Carbon fiber toughened silicon carbide-based fire-resistant high-temperature-resistant high-toughness plate as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of carbon-ceramic composite materials, particularly relates to a carbon fiber toughened silicon carbide-based fire-resistant high-temperature-resistant high-toughness plate and a preparation method thereof, and further relates to application of the carbon fiber toughened silicon carbide-based fire-resistant high-temperature-resistant high-toughness plate composition in aircraft engines and rocket propellers. The silicon carbide layer is firstly formed on the surface of the carbon fiber to serve as a transition layer, the transition layer can be firmly connected with the carbon fiber and can also be effectively connected with silicon carbide, the problem that the surface of the carbon fiber yarn and the interface of a silicon carbide material cannot be tightly connected is solved, and the sufficient filling and bonding strength of the silicon carbide on the carbon fiber fabric is improved; the toughness of the composite material is greatly improved, and the firmness of the whole structural component is improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of carbon-ceramic composite materials, and specifically relates to a carbon fiber toughened silicon carbide-based refractory, high-temperature resistant and high-toughness plate and a preparation method thereof, and also relates to an application of the carbon fiber toughened silicon carbide-based refractory, high-temperature resistant and high-toughness plate composition in aircraft engines and rocket thrusters. Background Art

[0002] Ceramic materials are increasingly valued by people due to their high strength, high temperature resistance, chemical corrosion resistance and other advantages. Currently, silicon carbide (SiC) is a special material used as a ceramic material. Silicon carbide is a common covalent bond compound. Silicon carbide has many excellent properties. First of all, 3.2g / cm 3 The density of about 100% makes silicon carbide lighter than general titanium, nickel and other metal materials. Secondly, because carbon and silicon are elements of the same family, silicon carbide has a stronger covalent bond energy, which directly leads to SiC's high wear resistance, large elastic modulus, and high hardness. Among the many application fields of silicon carbide, silicon carbide can be used as a refractory material because of its excellent thermal properties. The excellent thermal performance is reflected in the fact that silicon carbide has a high thermal conductivity, transfers heat energy quickly, and has good thermal shock resistance. The material is not easy to deform during thermal shock, and the thermal expansion coefficient is relatively small, so that silicon carbide products do not deform at high temperatures. Silicon carbide has become the preferred material that can cope with extremely harsh environments, such as aircraft engines and rocket thruster nozzle materials in the aerospace field.

[0003] However, the brittleness of silicon carbide materials means that this type of material still has the problem of insufficient toughness when dealing with extreme conditions, and it is easy to crack. In order to solve the disadvantage of high brittleness of ceramic materials, the use of carbon fiber as a reinforcement to make ceramic matrix composites can maximize the combination of the advantages of carbon fiber and silicon carbide. Carbon fiber plays the role of high toughness, high modulus, and high stability, making this type of composite material have the potential to play a greater role in the military field and aerospace field. Adding carbon fiber structure to the ceramic matrix can share part of the external load on the one hand, and on the other hand, it can also form a weak bonding interface between the fiber and the ceramic matrix. The destruction of these interfaces can absorb part of the external load, increase the difficulty of material fracture, and thus enhance the strength of the ceramic. Carbon fiber can also form a bridge between the fracture surfaces inside the ceramic material to prevent further expansion of the crack.

[0004] There are many kinds of fibers that can be used to toughen ceramic-based composites. The most mature fiber technology is carbon fiber technology. Carbon fiber is one of the most superior types of fibers currently and is widely used in reinforcing fibers of reinforced composites. The reason why carbon fiber can be widely used in the reinforcement phase of toughened ceramic-based composites is because of the various superior properties of carbon fiber. Carbon fiber is a fiber that combines excellent mechanical properties such as high toughness and high modulus. At the same time, carbon fiber also has excellent physical properties such as low thermal expansion, low density, high temperature resistance and high thermal conductivity. Especially in terms of chemical corrosion resistance, carbon fiber has similar properties to carbon and has good chemical corrosion resistance.

[0005] The slurry impregnation hot pressing method is one of the commonly used preparation methods for carbon fiber toughened silicon carbide composites. The main principle of the slurry impregnation hot pressing method is to first impregnate the reinforcing fiber preform in a slurry solution containing matrix powder, then weave the fiber impregnated with the slurry, cut it into shape, assemble the mold, and finally undergo hot pressing and sintering to prepare a composite material sample. The slurry is generally prepared by dissolving the matrix powder, organic binder and sintering aid in an organic solvent. It is relatively easy to obtain a dense composite material by this method, but this method of preparing ceramic-based composite materials also has defects that cannot be ignored. It is very easy to damage the fiber during the hot pressing process, making it difficult for the fiber to play the role of reinforcing the composite material. Secondly, the last step in the composite material preparation process is to go through the hot pressing stage, so the slurry impregnation hot pressing method is difficult to achieve for the preparation of composite materials with complex shapes. Moreover, during the hot pressing process, it begins to be oxidized and corroded at 400°C in an environment with oxygen, resulting in the loss of the reinforcing fiber function.

