A rapidly densified ceramic matrix composite slurry, its preparation method and application

Abstract

This invention discloses a rapid densification slurry for ceramic matrix composites, its preparation method, and its application, belonging to the field of composite material preparation technology. The slurry comprises slurry powder and a slurry solvent; the slurry powder comprises the following components by weight: 25-35 parts polycarbosilane, 10-15 parts SiC whiskers, 40-50 parts SiC ceramic powder, 0.5-3 parts calcium fluoride, 0.5-2 parts lanthanum oxide, and 10-25 parts boron-containing powder; the slurry solvent comprises the following components by weight: 60-70 parts ethanol, 20-25 parts polyurethane binder, 1-10 parts dispersant, and 1-10 parts thickener. This invention, by coating and penetrating the slurry into the interior of the raw ceramic matrix composite, can achieve rapid densification of the ceramic matrix composite, reduce the porosity inside the ceramic matrix composite, accelerate the preparation of the ceramic matrix composite, and improve the toughness and fracture resistance of the obtained ceramic matrix composite.

Description

Technical Field

[0001] This invention relates to the field of composite material preparation technology, specifically to a rapid densification ceramic matrix composite material slurry, its preparation method, and its application. Background Technology

[0002] Ceramic matrix composites, due to their excellent high-temperature mechanical properties, low density, corrosion resistance, and thermal shock resistance, have broad application prospects in aerospace, energy engineering, defense industry, and high-end manufacturing. While traditional bulk ceramic materials possess excellent high-temperature stability and wear resistance, they generally suffer from high brittleness and poor thermal shock resistance, limiting their application in engineering structural components that need to withstand complex loads or thermal stresses. To overcome this limitation, researchers have proposed introducing fiber-reinforcing phases into the ceramic matrix to significantly improve the toughness and fracture resistance of ceramic materials. This fiber-reinforced ceramic matrix composite greatly expands the application boundaries of ceramics.

[0003] However, traditional ceramic matrix composite (CMC) preparation technologies (such as PIP, CVI, and MI) suffer from drawbacks such as long preparation cycles and poor material density improvement, resulting in low efficiency in CMC preparation and severely hindering the improvement of CMC engineering applications. Taking the PIP preparation method as an example, its core steps include ceramic precursor infiltration, curing, and pyrolysis. This typically requires multiple iterations to achieve the desired density and strength, with each cycle taking a considerable amount of time (several days or even more than ten days), making it difficult to meet the needs of large-scale industrial production. Furthermore, the polymer-ceramic precursor undergoes significant volume shrinkage (typically 30%-50%) during pyrolysis, leading to numerous microcracks or localized damage within the ceramic matrix. Frequent thermal shock to the fibers also causes performance degradation, further limiting the improvement of CMC performance. Summary of the Invention

[0004] To address the aforementioned technical problems, the present invention aims to provide a rapidly densified ceramic matrix composite slurry, its preparation method, and its application, thereby solving the problems of long preparation cycles, poor material density improvement effects, and low preparation efficiency of ceramic matrix composites caused by the long densification cycle required in existing ceramic matrix composite preparation technologies.

[0005] The technical solution of the present invention to solve the above-mentioned technical problems is as follows:

[0006] A slurry for rapidly densifying ceramic matrix composite materials includes slurry powder and slurry solvent;

[0007] The slurry powder comprises the following components in parts by weight:

[0008] 25-35 parts of polycarbosilane, 10-15 parts of SiC whiskers, 40-50 parts of SiC ceramic powder, 0.5-3 parts of calcium fluoride, 0.5-2 parts of lanthanum oxide, and 10-25 parts of boron-containing powder;

[0009] The slurry solvent comprises the following components in parts by weight:

[0010] 60-70 parts ethanol, 20-25 parts polyurethane adhesive, 1-10 parts dispersant and 1-10 parts thickener.

[0011] The beneficial effects of the present invention are as follows: The present invention provides a slurry for accelerating the densification of ceramic matrix composites. By coating and penetrating the slurry into the interior of the blank ceramic matrix composite, the ceramic matrix composite can be rapidly densified, the internal porosity of the ceramic matrix composite can be reduced, and the preparation of the ceramic matrix composite can be accelerated.

