A carbon / carbon-silicon carbide gradient composite plate and a preparation method and application thereof

Abstract

The application relates to a carbon / carbon-silicon carbide gradient composite material flat plate and a preparation method and application thereof, and belongs to the field of powder metallurgy technology. The preparation method comprises the following steps: a silicon-containing carbon fiber composite preform is subjected to a chemical vapor co-deposition densification process and a chemical vapor co-deposition coating process to obtain a carbon / carbon-silicon carbide gradient composite material flat plate; and the silicon-containing carbon fiber composite flat plate preform is prepared by spraying or impregnating a carbon fiber preform with a silicon-containing precursor resin and / or a silicon-containing organic binder. The carbon / carbon-silicon carbide gradient composite material flat plate prepared by the application forms a gradient from inside to outside and in the thickness direction, reduces the reaction speed of the flat plate surface and oxygen at high temperatures, fundamentally solves the bonding problem of metal and the carrier plate during powder metallurgy sintering, and effectively improves the service life of the flat plate.

Description

Technical Field

[0001] This invention relates to the field of lithium battery electrode preparation technology, and in particular to a carbon / carbon-silicon carbide gradient composite material plate, its preparation method and application. Background Technology

[0002] In the sintering process of cemented carbide, graphite (sometimes carbon / carbon) boats or carrier plates are used. Since some alloying elements are prone to reacting or adhering with graphite or carbon / carbon, graphite plates or carbon / carbon composite plates with silicon carbide or composite coatings on the surface are produced. However, due to the mismatch in the coefficient of thermal expansion between the silicon carbide surface coating and the bulk graphite or carbon / carbon composite matrix, the silicon carbide coating is prone to delamination or peeling after a period of use, thus affecting the performance.

[0003] Patent CN 114014678 A provides a quartz fiber / carbon fiber reinforced carbon-based composite plate and its preparation method. The preform includes: an intermediate layer and a surface layer alternately stacked thereon with needled holes; the intermediate layer has an areal density of 280-600 g / m³. 2 Carbon fiber plain or twill fabric with a surface density of 80–120 g / m² 2 The surface layer is formed by alternating layers of short fiber mesh needle punched together; the surface layer has a surface density of 180–300 g / m². 2 The surface density of the quartz fiber nonwoven fabric is 60-120 g / m². 2 The composite plate is formed by alternating stacks and needle punching of short quartz fiber meshes. The resulting plate exhibits high strength and effectively reduces the reaction rate and extent between the surface layer and silicon vapor, making it suitable for use as an insulation cover for high-efficiency single-crystal furnaces and as a cover, top plate, and crucible guard for quasi-single-crystal ingot casting furnaces. However, the silicon carbide in this plate is obtained by reacting SiO2 from quartz fibers with deposited pyrolytic carbon, which affects the fiber strength. Furthermore, the resulting silicon carbide structure is relatively loose, making it unsuitable for cemented carbide sintering processes.

[0004] Therefore, there is an urgent need to design a carbon / carbon-silicon carbide gradient composite plate to fundamentally solve the problem of easy adhesion between cobalt-rich alloys and graphite or carbon / carbon composites during powder metallurgy sintering, so as to improve the service life of plates used in powder metallurgy sintering furnaces. Summary of the Invention

[0005] To address the shortcomings of existing graphite or carbon / carbon composite plates, such as low strength and short service life, this invention provides a carbon / carbon-silicon carbide gradient composite plate, its preparation method, and its application. Densification is achieved using chemical vapor deposition (CVD), followed by high-temperature treatment, machining, and finally a surface coating using CVD. This yields a carbon / carbon-silicon carbide gradient composite plate with a gradient distribution of pyrolytic carbon and silicon carbide ratios encapsulating the carbon fibers. This gradient distribution extends from the core of the plate to the upper and lower surfaces, resulting in high strength. Simultaneously, it reduces the possibility of reaction and adhesion with alloying elements at high temperatures. This fundamentally solves the problems of carbon-silicon reaction in current carbon / carbon composite plates used in single-crystal furnaces and the tendency for cobalt-rich alloys to adhere to graphite or carbon / carbon composites during powder metallurgy sintering, effectively improving the service life of the plate. The technical solution of this invention is as follows:

[0006] A method for preparing a carbon / carbon-silicon carbide gradient composite plate includes: obtaining a carbon / carbon-silicon carbide gradient composite plate by passing a silicon-containing carbon fiber composite plate preform through a chemical vapor deposition densification process and a chemical vapor deposition coating process.

