An antioxidant C sf / SiBCN composite material and preparation method thereof

Abstract

The present invention relates to the technical field of composite materials, and in particular to an antioxidant C sf / SiBCN composite material and preparation method thereof, the method comprising: uniformly mixing amorphous MA SiBCN powder, phenolic resin and organic solvent to obtain MA SiBCN slurry; preparing a short carbon fiber-MA SiBCN slurry layered structure system and performing a curing treatment to obtain a layered short carbon fiber-MA SiBCN blank; pyrolyzing the layered short carbon fiber-MA SiBCN blank under an inert gas protective atmosphere, cooling to room temperature, and obtaining a porous C sf / MA SiBCN composite materials; porous C sf / MA SiBCN composite material was subjected to at least one impregnation-crosslinking-pyrolysis treatment to obtain antioxidant C sf / SiBCN composite material; C prepared by the present invention sf / SiBCN composite materials have better oxidation resistance.

Description

Technical Field

[0001] The present invention relates to the technical field of composite materials, and in particular to an antioxidant C sf / SiBCN composite material and preparation method thereof. Background Art

[0002] With the rapid development of the aerospace industry, high-temperature structural materials and components are facing more extreme service environments. The development of high-temperature heat-resistant materials that can serve in high-temperature, oxygen-rich and complex environments is an urgent need for the development of modern aerospace technology. SiBCN ceramics have excellent thermal stability and oxidation resistance and have attracted widespread attention. Introducing carbon fiber into the SiBCN ceramic matrix can avoid the catastrophic fracture of pure SiBCN ceramics and improve their reliability. Therefore, C f / SiBCN composite materials have shown good development prospects in aerospace thermal protection structural parts.

[0003] The preparation process of SiBCN ceramics mainly includes precursor pyrolysis method (PDCs SiBCN) and mechanical alloying method (MASiBCN). f / SiBCN composite materials mainly include long fiber carbon (continuous carbon fiber) reinforced SiBCN composite materials (C cf / SiBCN) and short fiber reinforced SiBCN composites (C sf / SiBCN). There are significant differences in the preparation process, microstructure, and high temperature performance between the two. cf / SiBCN composite materials are mainly C cf / PDCs SiBCN, which has the advantages of low preparation temperature, uniform fiber distribution, and excellent toughening effect, but has the disadvantages of complex fiber weaving process, long PIP cycle, and high cost. In addition, the shrinkage during the pyrolysis of the precursor leads to more cracks in the PDCs SiBCN, making it easier for oxygen to diffuse into the material. sf / SiBCN composite materials have the advantages of convenient process, short preparation cycle and adjustable fiber content. sf / SiBCN composite materials undergo crystallization of the matrix and severe fiber damage due to the high sintering temperature, while amorphous SiBCN powder is difficult to densify and sinter at low temperatures, resulting in poor antioxidant performance. Summary of the Invention

[0004] The technical problem solved by the present invention is: the existing mechanical alloying method is combined with hot pressing sintering process to prepare C sf / SiBCN composite materials undergo crystallization of the matrix and severe fiber damage due to the high sintering temperature, while amorphous SiBCN powder is difficult to densify and sinter at low temperatures, resulting in poor antioxidant performance.

[0005] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0006] An antioxidant C sf A method for preparing a / SiBCN composite material, comprising:

[0007] Step S1, uniformly mixing amorphous MA SiBCN powder, phenolic resin and organic solvent to obtain MASiBCN slurry, wherein the amorphous MASiBCN powder is obtained by mechanical alloying;

[0008] Step S2, using the MA SiBCN slurry and short carbon fibers to prepare a short carbon fiber-MA SiBCN slurry layered structure system; wherein the short carbon fiber-MA SiBCN slurry layered structure system comprises a plurality of short carbon fiber layers and a plurality of MA SiBCN slurry layers, and the short carbon fiber layers and the MA SiBCN slurry layers are alternately arranged;

[0009] Step S3, curing the short carbon fiber-MA SiBCN slurry layered structure system to obtain a layered short carbon fiber-MA SiBCN blank;