[0012] Furthermore, the powder composition includes the following components in parts by weight:

[0013] 25-30 parts of polycarbosilane, 12-15 parts of SiC whiskers, 42-47 parts of SiC ceramic powder, 1-3 parts of calcium fluoride, 1-2 parts of lanthanum oxide, and 12-20 parts of boron-containing powder;

[0014] The solvent comprises the following components in parts by weight:

[0015] Ethanol 63-67 parts, polyurethane binder 22-25 parts, dispersant 3-7 parts and thickener 3-7 parts.

[0016] Preferably, the powder component comprises the following components in parts by weight:

[0017] 25 parts polycarbosilane, 15 parts SiC whiskers, 45 parts SiC ceramic powder, 2 parts calcium fluoride, 1 part lanthanum oxide, and 15 parts boron-containing powder;

[0018] The solvent comprises the following components in parts by weight:

[0019] 65 parts ethanol, 25 parts polyurethane binder, 5 parts dispersant and 5 parts thickener.

[0020] Furthermore, the boron-containing powder is B4C or BN; the dispersant is PVP; and the thickener is silicon nitride or acrylate.

[0021] Furthermore, the mass ratio of slurry powder to slurry solvent in the ceramic matrix composite slurry is (1-3):1, and the viscosity is 500-1500 mPa·s.

[0022] Preferably, the mass ratio of slurry powder to slurry solvent in the ceramic matrix composite slurry is 2:1.

[0023] Furthermore, the SiC whiskers have a whisker length of 10-20 μm, a diameter of 0.1-0.2 μm, and an aspect ratio of 100:1-200:1.

[0024] Preferably, the SiC whiskers have a whisker length of 15 μm, a diameter of 0.1 μm, and an aspect ratio of 150:1.

[0025] Furthermore, SiC whiskers are modified through the following steps:

[0026] First, SiC whiskers are impregnated in hydrofluoric acid solution and nitric acid solution in sequence, then filtered and dried. Next, they are impregnated in silane coupling agent solution, filtered and dried, and then subjected to high-temperature heat treatment to complete the modification.

[0027] Further, the hydrofluoric acid solution has a mass concentration of 5-20%, the nitric acid solution has a mass concentration of 5-20%, the silane coupling agent solution has a concentration of 1-10 g / L, and the silane coupling agent is KH-550;

[0028] The immersion time in hydrofluoric acid solution is 20-40 min, the immersion time in nitric acid solution is 30-90 min, and the immersion time in silane coupling agent solution is 3-5 h.

[0029] The conditions for high-temperature heat treatment are as follows: first, heat the temperature to 500-700℃ at a heating rate of 3-7℃ / min, hold for 30-90min, then heat the temperature to 1400-1600℃ at a heating rate of 8-12℃ / min, hold for 2-4h, and finally cool naturally to room temperature.

[0030] The beneficial effects of adopting the above-mentioned further technical solutions are as follows: The present invention enhances the dispersibility and wettability of SiC whiskers in solution by modifying them with hydrofluoric acid and silane coupling agents, avoids agglomeration in solution and the formation of large particle clumps, and effectively ensures that the slurry can achieve rapid densification during the densification process of ceramic matrix composites.

[0031] Preferably, the hydrofluoric acid solution has a mass concentration of 10%, the nitric acid solution has a mass concentration of 10%, the silane coupling agent solution has a concentration of 5 g / L, and the silane coupling agent is KH-550;

[0032] The immersion treatment time in hydrofluoric acid solution is 30 min, the immersion treatment time in nitric acid solution is 60 min, and the immersion treatment time in silane coupling agent solution is 4 h.

[0033] The conditions for high-temperature heat treatment are as follows: first, heat to 600℃ at a heating rate of 5℃ / min, hold for 30-90 min, then heat to 1500℃ at a heating rate of 10℃ / min, hold for 3 h, and finally cool naturally to room temperature.

[0034] Furthermore, the particle size of the SiC ceramic powder is 0.1-1μm, and D50≈0.5μm.