[0007] The preparation method of the silicon-containing carbon fiber composite preform includes:

[0008] With a surface density of 380~600 g / m³ 2 Carbon fiber plain weave or carbon fiber twill weave fabric with an areal density of 50~70g / m² 2 Short fiber meshes are alternately layered and needle-punched into a whole to form a carbon fiber flat preform;

[0009] The weight ratio of the carbon fiber plain weave fabric or carbon fiber twill weave fabric to the short fiber mesh is controlled at 9:1 to 6:4, and the density is 0.55 to 0.8 g / cm³. 3 The thickness is 10~35mm;

[0010] Place the carbon fiber flat preform on the mold, ensuring good contact between the inner surface of the carbon fiber flat preform and the outer surface of the mold. Then spray or impregnate it with a resin containing a silicon precursor and / or a silicon-containing organic binder. Let it stand for 1-3 hours, then place it on a flatbed hot press to cure and shape it. Control the temperature at 180-280℃ and keep it at that temperature for 5-6 hours. Cool down and demold to obtain the shaped silicon-containing carbon fiber composite flat preform.

[0011] Preferably, the mold is a stainless steel plate with a thickness of 1-3 mm.

[0012] Preferably, the resin containing the silicon precursor is a mixture of phenolic resin and polymethylsilane.

[0013] Preferably, the volume ratio of carbon source gas to trichloromethylsilane gas in the chemical vapor deposition densification process is 9:1 to 3:7.

[0014] Preferably, the carbon source gas is natural gas, propane, propylene, or a mixture of any two of them.

[0015] Preferably, the chemical vapor deposition densification process specifically comprises: one gas stream consisting of trichloromethylsilane, hydrogen as a dilution gas, and argon as a carrier gas; and another gas stream consisting of carbon source gas and hydrogen, which are simultaneously introduced into the deposition chamber in a specific ratio. The deposition temperature is 1000~1150℃, the furnace pressure is 1.5~10kPa, and the densification time is 150~300 hours, thereby densifying the silicon-carbon fiber composite preform to 1.4~1.7 g / cm³. 3 Afterwards, it undergoes high-temperature treatment at 1300~2000℃ for 2~10 hours, and is then machined to the required dimensions to obtain a carbon / carbon-silicon carbide gradient composite material plate.

[0016] Preferably, the co-deposition chemical vapor deposition coating process specifically comprises: one gas stream using trichloromethylsilane as the silicon carbide precursor, hydrogen as the dilution gas, and nitrogen or argon as the carrier gas; and another gas stream consisting of carbon source gas and hydrogen, which are simultaneously introduced into the deposition chamber in a specific ratio. The volume ratio of carbon source gas to trichloromethylsilane gas is 1:9 to 3:7. The deposition temperature is 1050 to 1150°C, the furnace pressure is 1.5 to 5 kPa, and the coating time is 10 to 50 hours, resulting in a carbon / carbon-silicon carbide gradient composite material with a density of 1.5 to 1.9 g / cm³. 3 .

[0017] A carbon / carbon-silicon carbide gradient composite plate prepared by the above-described preparation method.

[0018] The application of the aforementioned carbon / carbon-silicon carbide gradient composite plate as a carrier plate in the powder metallurgy production process.

