WO2022237749A1 - Method for increasing density of carbon/carbon composite thick plate - Google Patents

Method for increasing density of carbon/carbon composite thick plate Download PDF

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Publication number
WO2022237749A1
WO2022237749A1 PCT/CN2022/091847 CN2022091847W WO2022237749A1 WO 2022237749 A1 WO2022237749 A1 WO 2022237749A1 CN 2022091847 W CN2022091847 W CN 2022091847W WO 2022237749 A1 WO2022237749 A1 WO 2022237749A1
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carbon
density
fiber
carbon fiber
preform
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PCT/CN2022/091847
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French (fr)
Chinese (zh)
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张福勤
黄伯云
曾凡浩
杨宇
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中南大学
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Publication of WO2022237749A1 publication Critical patent/WO2022237749A1/en

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    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
    • C04B35/71—Ceramic products containing macroscopic reinforcing agents
    • C04B35/78—Ceramic products containing macroscopic reinforcing agents containing non-metallic materials
    • C04B35/80—Fibres, filaments, whiskers, platelets, or the like
    • C04B35/83—Carbon fibres in a carbon matrix
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
    • C04B35/622—Forming processes; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
    • D—TEXTILES; PAPER
    • D04—BRAIDING; LACE-MAKING; KNITTING; TRIMMINGS; NON-WOVEN FABRICS
    • D04H—MAKING TEXTILE FABRICS, e.g. FROM FIBRES OR FILAMENTARY MATERIAL; FABRICS MADE BY SUCH PROCESSES OR APPARATUS, e.g. FELTS, NON-WOVEN FABRICS; COTTON-WOOL; WADDING ; NON-WOVEN FABRICS FROM STAPLE FIBRES, FILAMENTS OR YARNS, BONDED WITH AT LEAST ONE WEB-LIKE MATERIAL DURING THEIR CONSOLIDATION
    • D04H1/00—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres
    • D04H1/40—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres from fleeces or layers composed of fibres without existing or potential cohesive properties
    • D04H1/42—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres from fleeces or layers composed of fibres without existing or potential cohesive properties characterised by the use of certain kinds of fibres insofar as this use has no preponderant influence on the consolidation of the fleece
    • D04H1/4209—Inorganic fibres
    • D04H1/4242—Carbon fibres
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
    • C04B2235/02—Composition of constituents of the starting material or of secondary phases of the final product
    • C04B2235/50—Constituents or additives of the starting mixture chosen for their shape or used because of their shape or their physical appearance
    • C04B2235/52—Constituents or additives characterised by their shapes
    • C04B2235/5208—Fibers
    • C04B2235/5212—Organic
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
    • C04B2235/60—Aspects relating to the preparation, properties or mechanical treatment of green bodies or pre-forms
    • C04B2235/614—Gas infiltration of green bodies or pre-forms
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
    • C04B2235/70—Aspects relating to sintered or melt-casted ceramic products
    • C04B2235/74—Physical characteristics
    • C04B2235/77—Density

Definitions

  • the invention discloses a method for increasing the densification density of thick plates of carbon/carbon composite materials, and belongs to the technical field of carbon/carbon composite material preparation.
  • Carbon/carbon composite material is an advanced composite material with carbon fiber reinforced carbon matrix. It has excellent properties such as light weight, high specific strength, low thermal expansion coefficient, good dimensional stability, and corrosion resistance, especially excellent friction and wear properties. It has broad application prospects in aviation, aerospace, thermal processing and other fields.
  • Chemical vapor deposition is an important method for preparing carbon/carbon composites.
  • the composites prepared by this method have a continuous pyrolytic carbon matrix structure, which can endow the composites with high mechanical properties and friction and wear properties. It is an important method to obtain high-performance carbon/carbon composites. , such as the preferred route for aerospace brake materials.
  • Chemical vapor deposition is obtained by decomposing carbon source gas at high temperature and depositing carbon atoms on the surface of carbon fibers. The prerequisite for the realization of chemical vapor deposition is.
  • the densification process of the carbon fiber preform by the existing chemical vapor deposition process is a non-uniform densification process, which is reflected in the fact that the densification speed of the surface is faster than that of the core, and the composite material produces a density gradient from the surface to the interior.
  • the surface density of the composite material reaches above 1.85g/cm 3 , forming surface sealing holes, which prevents the carbon source gas from penetrating from the surface to the core. It affects the densification efficiency, and it is difficult to obtain high-density carbon/carbon composite materials.
  • the object of the present invention is to provide a method for increasing the densification density of carbon/carbon composite thick plates.
  • Sisal fiber is a natural plant fiber with a diameter of 200-400 ⁇ m, which shrinks in volume by about 60% during carbonization.
  • the invention weaves sisal fibers into the carbon fiber prefabricated body, utilizes the carbonization and shrinkage of the sisal hemp fiber with a large diameter, forms pores in the carbon fiber woven prefabricated body with a thin diameter (about 7 ⁇ m), constructs a carbon source gas channel, and improves the carbon fiber prefabricated body Excellent air permeability, so that the carbon source gas can be delivered to the core of the preform remotely, solve the problem of uniform densification of carbon/carbon composite slabs (including disc-shaped carbon/carbon composite materials) along the thickness direction, and prepare high-density carbon / carbon composite.
  • the sisal fiber with a diameter of ⁇ 400 ⁇ m and a length of ⁇ 10 mm is first woven into the carbon fiber preform, and then densified by chemical vapor deposition.
  • the invention discloses a method for increasing the densification density of thick plates of carbon/carbon composite materials.
  • the carbon fiber prefabricated body is a thick plate with a thickness of 20-35 mm and a density of 0.3-0.6 g/cm 3 .
  • the invention discloses a method for increasing the densification density of a thick plate of carbon/carbon composite material.
  • the diameter of the sisal fiber is 200-400 ⁇ m, the length is 5-10 mm, and the mass percentage of the sisal fiber in the prefabricated body is 1-5%.
  • the invention discloses a method for increasing the densification density of carbon/carbon composite thick plates.
  • the carbon fiber prefabricated body is obtained by sequentially stacking the basic units of the prefabricated body through acupuncture; Fiber and carbon fiber non-weft cloth are stacked in sequence, and the sisal fiber is evenly spread on the surface of the carbon fiber mesh layer; after the first layer of prefabricated basic units are continuously acupunctured, the second layer of prefabricated basic units is superimposed on it And carry out continuous needle punching; realize the acupuncture hooking of sisal fiber and carbon fiber mesh layer in the same prefabricated basic unit and the acupuncture hooking of sisal fiber and carbon fiber non-woven fabric between adjacent prefabricated basic units, and so on , to obtain a carbon fiber prefabricated body obtained by needling the basic unit of the prefabricated body and meeting the design thickness requirements; in the carbon fiber prefabricated body, the sisal fibers are evenly distributed; The connection between the basic units of the adjacent prefabricated body is realized, and the other part is evenly distributed on the surface of the mesh tire of the
  • the sisal fiber carbonizes and shrinks, and the gas channels along the thickness direction of the preform and the gas channels along the surface of the mesh tire are formed to form other channels in a criss-cross pattern, which can greatly improve the density and the uniformity of the density distribution. sex.