[0035] The method for preparing the above-mentioned rapidly densified ceramic matrix composite slurry includes the following steps:

[0036] First, the slurry powder is mixed and ball-milled. Then, the ball-milled slurry powder is mixed evenly with the slurry solvent. Finally, it is degassed under vacuum to obtain the final product.

[0037] Furthermore, the ball milling speed is 200-400 rpm, and the time is 8-12 h; the vacuum degree of the vacuum degassing treatment is -0.08 to -0.1 MPa, and the time is 15-30 min.

[0038] The application of the above-mentioned rapid densification ceramic matrix composite slurry in ceramic densification processing.

[0039] A method for ceramic densification based on the above-mentioned rapid densification ceramic matrix composite slurry includes the following steps:

[0040] First, the above-mentioned rapidly densified ceramic matrix composite slurry is coated on the surface of the ceramic composite material and penetrates into the interior of the material. Then, it is dried and cured, and finally subjected to high-temperature sintering treatment.

[0041] Furthermore, the drying and curing temperature is 200-300℃, and the time is 20-30 hours;

[0042] The conditions for high-temperature sintering are as follows: first, heat the temperature to 100-300℃ at a heating rate of 1-3℃ / min, then heat it to 1000-1400℃ at a heating rate of 1-5℃ / min, hold it at that temperature for 1-3 hours, then heat it to 1500-1700℃ at a heating rate of 2-3℃ / min, hold it at that temperature for 1-3 hours, and finally cool it down naturally or at a cooling rate of 1-3℃ / min to room temperature.

[0043] The present invention has the following beneficial effects:

[0044] This invention provides a slurry for rapid densification of ceramic matrix composites and its preparation method. By coating and penetrating the slurry into the interior of the blank ceramic matrix composite, rapid densification of the ceramic matrix composite can be achieved, reducing the porosity inside the ceramic matrix composite and accelerating the preparation of the ceramic matrix composite. By introducing modified SiC whiskers, the rapid densification effect of the slurry in the processing of ceramic matrix composites is promoted on the one hand, and the toughness and fracture resistance of the obtained ceramic matrix composite are improved on the other hand. Attached Figure Description

[0045] Figure 1 The bar chart shows the density measurements of different samples in the test examples;

[0046] Figure 2 This is a bar chart showing the flexural strength measurements of different samples in the test examples. Detailed Implementation

[0047] The principles and features of the present invention are described below with reference to the accompanying drawings. The examples given are for illustrative purposes only and are not intended to limit the scope of the invention. Unless otherwise specified in the examples, conventional conditions or conditions recommended by the manufacturer should be followed. Reagents or instruments whose manufacturers are not specified are all commercially available products.

[0048] Example 1:

[0049] A method for preparing a rapidly densified ceramic matrix composite slurry includes the following steps:

[0050] (1) Raw material preparation

[0051] Weigh the following powder components by weight: 25 parts PCS, 15 parts SiC whiskers (aspect ratio of 150:1, length of 15μm, diameter of 0.1μm), 45 parts SiC ceramic powder (particle size of 0.1-1μm, D50≈0.5μm, purity ≥99%), 2 parts calcium fluoride (purity ≥99%), 1 part lanthanum oxide (purity ≥99%), and 15 parts B4C.

[0052] SiC whiskers are modified using the following methods:

[0053] First, take 5g of SiC whiskers and add them to 100mL of 10wt% HF solution. Sonicate for 30min, filter, and rinse with deionized water 4 times until the solution pH is 7.

[0054] Then, the SiC whiskers treated in the previous step were placed in 100 mL of 10 wt% HNO3 solution, stirred at 300 rpm for 1 h, filtered and rinsed 4 times, and dried in a vacuum drying oven at 80 ℃ for 6 h.

[0055] Next, the SiC whiskers treated in the previous step were added to a KH-500 ethanol solution with a concentration of 0.5 g / L, ultrasonically dispersed for 30 min, stirred at 50 °C for 4 h, filtered, rinsed three times with deionized water, and dried in a vacuum drying oven at 80 °C for 6 h.