[0019] Compared with the prior art, the present invention has the following advantages:

[0020] This invention provides a carbon / carbon-silicon carbide gradient composite material plate. During the curing and shaping of the preform, a silicon carbide precursor, polymethylsilane, is added to the resin or organic binder to obtain a carbon fiber composite preform containing the silicon carbide precursor. Upon heating and carbonization, the resulting preform contains silicon carbide. Then, chemical vapor deposition (CVD) is used for densification, simultaneously depositing pyrolytic carbon and a silicon carbide matrix. This allows the pyrolytic carbon and silicon carbide matrix surrounding the carbon fiber growth to be deposited simultaneously. During the deposition process, by adjusting the ratio of the two, a gradient structure is obtained, with the carbon and silicon carbide ratio from the fiber surface to the pyrolytic carbon and silicon carbide matrix surfaces distributed in a gradient from high to low. Finally, during the CVD coating process, increasing the proportion of silicon carbide can further form a gradient structure of carbon and silicon carbide from the core to the upper and lower surfaces within the plate. The obtained carbon / carbon-silicon carbide gradient composite plate can effectively reduce or avoid the reaction with alloying elements. The carbon / carbon-silicon carbide gradient composite plate obtained by this invention has a bending strength of over 220 MPa, which is higher than carbon / carbon plates and graphite plates, and increases the service life of the plate by more than 50%. It is suitable for mass production of plates for polycrystalline ingot furnaces and powder metallurgy sintering furnaces. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of pyrolytic carbon (containing silicon carbide) deposited around the carbon fiber in this invention.

[0022] Figure 2 This is a schematic diagram of the coating process in this invention (the surface coating is mainly composed of silicon carbide). Detailed Implementation

[0023] The technical solution of the present invention will be described below through specific embodiments.

[0024] Unless otherwise specified, the raw materials and equipment involved in this invention are all commercially available products.

[0025] Example 1

[0026] A method for preparing a carbon / carbon-silicon carbide gradient composite plate, comprising a silicon-containing carbon fiber composite preform prepared by chemical vapor deposition densification process and a co-deposition chemical vapor deposition process; the method for preparing the silicon-containing carbon fiber composite preform includes:

[0027] With a surface density of 420 g / m 2 Carbon fiber plain weave fabric with an areal density of 65 g / m 2 Short fiber meshes are alternately layered and needle-punched into a whole to form a carbon fiber flat preform;

[0028] The weight ratio of the carbon fiber plain weave fabric to the short fiber mesh is controlled at 9:1, with a density of 0.58 g / cm³. 3 The thickness is 18mm;

[0029] A carbon fiber preform is placed on a 1mm thick stainless steel plate to ensure good adhesion between the preform surface and the plate. Then, a resin containing a silicon precursor and / or a silicon-containing organic binder are sprayed or impregnated onto the preform. After 2 hours, the preform is placed in a hot press to cure and set its shape at 260℃ for 5 hours. After cooling, the preform is demolded to obtain a shaped silicon-containing carbon fiber composite preform with a density of 0.6~0.65g / cm³. 3 .

[0030] The resin containing the silicon precursor is a mixture of phenolic resin and polymethylsilane.

[0031] The chemical vapor deposition (CVD) densification process specifically involves: one gas stream using trichloromethylsilane as the silicon carbide precursor, hydrogen as the dilution gas, and argon as the carrier gas; and another gas stream consisting of natural gas and hydrogen, both introduced simultaneously into the deposition chamber in a specific ratio. The deposition temperature is controlled at 1100±5℃, the furnace pressure at 3±0.2 kPa, and the densification time at 180 hours, resulting in a density of 1.56 g / cm³ for the silicon-carbon fiber composite preform. 3 Afterwards, it undergoes high-temperature treatment at 1800℃ for 3 hours, and then is machined to the product size to obtain a carbon / carbon-silicon carbide gradient composite plate.

[0032] In the chemical vapor deposition densification process, the volume ratio of carbon source gas (natural gas) to trichloromethylsilane gas is 8:2 for 60 hours of deposition and densification. Then the volume ratio is adjusted to 7:3 for 60 hours of deposition. The volume ratio is then adjusted to 6:4 for 60 hours of deposition, and then the process is cooled with the furnace.

[0033] The co-deposition chemical vapor deposition coating process specifically involves: one gas stream using trichloromethylsilane as the silicon carbide precursor, hydrogen as the dilution gas, and argon as the carrier gas; and another gas stream consisting of natural gas and hydrogen. These are simultaneously introduced into the deposition chamber in a specific ratio. The volume ratio of carbon source gas to trichloromethylsilane gas is 3:7 (10 hours), 2:8 (10 hours), and 1:9 (10 hours). The deposition temperature is 1090±5℃, the furnace pressure is 2.5±0.2 kPa, and the deposition time is 30 hours, resulting in a carbon / carbon-silicon carbide gradient composite material plate with a density of 1.75 g / cm³. 3 .