  • the invention discloses a method for increasing the densification density of a carbon/carbon composite material thick plate.
  • the acupuncture direction is along the normal direction of the prefabricated body to realize the needle-punched hooking of the mesh layer and the weft-free cloth layer, and at the same time, introduce Sisal fiber.
  • the invention discloses a method for increasing the densification density of a carbon/carbon composite thick plate.
  • the needling density is: the distance between adjacent rows is ⁇ 2mm, and the distance within the same row is ⁇ 2mm.
  • the invention discloses a method for increasing the densification density of a carbon/carbon composite thick plate.
  • the carbon fiber prefabricated body there are 30 to 60 carbon fiber mesh layers and carbon fiber non-weft cloth layers respectively.
  • the carbon fiber mesh layer and the carbon fiber non-weft cloth layer are 40-50 layers of the carbon fiber mesh layer and the carbon fiber non-weft cloth layer respectively.
  • the invention relates to a method for increasing the densification density of a carbon/carbon composite thick plate.
  • the arrangement directions of adjacent non-weft cloths are 90° to each other.
  • the invention discloses a method for increasing the densification density of a thick plate of carbon/carbon composite material, wherein the sisal fiber is evenly spread on one surface and/or the other surface of a carbon fiber mesh layer.
  • the invention discloses a method for increasing the densification density of carbon/carbon composite thick plates.
  • a central through hole is arranged along the thickness direction of the carbon fiber prefabricated body to form a disk shape.
  • the inner diameter of the disk is 10-300mm, and the outer diameter of the disk is 200mm ⁇ 600mm, thickness 20 ⁇ 35mm.
  • the inner diameter of the disc is 200mm, the outer diameter is 450mm, and the thickness is 30mm.
  • the invention discloses a method for increasing the densification density of carbon/carbon composite thick plates.
  • the weaving structure of the carbon fiber prefabricated body is a needle-punched prefabricated body.
  • the carbon fiber mesh layer and the carbon fiber non-weft cloth layer are laminated alternately and obtained by continuous needling.
  • the present invention is a method for increasing the densification density of carbon/carbon composite thick plates.
  • the chemical vapor deposition process is as follows: using C3H6 as the carbon source gas and N2 as the dilution gas, the C3H6 and The flow ratio of N 2 is 4 ⁇ 100:1; the temperature is 950 ⁇ 1100°C; the pressure in the furnace is 0.5 ⁇ 10kPa.
  • the weight of the carbon fiber prefabricated body is weighed with a balance before and after each chemical vapor deposition, and the weight gain after each deposition is calculated, and the density is calculated , while machining and cleaning the surface dirt after each deposition.
  • the present invention weaves sisal fibers into the carbon fiber prefabricated body, utilizes the carbonization and shrinkage of the sisal hemp fiber with a large diameter, forms pores in the carbon fiber woven prefabricated body with a thin diameter (about 7 ⁇ m), constructs a carbon source gas channel, and improves the carbonization of the prefabricated body.
  • the gas permeability enables the carbon source gas to be delivered to the core of the preform remotely, and solves the problem of uniform densification in the thickness direction of the disc-shaped carbon/carbon composite material.
  • the density of the carbon/carbon composite material reaches above 1.8g/cm 3 .
  • the length of the sisal fiber is controlled within the range of 5-10mm, and the connectivity of the carbon source gas channel in the prefabricated body is the best, and if the length is too short, the gas channel formed after the carbonization and shrinkage of the sisal fiber is incoherent , the air permeability is not significantly improved; if the length is too long, the sisal fibers will agglomerate, which will affect the uniformity of the sisal fibers spreading on the surface of the mesh layer.
  • the prefabricated body will have the best air permeability to the carbon source gas, and if the mass fraction is too small, the air permeability will not be significantly improved; if the mass fraction is too large , it reduces the interlayer bonding of carbon fiber preforms and affects the mechanical properties of carbon/carbon composites.
  • the weaving structure of the carbon fiber prefabricated body of the present invention is a needle-punched prefabricated body.
  • the sisal fibers are evenly spread on the surface of the carbon fiber mesh layer, and then the carbon fiber mesh layer and the carbon fiber non-weft cloth layer are alternately laminated, and the needles are continuously stitched. Get stabbed.
  • the needle-punching direction is the normal direction of the prefabricated body, the needle-punching penetrates the adjacent mesh layer and the non-weft layer, and the sisal fiber laid on the mesh layer is pierced into the non-weft layer by using a needle with a hook. While realizing the needle-punched hooking of the mesh layer and the non-woven fabric layer, the sisal fiber is introduced in the normal direction of the prefabricated body.
  • the present invention weaves sisal fibers into the carbon fiber prefabricated body, utilizes the carbonization and shrinkage of the thick sisal fiber to form pores in the carbon fiber woven prefabricated body with a thin diameter (about 7 ⁇ m), and constructs a carbon source gas channel, especially the prefabricated body
  • the carbon source gas channel in the normal direction improves the air permeability of the preform, enables the carbon source gas to be delivered to the core of the preform remotely, and solves the problem of uniform densification in the thickness direction of the disc-shaped carbon/carbon composite material.
  • the material density reaches above 1.8g/cm 3 .
  • Fig. 1 is a schematic diagram of the basic unit structure of the preform of the present invention.
  • the carbon fiber mesh layer, sisal fiber, and carbon fiber non-weft cloth are stacked sequentially from bottom to top, and the acupuncture direction is the normal direction of the prefabricated body.
  • Sisal fibers are introduced in the normal direction of the preform.
  • sisal fibers with a diameter of 200-400 ⁇ m Take sisal fibers with a diameter of 200-400 ⁇ m, plant them into short fibers with a length of 9 mm, weave them into the carbon fiber prefabricated body, control the sisal fiber mass fraction in the prefabricated body to be 4%, and then make the carbon fiber prefabricated body Densification by chemical vapor deposition to prepare high-density carbon/carbon composite materials.
  • the shape of the carbon fiber preform is disc-shaped, the inner diameter is 200 mm, the outer diameter is 450 mm, the thickness is 30 mm, and the density of the preform is 0.5 g/cm 3 ;
  • the weaving structure of the carbon fiber preform is an acupuncture preform, First, the sisal fiber is evenly spread on the surface of the carbon fiber mesh layer, and then the carbon fiber mesh layer and the carbon fiber non-weft cloth layer are laminated alternately, and obtained by continuous needle punching, and the carbon fiber mesh layer and the carbon fiber non-weft layer in the prefabricated body are controlled.
  • Each cloth layer has 50 layers, and the arrangement directions of adjacent non-weft cloths are 90° to each other, and the needle punching density is such that the distance between rows is ⁇ 2 mm;
  • the chemical vapor deposition process is: using C 3 H 6 as carbon
  • the source gas and N 2 are diluent gas, the flow ratio of C 3 H 6 and N 2 is controlled to be 90:1, the temperature is 950°C, and the furnace pressure is 3kPa.
  • the deposition time is 150 h as a deposition cycle, and a disc-shaped carbon/carbon composite material is prepared after 4 deposition cycles, and the density of the obtained composite material is 1.8 g/cm 3 .