[0056] Finally, the SiC whiskers processed in the previous step were subjected to high-temperature heat treatment in a vacuum furnace. The conditions for high-temperature heat treatment were as follows: under an atmosphere of argon flow rate of 300 mL / min, the temperature was first increased to 600℃ at a heating rate of 5℃ / min and held for 1 hour, then increased to 1600℃ at a heating rate of 10℃ / min and held for 4 hours, and finally cooled naturally to room temperature before the SiC whiskers were removed.

[0057] (2) Solvent preparation

[0058] Weigh the solvent components according to the following mass percentages: 65% ethanol, 25% polyurethane binder, 5% dispersant (PVP), and 5% silicon nitride.

[0059] (3) Slurry preparation

[0060] First, ethanol and PVP were mixed and stirred until the dispersant was completely dissolved. Then, the powder components, polyurethane binder, and silicon nitride were added, and the mixture was stirred in a ball mill at 300 rpm for 5 hours to ensure uniform powder dispersion and obtain a homogeneous, bubble-free slurry. The mass ratio of total slurry powder to total slurry solvent was 2:1. The viscosity of the slurry was tested using a rotational viscometer, and the obtained viscosity was 784 mPa·s.

[0061] (4) Degassing treatment

[0062] The slurry obtained in step (3) was placed in a vacuum degassing device, the vacuum degree was set to -0.08MPa, and the degassing time was 30min, to obtain a rapidly densified ceramic matrix composite slurry.

[0063] The method for densifying ceramic matrix composites based on the above-mentioned rapid densification ceramic matrix composite slurry includes the following steps:

[0064] (5) Matrix treatment

[0065] A density of 1.0 g / cm³ was selected. 3 The C / SiC blank material was ultrasonically cleaned and dried at 120℃ for 2 hours to remove moisture.

[0066] (6) Penetrating grout

[0067] Using a spraying process, the slurry obtained in step (4) is uniformly coated onto the surface of the C / SiC blank material to ensure uniform coverage of the material surface.

[0068] (7) Filtration densification

[0069] The coated blank material is placed in a vacuum filtration device with a negative pressure set to -0.05MPa for 10 minutes to allow the slurry to fully penetrate the material pores.

[0070] Repeat steps (6) to (7) three times for filtration, and then dry in a 100°C drying oven for 2 hours to remove residual solvent.

[0071] (8) Curing and sintering

[0072] The densified material was placed in an argon atmosphere furnace, the heating rate was set to 2℃ / min, and it was cured at 400℃ for 2h. Then the temperature was increased to 1600℃ and held for 3h. Finally, it was allowed to cool naturally to room temperature with the furnace to obtain the densified ceramic matrix composite material.

[0073] Example 2:

[0074] A method for preparing a rapidly densified ceramic matrix composite slurry includes the following steps:

[0075] (1) Raw material preparation

[0076] Weigh the following powder components by weight: 25 parts PCS, 15 parts SiC whiskers (aspect ratio of 200:1, length of 20μm, diameter of 0.1μm), 50 parts SiC ceramic powder (particle size of 0.1-1μm, D50≈0.5μm, purity ≥99%), 3 parts calcium fluoride (purity ≥99%), 1.5 parts lanthanum oxide (purity ≥99%), and 20 parts B4C.

[0077] SiC whiskers are modified using the following methods:

[0078] First, take 5g of SiC whiskers and add them to 100mL of 10wt% HF solution. Sonicate for 30min, filter, and rinse with deionized water 4 times until the solution pH is 7.

[0079] Then, the SiC whiskers treated in the previous step were placed in 100 mL of 10 wt% HNO3 solution, stirred at 300 rpm for 1 h, filtered and rinsed 4 times, and dried in a vacuum drying oven at 80 ℃ for 6 h.

[0080] Next, the SiC whiskers treated in the previous step were added to a KH-500 ethanol solution with a concentration of 0.5 g / L, ultrasonically dispersed for 30 min, stirred at 50 °C for 4 h, filtered, rinsed three times with deionized water, and dried in a vacuum drying oven at 80 °C for 6 h.