[0010] Step S4: in an inert gas atmosphere, pyrolyze the layered short carbon fiber-MA SiBCN blank and cool it to room temperature to obtain a porous C sf / MASiBCN composites;

[0011] Step S5: sf / MA SiBCN composite material is subjected to at least one impregnation-crosslinking-pyrolysis treatment to obtain an antioxidant C sf / SiBCN composite material; wherein the impregnation-crosslinking-pyrolysis treatment comprises: sf After the / MASiBCN composite material is immersed in a polyborosilazane impregnation solution, a cross-linking reaction and a high-temperature cracking reaction are sequentially performed under an inert gas protective atmosphere.

[0012] Optionally, in step S5, the polyborosilazane impregnation solution is obtained by mixing polyborosilazane and dicumyl peroxide.

[0013] Optionally, the mass ratio of the polyborosilazane to the dicumyl peroxide in the polyborosilazane impregnation solution is 100:1-5, and the impregnation treatment time is 30-120 min.

[0014] Optionally, in step S5, the cross-linking reaction is carried out at a temperature of 120-180° C. and for a time of 2-4 hours.

[0015] Optionally, in step S5, the temperature of the high-temperature cracking reaction is 900-1100° C., and the time is 2-6 hours.

[0016] Optionally, in step S1, the amorphous MASiBCN powder is mixed by high-energy ball milling of boron nitride, silicon powder and graphite, and the molar ratio of the boron nitride, the silicon powder and the graphite in the amorphous MA SiBCN powder is 1:(1.5-2.5):(2.5-3.5). During the high-energy ball milling process, the mass ratio of grinding balls to powders is (10-30):1, the main disk speed of the ball mill is 300-450rpm, the planetary disk speed is 600-850rpm, and the high-energy ball milling time is 20-60h.

[0017] Optionally, in step S2, the use of the MA SiBCN slurry and short carbon fibers to prepare a short carbon fiber-MASiBCN slurry layered structure system comprises:

[0018] A MA SiBCN slurry layer is coated on the surface of the short carbon fiber layer one, a short carbon fiber layer two is stacked on the MA SiBCN slurry layer, and a MA SiBCN slurry layer is coated on the surface of the short carbon fiber layer two. The above steps are repeated to obtain the short carbon fiber-MASiBCN slurry layered structure system, wherein the short carbon fiber layer one and the short carbon fiber layer two are both prepared using short carbon fibers.

[0019] Optionally, in step S2, the short carbon fiber-MASiBCN slurry layered structure system comprises 30-50 short carbon fiber layers.

[0020] Optionally, in step S4, the temperature of the pyrolysis reaction is 900-1100°C.

[0021] The present invention also provides an antioxidant C sf / SiBCN composite material, using the antioxidant C sf / SiBCN composite material is prepared by a preparation method.

[0022] Compared with the prior art, the present invention first adopts a layer-laying method to prepare porous C at a lower temperature. sf / MASiBCN composite materials, but the porous C sf / MA SiBCN composite material has high porosity and poor oxidation resistance. sfThe MA / MA SiBCN composite was impregnated in a polyborosilazane impregnation solution, then filled with PDCs SiBCN components after curing and cracking to produce a dense layered short carbon fiber-reinforced MA SiBCN and PDCs SiBCN hybrid. The stacked distribution of fibers in the composite prevents fiber agglomeration and crack propagation along the fibers during breakage, thereby enhancing the fiber-strengthening and toughening effect on the matrix.