  • sisal fibers with a diameter of 200-400 ⁇ m Take sisal fibers with a diameter of 200-400 ⁇ m, plant them into short fibers with a length of 6 mm, weave them into the carbon fiber prefabricated body, control the sisal fiber mass fraction in the prefabricated body to be 2%, and then make the carbon fiber prefabricated body Densification by chemical vapor deposition to prepare high-density carbon/carbon composite materials.
  • the shape of the carbon fiber preform is disc-shaped, the inner diameter is 50 mm, the outer diameter is 500 mm, the thickness is 25 mm, and the density of the preform is 0.4 g/cm 3 ;
  • the weaving structure of the carbon fiber preform is an acupuncture preform, First, the sisal fiber is evenly spread on the surface of the carbon fiber mesh layer, and then the carbon fiber mesh layer and the carbon fiber non-weft cloth layer are laminated alternately, and obtained by continuous needle punching, and the carbon fiber mesh layer and the carbon fiber non-weft layer in the prefabricated body are controlled.
  • Each cloth layer has 33 layers, and the arrangement directions of adjacent non-weft cloths are 90° to each other, and the needle punching density is such that the distance between rows is ⁇ 2mm; the chemical vapor deposition process is: using C 3 H 6 as carbon
  • the source gas and N 2 are diluent gas, the flow ratio of C 3 H 6 and N 2 is controlled to be 40:1, the temperature is 1000°C, and the pressure in the furnace is 8kPa.
  • the deposition time is 150 h as a deposition cycle, and a disc-shaped carbon/carbon composite material is prepared after 4 deposition cycles.
  • the density of the obtained composite material is 1.81 g/cm 3 , and the bending strength is 130 MPa.
  • sisal fibers with a diameter of 200-400 ⁇ m Take sisal fibers with a diameter of 200-400 ⁇ m, plant them into short fibers with a length of 7 mm, weave them into the carbon fiber prefabricated body, control the sisal fiber mass fraction in the prefabricated body to 1%, and then make the carbon fiber prefabricated body Densification by chemical vapor deposition to prepare high-density carbon/carbon composite materials.
  • the shape of the carbon fiber preform is disc-shaped, the inner diameter is 260 mm, the outer diameter is 560 mm, the thickness is 20 mm, and the density of the preform is 0.6 g/cm 3 ;
  • the weaving structure of the carbon fiber preform is an acupuncture preform, First, the sisal fiber is evenly spread on the surface of the carbon fiber mesh layer, and then the carbon fiber mesh layer and the carbon fiber non-weft cloth layer are laminated alternately, and obtained by continuous needle punching, and the carbon fiber mesh layer and the carbon fiber non-weft layer in the prefabricated body are controlled.
  • Each cloth layer has 40 layers, and the arrangement directions of adjacent non-weft cloths are 90° to each other, and the needle punching density is such that the distance between rows is ⁇ 2 mm;
  • the chemical vapor deposition process is: using C 3 H 6 as carbon
  • the source gas and N 2 are diluent gas, the flow ratio of C 3 H 6 and N 2 is controlled to be 20:1, the temperature is 1050°C, and the pressure in the furnace is 2kPa.
  • the deposition time is 150 h as a deposition cycle, and a disc-shaped carbon/carbon composite material is prepared after 4 deposition cycles, and the density of the obtained composite material is 1.82 g/cm 3 .
  • sisal fibers with a diameter of 200-400 ⁇ m Take sisal fibers with a diameter of 200-400 ⁇ m, plant them into short fibers with a length of 5 mm, weave them into the carbon fiber prefabricated body, control the sisal fiber mass fraction in the prefabricated body to be 3%, and then make the carbon fiber prefabricated body Densification by chemical vapor deposition to prepare high-density carbon/carbon composite materials.
  • the shape of the carbon fiber preform is disc-shaped, the inner diameter is 150 mm, the outer diameter is 400 mm, the thickness is 35 mm, and the density of the preform is 0.3 g/cm 3 ;
  • the weaving structure of the carbon fiber preform is an acupuncture preform, First, the sisal fiber is evenly spread on the surface of the carbon fiber mesh layer, and then the carbon fiber mesh layer and the carbon fiber non-weft cloth layer are laminated alternately, and obtained by continuous needle punching, and the carbon fiber mesh layer and the carbon fiber non-weft layer in the prefabricated body are controlled.
  • Each cloth layer has 35 layers, the arrangement directions of adjacent non-weft cloths are 90° to each other, and the needle punching density is such that the distance between rows is ⁇ 2mm; the chemical vapor deposition process is: using C 3 H 6 as carbon
  • the source gas and N 2 are diluent gas, the flow ratio of C 3 H 6 and N 2 is controlled to be 40:1, the temperature is 980°C, and the furnace pressure is 1kPa.
  • the deposition time is 150 h as a deposition cycle, and a disc-shaped carbon/carbon composite material is prepared after 4 deposition cycles, and the density of the obtained composite material is 1.81 g/cm 3 .
  • Example 1 Other conditions are the same as in Example 1, except that the mass fraction of sisal fiber in the control preform is 8%. Because the mass fraction of sisal fiber in the preform is too large, the interlayer bonding of the carbon fiber preform is reduced, which affects the mechanical properties of the composite material.
  • the density of the obtained carbon/carbon composite material is 1.81g/cm 3 , and the bending strength is determined by Example 1. The 130MPa is reduced to 92MPa.

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Abstract

Disclosed in the present invention is a method for increasing the density of a carbon/carbon composite thick plate. The preparation method comprises: first weaving sisal fibers having a diameter smaller than or equal to 400 μm and a length smaller than or equal to 10 mm into a carbon fiber preform, and then performing chemical vapor deposition densification, wherein the mass fraction of the sisal fibers in the preform is 1-5%, the thickness of the carbon fiber preform is 20-35 mm, and the density of the preform is 0.3-0.6g/cm3. In the present invention, by innovatively using the carbonization shrinkage of large-diameter sisal fibers during chemical vapor deposition, a gas channel in the thickness direction of the preform and a gas channel along the surface of a mesh are constructed in the carbon fiber preform to form other crisscross channels, such that the air permeability of the carbon fiber preform is improved, carbon source gas can be remotely delivered to the core of the preform, the density and the uniformity of the density distribution of the carbon source gas can be greatly improved, the difficulty of uniform densification of the carbon/carbon composite is solved, and the density of the prepared carbon/carbon composite reaches more than 1.8 g/cm 3.

Description

一种提高碳/碳复合材料厚板增密密度的方法A Method for Improving the Densification Density of Carbon/Carbon Composite Thick Plates 技术领域technical field
本发明公开了一种提高碳/碳复合材料厚板增密密度的方法，属于碳/碳复合材料制备技术领域。The invention discloses a method for increasing the densification density of thick plates of carbon/carbon composite materials, and belongs to the technical field of carbon/carbon composite material preparation.
背景技术Background technique
碳/碳复合材料是一种以碳纤维增强碳基体的先进复合材料，具有质量轻、比强度高、热膨胀系数低、尺寸稳定性好、耐腐蚀等优异性能，特别是具有优异的摩擦磨损性能，在航空、航天、热加工等领域具有广阔的应用前景。Carbon/carbon composite material is an advanced composite material with carbon fiber reinforced carbon matrix. It has excellent properties such as light weight, high specific strength, low thermal expansion coefficient, good dimensional stability, and corrosion resistance, especially excellent friction and wear properties. It has broad application prospects in aviation, aerospace, thermal processing and other fields.