[0006] Patent document CN103102168A discloses a technology for compounding modified carbon fiber materials with ceramic materials. The main scheme is to use carbon fiber and zinc oxide ceramics for sol-gel growth synthesis, which improves the toughness and strength of zinc oxide. The preparation method disclosed in the patent document is to add carbon fiber to the ceramic matrix to form an overall homogeneous dispersion composite during the preparation of the material. The preparation process is relatively complicated, the cost is relatively high, and it is also difficult to achieve the preparation of ceramic-based composite materials with complex shapes. Patent document CN103864450B uses a composite integral method formed by mixing and sintering ceramic powder and short carbon fiber materials to improve the connection between ceramic materials. The patent document uses short chopped carbon fiber materials, which can achieve a limited toughening effect microscopically, and is prone to breakage during later applications. Summary of the invention

[0007] In view of the defects of the prior art, the object of the present invention is to provide a carbon fiber toughened silicon carbide based fire-resistant, high temperature resistant and high toughness plate and a preparation method thereof.

[0008] To achieve the above purpose, the solution adopted by the present invention is as follows:

[0009] In a first aspect, the present invention provides a method for preparing a carbon fiber toughened silicon carbide-based fire-resistant, high-temperature-resistant and high-toughness plate, comprising the following steps:

[0010] Carbon fiber fabrics that are woven from carbon fiber filaments into a mesh structure;

[0011] Dissolving silicon powder and a first binder in a first solvent to prepare a coating suspension having a viscosity of 300-500 mPa·s;

[0012] Applying the coating suspension on the carbon fiber fabric so that the suspension fills the pores of the carbon fiber fabric to form a carbon fiber prepreg;

[0013] Arranging the carbon fiber prepreg on a forming mold;

[0014] The whole is placed at 70-100°C for drying for 1-5 hours to form a preliminary shape, and the forming mold is removed after cooling to room temperature, and then the preliminary formed material is placed at 280-320°C for 2-10 hours to decompose the binder component, and then placed at 1500-1700°C for 2-20 hours to melt the silicon on the surface, forming a silicon carbide layer on the surface of the carbon fiber fabric;

[0015] Dissolving silicon carbide powder and a second binder in a second solvent to prepare a composite slurry having a viscosity of 1000-3000 mPa·s;

[0016] Impregnating the carbon fiber fabric having a silicon carbide layer on the surface into the composite slurry, so that the composite slurry fills the pores of the carbon fiber fabric having a silicon carbide layer on the surface;

[0017] The whole is dried at 70-100°C for 1-5h, then cured at 150-200°C for 2-10h, and finally carbonized at 700-1200°C for 6-20h to obtain a carbon fiber-reinforced silicon carbide-based fire-resistant, high-temperature-resistant and high-toughness plate.

[0018] Preferably, the diameter of the carbon fiber filament is 5-15 μm; the carbon fiber fabric has a multi-layer, porous structure with a mesh size of 0.5-5 mm, preferably 0.5-1.5 mm; the particle size of the silicon powder is 0.1-10 μm, and the particle size of the silicon carbide powder is 100-200 μm.

[0019] Preferably, the first binder and the second binder are independently selected from one or more of polyvinyl butyral, phenolic resin, epoxy resin, acrylic resin, polyimide resin, fluorocarbon resin, fluororesin, benzocyclobutene resin, bismaleimide triazine resin, fluorinated polyallyl ether, polyamide resin, polyiminoamide resin, aromatic polyester resin, polyphenylene ether resin and polydimethylsiloxane resin. Preferably, the second binder is polyvinyl butyral; the first solvent and the second solvent are independently selected from water, ethanol, methanol, n-butanol, tetrahydrofuran, tetrahydropyrrole, tetrahydrothiophene, 1,4-dioxane, 1,4-dithiophene, pyrrole, N-methylpyrrolidone ...1,4-dioxane, 1,4-dithiophene, 1,4-dioxane, 1,4-disulfide, 1,4-disulfide, 1,4-disulfide, 1,4-disulfide, 1,4-disulfide, 1,4-disulfide, 1,4-disulfide, 1,4-disulfide, 1,4-disulfide, 1,4-disulfide, 1,4-disulfide, 1,4-disulfide, 1,4-disulfide, 1,4-disulfide, 1, The invention can be selected from the group consisting of iodine, thiophene, furan, pyridine, acetone, N-methylpyrrolidone, diphenyl ketone, methyl ethyl ketone, methyl propyl ketone, isophorone, hexanophenone, dimethyl sulfoxide, N,N-dimethylformamide, N,N-diethylformamide, N,N-dimethylacetamide, N,N-diethylacetamide, N,N-dimethylpropionamide, N,N-diethylpropionamide, γ-butyrolactone, γ-valerolactone, dimethyl carbonate, ethyl acetate, benzyl benzoate, caprolactone, acetonitrile, N-(2-cyanoethyl)pyrrole, chloroacetonitrile, propionitrile, hexafluoroisopropanol, anisole, phenethyl ether, ethanolamine, ethylenediamine, diethylenetriamine, triethylenetetramine and tetraethylenepentamine, and preferably ethanol.