[0023] The preparation process of the present invention is simple, the preparation cycle is short, and dense C sf Preparation of / SiBCN composite materials. Reducing energy consumption can not only slow down the high temperature damage of short carbon fibers, but also avoid the high temperature preparation of C sf The crystallization of SiBCN matrix in the / SiBCN composite material has an adverse effect on the oxidation resistance. In addition, the present invention combines the MASiBCN and PDCs SiBCN processes, which makes up for the problems of crystallization caused by the high sintering temperature of MASiBCN (>1800℃) and cracks caused by the large shrinkage during the pyrolysis of PDCs SiBCN. At the same time, the coupling effect of the oxidation process of MA SiBCN and PDCs SiBCN is used to form a continuous and dense oxide layer, which effectively hinders the diffusion of oxygen into the interior and gives C sf / SiBCN composite materials have good oxidation resistance. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 is the antioxidant C in the embodiment of the present invention sf Schematic diagram of the preparation process of / SiBCN composite material;

[0025] Figure 2 C prepared in Examples 1-5 and Comparative Examples sf XRD analysis pattern of / SiBCN composite material;

[0026] Figure 3 C prepared in the comparative example sf Thermogravimetric analysis of / SiBCN composite materials;

[0027] Figure 4 C prepared in Example 1 sf Thermogravimetric analysis of / SiBCN composite materials;

[0028] Figure 5 C prepared in Example 1 and Comparative Example sf Comparison of macroscopic images of the SiBCN / SiBCN composite materials after oxidation at 1400℃, 1500℃ and 1600℃ for 5h;

[0029] Figure 6 C prepared in Example 1 and Comparative Example sfComparison of SEM images of the surfaces of the SiBCN / SiBCN composite materials after oxidation at 1400℃ for 5h. DETAILED DESCRIPTION

[0030] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, specific embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0031] It should be noted that, unless otherwise specified, the features of the embodiments of the present invention may be combined with each other. The terms "comprising," "including," "containing," and "having" are non-restrictive and may include other steps and other components that do not affect the results. The above terms encompass the terms "consisting of" and "consisting essentially of." Unless otherwise specified, materials, equipment, and reagents were commercially available.

[0032] In addition, it should be noted that, in the present invention, "the short carbon fiber layer and the SiBCN slurry layer are arranged alternately" should be understood as a layer of SiBCN slurry layer covering the short carbon fiber layer, and then another layer of short carbon fiber layer covering the SiBCN slurry layer, and so on.

[0033] It has been found that combining polyborosilazane with inorganic inert fillers (such as SiC, B4C, BN, etc.) can reduce the shrinkage of the precursor during the cracking process, thereby reducing the formation of cracks in PDCs SiBCN. sf / MASiBCN, and then prepare dense carbon fiber reinforced MASiBCN and PDCs SiBCN hybrid materials through curing and cracking. sf The low-temperature preparation of C / SiBCN composite materials can not only effectively avoid the mechanical alloying method combined with hot pressing sintering to prepare C sf The high sintering temperature of the SiBCN composite material can reduce the matrix crystallization and fiber damage caused by it, and can also reduce the cracks caused by the large shrinkage during the pyrolysis of polyborosilazane.

[0034] On the other hand, amorphous MA SiBCN and PDCs SiBCN exhibit different oxidation products and behaviors: the oxidation product of pure amorphous MA SiBCN is primarily an amorphous glass phase, which readily transforms into a molten state at high temperatures, helping to bridge cracks and pores in the oxide layer. However, it is easily separated from the ceramic surface by the gases produced during oxidation. In contrast, the oxidation product of pure PDCs SiBCN is primarily cristobalite particles. During oxidation, oxygen readily diffuses through the pores of the cristobalite particles. Furthermore, cracks in the PDCs SiBCN itself during pyrolysis serve as pathways for oxygen diffusion, promoting oxidation damage to the material. Therefore, by leveraging the coupled oxidation behaviors of amorphous MA SiBCN and PDCs SiBCN, carbon fiber-reinforced PDCs SiBCN hybrid MA SiBCN composites can be prepared. A continuous and dense oxide layer forms on the surface during oxidation, potentially improving the composite's oxidation resistance.