技术问题technical problem
化学气相沉积是制备碳/碳复合材料的重要方法，该方法制备的复合材料具有连续热解碳基体结构，可赋予复合材料高的力学性能和摩擦磨损性能，是获得高性能碳/碳复合材料，如航空刹车材料的首选途径。化学气相沉积通过碳源气体在高温下裂解，将碳原子沉积至碳纤维表面得到。实现化学气相沉积的前提条件是。现有化学气相沉积工艺对碳纤维预制体的增密过程是一种非均匀增密过程，体现在表面比芯部增密速度快，复合材料产生由表及里密度梯度。当碳纤维预制体增密到一定程度（如密度达1.6g/cm 3）时，复合材料表面密度达到1.85g/cm 3以上，形成表面封孔，阻碍碳源气体通过表面向芯部的渗透，影响增密效率，难以获得高密度的碳/碳复合材料。 Chemical vapor deposition is an important method for preparing carbon/carbon composites. The composites prepared by this method have a continuous pyrolytic carbon matrix structure, which can endow the composites with high mechanical properties and friction and wear properties. It is an important method to obtain high-performance carbon/carbon composites. , such as the preferred route for aerospace brake materials. Chemical vapor deposition is obtained by decomposing carbon source gas at high temperature and depositing carbon atoms on the surface of carbon fibers. The prerequisite for the realization of chemical vapor deposition is. The densification process of the carbon fiber preform by the existing chemical vapor deposition process is a non-uniform densification process, which is reflected in the fact that the densification speed of the surface is faster than that of the core, and the composite material produces a density gradient from the surface to the interior. When the carbon fiber prefabricated body is densified to a certain extent (for example, the density reaches 1.6g/cm 3 ), the surface density of the composite material reaches above 1.85g/cm 3 , forming surface sealing holes, which prevents the carbon source gas from penetrating from the surface to the core. It affects the densification efficiency, and it is difficult to obtain high-density carbon/carbon composite materials.
因此，如何提高碳/碳复合材料厚板增密密度及改善其密度的均匀性，一直以来都是碳/碳复合材料制备技术领域的技术难题。Therefore, how to increase the densification density of carbon/carbon composite thick plates and improve the uniformity of density has always been a technical problem in the field of carbon/carbon composite material preparation technology.
技术解决方案technical solution
针对现有技术的不足，本发明的目的在于提供一种提高碳/碳复合材料厚板增密密度的方法。Aiming at the deficiencies of the prior art, the object of the present invention is to provide a method for increasing the densification density of carbon/carbon composite thick plates.
剑麻纤维是一种天然植物纤维，直径为200~400μm，在碳化时产生60%左右的体积收缩。本发明将剑麻纤维编织入碳纤维预制体中，利用粗直径的剑麻纤维碳化收缩，在细直径（约7μm）的碳纤维编织的预制体中形成孔隙，构建碳源气体通道，改善碳纤维预制体的透气性，使碳源气体能够远程送达预制体芯部，解决碳/碳复合材料厚板（含圆盘状碳/碳复合材料）沿厚度方向的均匀增密难题，制备高密度的碳/碳复合材料。Sisal fiber is a natural plant fiber with a diameter of 200-400 μm, which shrinks in volume by about 60% during carbonization. The invention weaves sisal fibers into the carbon fiber prefabricated body, utilizes the carbonization and shrinkage of the sisal hemp fiber with a large diameter, forms pores in the carbon fiber woven prefabricated body with a thin diameter (about 7 μm), constructs a carbon source gas channel, and improves the carbon fiber prefabricated body Excellent air permeability, so that the carbon source gas can be delivered to the core of the preform remotely, solve the problem of uniform densification of carbon/carbon composite slabs (including disc-shaped carbon/carbon composite materials) along the thickness direction, and prepare high-density carbon / carbon composite.
为了实现上述目的，本发明一种提高碳/碳复合材料厚板增密密度的方法，是采用下述方案实现的： In order to achieve the above object, a method for increasing the densification density of carbon/carbon composite thick plates of the present invention is achieved by the following scheme:
先将直径≤400μm、长度≤10mm的剑麻纤维编织到碳纤维预制体中，然后进行化学气相沉积增密。The sisal fiber with a diameter of ≤400 μm and a length of ≤10 mm is first woven into the carbon fiber preform, and then densified by chemical vapor deposition.
本发明一种提高碳/碳复合材料厚板增密密度的方法，所述碳纤维预制体是厚板，厚度为20~35mm，密度为0.3~0.6g/cm 3。 The invention discloses a method for increasing the densification density of thick plates of carbon/carbon composite materials. The carbon fiber prefabricated body is a thick plate with a thickness of 20-35 mm and a density of 0.3-0.6 g/cm 3 .
本发明一种提高碳/碳复合材料厚板增密密度的方法，所述剑麻纤维直径为200~400μm，长度5~10mm，剑麻纤维占预制体的质量百分数为1~5%。The invention discloses a method for increasing the densification density of a thick plate of carbon/carbon composite material. The diameter of the sisal fiber is 200-400 μm, the length is 5-10 mm, and the mass percentage of the sisal fiber in the prefabricated body is 1-5%.
本发明一种提高碳/碳复合材料厚板增密密度的方法，所述碳纤维预制体由预制体基本单元依次叠置通过针刺得到；所述预制体基本单元由碳纤维网胎层、剑麻纤维、碳纤维无纬布依次叠置构成，且剑麻纤维均匀平铺在碳纤维网胎层的表面；第一层预制体基本单元连续针刺后，在其上叠置第二层预制体基本单元并进行连续针刺；实现同一预制体基本单元中剑麻纤维与碳纤维网胎层的针刺勾连及相邻预制体基本单元之间剑麻纤维与碳纤维无纬布的针刺勾连，以此类推，得到由预制体基本单元通过针刺得到的、满足设计厚度要求的碳纤维预制体；所述碳纤维预制体中，剑麻纤维均匀分布；在同一预制体基本单元中的剑麻纤维，一部分与相邻预制体基本单元之间实现勾连，另一部分均匀分布在预制体基本单元的网胎表面。化学气相沉积时，剑麻纤维碳化收缩，构建沿预制体厚度方向的气体通道和沿网胎表面的气体通道，形成纵横交错的其他通道，可以大幅度提高增密密度及增密密度分布的均匀性。The invention discloses a method for increasing the densification density of carbon/carbon composite thick plates. The carbon fiber prefabricated body is obtained by sequentially stacking the basic units of the prefabricated body through acupuncture; Fiber and carbon fiber non-weft cloth are stacked in sequence, and the sisal fiber is evenly spread on the surface of the carbon fiber mesh layer; after the first layer of prefabricated basic units are continuously acupunctured, the second layer of prefabricated basic units is superimposed on it And carry out continuous needle punching; realize the acupuncture hooking of sisal fiber and carbon fiber mesh layer in the same prefabricated basic unit and the acupuncture hooking of sisal fiber and carbon fiber non-woven fabric between adjacent prefabricated basic units, and so on , to obtain a carbon fiber prefabricated body obtained by needling the basic unit of the prefabricated body and meeting the design thickness requirements; in the carbon fiber prefabricated body, the sisal fibers are evenly distributed; The connection between the basic units of the adjacent prefabricated body is realized, and the other part is evenly distributed on the surface of the mesh tire of the basic unit of the prefabricated body. During chemical vapor deposition, the sisal fiber carbonizes and shrinks, and the gas channels along the thickness direction of the preform and the gas channels along the surface of the mesh tire are formed to form other channels in a criss-cross pattern, which can greatly improve the density and the uniformity of the density distribution. sex.
