Medium-high temperature gradient antioxidant C / C-SiC-SiB6atAl2O3 / MoSi2atY2O3 composite material and preparation method thereof

Abstract

The invention discloses a medium-high temperature gradient anti-oxidation C / C-SiC-SiB6 coated Al2O3 / MoSi2 coated Y2O3 composite material and a preparation method thereof, the preparation method comprises the following steps: cutting, polishing, cleaning and drying the C / C composite material, and embedding to obtain a C / C-SiC composite material; the preparation method comprises the following steps: respectively preparing MoSi2 (at) Y2O3 core-shell powder and SiB6 (at) Al2O3 core-shell powder, and coating SiB6 (at) Al2O3 / MoSi2 (at) Y2O3 on the surface of C / C-SiC by adopting a hot dipping method to obtain a C / C-SiC-SiB6 (at) Al2O3 / MoSi2 (at) Y2O3 composite material; shell materials (Al2O3 and Y2O3) of the core-shell microcapsules and oxidation products of the core materials can generate mullite whiskers and yttrium silicate whiskers in situ at high temperature, directional healing can be achieved, defects in the coating can be healed and blocked, a large amount of oxygen is prevented from entering the coating, and therefore in-situ self-toughening of crack parts is achieved; wide-temperature-range long-acting anti-oxidation protection of the carbon / carbon composite material in a medium-high temperature environment is realized; the weight loss rate is only 1.01% after the catalyst is oxidized in air at 1300 DEG C for 500 hours.

Description

Technical Field

[0001] The present invention belongs to the technical field of functional materials and relates to an antioxidant C / C composite material, and specifically relates to a medium- and high-temperature gradient antioxidant C / C-SiC-SiB6@Al2O3 / MoSi2@Y2O3 composite material and a preparation method thereof. Background Art

[0002] Carbon / carbon composites, which are composites reinforced with graphite or carbon fibers in a carbon matrix, are a new type of composite material with unique properties and functions. They possess numerous excellent physical and chemical properties, such as low density and low mass. They exhibit excellent ablation resistance, high strength, and high modulus at high temperatures. Especially at ultra-high temperatures, the mechanical properties of carbon / carbon composites not only do not decrease but actually strengthen with increasing temperature, enabling them to serve long-term in demanding environments such as aerospace and advanced weaponry.

[0003] Unfortunately, when carbon / carbon composites are exposed to air at temperatures exceeding 643K, they begin to oxidize with oxygen in the air. As the temperature continues to rise above 773K, the oxidation becomes increasingly severe. This results in a sharp decrease in the physical and chemical properties of carbon / carbon composites, greatly limiting their application in high-temperature, aerobic environments. Summary of the Invention

[0004] In view of the shortcomings of the existing technology, the purpose of the present invention is to provide a medium- and high-temperature gradient antioxidant C / C-SiC-SiB6@Al2O3 / MoSi2@Y2O3 composite material and a preparation method thereof. By preparing a uniform and dense SiB6@Al2O3 / MoSi2@Y2O3 antioxidant coating on the surface of the C / C-SiC composite material, long-term antioxidant effect can be achieved in a high-temperature environment.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] A method for preparing a medium- and high-temperature gradient antioxidant C / C-SiC-SiB6@Al2O3 / MoSi2@Y2O3 composite material comprises the following steps:

[0007] Step 1: After cutting, grinding, cleaning and drying the C / C composite material, evenly embed it in a graphite crucible filled with embedding powder and keep it in an argon atmosphere at 1600-2500°C for 2-8 hours for primary embedding. After completion, a secondary embedding is performed according to the same process to obtain a C / C-SiC composite material;

[0008] Step 2: Prepare MoSi2@Y2O3 core-shell powder and SiB6@Al2O3 core-shell powder respectively, and mix the two powders to obtain mixed powder A with a mass proportion of MoSi2@Y2O3 of 40-80%, mixed powder B with a mass proportion of MoSi2@Y2O3 of 60-90%, and mixed powder C with a mass proportion of MoSi2@Y2O3 of 70-95%;

[0009] Step 3: Measure three groups of 10 ml of 30% silica sol and 30 ml of ultrapure water, stir to mix them evenly, add 5 g of mixed powder A, powder B and powder C respectively, and stir until the powders are evenly dispersed to obtain suspension A, suspension B and suspension C respectively;

[0010] Step 4: Preheat the C / C-SiC composite material sample to 60-70°C, then soak it in suspension A for 10-20 seconds; remove it and perform ultrasonic cleaning for 10-20 seconds, then place the cleaned sample in an oven and dry it at 60-70°C for 1-2 minutes, repeating the above steps 30-60 times;

[0011] Step 5: Place the sample processed in step 4 into suspension B and process it according to the method in step 4;

[0012] Step 6: Place the sample treated in step 5 into suspension C and treat it according to the method of step 4 to obtain a C / C-SiC-SiB6@Al2O3 / MoSi2@Y2O3 composite material.