[0035] Based on the above considerations, if Figure 1 As shown, the embodiment of the present invention provides an antioxidant C sf A method for preparing a / SiBCN composite material, comprising:

[0036] Step S1, uniformly mixing amorphous MA SiBCN powder, phenolic resin and organic solvent to obtain MASiBCN slurry, wherein the amorphous MA SiBCN powder is obtained by mechanical alloying;

[0037] Step S2, using the MASiBCN slurry and short carbon fibers to prepare a short carbon fiber-MA SiBCN slurry layered structure system; wherein the short carbon fiber-MA SiBCN slurry layered structure system comprises a plurality of short carbon fiber layers and a plurality of MASiBCN slurry layers, and the short carbon fiber layers and the MA SiBCN slurry layers are alternately arranged;

[0038] Step S3, curing the short carbon fiber-MA SiBCN slurry layered structure system to obtain a layered short carbon fiber-MA SiBCN blank;

[0039] Step S4: in an inert gas atmosphere, pyrolyze the layered short carbon fiber-MASiBCN blank and cool it to room temperature to obtain a porous C sf / MASiBCN composites;

[0040] Step S5: sf / MA SiBCN composite material is subjected to at least one impregnation-crosslinking-pyrolysis treatment to obtain an antioxidant C sf / SiBCN composite material; wherein the impregnation-crosslinking-pyrolysis treatment comprises: sfAfter the / MASiBCN composite material is immersed in a polyborosilazane impregnation solution, a cross-linking reaction and a high-temperature cracking reaction are sequentially performed under an inert gas protective atmosphere.

[0041] Compared with the prior art, the present invention first adopts a layer-laying method to prepare porous C at a lower temperature. sf / MASiBCN composite materials, but the porous C sf / MASiBCN composite material has high porosity and poor oxidation resistance. sf The MA / MASiBCN composite was impregnated in a polyborosilazane impregnation solution, then filled with PDCs SiBCN components after curing and cracking to produce a dense layered short carbon fiber-reinforced MA SiBCN and PDCs SiBCN hybrid. The stacked distribution of fibers in the composite prevents fiber agglomeration and crack propagation along the fibers during breakage, thereby enhancing the fiber-strengthening and toughening effect on the matrix.

[0042] The preparation process of the present invention is simple, the preparation cycle is short, and dense C sf Preparation of / SiBCN composite materials. Reducing energy consumption can not only slow down the high temperature damage of short carbon fibers, but also avoid the high temperature preparation of C sf The crystallization of SiBCN matrix in the / SiBCN composite material has an adverse effect on the oxidation resistance. In addition, the present invention combines the MASiBCN and PDCs SiBCN processes, which makes up for the problems of crystallization caused by the high sintering temperature of MASiBCN (>1800℃) and cracks caused by the large shrinkage during the pyrolysis of PDCs SiBCN. At the same time, the coupling effect of the oxidation process of MA SiBCN and PDCs SiBCN is used to form a continuous and dense oxide layer, which effectively hinders the diffusion of oxygen into the interior and gives C sf / SiBCN composite materials have good oxidation resistance.

[0043] In some embodiments of the present invention, in step S1, the amorphous MA SiBCN powder is mixed by high-energy ball milling of boron nitride, silicon powder and graphite, and the molar ratio of the boron nitride, the silicon powder and the graphite in the amorphous MA SiBCN powder is 1: (1.5-2.5): (2.5-3.5). During the high-energy ball milling process, the mass ratio of grinding balls to powders is (10-30): 1, the main disk speed of the ball mill is 300-450 rpm, the planetary disk speed is 600-850 rpm, and the high-energy ball milling time is 20-60 h. For example, boron nitride, silicon powder, and graphite were ball-milled in a molar ratio of 1:2:3 under an argon atmosphere. The main milling disc rotated at 400 rpm, the planetary disc rotated at 800 rpm, and the mixing time was 40 hours. The mill was operated for 50 minutes and then paused for 10 minutes. After the milling, the powder was removed from the argon-filled glove box. The ball-to-graphite mass ratio was 20:1. The SiBCN powder produced by high-energy ball milling is more uniformly mixed.

[0044] In some embodiments of the present invention, in step S5, the polyborosilazane impregnation solution is obtained by mixing polyborosilazane with dicumyl peroxide (DCP). The mass ratio of the polyborosilazane to the dicumyl peroxide in the polyborosilazane impregnation solution is 100:1-5, and the impregnation treatment time is 30-120 minutes, thereby ensuring that the porous C sf Preferably, the impregnation is performed under vacuum conditions to prevent the polyborosilazane impregnation solution from deteriorating.