本发明一种提高碳/碳复合材料厚板增密密度的方法，针刺方向沿预制体的法线方向实现网胎层和无纬布层针刺勾连的同时，在预制体法线方向引入剑麻纤维。The invention discloses a method for increasing the densification density of a carbon/carbon composite material thick plate. The acupuncture direction is along the normal direction of the prefabricated body to realize the needle-punched hooking of the mesh layer and the weft-free cloth layer, and at the same time, introduce Sisal fiber.
本发明一种提高碳/碳复合材料厚板增密密度的方法，针刺密度为：相邻行之间的距离≤2mm，同一行内的间距≤2mm。The invention discloses a method for increasing the densification density of a carbon/carbon composite thick plate. The needling density is: the distance between adjacent rows is ≤2mm, and the distance within the same row is ≤2mm.
本发明一种提高碳/碳复合材料厚板增密密度的方法，所述碳纤维预制体中，碳纤维网胎层与碳纤维无纬布层各有30~60层。The invention discloses a method for increasing the densification density of a carbon/carbon composite thick plate. In the carbon fiber prefabricated body, there are 30 to 60 carbon fiber mesh layers and carbon fiber non-weft cloth layers respectively.
优选地，所述碳纤维网胎层与碳纤维无纬布层各有40~50层。Preferably, there are 40-50 layers of the carbon fiber mesh layer and the carbon fiber non-weft cloth layer respectively.
本发明一种提高碳/碳复合材料厚板增密密度的方法，所述碳纤维预制体中，相邻无纬布的排列方向互成90°。The invention relates to a method for increasing the densification density of a carbon/carbon composite thick plate. In the carbon fiber prefabricated body, the arrangement directions of adjacent non-weft cloths are 90° to each other.
本发明一种提高碳/碳复合材料厚板增密密度的方法，所述剑麻纤维均匀平铺在碳纤维网胎层的一个表面和/或另一个表面。The invention discloses a method for increasing the densification density of a thick plate of carbon/carbon composite material, wherein the sisal fiber is evenly spread on one surface and/or the other surface of a carbon fiber mesh layer.
本发明一种提高碳/碳复合材料厚板增密密度的方法，沿碳纤维预制体的厚度方向设有中心通孔形成一圆盘状，圆盘内径为10~300mm，圆盘外径为200~600mm，厚度为20~35mm。The invention discloses a method for increasing the densification density of carbon/carbon composite thick plates. A central through hole is arranged along the thickness direction of the carbon fiber prefabricated body to form a disk shape. The inner diameter of the disk is 10-300mm, and the outer diameter of the disk is 200mm ~600mm, thickness 20~35mm.
优选地，所述圆盘的内径为200mm，外径为450mm，厚度为30mm。Preferably, the inner diameter of the disc is 200mm, the outer diameter is 450mm, and the thickness is 30mm.
本发明一种提高碳/碳复合材料厚板增密密度的方法，所述碳纤维预制体的编织结构为针刺预制体，首先将剑麻纤维均匀平铺于碳纤维网胎层表面，然后将所述碳纤维网胎层与碳纤维无纬布层相间叠层，连续针刺得到。The invention discloses a method for increasing the densification density of carbon/carbon composite thick plates. The weaving structure of the carbon fiber prefabricated body is a needle-punched prefabricated body. The carbon fiber mesh layer and the carbon fiber non-weft cloth layer are laminated alternately and obtained by continuous needling.
本发明一种提高碳/碳复合材料厚板增密密度的方法，所述化学气相沉积的工艺为：以C 3H 6为碳源气体、N 2为稀释气体，所述C 3H 6与N 2的流量比为4~100:1；温度为950~1100℃；炉内压力为0.5~10kPa。 The present invention is a method for increasing the densification density of carbon/carbon composite thick plates. The chemical vapor deposition process is as follows: using C3H6 as the carbon source gas and N2 as the dilution gas, the C3H6 and The flow ratio of N 2 is 4~100:1; the temperature is 950~1100℃; the pressure in the furnace is 0.5~10kPa.
在本发明中，经过多次化学气相沉积直至碳/碳复合材料完成增密，在每次化学气相沉积前后用天平分别称量碳纤维预制体质量，计算每次沉积后的增重，并计算密度，同时在每次沉积完成后进行机加工，并清洗表面污物。In the present invention, after several times of chemical vapor deposition until the carbon/carbon composite material is densified, the weight of the carbon fiber prefabricated body is weighed with a balance before and after each chemical vapor deposition, and the weight gain after each deposition is calculated, and the density is calculated , while machining and cleaning the surface dirt after each deposition.
有益效果Beneficial effect
本发明将剑麻纤维编织入碳纤维预制体中，利用粗直径的剑麻纤维碳化收缩，在细直径（约7μm）的碳纤维编织的预制体中形成孔隙，构建碳源气体通道，改善预制体的透气性，使碳源气体能够远程送达预制体芯部，解决圆盘状碳/碳复合材料厚度方向的均匀增密难题，碳/碳复合材料密度达到1.8g/cm 3以上。 The present invention weaves sisal fibers into the carbon fiber prefabricated body, utilizes the carbonization and shrinkage of the sisal hemp fiber with a large diameter, forms pores in the carbon fiber woven prefabricated body with a thin diameter (about 7 μm), constructs a carbon source gas channel, and improves the carbonization of the prefabricated body. The gas permeability enables the carbon source gas to be delivered to the core of the preform remotely, and solves the problem of uniform densification in the thickness direction of the disc-shaped carbon/carbon composite material. The density of the carbon/carbon composite material reaches above 1.8g/cm 3 .
在本发明中，将剑麻纤维的长度控制在5~10mm范围内，预制体中碳源气体通道的连通性最佳，而长度过短，则剑麻纤维碳化收缩后形成的气体通道不连贯，透气性提升不明显；长度太长，则剑麻纤维团聚，影响剑麻纤维在网胎层表面铺展的均匀性。In the present invention, the length of the sisal fiber is controlled within the range of 5-10mm, and the connectivity of the carbon source gas channel in the prefabricated body is the best, and if the length is too short, the gas channel formed after the carbonization and shrinkage of the sisal fiber is incoherent , the air permeability is not significantly improved; if the length is too long, the sisal fibers will agglomerate, which will affect the uniformity of the sisal fibers spreading on the surface of the mesh layer.