[0034] The resulting carbon / carbon-silicon carbide gradient composite plate has a flexural strength of 210±3MPa and a service life of 12 months in a cemented carbide sintering furnace. The plate does not bond with the alloy.

[0035] Example 2

[0036] A method for preparing a carbon / carbon-silicon carbide gradient composite plate includes: obtaining a carbon / carbon-silicon carbide gradient composite plate by passing a silicon-containing carbon fiber composite plate preform through a chemical vapor deposition densification process and a chemical vapor deposition coating process.

[0037] The preparation method of the silicon-containing carbon fiber composite preform includes:

[0038] With a surface density of 380 g / m 2 Carbon fiber plain weave or carbon fiber twill weave fabric with an areal density of 70 g / m² 2 Short fiber meshes are alternately layered and needle-punched into a whole to form a carbon fiber flat preform;

[0039] The weight ratio of the carbon fiber plain weave fabric or carbon fiber twill weave fabric to the short fiber mesh is controlled at 96:4, with a density of 0.55 g / cm³. 3 The thickness is 35mm;

[0040] The carbon fiber preform is placed on a 3mm thick stainless steel plate to ensure good adhesion between the surface of the carbon fiber preform and the mold. Then, the resin containing the silicon precursor and / or the silicon-containing organic binder are sprayed or impregnated. After 3 hours, the preform is placed on a hot press to cure and shape it. The temperature is controlled at 280℃ and kept at that temperature for 6 hours. After cooling, the preform is demolded to obtain the shaped silicon-containing carbon fiber composite preform.

[0041] The resin containing the silicon precursor is a mixture of phenolic resin and polymethylsilane.

[0042] The carbon source gas is natural gas, propane, propylene, or a mixture of any two of them.

[0043] The chemical vapor deposition (CVD) densification process specifically involves: one gas stream consisting of trichloromethylsilane, hydrogen as a dilution gas, and argon as a carrier gas; and another gas stream consisting of a carbon source gas and hydrogen, which are simultaneously introduced into the deposition chamber in a specific ratio. The deposition temperature is 1000–1150°C, the furnace pressure is 1.5–10 kPa, and the densification time is 150–300 hours, resulting in a density of 1.4–1.7 g / cm³ for the silicon-carbon fiber composite preform. 3 Subsequently, a high-temperature treatment is performed at 1300~2000℃ for 2~10 hours, followed by machining to the required product dimensions to obtain a carbon / carbon-silicon carbide gradient composite material plate. In the chemical vapor deposition densification process, the volume ratio of carbon source gas to trichloromethylsilane gas is 9:1~3:7.

[0044] The co-deposition chemical vapor deposition coating process specifically involves: one gas stream using trichloromethylsilane as the silicon carbide precursor, hydrogen as the dilution gas, and nitrogen or argon as the carrier gas; and another gas stream containing carbon source gas and hydrogen, which are simultaneously introduced into the deposition chamber in a specific ratio. The volume ratio of carbon source gas to trichloromethylsilane gas is 1:9 to 3:7. The deposition temperature is 1050 to 1150°C, the furnace pressure is 1.5 to 5 kPa, and the coating time is 10 to 50 hours, resulting in a carbon / carbon-silicon carbide gradient composite material with a density of 1.5 to 1.9 g / cm³. 3 .

[0045] The resulting carbon / carbon-silicon carbide gradient composite plate has a flexural strength of 210±3MPa and a service life of 12 months in a cemented carbide sintering furnace. The plate does not bond with the alloy.

[0046] Example 3

[0047] A method for preparing a carbon / carbon-silicon carbide gradient composite plate includes: obtaining a carbon / carbon-silicon carbide gradient composite plate by passing a silicon-containing carbon fiber composite plate preform through a chemical vapor deposition densification process and a chemical vapor deposition coating process.