[0020] Preferably, the mass ratio of the silicon powder to the coating suspension is 1:4-1:3; the mass ratio of the first binder to the first solvent is 1:(10-60); the mass concentration of silicon carbide in the composite slurry is 40%-60%; the mass ratio of the second binder to the second solvent is 1:(8-10).

[0021] Preferably, the coating suspension is applied to the surface of the carbon fiber fabric in an amount of 120-280 g / m 2 In order to fully fill the pores of the carbon fiber fabric with the suspension, coating is performed n times (n≥1) on each surface of the carbon fiber fabric.

[0022] Preferably, the carbon fiber fabric having a silicon carbide layer on the surface is impregnated in the composite slurry under vacuum pressure, the impregnation time is 0.5-4h, and the pressure is 1-10Mpa.

[0023] Preferably, the forming mold is a cylindrical, square cylindrical or plate-shaped metal forming mold.

[0024] Preferably, in the step of arranging the carbon fiber prepreg on a metal forming mold, the metal forming mold is preheated at 70-100° C. to ensure that the carbon fiber prepreg has an ambient temperature of 50-70° C. during the arrangement process.

[0025] In a second aspect, the present invention further provides a carbon fiber toughened silicon carbide-based refractory, high temperature resistant and high toughness plate prepared by the preparation method as described above, wherein the refractory, high temperature resistant and high toughness plate is a silicon carbide ceramic composite material with carbon fiber as a skeleton, and the fracture toughness of the refractory, high temperature resistant and high toughness plate is 4-10MPa·m 1 / 2 .

[0026] In a third aspect, the present invention also provides an application of the carbon fiber-reinforced silicon carbide-based fire-resistant, high-temperature-resistant and high-toughness plate in aircraft engines and rocket thrusters.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] 1) Compared with the homogeneous dispersion compound of the existing method, the preparation process of the present invention is simple, low in cost, and has low requirements for sintering process control. The size and structure can be conveniently adjusted according to actual application requirements, and the subsequent mechanical processing is easy;

[0029] 2) Compared with the existing method of using short-cut carbon fiber materials and ceramic composites, the present invention uses a carbon fiber fabric woven from carbon fiber filaments and a composite of silicon carbide ceramics, which significantly improves the toughening effect and the composite material is not prone to breakage during application;

[0030] 3) The present invention uses polyvinyl butyral (PVB) as a binder for the silicon carbide composite slurry, which improves the full filling and bonding strength of silicon carbide on the carbon fiber fabric with a silicon carbide layer on the surface, and the toughness of the composite material is greatly improved.

[0031] 4) A layer of silicon carbide is first formed on the surface of the carbon fiber fabric as a transition layer, which can be firmly connected to the carbon fiber and effectively connected to silicon carbide, solving the problem that the surface of the carbon fiber and the interface of the silicon carbide material cannot be tightly connected, improving the full filling and bonding strength of silicon carbide on the carbon fiber fabric, greatly improving the toughness of the composite material, and improving the firmness of the overall structural components. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 The present invention is a schematic diagram of the structure of the carbon fiber skeleton in the carbon fiber toughened silicon carbide based fire-resistant, high-temperature resistant and high-toughness plate material.

[0033] Figure 2 The present invention provides a schematic structural diagram of a pipe obtained by compounding a carbon fiber skeleton and a silicon carbide ceramic matrix in a carbon fiber toughened silicon carbide-based fire-resistant, high-temperature-resistant and high-toughness plate.

[0034] Figure 3 It is a structural cross-sectional view of the carbon fiber toughened silicon carbide based fire-resistant, high-temperature resistant and high-toughness plate material involved in the present invention. DETAILED DESCRIPTION

[0035] The technical solution of the present invention is further described below in conjunction with the accompanying drawings and specific implementation methods.

[0036] The present invention provides a method for preparing a carbon fiber toughened silicon carbide-based fire-resistant, high-temperature-resistant and high-toughness plate, comprising the following steps:

[0037] Step (1), weaving carbon fiber filaments into a carbon fiber fabric with a mesh structure.

[0038] The carbon fiber filaments used in the present invention may include, but are not limited to, polyester fibers, polyamide fibers, polyacrylonitrile fibers (PAN fibers), polypropylene fibers, polyurethane fibers, polyvinyl alcohol fibers, viscose fibers, asphalt fibers, lignin fibers or other organic fiber-based carbon fibers (natural fibers, regenerated fibers, and polycyclic aromatic fibers, etc.) according to the type of precursor fibers. The type of precursor material of the carbon fiber filaments used in the present invention is not limited.

