnace, evacuate to below 200 Pa, the heating time is 120 min to 150 min. When the temperature is raised to 1420 °C, the telescopic structure compresses the lower mold through the pressing plate at a speed of 10 km / h, reducing the gap between the product and the device in the device, so that the melted liquid silicon does not sink. At the same time, the rotating table rotates the whole device at a speed of 10 r / min. When the temperature is raised to 1570 - 1630 °C for silicon infiltration, the holding time is 15 - 30 min, and the finished product is prepared.

2. The molten silicon infiltration method according to claim 1, characterized in that The molten silicon infiltration device further includes fixing pins located between the upper mold and the side fixing plates.

3. The molten silicon infiltration method according to claim 1, wherein, The molten silicon infiltration device is all made of high-density graphite.

4. The molten silicon infiltration method according to claim 1, characterized in that, The top of the upper mold is provided with a feed inlet.

5. The molten silicon infiltration method according to claim 1, characterized in that, In the step S1, the carbon fiber raw material is integrally three-dimensionally woven, and a carbon fiber reinforcing body is made with 2.5d needle-punched carbon felt as the reinforcing body. The carbon fiber reinforcing body is placed in a CVI furnace for chemical vapor deposition. The density is deposited to 1.1 - 1.3 g / cm³, the open porosity is 28 - 36%, and the carbon content is 46 - 62 wt%, to obtain a C / C composite material, which is machined into a large-size thin-walled composite material product.

6. The molten silicon infiltration method according to claim 1, characterized in that In the step S2, after being fixed with the side fixing plates, the fixing pins are inserted into the gap between the side fixing plates and the upper mold to fix the whole device.

7. The molten silicon infiltration method according to claim 1, wherein In the step S3, the particle size of the silicon powder is 200 mesh, and the purity > 99.99%.

8. The molten silicon infiltration method according to claim 1, wherein In the step S3, the silicon powder fills the gap between the product and the device through the feed inlet at the top of the upper mold.

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