[0045] In some embodiments of the present invention, in step S5, the temperature of the cross-linking reaction is 120-180° C. and the time is 2-4 hours to ensure that the cross-linking reaction proceeds fully and maximize the ceramic yield.

[0046] In some embodiments of the present invention, in step S5, the temperature of the high-temperature pyrolysis reaction is 900-1100° C., and the time is 2-6 hours.

[0047] In some embodiments of the present invention, in step S2, the method for preparing the short carbon fiber layer includes: cutting the carbon fiber to a length of 6-8 mm, ultrasonically dispersing it, filtering it out using a sieve, laying it flat and drying it naturally to obtain a short carbon fiber layer.

[0048] In some embodiments of the present invention, in step S2, the step of using the MASiBCN slurry and short carbon fibers to prepare a short carbon fiber-MA SiBCN slurry layered structure system comprises:

[0049] A MASiBCN slurry layer is coated on the surface of the short carbon fiber layer one, a short carbon fiber layer two is stacked on the MA SiBCN slurry layer, and a MA SiBCN slurry layer is coated on the surface of the short carbon fiber layer two. The above steps are repeated to obtain the short carbon fiber-MA SiBCN slurry layered structure system, wherein the short carbon fiber layer one and the short carbon fiber layer two are both prepared using the short carbon fiber.

[0050] In some embodiments of the present invention, in step S2, the short carbon fiber-MA SiBCN slurry layered structure system comprises 30-50 short carbon fiber layers.

[0051] In some embodiments of the present invention, in step S4, the temperature of the pyrolysis reaction is 900-1100° C. and the time is 3-5 hours to ensure sufficient pyrolysis of the phenolic resin, and the pyrolysis atmosphere is preferably high-purity nitrogen.

[0052] In some embodiments of the present invention, in step S3, the curing treatment includes: first drying the short carbon fiber-MASiBCN slurry layered structure system at 40-60°C for 10-14 hours, and then heating it at 100-150°C for 30-60 minutes to cure the short carbon fiber-MA SiBCN slurry layered structure system.

[0053] The present invention also provides an antioxidant C sf / SiBCN composite material, using the antioxidant C sf / SiBCN composite material is prepared by a preparation method.

[0054] The present invention will be further described below with reference to specific examples. It should be understood that these examples are only intended to illustrate the present invention and are not intended to limit the scope of the present invention.

[0055] Example 1

[0056] 1.1. First, cut the carbon fiber into 7mm lengths, put it into ethanol for ultrasonic dispersion, then filter it out using a sieve, lay it flat and dry it naturally to obtain a short carbon fiber layer;

[0057] 1.2. Under an argon atmosphere, boron nitride, silicon powder, and graphite were ball-milled in a molar ratio of 1:2:3 to obtain amorphous MA SiBCN powder. The main disc speed of the ball mill was 400 rpm, the planetary disc speed was 800 rpm, and the mixing time was 40 h. The ball mill was operated for 50 min and paused for 10 min. After the ball milling, the powder was collected in an argon-filled glove box. The ball-to-material mass ratio was 20:1.

[0058] 1.3. Add 4.51 g of amorphous MA SiBCN powder to 1.66 g of anhydrous ethanol, then add 2.05 g of phenolic resin to 2.03 g of anhydrous ethanol, stir magnetically, and then mix the two by ultrasonic dispersion to obtain MA SiBCN slurry;

[0059] 1.4. Uniformly apply a layer of MA SiBCN slurry on the surface of a short carbon fiber layer, then stack another short carbon fiber layer, and repeat the above steps to obtain a short carbon fiber-SiBCN slurry layered structure system, wherein the short carbon fiber-MA SiBCN slurry layered structure system comprises 40 short carbon fiber layers;

[0060] 1.5. Place the short carbon fiber-MASiBCN slurry layered structure system in an oven at 50°C for 12 hours, and then heat it at 100°C for 30 minutes and at 150°C for 60 minutes to solidify the short carbon fiber-MASiBCN slurry layered structure system to obtain a layered short carbon fiber-MASiBCN blank;