[0039] In this step, the carbon fiber filaments are woven into a carbon fiber fabric with a gauze structure, which can be divided into plain weave, twill weave, bias weave, interlaced weave, weft-reinforced weave, three-dimensional weave or cloth weave according to different weaving methods, and the diameter of the carbon fiber filaments used is 5-15 μm (for example, 10 μm). The weaving method of weaving the carbon fiber filaments into a carbon fiber fabric with a gauze structure is not limited in the present invention, and it can also be a carbon fiber fabric with multiple layers, and the weaving method of each layer can be the same or different, and the formed carbon fiber fabric has a porous structure with a mesh size of 0.5-5 mm (for example, 1 mm).

[0040] If the mesh size of the carbon fiber fabric woven by the present invention is too large, the reinforcement and toughness enhancement of the carbon fiber as a skeleton structure in the composite material will be affected. If the mesh size is too small, the slurry will not easily enter the pores of the carbon fiber fabric during the process of immersing the carbon fiber fabric in the slurry, and it is easy to form holes or fractures in the composite material finally formed, and the toughness and life of the composite material are also affected. In some embodiments, the physical properties such as toughness of the composite material finally formed can also be changed by adjusting the density (i.e., mesh size) and distribution (i.e., different weaving methods) of the carbon fiber according to the size, shape and performance requirements of the finished plate.

[0041] Step (2), dissolving silicon powder and a first binder in a first solvent to prepare a coating suspension having a viscosity of 300-500 mPa·s;

[0042] In this step, the silicon powder used is pure silicon powder with a purity greater than 99% and a particle size of 0.1-10 μm (preferably 1 μm). The first binder used includes but is not limited to polyvinyl butyral, phenolic resin, epoxy resin, acrylic resin, polyimide resin, fluorocarbon resin, fluororesin, benzocyclobutene resin, bismaleimide triazine resin, fluorinated polyallyl ether, polyamide resin, polyimide amide resin, aromatic polyester resin, polyphenylene ether resin, polydimethylsiloxane resin, etc. In the embodiment of the present invention, polyvinyl butyral is used as an example. The first solvent used includes, but is not limited to, water, ethanol, methanol, n-butanol, tetrahydrofuran, tetrahydropyrrole, tetrahydrothiophene, 1,4-dioxane, 1,4-dithiophene, pyrrole, N-methylpyrrole, thiophene, furan, pyridine, acetone, N-methylpyrrolidone, diphenyl ketone, methyl ethyl ketone, methyl propyl ketone, isophorone, hexanophenone, dimethyl sulfoxide, N,N-dimethylformamide, N,N-diethylformamide, N,N-dimethyl N,N-diethylacetamide, N,N-dimethylpropionamide, N,N-diethylpropionamide, γ-butyrolactone, γ-valerolactone, dimethyl carbonate, ethyl acetate, benzyl benzoate, caprolactone, acetonitrile, N-(2-cyanoethyl)pyrrole, chloroacetonitrile, propionitrile, hexafluoroisopropanol, anisole, phenethyl ether, ethanolamine, ethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, etc., and ethanol is used as an example in the embodiment of the present invention. In the present invention, the mass ratio of silicon powder to the coating suspension is 1:4-1:3, and the mass ratio of the first binder to the first solvent is 1:(10-60), so as to configure a coating suspension with a viscosity of 300-500psc.

[0043] Step (3), coating the coating suspension on the carbon fiber fabric so that the suspension fills the pores of the carbon fiber fabric to form a carbon fiber prepreg;

[0044] In this step, the coating suspension is applied to the surface of the carbon fiber fabric in an amount of 120-280 g / m 2 .

[0045] In this step, in order to enhance the coating effect of the coating suspension on the carbon fiber fabric and allow the suspension to fully fill the pores of the carbon fiber fabric, multiple coatings may be performed on each surface of the carbon fiber fabric.

[0046] Step (4), placing the carbon fiber prepreg on a forming mold;

[0047] In this step, the metal forming mold used in the present invention can be cylindrical, square cylindrical or plate-shaped, and the carbon fiber prepreg arranged on the metal forming mold can form a cylindrical, square cylindrical or plate-shaped composite material pipe or plate, which can be designed and manufactured at any time according to the product shape and size requirements of the specific actual application.

[0048] In this step, the metal forming mold can also be preheated at 70-100°C to ensure that the carbon fiber prepreg has an ambient temperature of 50-70°C during the layout process, which is conducive to allowing the prepreg and the mold to quickly reach the same temperature and shorten the overall curing time.

[0049] Step (5), drying the whole at 70-100° C. for 1-5 hours to form a preliminary shape, removing the forming mold after cooling to room temperature, and then placing the preliminary formed material at 280-320° C. for 2-10 hours to decompose the binder component, and then placing it at 1500-1700° C. for 2-20 hours to melt the silicon on the surface, thereby forming a silicon carbide layer on the surface of the carbon fiber fabric;

[0050] Step (6), dissolving silicon carbide powder and a second binder in a second solvent to prepare a composite slurry with a viscosity of 1000-3000 mPa·s; then, dipping a carbon fiber fabric having a silicon carbide layer on its surface into the composite slurry, so that the composite slurry fills the pores of the carbon fiber fabric having a silicon carbide layer on its surface;

[0051] In this step, in some embodiments, the particle size of the silicon carbide powder used in the present invention is 100-200 μm (eg, 150 μm).