[0013] The present invention also has the following technical features:

[0014] Preferably, the embedding powder used in the primary embedding comprises silicon powder, carbon powder and aluminum oxide in a mass ratio of 5:(0.5-1.5):(0.5-1.5).

[0015] Preferably, the embedding powder used in the secondary embedding comprises silicon powder, carbon powder and boron trioxide in a mass ratio of 5:(0.5-1.5):(0.5-1.5).

[0016] Preferably, the preparation method of MoSi2@Y2O3 core-shell powder includes:

[0017] 1.092 g of MoSi2 was weighed and added to 50 ml of ultrapure water and magnetically stirred for 1 to 2 h to obtain a mixed solution A. Based on the molar ratio of MoSi2 to Y2O3 being 1:(0.5 to 1.5), yttrium nitrate hexahydrate was added to the mixed solution A and magnetically stirred for 3 h to form a mixed solution B.

[0018] The mixed solution B is then loaded into a hydrothermal reactor and transferred to a homogeneous reactor, where the parameters are set at 363 K and the temperature is maintained for 4 to 7 hours. After the reaction is completed, the product is filtered, washed, and dried. The product is then placed in an argon tube furnace, where the parameters are set at 1073 K and the temperature is maintained for 1 to 4 hours. After the heat treatment is completed, MoSi2@Y2O3 core-shell powder is obtained.

[0019] Preferably, the preparation method of SiB6@Al2O3 core-shell powder includes:

[0020] 2.0 g of SiB6 was added to a beaker, followed by 600 ml of ultrapure water, followed by ultrasonic treatment for 2 hours to allow the SiB6 to be fully dispersed in the water to form a suspension;

[0021] According to the molar ratio of SiB6 to Al2O3 of 1: (2 to 5), aluminum nitrate nonahydrate was added to the suspension and stirred thoroughly. Ammonia water was added to the beaker to adjust the pH of the suspension to 7 to 9. Stirring was continued for 12 hours. After filtration, washing, and drying, the suspension was placed in a muffle furnace and treated at 593K for 2 to 4 hours to obtain SiB6@Al2O3 core-shell powder.

[0022] The present invention also protects a medium-high temperature gradient antioxidant C / C-SiC-SiB6@Al2O3 / MoSi2@Y2O3 composite material prepared by the method as described above.

[0023] Compared with the prior art, the present invention has the following technical effects:

[0024] The present invention adopts a hot-dip method to prepare SiB6@Al2O3 and MoSi2@Y2O3 coatings on the surface of C / C-SiC composite materials. On the one hand, the SiB6@Al2O3 / MoSi2@Y2O3 coatings generate cracks under stress, and the core-shell microcapsules rupture and overflow the core material, which relieves thermal stress, improves interface matching, and greatly enhances the anti-oxidation effect of the coatings. On the other hand, the shell materials (Al2O3, Y2O3) of the core-shell microcapsules react with the oxidation products of the core material at high temperatures to generate mullite whiskers and yttrium silicate whiskers in situ, which can achieve directional healing, heal and seal defects in the coating, and prevent a large amount of oxygen from entering, thereby achieving in-situ self-toughening of the cracked parts and realizing long-term anti-oxidation protection of the carbon / carbon composite material over a wide temperature range under medium and high temperature environments. After oxidation in air at 1300°C for 500 hours, the weight loss rate is only 1.01%.