[0081] Finally, the SiC whiskers processed in the previous step were subjected to high-temperature heat treatment in a vacuum furnace. The conditions for high-temperature heat treatment were as follows: under an atmosphere of argon flow rate of 300 mL / min, the temperature was first increased to 600℃ at a heating rate of 5℃ / min and held for 1 hour, then increased to 1600℃ at a heating rate of 10℃ / min and held for 4 hours, and finally cooled naturally to room temperature before the SiC whiskers were removed.

[0082] (2) Solvent preparation

[0083] Weigh the solvent components according to the following mass percentages: 65% ethanol, 25% polyurethane binder, 5% dispersant (PVP), and 5% silicon nitride.

[0084] (3) Slurry preparation

[0085] First, ethanol and PVP were mixed and stirred until the dispersant was completely dissolved. Then, the powder components, polyurethane binder, and silicon nitride were added, and the mixture was stirred in a ball mill at 300 rpm for 5 hours to ensure uniform powder dispersion and obtain a uniform, bubble-free slurry. The viscosity of the slurry was tested using a rotational viscometer, and the obtained viscosity was 816 mPa·s.

[0086] (4) Degassing treatment

[0087] The slurry obtained in step (3) was placed in a vacuum degassing device, the vacuum degree was set to -0.08MPa, and the degassing time was 30min, to obtain a rapidly densified ceramic matrix composite slurry.

[0088] The method for densifying ceramic matrix composites based on the above-mentioned rapid densification ceramic matrix composite slurry includes the following steps:

[0089] (5) Matrix treatment

[0090] A density of 1.0 g / cm³ was selected. 3 The C / SiC blank material was ultrasonically cleaned and dried at 120℃ for 2 hours to remove moisture.

[0091] (6) Penetrating grout

[0092] Using a spraying process, the slurry obtained in step (4) is uniformly coated onto the surface of the C / SiC blank material to ensure uniform coverage of the material surface.

[0093] (7) Filtration densification

[0094] The coated blank material is placed in a vacuum filtration device with a negative pressure set to -0.05MPa for 10 minutes to allow the slurry to fully penetrate the material pores.

[0095] Repeat steps (6) to (7) three times for filtration, and then dry in a 100°C drying oven for 2 hours to remove residual solvent.

[0096] (8) Curing and sintering

[0097] The densified material was placed in an argon atmosphere furnace, the heating rate was set to 2℃ / min, and it was cured at 400℃ for 2h. Then the temperature was increased to 1600℃ and held for 3h. Finally, it was allowed to cool naturally to room temperature with the furnace to obtain the densified ceramic matrix composite material.

[0098] Example 3:

[0099] A method for preparing a rapidly densified ceramic matrix composite slurry includes the following steps:

[0100] (1) Raw material preparation

[0101] Weigh the following powder components by weight: 25 parts PCS, 12.5 parts SiC whiskers (aspect ratio of 200:1, length of 20μm, diameter of 0.1μm), 40 parts SiC ceramic powder (particle size of 0.1-1μm, D50≈0.5μm, purity ≥99%), 1 part calcium fluoride (purity ≥99%), 0.5 parts lanthanum oxide (purity ≥99%), and 10 parts B4C.

[0102] SiC whiskers are modified using the following methods:

[0103] First, take 5g of SiC whiskers and add them to 100mL of 10wt% HF solution. Sonicate for 30min, filter, and rinse with deionized water 4 times until the solution pH is 7.

[0104] Then, the SiC whiskers treated in the previous step were placed in 100 mL of 10 wt% HNO3 solution, stirred at 300 rpm for 1 h, filtered and rinsed 4 times, and dried in a vacuum drying oven at 80 ℃ for 6 h.

[0105] Next, the SiC whiskers treated in the previous step were added to a KH-500 ethanol solution with a concentration of 0.5 g / L, ultrasonically dispersed for 30 min, stirred at 50 °C for 4 h, filtered, rinsed three times with deionized water, and dried in a vacuum drying oven at 80 °C for 6 h.