[0048] The preparation method of the silicon-containing carbon fiber composite preform includes:

[0049] With a surface density of 600 g / m 2 Carbon fiber plain weave or carbon fiber twill weave fabric with an areal density of 50 g / m² 2 Short fiber meshes are alternately layered and needle-punched into a whole to form a carbon fiber flat preform;

[0050] The weight ratio of the carbon fiber plain weave fabric or carbon fiber twill weave fabric to the short fiber mesh is controlled at 9:1 to 6:4, and the density is 0.55 to 0.8 g / cm³. 3 The thickness is 10~35mm;

[0051] Place the carbon fiber flat preform on the mold, ensuring good adhesion between the surface of the carbon fiber flat preform and the mold. Then spray or impregnate it with a resin containing a silicon precursor and / or a silicon-containing organic binder. Let it stand for 1-3 hours, then place it on a flatbed hot press to cure and shape it. Control the temperature at 180-280℃ and keep it at that temperature for 5-6 hours. Cool down and demold to obtain the shaped silicon-containing carbon fiber composite flat preform.

[0052] The mold is a stainless steel plate with a thickness of 1-3 mm.

[0053] The resin containing the silicon precursor is a mixture of phenolic resin and polymethylsilane.

[0054] The carbon source gas is natural gas, propane, propylene, or a mixture of any two of them.

[0055] The chemical vapor deposition (CVD) densification process specifically involves: one gas stream consisting of trichloromethylsilane, hydrogen as a dilution gas, and argon as a carrier gas; and another gas stream consisting of a carbon source gas and hydrogen, which are simultaneously introduced into the deposition chamber in a specific ratio. The deposition temperature is 1000–1150°C, the furnace pressure is 1.5–10 kPa, and the densification time is 150–300 hours, resulting in a density of 1.4–1.7 g / cm³ for the silicon-carbon fiber composite preform. 3 Subsequently, a high-temperature treatment is performed at 1300~2000℃ for 2~10 hours, followed by machining to the required product dimensions to obtain a carbon / carbon-silicon carbide gradient composite material plate. In the chemical vapor deposition densification process, the volume ratio of carbon source gas to trichloromethylsilane gas is 9:1~3:7.

[0056] The co-deposition chemical vapor deposition coating process specifically involves: one gas stream using trichloromethylsilane as the silicon carbide precursor, hydrogen as the dilution gas, and nitrogen or argon as the carrier gas; and another gas stream containing carbon source gas and hydrogen, which are simultaneously introduced into the deposition chamber in a specific ratio. The volume ratio of carbon source gas to trichloromethylsilane gas is 1:9 to 3:7. The deposition temperature is 1050 to 1150°C, the furnace pressure is 1.5 to 5 kPa, and the coating time is 10 to 50 hours, resulting in a carbon / carbon-silicon carbide gradient composite material with a density of 1.5 to 1.9 g / cm³. 3 .

[0057] The resulting carbon / carbon-silicon carbide gradient composite plate has a flexural strength of 208±3MPa and a service life of 12 months in a cemented carbide sintering furnace. The plate does not bond with the alloy.

[0058] Comparative Example 1

[0059] A pyrolytic carbon + silicon carbide matrix was obtained without using a chemical vapor deposition (CVD) densification process. A carbon / carbon composite plate was then prepared using a CVD densification process. Finally, a carbon / carbon-silicon carbide partially gradient composite plate was obtained by CVD co-deposition of the pyrolytic carbon + silicon carbide matrix, with a density of 1.63 g / cm³. 3 Other processes are the same as in Example 1.

[0060] The flexural strength of the obtained carbon / carbon-silicon carbide partially gradient composite plate is 132±3MPa. After 6 months of use, the plate locally bonded to the alloy, and the service life of the plate is 8.5 months.

[0061] Comparative Example 2

[0062] A carbon / carbon composite plate with a density of 1.55 g / cm³ was prepared by obtaining a pyrolytic carbon + silicon carbide matrix without using a chemical vapor deposition (CVD) densification process and by forming a surface coating without using a CVD coating process. 3The rest is the same as in Example 1.

[0063] The flexural strength of the obtained carbon / carbon composite plate is 98±2MPa. After 3 months of use, the plate locally bonded to the alloy, and the service life of the plate is 7 months.