[0025] The SiB6@Al2O3 and MoSi2@Y2O3 powders prepared by the sol-gel method in the present invention realize a capsule structure, so that they can be broken by the action of stress at high temperature, releasing the internal substances to achieve the desired purpose;

[0026] The present invention adopts the hot dipping method to synthesize the anti-oxidation coating of the C / C composite material, which has low cost and relatively simple process, does not require complicated equipment, and the dipping and drying processes are easy to operate and highly efficient, and can achieve economic benefits in large-scale production. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 The XRD pattern of the surface of the SiB6@Al2O3 / MoSi2@Y2O3 gradient coating prepared by the hot-dip method in Example 1;

[0028] Figure 2 This is the SEM image of the surface of the SiB6@Al2O3 / MoSi2@Y2O3 gradient coating prepared by the hot-dip method in Example 1;

[0029] Figure 3 This is the oxidation mass loss curve of the C / C-SiC-SiB6@Al2O3 / MoSi2@Y2O3 gradient coating sample prepared in Example 1 under air atmosphere at 1573K. DETAILED DESCRIPTION

[0030] The specific contents of the present invention are further explained in detail below with reference to the embodiments.

[0031] Example 1

[0032] This embodiment provides a method for preparing a medium- and high-temperature gradient antioxidant C / C-SiC-SiB6@Al2O3 / MoSi2@Y2O3 composite material, comprising the following steps:

[0033] Step 1: After cutting, grinding, cleaning and drying the C / C composite material, it is evenly embedded in a graphite crucible filled with embedding powder and kept in an argon atmosphere at 1700°C for 5 hours for primary embedding. After completion, a secondary embedding is performed according to the same process to obtain a C / C-SiC composite material;

[0034] The embedding powder used in the first embedding process includes silicon powder, carbon powder and aluminum oxide in a mass ratio of 5:1:1;

[0035] The embedding powder used in the secondary embedding includes silicon powder, carbon powder and boron trioxide in a mass ratio of 5:1:1;

[0036] Step 2: Prepare MoSi2@Y2O3 core-shell powder and SiB6@Al2O3 core-shell powder respectively, and mix the two powders to obtain mixed powder A with a mass proportion of MoSi2@Y2O3 of 60%, mixed powder B with a mass proportion of MoSi2@Y2O3 of 80%, and mixed powder C with a mass proportion of MoSi2@Y2O3 of 90%;

[0037] The preparation method of MoSi2@Y2O3 core-shell powder includes:

[0038] 1.092 g of MoSi2 was weighed and added to 50 ml of ultrapure water and magnetically stirred for 2 h to obtain a mixture A. Based on the molar ratio of MoSi2 to Y2O3 being 1:1, yttrium nitrate hexahydrate was added to the mixture A and magnetically stirred for 3 h to form a mixture B.

[0039] The mixed solution B was then loaded into a hydrothermal reactor and transferred to a homogeneous reactor with the parameters set at 363K for 7 hours. After the reaction was completed, the product was filtered, washed and dried. The product was then placed in an argon tube furnace with the parameters set at 1073K for 4 hours. After the heat treatment was completed, MoSi2@Y2O3 core-shell powder was obtained.

[0040] The preparation method of SiB6@Al2O3 core-shell powder includes:

[0041] 2.0 g of SiB6 was added to a beaker, followed by 600 ml of ultrapure water, followed by ultrasonic treatment for 2 hours to allow the SiB6 to be fully dispersed in the water to form a suspension;

[0042] According to the molar ratio of SiB6 to Al2O3 of 1:3, aluminum nitrate nonahydrate was added to the suspension and stirred thoroughly. Ammonia water was added to the beaker to adjust the pH of the suspension to 7. Stirring was continued for 12 hours. After filtration, washing, and drying, the suspension was placed in a muffle furnace and treated at 593K for 4 hours to obtain SiB6@Al2O3 core-shell powder.

[0043] Step 3: Measure three groups of 10 ml of 30% silica sol and 30 ml of ultrapure water, stir magnetically for 2 hours to mix them evenly, add 5 g of mixed powder A, powder B and powder C respectively, and stir until the powders are evenly dispersed to obtain suspension A, suspension B and suspension C respectively;

[0044] Step 4: Preheat the C / C-SiC composite material sample to 70°C, then soak it in suspension A for 15 seconds; remove it and perform ultrasonic cleaning for 15 seconds, then place the cleaned sample in an oven and dry it at 60°C for 2 minutes. Repeat the above steps 40 times;

[0045] Step 5: Place the sample processed in step 4 into suspension B and process it according to the method in step 4;

[0046] Step 6: Place the sample treated in step 5 into suspension C and treat it according to the method of step 4 to obtain a C / C-SiC-SiB6@Al2O3 / MoSi2@Y2O3 composite material.