[0061] 1.6. Finally, the layered short carbon fiber-MA SiBCN blank was pyrolyzed at a heating rate of 2°C / min to 1100°C for 4 h under high-purity nitrogen, cooled to 600°C at a heating rate of 3°C / min, and then cooled to room temperature in the furnace to obtain porous C sf / MASiBCN composites;

[0062] 1.7. First, polyborosilazane and dicumyl peroxide (DCP) are mixed to obtain a polyborosilazane impregnation solution, wherein the mass ratio of the polyborosilazane to the dicumyl peroxide in the polyborosilazane impregnation solution is 100:1;

[0063] 1.8, the porous C sf / MASiBCN composite materials were treated with impregnation-crosslinking-pyrolysis for 5 times to obtain dense antioxidant C sf / MASiBCN composite material; wherein the impregnation-crosslinking-pyrolysis treatment includes: sf The / MA SiBCN composite material was impregnated with polyborosilazane impregnation solution for 45 min, and then heated to 170°C at a heating rate of 1°C / min in a high-purity nitrogen atmosphere for crosslinking for 2 h, and then pyrolyzed to 1100°C at a heating rate of 5°C / min for 2 h.

[0064] Example 2

[0065] The difference from Example 1 is that the porous C sf / MA SiBCN composite materials were subjected to one impregnation-crosslinking-pyrolysis treatment, and the other processes were the same.

[0066] Example 3

[0067] The difference from Example 1 is that the porous C sf / MA SiBCN composites were subjected to two impregnation-crosslinking-pyrolysis treatments, and the other processes were the same.

[0068] Example 4

[0069] The difference from Example 1 is that the porous C sf / MASiBCN composite materials were subjected to three impregnation-crosslinking-pyrolysis treatments, and the other processes were the same.

[0070] Example 5

[0071] The difference from Example 1 is that the porous C sf / MASiBCN composite materials were subjected to four impregnation-crosslinking-pyrolysis treatments, and the other processes were the same.

[0072] Comparative Example

[0073] A1. First, cut the carbon fiber into 7mm length, put it into ethanol for ultrasonic dispersion, then filter it out with a sieve, lay it flat and dry it naturally to obtain a short carbon fiber layer.

[0074] A2. Under an argon atmosphere, boron nitride, silicon powder, and graphite in a molar ratio of 1:2:3 were mixed by high-energy ball milling to obtain amorphous MASiBCN powder. The main disk speed of the ball mill was 400 rpm, the planetary disk speed was 800 rpm, the mixing time was 40 h, and the ball mill was paused for 10 min every 50 min. After the ball milling, the powder was collected in an argon-filled glove box. The ball-to-material mass ratio was 20:1.

[0075] A3. Add 4.51 g of amorphous MASiBCN powder to 1.66 g of anhydrous ethanol, then add 2.05 g of phenolic resin to 2.03 g of anhydrous ethanol, stir magnetically, and then mix the two by ultrasonic dispersion to obtain a MASiBCN slurry;

[0076] A4. Uniformly apply a layer of MASiBCN slurry on the surface of a short carbon fiber layer, stack another short carbon fiber layer, and repeat the above steps to obtain a short carbon fiber-MASiBCN slurry layered structure system, wherein the short carbon fiber-MASiBCN slurry layered structure system comprises 40 short carbon fiber layers;

[0077] A5. The short carbon fiber-MASiBCN slurry layered structure system was placed in an oven and dried at 50° C. for 12 h, and then heated at 100° C. for 30 min and at 150° C. for 60 min to solidify the short carbon fiber-MASiBCN slurry layered structure system to obtain a layered short carbon fiber-MA SiBCN blank;

[0078] A6. Finally, the layered short carbon fiber-SiBCN blank was heated to 1100℃ at a heating rate of 2℃ / min for 4h under high-purity nitrogen, cooled to 600℃ at a heating rate of 3℃ / min, and then cooled to room temperature in the furnace to obtain porous C sf / MA SiBCN composite materials.