在本发明中，将剑麻纤维的质量分数控制在1~5%范围内，预制体对碳源气体的透气性最佳，而质量分数过小，则透气性提升不明显；质量分数太大，则降低碳纤维预制体层间结合，影响碳/碳复合材料的力学性能。In the present invention, if the mass fraction of sisal fiber is controlled within the range of 1-5%, the prefabricated body will have the best air permeability to the carbon source gas, and if the mass fraction is too small, the air permeability will not be significantly improved; if the mass fraction is too large , it reduces the interlayer bonding of carbon fiber preforms and affects the mechanical properties of carbon/carbon composites.
本发明的碳纤维预制体的编织结构为针刺预制体，首先将剑麻纤维均匀平铺于碳纤维网胎层表面，然后将所述碳纤维网胎层与碳纤维无纬布层相间叠层，连续针刺得到。针刺方向为预制体的法线方向，针刺穿透相邻的网胎层和无纬布层，利用带钩的针将网胎层上平铺的剑麻纤维刺入无纬布层，在实现网胎层和无纬布层针刺勾连的同时，在预制体法线方向引入剑麻纤维。The weaving structure of the carbon fiber prefabricated body of the present invention is a needle-punched prefabricated body. First, the sisal fibers are evenly spread on the surface of the carbon fiber mesh layer, and then the carbon fiber mesh layer and the carbon fiber non-weft cloth layer are alternately laminated, and the needles are continuously stitched. Get stabbed. The needle-punching direction is the normal direction of the prefabricated body, the needle-punching penetrates the adjacent mesh layer and the non-weft layer, and the sisal fiber laid on the mesh layer is pierced into the non-weft layer by using a needle with a hook. While realizing the needle-punched hooking of the mesh layer and the non-woven fabric layer, the sisal fiber is introduced in the normal direction of the prefabricated body.
本发明将剑麻纤维编织入碳纤维预制体中，利用粗直径的剑麻纤维碳化收缩，在细直径（约7μm）的碳纤维编织的预制体中形成孔隙，构建碳源气体通道，特别是预制体法线方向的碳源气体通道，改善预制体的透气性，使碳源气体能够远程送达预制体芯部，解决圆盘状碳/碳复合材料厚度方向的均匀增密难题，碳/碳复合材料密度达到1.8g/cm 3以上。 The present invention weaves sisal fibers into the carbon fiber prefabricated body, utilizes the carbonization and shrinkage of the thick sisal fiber to form pores in the carbon fiber woven prefabricated body with a thin diameter (about 7 μm), and constructs a carbon source gas channel, especially the prefabricated body The carbon source gas channel in the normal direction improves the air permeability of the preform, enables the carbon source gas to be delivered to the core of the preform remotely, and solves the problem of uniform densification in the thickness direction of the disc-shaped carbon/carbon composite material. The material density reaches above 1.8g/cm 3 .
附图说明Description of drawings
图1为本发明预制体基本单元结构示意图。Fig. 1 is a schematic diagram of the basic unit structure of the preform of the present invention.
 图1中，碳纤维网胎层、剑麻纤维、碳纤维无纬布从下向上依次叠置，针刺方向为预制体的法线方向，实现网胎层和无纬布层针刺勾连的同时，在预制体法线方向引入剑麻纤维。In Figure 1, the carbon fiber mesh layer, sisal fiber, and carbon fiber non-weft cloth are stacked sequentially from bottom to top, and the acupuncture direction is the normal direction of the prefabricated body. Sisal fibers are introduced in the normal direction of the preform.
本发明的实施方式Embodiments of the present invention
实施例Example 11
取直径为200~400μm的剑麻纤维，栽切成长度为9mm的短纤维，将其编织入碳纤维预制体中，控制预制体中剑麻纤维质量分数为4%，然后将所述碳纤维预制体进行化学气相沉积增密，制备高密度的碳/碳复合材料。所述碳纤维预制体的形状为圆盘状，内径为200mm、外径为450mm、厚度为30mm，预制体的密度为0.5g/cm 3；所述碳纤维预制体的编织结构为针刺预制体，首先将剑麻纤维均匀平铺于碳纤维网胎层表面，然后将所述碳纤维网胎层与碳纤维无纬布层相间叠层，连续针刺得到，控制预制体中碳纤维网胎层与碳纤维无纬布层各有50层，相邻无纬布的排列方向互成90°，针刺密度为行与行之间的距离≤2mm；所述化学气相沉积的工艺为：以C 3H 6为碳源气体、N 2为稀释气体，控制C 3H 6与N 2的流量比为90:1、温度为950℃、炉内压力为3kPa。沉积时间以150h为一个沉积周期，沉积4个周期后制备得到圆盘状碳/碳复合材料，所得复合材料密度为1.8g/cm 3。 Take sisal fibers with a diameter of 200-400 μm, plant them into short fibers with a length of 9 mm, weave them into the carbon fiber prefabricated body, control the sisal fiber mass fraction in the prefabricated body to be 4%, and then make the carbon fiber prefabricated body Densification by chemical vapor deposition to prepare high-density carbon/carbon composite materials. The shape of the carbon fiber preform is disc-shaped, the inner diameter is 200 mm, the outer diameter is 450 mm, the thickness is 30 mm, and the density of the preform is 0.5 g/cm 3 ; the weaving structure of the carbon fiber preform is an acupuncture preform, First, the sisal fiber is evenly spread on the surface of the carbon fiber mesh layer, and then the carbon fiber mesh layer and the carbon fiber non-weft cloth layer are laminated alternately, and obtained by continuous needle punching, and the carbon fiber mesh layer and the carbon fiber non-weft layer in the prefabricated body are controlled. Each cloth layer has 50 layers, and the arrangement directions of adjacent non-weft cloths are 90° to each other, and the needle punching density is such that the distance between rows is ≤2 mm; the chemical vapor deposition process is: using C 3 H 6 as carbon The source gas and N 2 are diluent gas, the flow ratio of C 3 H 6 and N 2 is controlled to be 90:1, the temperature is 950°C, and the furnace pressure is 3kPa. The deposition time is 150 h as a deposition cycle, and a disc-shaped carbon/carbon composite material is prepared after 4 deposition cycles, and the density of the obtained composite material is 1.8 g/cm 3 .