[0047] The samples were placed in a silicon carbon rod high temperature furnace and subjected to thermal shock resistance tests at 1300°C and 1400°C respectively;

[0048] Figure 1 The XRD pattern of the surface of the SiB6@Al2O3 / MoSi2@Y2O3 gradient coating prepared by the hot-dip method in Example 1; Figure 1 It can be seen that the diffraction peaks of Y2O3 phase and MoSi2 appear between 20° and 75°, and the peaks are sharp, indicating that the obtained product contains only Y2O3 phase and MoSi2 phase with good crystallinity, and the raw materials are not destroyed or reacted during the core-shell preparation process.

[0049] Figure 2 The SEM image of the surface of the SiB6@Al2O3 / MoSi2@Y2O3 gradient coating prepared by the hot-dip method in Example 1; Figure 2 It can be seen that a uniform SiB6@Al2O3 / MoSi2@Y2O3 gradient coating was prepared on the surface of the C / C-SiC sample, and the surface flatness was good.

[0050] Figure 3 The oxidation mass loss curve of the C / C-SiC-SiB6@Al2O3 / MoSi2@Y2O3 gradient coating sample prepared in Example 1 under air atmosphere at 1573K is shown in Figure 2. Figure 3 It can be seen that the prepared coating sample can protect the carbon / carbon matrix at 1573K for 460h and still maintain a low weight loss rate, with a weight loss per unit area of ​​3.25×10 -3 g·cm -2 The corresponding oxidation weight loss rate is 0.70×10 -5 g·cm -2 ·h -1 The final weight loss rate after 500h of oxidation was 1.01%.

[0051] Example 2

[0052] This embodiment provides a method for preparing a medium- and high-temperature gradient antioxidant C / C-SiC-SiB6@Al2O3 / MoSi2@Y2O3 composite material, comprising the following steps:

[0053] Step 1: After cutting, grinding, cleaning and drying the C / C composite material, it is evenly embedded in a graphite crucible filled with embedding powder and kept in an argon atmosphere at 2000°C for 6 hours for primary embedding. After completion, a secondary embedding is performed according to the same process to obtain a C / C-SiC composite material;

[0054] The embedding powder used in the first embedding process includes silicon powder, carbon powder and aluminum oxide in a mass ratio of 5:0.5:0.5;

[0055] The embedding powder used in the secondary embedding includes silicon powder, carbon powder and boron trioxide in a mass ratio of 5:0.5:0.5;

[0056] Step 2: Prepare MoSi2@Y2O3 core-shell powder and SiB6@Al2O3 core-shell powder respectively, and mix the two powders to obtain mixed powder A with a mass proportion of MoSi2@Y2O3 of 50%, mixed powder B with a mass proportion of MoSi2@Y2O3 of 70%, and mixed powder C with a mass proportion of MoSi2@Y2O3 of 80%;

[0057] The preparation method of MoSi2@Y2O3 core-shell powder includes:

[0058] 1.092 g of MoSi2 was weighed and added to 50 ml of ultrapure water and magnetically stirred for 1 h to obtain a mixed solution A. Based on the molar ratio of MoSi2 to Y2O3 being 1:0.5, yttrium nitrate hexahydrate was added to the mixed solution A and magnetically stirred for 3 h to form a mixed solution B.

[0059] The mixed solution B was then loaded into a hydrothermal reactor and transferred to a homogeneous reactor, with the parameters set at 363K and kept warm for 6 hours. After the reaction was completed, the product was filtered, washed and dried. The product was then placed in an argon tube furnace, with the parameters set at 1073K and kept warm for 4 hours. After the heat treatment was completed, MoSi2@Y2O3 core-shell powder was obtained.

[0060] The preparation method of SiB6@Al2O3 core-shell powder includes:

[0061] 2.0 g of SiB6 was added to a beaker, followed by 600 ml of ultrapure water, followed by ultrasonic treatment for 2 hours to allow the SiB6 to be fully dispersed in the water to form a suspension;

[0062] According to the molar ratio of SiB6 to Al2O3 of 1:2, aluminum nitrate nonahydrate was added to the suspension and stirred thoroughly. Ammonia water was added to the beaker to adjust the pH of the suspension to 8. Stirring was continued for 12 hours. After filtration, washing, and drying, the suspension was placed in a muffle furnace and treated at 593K for 4 hours to obtain SiB6@Al2O3 core-shell powder.