[0079] Experimental example

[0080] It should be noted that Figure 2-5 In the example, “PIP-5” corresponds to Example 1, “PIP-0” corresponds to Example 2, “PIP-1” corresponds to Example 2, “PIP-2” corresponds to Example 3, “PIP-3” corresponds to Example 4, and “PIP-4” corresponds to Example 5.

[0081] The C prepared in Examples 1-5 and Comparative Examples sf / SiBCN composite materials were characterized by XRD. The results are shown in Figure 2 ,Depend on Figure 2 It can be seen that there is no crystallization peak in the XRD patterns of Examples 1-5 and the comparative example, indicating that after the impregnation-crosslinking-pyrolysis treatment, C sf / SiBCN composite materials are still amorphous.

[0082] The C prepared in Example 1 and the comparative example sf / SiBCN composite materials were subjected to thermogravimetric analysis in air atmosphere. The results are shown in Figure 3 and Figure 4 ,Depend on Figure 3 and Figure 4 It can be seen that the C obtained in the comparative example sf The maximum weight loss rate of the C / SiBCN composite material was significantly higher than that of the C / SiBCN composite material prepared in Example 1. sf / SiBCN composite materials, indicating that the C sf Oxidation resistance of WT / SiBCN composites.

[0083] C prepared in Example 1 and Comparative Example sf The macroscopic images of the SiBCN composite materials after oxidation at 1400℃, 1500℃ and 1600℃ for 5h are compared. Figure 5 ,from Figure 5 It can be seen that after the impregnation-crosslinking-pyrolysis treatment, C sf The main structure of / SiBCN remained intact after oxidation without obvious collapse. sf The density of the / SiBCN composite material is 1.69 g / cm 3After oxidation at 1400℃ for 5h, the weight loss per unit surface area is 0.09mg / mm 2 , which is less than the C prepared in the comparative example sf / SiBCN composite material unit surface area weight loss (0.11mg / mm 2 ); After oxidation at 1500℃ for 5h, the weight loss per unit surface area is 0.15mg / mm 2 , which is less than the C prepared in the comparative example sf / SiBCN composite material unit surface area weight loss (0.23mg / mm 2 ); After oxidation at 1400℃ for 5h, the weight loss per unit surface area is 0.14mg / mm 2 , which is less than the C prepared in the comparative example sf / SiBCN composite material unit surface area weight loss (0.33mg / mm 2 ). Figure 6 C prepared in Example 1 and Comparative Example sf SEM contrast images of the surface of the SiBCN / SiBCN composite material after oxidation at 1400℃ for 5h, where: Figure 6 (a) corresponding proportions, Figure 6 (b) Corresponding to Example 1, Figure 6 (a) It can be seen that the C prepared in the comparative example sf / SiBCN composite materials are severely oxidized, and large holes are formed on the surface. This is because the oxidation product of amorphous MA-SiBCN is mainly a single glass phase. Under the action of the gas generated during the oxidation process, the glass phase separates from the material surface and forms holes. Figure 6 (b) It can be seen that the C prepared in Example 1 sf The surface of the oxidized / SiBCN composite material is relatively dense and complete, and has good anti-oxidation performance. This is mainly due to the C prepared in Example 1. sf During the oxidation process of MA-SiBCN / SiBCN composite materials, the synergistic effect between the oxidation products (glass phase and cristobalite) of MA-SiBCN and PDCs-SiBCN formed a continuous and complete oxide layer, which played a certain protective role on the material.

[0084] In addition, it should be noted that, although the present invention is disclosed as above, the scope of protection of the present invention is not limited thereto. Those skilled in the art may make various changes and modifications without departing from the spirit and scope of the present invention, and these changes and modifications will fall within the scope of protection of the present invention.