[0052] In some embodiments, the second binder used in the present invention includes but is not limited to polyvinyl butyral, phenolic resin, epoxy resin, acrylic resin, polyimide resin, fluorocarbon resin, fluororesin, benzocyclobutene resin, bismaleimide triazine resin, fluorinated polyallyl ether, polyamide resin, polyiminoamide resin, aromatic polyester resin, polyphenylene ether resin, polydimethylsiloxane resin, etc. The first binder and the second binder can be the same or different. In the present invention, polyvinyl butyral is preferably used as the second binder of the composite slurry. Polyvinyl butyral (PVB) is a product of condensation of polyvinyl alcohol and butyraldehyde under acid catalysis. Since the PVB molecule contains a relatively long side chain, it has good flexibility, and a low glass transition temperature, and has high stretching and adhesion properties. Moreover, PVB has good solubility and film-forming properties, and has high adhesion to materials such as silicon carbide and glass. In the present invention, PVB is used as the binder of the composite slurry. Compared with other binders such as phenolic resin, epoxy resin, and polyamide resin, it has higher bonding force with silicon carbide powder material. More importantly, the formed composite slurry has better wettability to carbon fiber with a silicon carbide layer on the surface. During the impregnation process, it can more easily enter the pores of the carbon fiber fabric with a silicon carbide layer on the surface, so it can carry more silicon carbide to fill the pores of the fabric, that is, the silicon carbide content filled in the fabric can reach a higher level.

[0053] In some embodiments, the second solvent used in the present invention includes but is not limited to water, ethanol, methanol, n-butanol, tetrahydrofuran, tetrahydropyrrole, tetrahydrothiophene, 1,4-dioxane, 1,4-dithiophene, pyrrole, N-methylpyrrole, thiophene, furan, pyridine, acetone, N-methylpyrrolidone, diphenyl ketone, methyl ethyl ketone, methyl propyl ketone, isophorone, hexanophenone, dimethyl sulfoxide, N,N-dimethylformamide, N,N The first solvent and the second solvent can be the same or different. In the present invention, ethanol is preferably used as the second solvent.

[0054] As an embodiment of the present invention, the mass concentration of the silicon carbide in the composite slurry is 40%-60%. The mass ratio of the binder to the solvent is 1:(8-10).

[0055] The higher the mass concentration of silicon carbide in the composite slurry, the more silicon carbide can be carried in the composite slurry at the same volume, and the higher the silicon carbide content filled in the carbon fiber fabric by the composite slurry. However, if the mass concentration of silicon carbide in the composite slurry is too high, the adhesion of silicon carbide in the slurry will decrease, and silicon carbide will easily fall off during the impregnation process and the subsequent high-temperature carbonization sintering process; if the mass concentration of silicon carbide in the composite slurry is too low, the viscosity of the slurry will be too low, and the slurry will easily flow during the impregnation process, which will also affect the performance of the composite material finally formed.

[0056] In this step, in order to improve the impregnation effect and efficiency, a pressurized impregnation method can be adopted. For example, the carbon fiber fabric with a silicon carbide layer on the surface impregnated in the composite slurry is placed in a closed container with a pressure of 1-10 MPa and impregnated under pressure for 0.5-4 hours, so that the composite slurry can be fully and quickly filled in the pores of the carbon fiber fabric with a silicon carbide layer on the surface.

[0057] Step (7), drying the whole at 70-100°C for 1-5h, then curing the material at 150-200°C for 2-10h, and then carbonizing at 700-1200°C for 6-20h, to obtain a carbon fiber toughened silicon carbide-based fire-resistant, high-temperature-resistant and high-toughness plate.

[0058] In the present invention, a silicon carbide layer is creatively formed on the surface of the carbon fiber fabric, which can be firmly connected to the carbon fiber and effectively connected to the silicon carbide filled in the pores of the carbon fiber fabric, forming a transition layer between the carbon fiber material and the silicon carbide filler, solving the problem of insufficient toughness of the composite material caused by the inability to tightly connect the interface between the carbon fiber filaments and the silicon carbide material, improving the full filling and bonding toughness of silicon carbide on the carbon fiber fabric, and greatly improving the toughness of the composite material.

[0059] The carbon fiber-toughened silicon carbide-based fire-resistant, high-temperature-resistant and high-toughness plate prepared by the above preparation method is a silicon carbide ceramic composite material with carbon fiber as the skeleton.

[0060] See also Figure 1 and Figure 2 The fire-resistant, high-temperature-resistant and high-toughness plate 100 provided by the present invention is specifically composed of a carbon fiber skeleton 110 and a ceramic matrix 120. The ceramic matrix 120 covers the entire carbon fiber skeleton 110 and fully fills the gaps in the carbon fiber skeleton 110.