[0106] Finally, the SiC whiskers processed in the previous step were subjected to high-temperature heat treatment in a vacuum furnace. The conditions for high-temperature heat treatment were as follows: under an atmosphere of argon flow rate of 300 mL / min, the temperature was first increased to 600℃ at a heating rate of 5℃ / min and held for 1 hour, then increased to 1600℃ at a heating rate of 10℃ / min and held for 4 hours, and finally cooled naturally to room temperature before the SiC whiskers were removed.

[0107] (2) Solvent preparation

[0108] Weigh the solvent components according to the following mass percentages: 65% ethanol, 25% polyurethane binder, 5% dispersant (PVP), and 5% silicon nitride.

[0109] (3) Slurry preparation

[0110] First, ethanol and PVP were mixed and stirred until the dispersant was completely dissolved. Then, the powder components, polyurethane binder, and silicon nitride were added, and the mixture was stirred in a ball mill at 300 rpm for 5 hours to ensure uniform powder dispersion and obtain a homogeneous, bubble-free slurry. The viscosity of the slurry was tested using a rotational viscometer, and the obtained viscosity was 699 mPa·s.

[0111] (4) Degassing treatment

[0112] The slurry obtained in step (3) was placed in a vacuum degassing device, the vacuum degree was set to -0.08MPa, and the degassing time was 30min, to obtain a rapidly densified ceramic matrix composite slurry.

[0113] The method for densifying ceramic matrix composites based on the above-mentioned rapid densification ceramic matrix composite slurry includes the following steps:

[0114] (5) Matrix treatment

[0115] A density of 1.0 g / cm³ was selected. 3 The C / SiC blank material was ultrasonically cleaned and dried at 120℃ for 2 hours to remove moisture.

[0116] (6) Penetrating grout

[0117] Using a spraying process, the slurry obtained in step (4) is uniformly coated onto the surface of the C / SiC blank material to ensure uniform coverage of the material surface.

[0118] (7) Filtration densification

[0119] The coated blank material is placed in a vacuum filtration device with a negative pressure set to -0.05MPa for 10 minutes to allow the slurry to fully penetrate the material pores.

[0120] Repeat steps (6) to (7) three times for filtration, and then dry in a 100°C drying oven for 2 hours to remove residual solvent.

[0121] (8) Curing and sintering

[0122] The densified material was placed in an argon atmosphere furnace, the heating rate was set to 2℃ / min, and it was cured at 400℃ for 2h. Then the temperature was increased to 1600℃ and held for 3h. Finally, it was allowed to cool naturally to room temperature with the furnace to obtain the densified ceramic matrix composite material.

[0123] Comparative Example 1:

[0124] A method for preparing a rapidly densified ceramic matrix composite slurry includes the following steps:

[0125] The preparation method is the same as in Example 1, except that the SiC whiskers were not modified in step (1) of this comparative example, while the other steps remain unchanged.

[0126] The method for densifying ceramic matrix composites based on the above-mentioned rapid densification ceramic matrix composite slurry is the same as in Example 1.

[0127] Comparative Example 2:

[0128] A method for preparing a rapidly densified ceramic matrix composite slurry includes the following steps:

[0129] The preparation method is the same as in Example 1, except that the aspect ratio of SiC whiskers in step (1) of this comparative example is changed to 50:1, while the other steps remain unchanged.

[0130] The method for densifying ceramic matrix composites based on the above-mentioned rapid densification ceramic matrix composite slurry is the same as in Example 1.

[0131] Comparative Example 3:

[0132] A method for preparing a rapidly densified ceramic matrix composite slurry includes the following steps:

[0133] The preparation method is the same as in Example 1, except that the aspect ratio of SiC whiskers in step (1) of this comparative example is changed to 250:1, while the other steps remain unchanged.

[0134] The method for densifying ceramic matrix composites based on the above-mentioned rapid densification ceramic matrix composite slurry is the same as in Example 1.

[0135] Comparative Example 4:

[0136] A method for preparing a rapidly densified ceramic matrix composite slurry includes the following steps:

[0137] The preparation method is the same as in Example 1, except that the weight of B4C in step (1) of this comparative example is changed to 5 parts, while the other steps remain unchanged.