[0064] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Any other modifications or equivalent substitutions made by those skilled in the art to the technical solutions of the present invention, as long as they do not depart from the principles and scope of the technical solutions of the present invention, should be covered within the scope of the claims of the present invention.

Claims

1. The application of a carbon / carbon-silicon carbide gradient composite plate as a carrier plate in the powder metallurgy production process, characterized in that, A method for preparing carbon / carbon-silicon carbide gradient composite plate includes: obtaining a carbon / carbon-silicon carbide gradient composite plate by passing a silicon-containing carbon fiber composite plate preform through a chemical vapor deposition densification process and a chemical vapor deposition coating process. The preparation method of the silicon-containing carbon fiber composite preform includes: With a surface density of 380~600 g / m³ 2 Carbon fiber plain or twill fabric with an areal density of 50~70 g / m 2 Short fiber meshes are alternately layered and needle-punched into a whole to form a carbon fiber flat preform; The weight ratio of the carbon fiber plain weave fabric or twill weave fabric to the short fiber mesh is controlled at 9:1 to 6:4, and the density of the prefabricated part is 0.55 to 0.8 g / cm³. 3 The thickness is 10~35mm; Place the carbon fiber flat preform on a mold, then spray or impregnate it with a resin containing a silicon precursor and / or a silicon-containing organic binder. Let it stand for 1 to 3 hours, then place it on a flat hot press to cure and shape it. The temperature is controlled at 180 to 280℃ and kept at that temperature for 5 to 6 hours. After cooling, demold to obtain the shaped silicon-containing carbon fiber composite flat preform. When using chemical vapor deposition for densification, pyrolytic carbon and silicon carbide substrates that encapsulate carbon fiber growth are deposited simultaneously. During the deposition process, by adjusting the ratio of the two, a gradient structure is obtained, with the ratio of carbon to silicon carbide on the fiber surface and the surface of the pyrolytic carbon and silicon carbide substrates distributed in a gradient from high to low. When using chemical vapor deposition coating, the proportion of silicon carbide is increased, further forming a gradient structure of carbon and silicon carbide from the core to the upper and lower surfaces in the plate.

2. The application according to claim 1, characterized in that, The mold is a stainless steel plate with a thickness of 1-3 mm.

3. The application according to claim 1, characterized in that, The resin containing the silicon precursor is a mixture of phenolic resin and polymethylsilane.

4. The application according to claim 1, characterized in that, In the chemical vapor deposition densification process, the volume ratio of carbon source gas to trichloromethylsilane gas is 9:1 to 3:

7.

5. The application according to claim 4, characterized in that, The carbon source gas is natural gas, propane, propylene, or a mixture of any two of these.

6. The application according to claim 5, characterized in that, The chemical vapor deposition (CVD) densification process specifically involves: one gas stream using trichloromethylsilane as a silicon carbide precursor, hydrogen as a dilution gas, and nitrogen or argon as a carrier gas; and another gas stream consisting of a carbon source gas and hydrogen, both introduced simultaneously into the deposition chamber in a specific ratio. The deposition temperature is 1000–1150°C, the furnace pressure is 1.5–10 kPa, and the densification time is 150–300 hours, resulting in a density of 1.4–1.7 g / cm³ for the silicon-carbon fiber composite flat plate preform. 3 Afterwards, it undergoes high-temperature treatment at 1300~2000℃ for 2~10 hours, and is then machined to the required dimensions to obtain a carbon / carbon-silicon carbide gradient composite material plate.

7. The application according to claim 1, characterized in that, The co-deposition chemical vapor deposition coating process specifically involves: one gas stream using trichloromethylsilane as the silicon carbide precursor, hydrogen as the dilution gas, and nitrogen or argon as the carrier gas; and another gas stream containing carbon source gas and hydrogen, which are simultaneously introduced into the deposition chamber in a specific ratio. The volume ratio of carbon source gas to trichloromethylsilane gas is 1:9 to 3:

7. The deposition temperature is 1050 to 1150°C, the furnace pressure is 1.5 to 5 kPa, and the coating time is 10 to 50 hours, resulting in a carbon / carbon-silicon carbide gradient composite material with a density of 1.5 to 1.9 g / cm³. 3 .

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