[0061] See also Figure 3 , which shows a cross-sectional view of the structure of the carbon fiber toughened silicon carbide-based fire-resistant, high-temperature-resistant and high-toughness plate formed by the present invention. As an example, from Figure 3It can be seen that in the fire-resistant, high-temperature-resistant and high-toughness plate 100, the carbon fiber skeleton 110 has an inner skeleton 110a, a middle skeleton 110b and an outer skeleton 110c. During the preparation process, the number of circles of the carbon fiber prepreg arranged on the square cylindrical forming mold is three circles, so that the carbon fiber toughened silicon carbide-based composite material pipe formed has the following characteristics: Figure 3 The structures of the inner skeleton 110a, the middle skeleton 110b and the outer skeleton 110c are shown.

[0062] The technical solution of the present invention is further described below in conjunction with specific embodiments, but the protection scope of the present invention is not limited to these embodiments. Any changes or equivalent substitutions that do not deviate from the concept of the present invention are included in the protection scope of the present invention.

[0063] Embodiment 1~3:

[0064] This embodiment provides a carbon fiber toughened silicon carbide-based fire-resistant, high-temperature-resistant and high-toughness plate, and the preparation method thereof comprises the following steps:

[0065] 1) weaving carbon fiber filaments with a diameter of 10 μm into a carbon fiber fabric with a mesh structure, the mesh size of which is greater than 1 mm;

[0066] 2) dissolving pure silicon powder with a particle size of 1 μm and polyvinyl alcohol butyral in ethanol to prepare a coating suspension, wherein the mass concentration of the pure silicon powder in the coating suspension is A, and the viscosity of the prepared coating suspension is B;

[0067] 3) coating the coating suspension on the carbon fiber fabric so that the suspension fills the pores of the carbon fiber fabric to form a carbon fiber prepreg. To enhance the coating effect and allow the suspension to fully fill the pores of the carbon fiber fabric, the front and back sides of the carbon fiber fabric are coated twice each. The coating amount of the coating suspension on the surface of the carbon fiber fabric is E;

[0068] 4) Winding the carbon fiber prepreg obtained in step 3) on a metal square cylindrical mold, the square cylindrical mold is preheated at 80° C. to ensure that the carbon fiber prepreg has an ambient temperature of 50-70° C. during the winding process, which is conducive to allowing the prepreg and the mold to quickly reach the same temperature and shorten the overall curing time;

[0069] 5) drying the whole at 80° C. for 2 hours to form a preliminary shape, removing the mold after cooling to room temperature, and then placing the preliminary formed material at 300° C. for 4 hours to decompose the binder component, and then placing it at 1600° C. for 12 hours to melt the silicon on the surface and form a silicon carbide layer on the surface of the carbon fiber fabric;

[0070] 6) dissolving silicon carbide powder with a particle size of 150 μm and polyvinyl butyral in ethanol to prepare a composite slurry, wherein the mass concentration of silicon carbide in the composite slurry is C, and the viscosity of the prepared composite slurry is D;

[0071] 7) impregnating the carbon fiber fabric with a silicon carbide layer on the surface obtained in step 5) into the composite slurry of step 6). In order to improve the impregnation effect and efficiency, the carbon fiber fabric with a silicon carbide layer on the surface impregnated in the composite slurry is placed in a closed container with a pressure of 6 MPa and impregnated for 3 hours, so that the composite slurry is fully and quickly filled in the pores of the carbon fiber fabric with a silicon carbide layer on the surface;

[0072] 8) The whole is dried at 80°C for 2.5 hours, then cured at 170°C for 8 hours, and finally carbonized at 950°C for 16 hours to obtain a carbon fiber-reinforced silicon carbide-based fire-resistant, high-temperature-resistant and high-toughness plate.

[0073] Comparative Examples 1 to 3:

[0074] On the basis of Examples 1 to 3, the polyvinyl butyral in step 6) is replaced with phenolic resin.

[0075] Comparative Examples 4 to 6 (no coating suspension containing silicon powder):

[0076] This embodiment provides a carbon fiber toughened silicon carbide-based fire-resistant, high-temperature-resistant and high-toughness plate, and the preparation method thereof comprises the following steps:

[0077] 1) weaving carbon fiber filaments with a diameter of 10 μm into a carbon fiber fabric with a mesh structure, the mesh size of which is greater than 1 mm;

[0078] 2) dissolving silicon carbide powder with a particle size of 150 μm and polyvinyl butyral in ethanol to prepare a composite slurry, wherein the mass concentration of silicon carbide in the composite slurry is C, and the viscosity of the prepared composite slurry is D;

[0079] 3) impregnating the carbon fiber fabric obtained in step 2) in the composite slurry of step 2), specifically placing it in a closed container at a pressure of 6 MPa and impregnating it under vacuum pressure for 3 hours, so that the composite slurry is fully and quickly filled in the pores of the carbon fiber fabric to form a carbon fiber prepreg;

[0080] 4) Winding the carbon fiber prepreg obtained in step 3) on a metal square cylindrical mold, the square cylindrical mold is preheated at 80° C. to ensure that the carbon fiber prepreg has an ambient temperature of 50-70° C. during the winding process, which is conducive to allowing the prepreg and the mold to quickly reach the same temperature and shorten the overall curing time;

[0081] 5) The whole is placed at 80°C for drying for 2 hours to form a preliminary shape. After cooling to room temperature, the forming mold is removed. The preliminary formed material is then placed at 170°C for curing for 8 hours, and then placed at 950°C for carbonization for 16 hours to obtain the corresponding plate.