[0063] Step 3: Measure three groups of 10 ml of 30% silica sol and 30 ml of ultrapure water, stir to mix them evenly, add 5 g of mixed powder A, powder B and powder C respectively, and stir until the powders are evenly dispersed to obtain suspension A, suspension B and suspension C respectively;

[0064] Step 4: Preheat the C / C-SiC composite material sample to 60°C, then soak it in suspension A for 10 seconds; remove it and perform ultrasonic cleaning for 10 seconds, then place the cleaned sample in an oven and dry it at 60°C for 1 minute. Repeat the above steps 30 times;

[0065] Step 5: Place the sample processed in step 4 into suspension B and process it according to the method in step 4;

[0066] Step 6: Place the sample treated in step 5 into suspension C and treat it according to the method of step 4 to obtain a C / C-SiC-SiB6@Al2O3 / MoSi2@Y2O3 composite material.

[0067] Example 3

[0068] This embodiment provides a method for preparing a medium- and high-temperature gradient antioxidant C / C-SiC-SiB6@Al2O3 / MoSi2@Y2O3 composite material, comprising the following steps:

[0069] Step 1: After cutting, grinding, cleaning and drying the C / C composite material, it is evenly embedded in a graphite crucible filled with embedding powder and kept in an argon atmosphere at 1600°C for 8 hours for primary embedding. After completion, a secondary embedding is performed according to the same process to obtain a C / C-SiC composite material;

[0070] The embedding powder used in the first embedding process includes silicon powder, carbon powder and aluminum oxide in a mass ratio of 5:1.5:1.5;

[0071] The embedding powder used in the secondary embedding includes silicon powder, carbon powder and boron trioxide in a mass ratio of 5:1.5:1.5;

[0072] Step 2: Prepare MoSi2@Y2O3 core-shell powder and SiB6@Al2O3 core-shell powder respectively, and mix the above two powders to obtain mixed powder A with a mass proportion of MoSi2@Y2O3 of 80%, mixed powder B with a mass proportion of MoSi2@Y2O3 of 90%, and mixed powder C with a mass proportion of MoSi2@Y2O3 of 95%;

[0073] The preparation method of MoSi2@Y2O3 core-shell powder includes:

[0074] 1.092 g of MoSi2 was weighed and added to 50 ml of ultrapure water and magnetically stirred for 1.5 h to obtain a mixed solution A. Based on the molar ratio of MoSi2 to Y2O3 being 1:1.5, yttrium nitrate hexahydrate was added to the mixed solution A and magnetically stirred for 3 h to form a mixed solution B.

[0075] The mixed solution B was then loaded into a hydrothermal reactor and transferred to a homogeneous reactor with the parameters set at 363K for 4 hours. After the reaction was completed, the product was filtered, washed and dried. The product was then placed in an argon tube furnace with the parameters set at 1073K for 1 hour. After the heat treatment was completed, MoSi2@Y2O3 core-shell powder was obtained.

[0076] The preparation method of SiB6@Al2O3 core-shell powder includes:

[0077] 2.0 g of SiB6 was added to a beaker, followed by 600 ml of ultrapure water, followed by ultrasonic treatment for 2 hours to allow the SiB6 to be fully dispersed in the water to form a suspension;

[0078] According to the molar ratio of SiB6 to Al2O3 of 1:2, aluminum nitrate nonahydrate was added to the suspension and stirred thoroughly. Ammonia water was added to the beaker to adjust the pH of the suspension to 9. Stirring was continued for 12 hours. After filtration, washing, and drying, the suspension was placed in a muffle furnace and treated at 593K for 2 hours to obtain SiB6@Al2O3 core-shell powder.

[0079] Step 3: Measure three groups of 10 ml of 30% silica sol and 30 ml of ultrapure water, stir to mix them evenly, add 5 g of mixed powder A, powder B and powder C respectively, and stir until the powders are evenly dispersed to obtain suspension A, suspension B and suspension C respectively;

[0080] Step 4: Preheat the C / C-SiC composite material sample to 70°C, then soak it in suspension A for 20 seconds; remove it and perform ultrasonic cleaning for 20 seconds, then place the cleaned sample in an oven and dry it at 70°C for 1 minute, repeating the above steps 50 times;

[0081] Step 5: Place the sample processed in step 4 into suspension B and process it according to the method in step 4;

[0082] Step 6: Place the sample treated in step 5 into suspension C and treat it according to the method of step 4 to obtain a C / C-SiC-SiB6@Al2O3 / MoSi2@Y2O3 composite material.