实施例Example 22
取直径为200~400μm的剑麻纤维，栽切成长度为6mm的短纤维，将其编织入碳纤维预制体中，控制预制体中剑麻纤维质量分数为2%，然后将所述碳纤维预制体进行化学气相沉积增密，制备高密度的碳/碳复合材料。所述碳纤维预制体的形状为圆盘状，内径为50mm、外径为500mm、厚度为25mm，预制体的密度为0.4g/cm 3；所述碳纤维预制体的编织结构为针刺预制体，首先将剑麻纤维均匀平铺于碳纤维网胎层表面，然后将所述碳纤维网胎层与碳纤维无纬布层相间叠层，连续针刺得到，控制预制体中碳纤维网胎层与碳纤维无纬布层各有33层，相邻无纬布的排列方向互成90°，针刺密度为行与行之间的距离≤2mm；所述化学气相沉积的工艺为：以C 3H 6为碳源气体、N 2为稀释气体，控制C 3H 6与N 2的流量比为40:1、温度为1000℃、炉内压力为8kPa。沉积时间以150h为一个沉积周期，沉积4个周期后制备得到圆盘状碳/碳复合材料，所得复合材料密度为1.81g/cm 3，弯曲强度为130MPa。 Take sisal fibers with a diameter of 200-400 μm, plant them into short fibers with a length of 6 mm, weave them into the carbon fiber prefabricated body, control the sisal fiber mass fraction in the prefabricated body to be 2%, and then make the carbon fiber prefabricated body Densification by chemical vapor deposition to prepare high-density carbon/carbon composite materials. The shape of the carbon fiber preform is disc-shaped, the inner diameter is 50 mm, the outer diameter is 500 mm, the thickness is 25 mm, and the density of the preform is 0.4 g/cm 3 ; the weaving structure of the carbon fiber preform is an acupuncture preform, First, the sisal fiber is evenly spread on the surface of the carbon fiber mesh layer, and then the carbon fiber mesh layer and the carbon fiber non-weft cloth layer are laminated alternately, and obtained by continuous needle punching, and the carbon fiber mesh layer and the carbon fiber non-weft layer in the prefabricated body are controlled. Each cloth layer has 33 layers, and the arrangement directions of adjacent non-weft cloths are 90° to each other, and the needle punching density is such that the distance between rows is ≤2mm; the chemical vapor deposition process is: using C 3 H 6 as carbon The source gas and N 2 are diluent gas, the flow ratio of C 3 H 6 and N 2 is controlled to be 40:1, the temperature is 1000°C, and the pressure in the furnace is 8kPa. The deposition time is 150 h as a deposition cycle, and a disc-shaped carbon/carbon composite material is prepared after 4 deposition cycles. The density of the obtained composite material is 1.81 g/cm 3 , and the bending strength is 130 MPa.
实施例Example 33
取直径为200~400μm的剑麻纤维，栽切成长度为7mm的短纤维，将其编织入碳纤维预制体中，控制预制体中剑麻纤维质量分数为1%，然后将所述碳纤维预制体进行化学气相沉积增密，制备高密度的碳/碳复合材料。所述碳纤维预制体的形状为圆盘状，内径为260mm、外径为560mm、厚度为20mm，预制体的密度为0.6g/cm 3；所述碳纤维预制体的编织结构为针刺预制体，首先将剑麻纤维均匀平铺于碳纤维网胎层表面，然后将所述碳纤维网胎层与碳纤维无纬布层相间叠层，连续针刺得到，控制预制体中碳纤维网胎层与碳纤维无纬布层各有40层，相邻无纬布的排列方向互成90°，针刺密度为行与行之间的距离≤2mm；所述化学气相沉积的工艺为：以C 3H 6为碳源气体、N 2为稀释气体，控制C 3H 6与N 2的流量比为20:1、温度为1050℃、炉内压力为2kPa。沉积时间以150h为一个沉积周期，沉积4个周期后制备得到圆盘状碳/碳复合材料，所得复合材料密度为1.82g/cm 3。 Take sisal fibers with a diameter of 200-400 μm, plant them into short fibers with a length of 7 mm, weave them into the carbon fiber prefabricated body, control the sisal fiber mass fraction in the prefabricated body to 1%, and then make the carbon fiber prefabricated body Densification by chemical vapor deposition to prepare high-density carbon/carbon composite materials. The shape of the carbon fiber preform is disc-shaped, the inner diameter is 260 mm, the outer diameter is 560 mm, the thickness is 20 mm, and the density of the preform is 0.6 g/cm 3 ; the weaving structure of the carbon fiber preform is an acupuncture preform, First, the sisal fiber is evenly spread on the surface of the carbon fiber mesh layer, and then the carbon fiber mesh layer and the carbon fiber non-weft cloth layer are laminated alternately, and obtained by continuous needle punching, and the carbon fiber mesh layer and the carbon fiber non-weft layer in the prefabricated body are controlled. Each cloth layer has 40 layers, and the arrangement directions of adjacent non-weft cloths are 90° to each other, and the needle punching density is such that the distance between rows is ≤2 mm; the chemical vapor deposition process is: using C 3 H 6 as carbon The source gas and N 2 are diluent gas, the flow ratio of C 3 H 6 and N 2 is controlled to be 20:1, the temperature is 1050°C, and the pressure in the furnace is 2kPa. The deposition time is 150 h as a deposition cycle, and a disc-shaped carbon/carbon composite material is prepared after 4 deposition cycles, and the density of the obtained composite material is 1.82 g/cm 3 .
实施例Example 44
取直径为200~400μm的剑麻纤维，栽切成长度为5mm的短纤维，将其编织入碳纤维预制体中，控制预制体中剑麻纤维质量分数为3%，然后将所述碳纤维预制体进行化学气相沉积增密，制备高密度的碳/碳复合材料。所述碳纤维预制体的形状为圆盘状，内径为150mm、外径为400mm、厚度为35mm，预制体的密度为0.3g/cm 3；所述碳纤维预制体的编织结构为针刺预制体，首先将剑麻纤维均匀平铺于碳纤维网胎层表面，然后将所述碳纤维网胎层与碳纤维无纬布层相间叠层，连续针刺得到，控制预制体中碳纤维网胎层与碳纤维无纬布层各有35层，相邻无纬布的排列方向互成90°，针刺密度为行与行之间的距离≤2mm；所述化学气相沉积的工艺为：以C 3H 6为碳源气体、N 2为稀释气体，控制C 3H 6与N 2的流量比为40:1、温度为980℃、炉内压力为1kPa。沉积时间以150h为一个沉积周期，沉积4个周期后制备得到圆盘状碳/碳复合材料，所得复合材料密度为1.81g/cm 3。 Take sisal fibers with a diameter of 200-400 μm, plant them into short fibers with a length of 5 mm, weave them into the carbon fiber prefabricated body, control the sisal fiber mass fraction in the prefabricated body to be 3%, and then make the carbon fiber prefabricated body Densification by chemical vapor deposition to prepare high-density carbon/carbon composite materials. The shape of the carbon fiber preform is disc-shaped, the inner diameter is 150 mm, the outer diameter is 400 mm, the thickness is 35 mm, and the density of the preform is 0.3 g/cm 3 ; the weaving structure of the carbon fiber preform is an acupuncture preform, First, the sisal fiber is evenly spread on the surface of the carbon fiber mesh layer, and then the carbon fiber mesh layer and the carbon fiber non-weft cloth layer are laminated alternately, and obtained by continuous needle punching, and the carbon fiber mesh layer and the carbon fiber non-weft layer in the prefabricated body are controlled. Each cloth layer has 35 layers, the arrangement directions of adjacent non-weft cloths are 90° to each other, and the needle punching density is such that the distance between rows is ≤2mm; the chemical vapor deposition process is: using C 3 H 6 as carbon The source gas and N 2 are diluent gas, the flow ratio of C 3 H 6 and N 2 is controlled to be 40:1, the temperature is 980°C, and the furnace pressure is 1kPa. The deposition time is 150 h as a deposition cycle, and a disc-shaped carbon/carbon composite material is prepared after 4 deposition cycles, and the density of the obtained composite material is 1.81 g/cm 3 .