[0082] The values ​​of A, B, C, D and E in Examples 1-3 and Comparative Examples 1-6 are listed in Table 1.

[0083] Physical performance test:

[0084] The physical property testing method of the carbon fiber toughened silicon carbide based fire-resistant, high temperature resistant and high toughness plate prepared according to Examples 1-3 and Comparative Examples 1-6 includes:

[0085] (a) The prepared carbon fiber toughened silicon carbide-based fire-resistant and high-temperature resistant high-toughness plate is precracked in the middle of the sample according to the single-side bevel cut precrack method mentioned in GB / T 23806-2009, and then loaded under three-point bending conditions until it breaks, so as to measure and calculate the fracture toughness of the material;

[0086] (b) The density of the prepared carbon fiber toughened silicon carbide-based fire-resistant, high-temperature-resistant and high-toughness plate sample is measured using a digital solid density tester.

[0087] The physical property test results of the carbon fiber toughened silicon carbide based fire-resistant, high temperature resistant and high toughness plates prepared in Examples 1-3 and Comparative Examples 1-6 are listed in Table 1.

[0088] Among them, in Table 1, the mass concentration of pure silicon powder in the coating suspension is A, the viscosity of the prepared coating suspension is B, the mass concentration of silicon carbide in the composite slurry is C, the viscosity of the prepared composite slurry is D, and the coating amount of the coating suspension on the surface of the carbon fiber fabric is E.

[0089] Table 1

[0090]

[0091] From Table 1 we can see that:

[0092] It can be seen from Examples 1 to 3 and Comparative Examples 1 to 3 that, compared with Comparative Examples 1 to 3 in which phenolic resin is used as a binder for silicon carbide composite slurry, Examples 1 to 3 of the present invention use polyvinyl butyral (PVB) as a binder for silicon carbide composite slurry, and the density and toughness of the obtained composite materials are greatly improved. This is because the composite material using phenolic resin material has a lot of residual carbon after sintering and carbonization, but the adhesion of phenolic resin is not as good as polyvinyl butyral, so the content of silicon carbide on the carbon fiber fabric is reduced. Under the same impregnation conditions, the density of the composite material obtained by using phenolic resin as a binder for the composite slurry is reduced, and the interface between silicon carbide and the carbon after sintering of phenolic resin becomes more, resulting in a significant reduction in toughness.

[0093] It can be seen from Examples 1 to 3 and Comparative Examples 4 to 6 that, compared with Comparative Examples 4 to 6 in which a silicon carbide transition layer is not formed on the surface of the carbon fiber fabric in advance, under the same composite slurry and the same impregnation conditions, Examples 1 to 3 of the present invention use a silicon carbide transition layer formed on the surface of the carbon fiber fabric in advance, and the density of the composite material obtained is lower than that of the composite material obtained in Comparative Examples 4 to 6 in which a silicon carbide transition layer is not formed on the surface of the carbon fiber fabric in advance, but the toughness is greatly improved. This is because the silicon carbide transition layer formed on the surface of the carbon fiber fabric strengthens the connection toughness between the carbon fiber fabric and the silicon carbide filled in the carbon fiber fabric, and also improves the full filling of silicon carbide on the carbon fiber fabric.

[0094] Compared with the slurry impregnation hot pressing method in the prior art, the preparation process of the present invention is not easy to cause damage to the carbon fiber, so that the carbon fiber can play a role in reinforcing the composite material. Secondly, by weaving the long fibers, the preparation of composite materials with complex shapes is not restricted.

[0095] Compared with the homogeneous dispersion compounding of the existing method, the preparation process of the present invention is simple, low-cost, and has low requirements for sintering process control. The size and structure can be conveniently adjusted according to actual application requirements, and the subsequent mechanical processing is easy.

[0096] Compared with the existing method of using short-cut carbon fiber materials and ceramic composites, the present invention uses a carbon fiber fabric woven from carbon fiber filaments and a composite of silicon carbide ceramics, which significantly improves the toughening effect and the composite material is not prone to breakage during application.

[0097] The carbon fiber-reinforced silicon carbide-based fire-resistant, high-temperature-resistant and high-toughness plate provided by the present invention can be applied to fields such as aircraft engines and rocket thruster nozzles that need to cope with extreme conditions.