[0083] Example 4

[0084] This embodiment provides a method for preparing a medium- and high-temperature gradient antioxidant C / C-SiC-SiB6@Al2O3 / MoSi2@Y2O3 composite material, comprising the following steps:

[0085] Step 1: After cutting, grinding, cleaning and drying the C / C composite material, it is evenly embedded in a graphite crucible filled with embedding powder and kept in an argon atmosphere at 2500°C for 2 hours for primary embedding. After completion, a secondary embedding is performed according to the same process to obtain a C / C-SiC composite material;

[0086] The embedding powder used in the first embedding process includes silicon powder, carbon powder and aluminum oxide in a mass ratio of 5:1:1.5;

[0087] The embedding powder used in the secondary embedding includes silicon powder, carbon powder and boron trioxide in a mass ratio of 5:1:1.5;

[0088] Step 2: Prepare MoSi2@Y2O3 core-shell powder and SiB6@Al2O3 core-shell powder respectively, and mix the two powders to obtain mixed powder A with a mass proportion of MoSi2@Y2O3 of 40%, mixed powder B with a mass proportion of MoSi2@Y2O3 of 60%, and mixed powder C with a mass proportion of MoSi2@Y2O3 of 70%;

[0089] The preparation method of MoSi2@Y2O3 core-shell powder includes:

[0090] 1.092 g of MoSi2 was weighed and added to 50 ml of ultrapure water and magnetically stirred for 1 h to obtain a mixed solution A. Based on the molar ratio of MoSi2 to Y2O3 being 1:1.2, yttrium nitrate hexahydrate was added to the mixed solution A and magnetically stirred for 3 h to form a mixed solution B.

[0091] The mixed solution B was then loaded into a hydrothermal reactor and transferred to a homogeneous reactor with the parameters set at 363K for 4 hours. After the reaction was completed, the product was filtered, washed and dried. The product was then placed in an argon tube furnace with the parameters set at 1073K for 3 hours. After the heat treatment was completed, MoSi2@Y2O3 core-shell powder was obtained.

[0092] The preparation method of SiB6@Al2O3 core-shell powder includes:

[0093] 2.0 g of SiB6 was added to a beaker, followed by 600 ml of ultrapure water, followed by ultrasonic treatment for 2 hours to allow the SiB6 to be fully dispersed in the water to form a suspension;

[0094] According to the molar ratio of SiB6 to Al2O3 of 1:5, aluminum nitrate nonahydrate was added to the suspension and stirred thoroughly. Ammonia water was added to the beaker to adjust the pH of the suspension to 9. Stirring was continued for 12 hours. After filtration, washing, and drying, the suspension was placed in a muffle furnace and treated at 593K for 3 hours to obtain SiB6@Al2O3 core-shell powder.

[0095] Step 3: Measure three groups of 10 ml of 30% silica sol and 30 ml of ultrapure water, stir to mix them evenly, add 5 g of mixed powder A, powder B and powder C respectively, and stir until the powders are evenly dispersed to obtain suspension A, suspension B and suspension C respectively;

[0096] Step 4: Preheat the C / C-SiC composite material sample to 65°C, then soak it in suspension A for 20 seconds; remove it and perform ultrasonic cleaning for 20 seconds, then place the cleaned sample in an oven and dry it at 65°C for 1.5 minutes, repeating the above steps 60 times;

[0097] Step 5: Place the sample processed in step 4 into suspension B and process it according to the method in step 4;

[0098] Step 6: Place the sample treated in step 5 into suspension C and treat it according to the method of step 4 to obtain a C / C-SiC-SiB6@Al2O3 / MoSi2@Y2O3 composite material.

[0099] Other implementation examples are not listed here. Without departing from the concept of the present invention, deductions or replacements made by those skilled in the art shall fall within the protection scope of the present invention.