对比例comparative example 11
其他条件与实施例1相同，仅是将剑麻纤维的长度栽切成2mm的短纤维。由于剑麻纤维的长度过短，剑麻纤维碳化收缩后形成的气体通道不连贯，透气性提升不明显，所得碳/碳复合材料密度为1.64g/cm 3。 Other conditions are identical with embodiment 1, only the short fiber that the length of sisal fiber is planted into 2mm. Because the length of the sisal fiber is too short, the gas channel formed by the carbonization and shrinkage of the sisal fiber is incoherent, and the air permeability is not significantly improved. The density of the obtained carbon/carbon composite material is 1.64g/cm 3 .
对比例comparative example 22
其他条件与实施例1相同，仅是控制预制体中剑麻纤维质量分数为8%。由于预制体中剑麻纤维质量分数太大，降低了碳纤维预制体的层间结合，影响复合材料的力学性能，所得碳/碳复合材料的密度为1.81g/cm 3，弯曲强度由实施例1的130MPa降低到92MPa。 Other conditions are the same as in Example 1, except that the mass fraction of sisal fiber in the control preform is 8%. Because the mass fraction of sisal fiber in the preform is too large, the interlayer bonding of the carbon fiber preform is reduced, which affects the mechanical properties of the composite material. The density of the obtained carbon/carbon composite material is 1.81g/cm 3 , and the bending strength is determined by Example 1. The 130MPa is reduced to 92MPa.
对比例comparative example 33
碳纤维预制体中不编入剑麻纤维，其他条件与实施例1相同，所得碳/碳复合材料的密度为1.61g/cm 3。 No sisal fibers were woven into the carbon fiber preform, other conditions were the same as in Example 1, and the density of the obtained carbon/carbon composite material was 1.61 g/cm 3 .

Claims (10)

  1. 一种提高碳/碳复合材料厚板增密密度的方法，其特征在于： A method for increasing the densification density of carbon/carbon composite thick plates, characterized in that:
    先将直径≤400μm、长度≤10mm的剑麻纤维编织到碳纤维预制体中，然后进行化学气相沉积增密。The sisal fiber with a diameter of ≤400 μm and a length of ≤10 mm is first woven into the carbon fiber preform, and then densified by chemical vapor deposition.
  2. 根据权利要求1所述的一种提高碳/碳复合材料厚板增密密度的方法，其特征在于：所述碳纤维预制体是厚板，厚度为20~35mm，密度为0.3~0.6g/cm 3。 A method for increasing the densification density of carbon/carbon composite thick plates according to claim 1, characterized in that: the carbon fiber prefabricated body is a thick plate with a thickness of 20-35mm and a density of 0.3-0.6g/cm 3 .
  3. 根据权利要求2所述的一种提高碳/碳复合材料厚板增密密度的方法，其特征在于：所述碳纤维预制体由预制体基本单元依次叠置通过针刺得到；所述预制体基本单元由碳纤维网胎层、剑麻纤维、碳纤维无纬布依次叠置构成，且剑麻纤维均匀平铺在碳纤维网胎层的表面；第一层预制体基本单元连续针刺后，在其上叠置第二层预制体基本单元并进行连续针刺；实现同一预制体基本单元中剑麻纤维与碳纤维网胎层的针刺勾连及相邻预制体基本单元之间剑麻纤维与碳纤维无纬布的针刺勾连，以此类推，得到由预制体基本单元通过针刺得到的碳纤维预制体。A method for increasing the densification density of carbon/carbon composite thick plates according to claim 2, characterized in that: the carbon fiber preform is obtained by sequentially stacking the basic units of the preform through acupuncture; the preform is basically The unit is composed of carbon fiber mesh layer, sisal fiber, and carbon fiber non-weft cloth in sequence, and the sisal fiber is evenly spread on the surface of the carbon fiber mesh layer; Overlay the basic unit of the second layer of prefabricated body and perform continuous needle punching; realize the needle-punched connection of sisal fiber and carbon fiber mesh layer in the same prefabricated basic unit and the latitude of sisal fiber and carbon fiber between adjacent prefabricated basic units The needle-punched hooking of the cloth, and so on, can obtain the carbon fiber preform obtained by needle-punching the basic unit of the preform.
  4. 根据权利要求3所述的一种提高碳/碳复合材料厚板增密密度的方法，其特征在于：针刺密度为：相邻行之间的距离≤2mm，同一行内的间距≤2mm。A method for increasing the densification density of carbon/carbon composite slabs according to claim 3, characterized in that: the needling density is: the distance between adjacent rows is ≤ 2mm, and the distance in the same row is ≤ 2mm.
  5. 根据权利要求4所述的一种提高碳/碳复合材料厚板增密密度的方法，其特征在于：所述碳纤维预制体中，相邻无纬布的排列方向互成90°。A method for increasing the densification density of a carbon/carbon composite thick plate according to claim 4, characterized in that: in the carbon fiber prefabricated body, the arrangement directions of adjacent non-weft fabrics are 90° to each other.
  6. 根据权利要求1-5任意一项所述的一种提高碳/碳复合材料厚板增密密度的方法，其特征在于：所述剑麻纤维均匀平铺在碳纤维网胎层的一个表面和/或另一个表面。A method for increasing the densification density of carbon/carbon composite slabs according to any one of claims 1-5, characterized in that: the sisal fibers are evenly spread on one surface of the carbon fiber mesh layer and/or or another surface.
  7. 根据权利要求6所述的一种提高碳/碳复合材料厚板增密密度的方法，其特征在于：所述剑麻纤维直径为200~400μm，长度5~10mm。A method for increasing the densification density of a carbon/carbon composite thick plate according to claim 6, characterized in that: the diameter of the sisal fiber is 200-400 μm, and the length is 5-10 mm.
  8. 根据权利要求7所述的一种提高碳/碳复合材料厚板增密密度的方法，其特征在于：所述剑麻纤维占预制体的质量百分数为1~5%。A method for increasing the densification density of a carbon/carbon composite thick plate according to claim 7, characterized in that: the mass percentage of the sisal fiber in the prefabricated body is 1-5%.
  9. 根据权利要求8所述的一种提高碳/碳复合材料厚板增密密度的方法，其特征在于：沿碳纤维预制体的厚度方向设有中心通孔形成一圆盘状，圆盘内径为10~300mm，圆盘外径为200~600mm，厚度为20~35mm。A method for increasing the densification density of carbon/carbon composite thick plates according to claim 8, characterized in that: a central through hole is provided along the thickness direction of the carbon fiber prefabricated body to form a disc shape, and the inner diameter of the disc is 10 ~300mm, the outer diameter of the disc is 200~600mm, and the thickness is 20~35mm.
  10. 根据权利要求9所述的一种提高碳/碳复合材料厚板增密密度的方法，其特征在于：所述化学气相沉积的工艺为：以C 3H 6为碳源气体、N 2为稀释气体，所述C 3H 6与N 2的流量比为4~100:1；温度为950~1100℃；炉内压力为0.5~10kPa。 A method for increasing the densification density of carbon/carbon composite thick plates according to claim 9, characterized in that: the chemical vapor deposition process is: using C 3 H 6 as the carbon source gas and N 2 as the dilution gas, the flow ratio of C 3 H 6 to N 2 is 4-100:1; the temperature is 950-1100°C; the pressure in the furnace is 0.5-10kPa.
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