[0098] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for preparing a carbon fiber toughened silicon carbide-based fire-resistant, high-temperature-resistant and high-toughness plate, characterized in that: The steps include: Carbon fiber fabrics that are woven from carbon fiber filaments into a mesh structure; Dissolving silicon powder and a first binder in a first solvent to prepare a coating suspension having a viscosity of 300-500 mPa·s; Applying the coating suspension on the carbon fiber fabric so that the suspension fills the pores of the carbon fiber fabric to form a carbon fiber prepreg; Arranging the carbon fiber prepreg on a forming mold; The whole is placed at 70-100°C for drying for 1-5 hours to form a preliminary shape, and the forming mold is removed after cooling to room temperature, and then the preliminary formed material is placed at 280-320°C for 2-10 hours to decompose the binder component, and then placed at 1500-1700°C for 2-20 hours to melt the silicon on the surface, forming a silicon carbide layer on the surface of the carbon fiber fabric; Dissolving silicon carbide powder and a second binder in a second solvent to prepare a composite slurry having a viscosity of 1000-3000 mPa·s; Impregnating the carbon fiber fabric having a silicon carbide layer on the surface into the composite slurry, so that the composite slurry fills the pores of the carbon fiber fabric having a silicon carbide layer on the surface; The whole is dried at 70-100°C for 1-5h, then cured at 150-200°C for 2-10h, and finally carbonized at 700-1200°C for 6-20h to obtain a carbon fiber-reinforced silicon carbide-based fire-resistant, high-temperature-resistant and high-toughness plate.

2. The preparation method according to claim 1, characterized in that: The diameter of the carbon fiber filament is 5-15 μm; the carbon fiber fabric has a multi-layer, porous structure with a mesh size of 0.5-5 mm; the particle size of the silicon powder is 0.1-10 μm, and the particle size of the silicon carbide powder is 100-200 μm.

3. The preparation method according to claim 1, characterized in that: The first binder and the second binder are independently selected from one or more of polyvinyl butyral, phenolic resin, epoxy resin, acrylic resin, polyimide resin, fluorocarbon resin, fluororesin, benzocyclobutene resin, bismaleimide triazine resin, fluorinated polyallyl ether, polyamide resin, polyiminoamide resin, aromatic polyester resin, polyphenylene ether resin and polydimethylsiloxane resin. Preferably, the second binder is polyvinyl butyral; the first solvent and the second solvent are independently selected from water, ethanol, methanol, n-butanol, tetrahydrofuran, tetrahydropyrrole, tetrahydrothiophene, 1,4-dioxane, 1,4-dithiophene, pyrrole, N-methylpyrrole, Thiophene, furan, pyridine, acetone, N-methylpyrrolidone, diphenyl ketone, methyl ethyl ketone, methyl propyl ketone, isophorone, hexanophenone, dimethyl sulfoxide, N,N-dimethylformamide, N,N-diethylformamide, N,N-dimethylacetamide, N,N-diethylacetamide, N,N-dimethylpropionamide, N,N-diethylpropionamide, γ-butyrolactone, γ-valerolactone, dimethyl carbonate, ethyl acetate, benzyl benzoate, caprolactone, acetonitrile, N-(2-cyanoethyl)pyrrole, chloroacetonitrile, propionitrile, hexafluoroisopropanol, anisole, phenethyl ether, ethanolamine, ethylenediamine, diethylenetriamine, triethylenetetramine and tetraethylenepentamine. One or more, preferably ethanol.

4. The preparation method according to claim 1, characterized in that: The mass ratio of the silicon powder to the coating suspension is 1:4-1:3; the mass ratio of the first binder to the first solvent is 1:(10-60); the mass concentration of silicon carbide in the composite slurry is 40%-60%; the mass ratio of the second binder to the second solvent is 1:(8-10).

5. The preparation method according to claim 1, characterized in that: The coating suspension is applied on the surface of the carbon fiber fabric in an amount of 120-280 g / m 2 In order to fully fill the pores of the carbon fiber fabric with the suspension, coating is performed n times (n≥1) on each surface of the carbon fiber fabric.

6. The preparation method according to claim 1, characterized in that: The carbon fiber fabric with a silicon carbide layer on the surface is impregnated in the composite slurry under vacuum pressure, the pressure-maintaining impregnation time is 0.5-4 hours, and the pressure is 1-10 MPa.

7. The preparation method according to claim 1, characterized in that: The forming mold is a cylindrical, square cylindrical or plate-shaped metal forming mold.

8. The preparation method according to claim 1 or 7, characterized in that: In the step of arranging the carbon fiber prepreg on a metal forming mold, the metal forming mold is preheated at 70-100° C. to ensure that the carbon fiber prepreg has an ambient temperature of 50-70° C. during the arrangement process.

9. A carbon fiber-toughened silicon carbide-based fire-resistant, high-temperature-resistant, high-toughness plate prepared by the preparation method according to any one of claims 1 to 8, characterized in that: The fire-resistant, high-temperature-resistant and high-toughness plate is a silicon carbide ceramic composite material with carbon fiber as the skeleton, and the fracture toughness of the fire-resistant, high-temperature-resistant and high-toughness plate is 4-10MPa·m 1 / 2 .

10. Use of the carbon fiber-toughened silicon carbide-based fire-resistant, high-temperature-resistant and high-toughness plate as claimed in claim 9 in aircraft engines and rocket thrusters.

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