Claims

1. An antioxidant C sf A method for preparing a / SiBCN composite material, characterized in that: include: Step S1, uniformly mixing amorphous MA SiBCN powder, phenolic resin and organic solvent to obtain MA SiBCN slurry, wherein the amorphous MA SiBCN powder is obtained by mechanical alloying; Step S2, using the MA SiBCN slurry and short carbon fibers to prepare a short carbon fiber-MA SiBCN slurry layered structure system; wherein the short carbon fiber-MA SiBCN slurry layered structure system comprises a plurality of short carbon fiber layers and a plurality of MA SiBCN slurry layers, and the short carbon fiber layers and the MA SiBCN slurry layers are alternately arranged; Step S3, curing the short carbon fiber-MA SiBCN slurry layered structure system to obtain a layered short carbon fiber-MA SiBCN blank; Step S4: in an inert gas atmosphere, pyrolyze the layered short carbon fiber-MA SiBCN blank and cool it to room temperature to obtain a porous C sf / MASiBCN composites; Step S5: sf / MA SiBCN composite material is subjected to at least one impregnation-crosslinking-pyrolysis treatment to obtain an antioxidant C sf / SiBCN composite material; wherein the impregnation-crosslinking-pyrolysis treatment comprises: sf After the MA SiBCN composite material is immersed in a polyborosilazane impregnation solution, a cross-linking reaction and a high-temperature cracking reaction are sequentially performed under an inert gas protective atmosphere.

2. The antioxidant C according to claim 1 sf A method for preparing a / SiBCN composite material, characterized in that: In step S5, the polyborosilazane impregnation solution is obtained by mixing polyborosilazane and dicumyl peroxide.

3. The antioxidant C according to claim 2 sf A method for preparing a / SiBCN composite material, characterized in that: The mass ratio of the polyborosilazane to the dicumyl peroxide in the polyborosilazane impregnation solution is 100:1-5, and the impregnation treatment time is 30-120 minutes.

4. The antioxidant C according to claim 1 sf A method for preparing a / SiBCN composite material, characterized in that: In step S5, the cross-linking reaction is carried out at a temperature of 120-180° C. and for a time of 2-4 hours.

5. The antioxidant C according to claim 1 sf A method for preparing a / SiBCN composite material, characterized in that: In step S5, the temperature of the high-temperature cracking reaction is 900-1100° C., and the time is 2-6 hours.

6. The antioxidant C according to claim 1 sf A method for preparing a / SiBCN composite material, characterized in that: In step S1, the amorphous MA SiBCN powder is mixed by high-energy ball milling of boron nitride, silicon powder and graphite. The molar ratio of the boron nitride, the silicon powder and the graphite in the amorphous MA SiBCN powder is 1:(1.5-2.5):(2.5-3.5). During the high-energy ball milling process, the mass ratio of the grinding balls to the powder is (10-30):

1. The main disk speed of the ball mill is 300-450 rpm, the planetary disk speed is 600-850 rpm, and the high-energy ball milling time is 20-60 h.

7. The antioxidant C according to claim 1 sf A method for preparing a / SiBCN composite material, characterized in that: In step S2, the method of using the MASiBCN slurry and short carbon fibers to prepare a short carbon fiber-MA SiBCN slurry layered structure system comprises: A MA SiBCN slurry layer is coated on the surface of the short carbon fiber layer one, a short carbon fiber layer two is stacked on the MA SiBCN slurry layer, and a MA SiBCN slurry layer is coated on the surface of the short carbon fiber layer two. The above steps are repeated to obtain the short carbon fiber-MASiBCN slurry layered structure system, wherein the short carbon fiber layer one and the short carbon fiber layer two are both prepared using the short carbon fiber.

8. The antioxidant C according to claim 1 sf A method for preparing a / SiBCN composite material, characterized in that: In step S2, the short carbon fiber-MA SiBCN slurry layered structure system comprises 30-50 short carbon fiber layers.

9. The antioxidant C according to claim 1 sf A method for preparing a / SiBCN composite material, characterized in that: In step S4, the temperature of the pyrolysis reaction is 900-1100°C. 10.An antioxidant C sf / SiBCN composite material, characterized in that Using the antioxidant C as described in any one of claims 1-9 sf / SiBCN composite material is prepared by a preparation method.

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