Claims

1. A method for preparing a medium- and high-temperature gradient antioxidant C / C-SiC-SiB6@Al2O3 / MoSi2@Y2O3 composite material, characterized in that: The following steps are involved: Step 1: After cutting, grinding, cleaning and drying the C / C composite material, evenly embed it in a graphite crucible filled with embedding powder and keep it in an argon atmosphere at 1600-2500°C for 2-8 hours for primary embedding. After completion, a secondary embedding is performed according to the same process to obtain a C / C-SiC composite material; Step 2: Prepare MoSi2@Y2O3 core-shell powder and SiB6@Al2O3 core-shell powder respectively, and mix the two powders to obtain mixed powder A with a mass proportion of MoSi2@Y2O3 of 40-80%, mixed powder B with a mass proportion of MoSi2@Y2O3 of 60-90%, and mixed powder C with a mass proportion of MoSi2@Y2O3 of 70-95%; Step 3: Measure three groups of 10 ml of 30% silica sol and 30 ml of ultrapure water, stir to mix them evenly, add 5 g of mixed powder A, powder B and powder C respectively, and stir until the powders are evenly dispersed to obtain suspension A, suspension B and suspension C respectively; Step 4: Preheat the C / C-SiC composite material sample to 60-70°C, then soak it in suspension A for 10-20 seconds; remove it and perform ultrasonic cleaning for 10-20 seconds, then place the cleaned sample in an oven and dry it at 60-70°C for 1-2 minutes, repeating the above steps 30-60 times; Step 5: Place the sample processed in step 4 into suspension B and process it according to the method in step 4; Step 6: Place the sample treated in step 5 into suspension C and treat it according to the method of step 4 to obtain a C / C-SiC-SiB6@Al2O3 / MoSi2@Y2O3 composite material.

2. The method for preparing the medium-high temperature gradient antioxidant C / C-SiC-SiB6@Al2O3 / MoSi2@Y2O3 composite material according to claim 1, characterized in that: The embedding powder used in the primary embedding comprises silicon powder, carbon powder and aluminum oxide in a mass ratio of 5: (0.5-1.5): (0.5-1.5).

3. The method for preparing the medium-high temperature gradient antioxidant C / C-SiC-SiB6@Al2O3 / MoSi2@Y2O3 composite material according to claim 1, characterized in that: The embedding powder used in the secondary embedding comprises silicon powder, carbon powder and boron trioxide in a mass ratio of 5: (0.5-1.5): (0.5-1.5).

4. The method for preparing the medium- and high-temperature gradient antioxidant C / C-SiC-SiB6@Al2O3 / MoSi2@Y2O3 composite material according to claim 1, characterized in that: The preparation method of MoSi2@Y2O3 core-shell powder includes: 1.092 g of MoSi2 was weighed and added to 50 ml of ultrapure water and magnetically stirred for 1 to 2 h to obtain a mixed solution A. Based on the molar ratio of MoSi2 to Y2O3 being 1:(0.5 to 1.5), yttrium nitrate hexahydrate was added to the mixed solution A and magnetically stirred for 3 h to form a mixed solution B. The mixed solution B is then loaded into a hydrothermal reactor and transferred to a homogeneous reactor, where the parameters are set at 363 K and the temperature is maintained for 4 to 7 hours. After the reaction is completed, the product is filtered, washed, and dried. The product is then placed in an argon tube furnace, where the parameters are set at 1073 K and the temperature is maintained for 1 to 4 hours. After the heat treatment is completed, MoSi2@Y2O3 core-shell powder is obtained.

5. The method for preparing the medium-high temperature gradient antioxidant C / C-SiC-SiB6@Al2O3 / MoSi2@Y2O3 composite material according to claim 1, characterized in that: The preparation method of SiB6@Al2O3 core-shell powder includes: 2.0 g of SiB6 was added to a beaker, followed by 600 ml of ultrapure water, followed by ultrasonic treatment for 2 hours to allow the SiB6 to be fully dispersed in the water to form a suspension; According to the molar ratio of SiB6 to Al2O3 of 1: (2 to 5), aluminum nitrate nonahydrate was added to the suspension and stirred thoroughly. Ammonia water was added to the beaker to adjust the pH of the suspension to 7 to 9. Stirring was continued for 12 hours. After filtration, washing, and drying, the suspension was placed in a muffle furnace and treated at 593K for 2 to 4 hours to obtain SiB6@Al2O3 core-shell powder.

6. A medium-high temperature gradient antioxidant C / C-SiC-SiB6@Al2O3 / MoSi2@Y2O3 composite material prepared by the method according to any one of claims 1 to 5.

Images