[0138] The method for densifying ceramic matrix composites based on the above-mentioned rapid densification ceramic matrix composite slurry is the same as in Example 1.

[0139] Comparative Example 5:

[0140] A method for preparing a rapidly densified ceramic matrix composite slurry includes the following steps:

[0141] The preparation method is the same as in Example 1, except that B4C is not added to the powder component in step (1) of this comparative example, while the other steps remain unchanged.

[0142] The method for densifying ceramic matrix composites based on the above-mentioned rapid densification ceramic matrix composite slurry is the same as in Example 1.

[0143] Comparative Example 6:

[0144] A method for preparing a rapidly densified ceramic matrix composite slurry includes the following steps:

[0145] The preparation method is the same as in Example 1, except that lanthanum oxide is not added to the powder component in step (1) of this comparative example, while the other steps remain unchanged.

[0146] The method for densifying ceramic matrix composites based on the above-mentioned rapid densification ceramic matrix composite slurry is the same as in Example 1.

[0147] Experimental example:

[0148] The ceramic matrix composites prepared in Examples 1-3 and Comparative Examples 1-6 were subjected to density measurements at room temperature (22°C), humidity (31%), and atmospheric pressure (99 kPa). The experimental results are as follows: Figure 1 As shown.

[0149] The results showed that the ceramic matrix composites prepared in Examples 1-3 were similar and all had good densities, proving the successful preparation of dense ceramic matrix composites. In Comparative Example 1, because the SiC whiskers were not modified, the SiC whiskers had insufficient dispersibility and wettability in solution, easily agglomerating into large particles instead of uniformly distributed whiskers, thus leading to a significant decrease in the density of the ceramic matrix composite. The densities of the ceramic matrix composites in Examples 1, 4, and 5 decreased sequentially, mainly because the proportion of boron carbide as a sintering aid decreased sequentially. Boron carbide has good chemical compatibility with SiC or SiC whiskers, and can form a B-Si-C eutectic or reaction interface at high temperatures, significantly reducing the sintering temperature and promoting densification. As shown in Examples 1 and 6, lanthanum oxide can increase the density of the ceramic matrix composite, mainly because lanthanum oxide can enhance the formation of the liquid phase during sintering, accelerating densification.

[0150] The ceramic matrix composites prepared in Examples 1-3 and Comparative Examples 1-6 were used to measure the flexural strength of the Instron 8801 electro-hydraulic servo fatigue testing system under the conditions of room temperature 20°C, humidity 32%, and atmospheric pressure 99 kPa. The experimental results are as follows: Figure 2 As shown.

[0151] The results showed that the flexural strength of Examples 1-3 differed little and all met the production standards for ceramic matrix composites. However, the ceramic matrix composite prepared in Comparative Example 2, due to the low aspect ratio of the silicon carbide used, exhibited a significant decrease in flexural strength even without a significant change in material density. The main reason for this is that although low aspect ratio SiC whiskers have good dispersibility, their effect on enhancing fracture toughness and flexural strength in ceramic matrix composites is limited, making it difficult to effectively inhibit crack propagation.

[0152] The flexural strength of the ceramic matrix composite material prepared in Comparative Example 3 is close to that of Examples 1-3, mainly because the whisker has a high aspect ratio, which significantly enhances the pull-out effect. When the crack propagates to the region where the SiC whisker is located, the interfacial bonding force is moderate, so that the whisker does not break directly but is gradually pulled out from the matrix. In this process, it is necessary to overcome the interfacial friction and adhesion forces, consuming additional fracture energy, thereby effectively improving the flexural strength of the material.

[0153] The significant decrease in flexural strength in Comparative Example 5 was mainly due to the lack of boron carbide in the slurry, resulting in poor wettability and impregnation on the carbon fiber framework, making it difficult to form a dense interfacial bonding layer. During high-temperature sintering, poor interfacial bonding exacerbated the oxidative damage to the carbon fibers, leading to a significant decrease in the mechanical properties of the composite material, manifested as a substantial reduction in flexural strength.

[0154] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A rapidly densified ceramic matrix composite slurry, characterized in that, Includes slurry powder and slurry solvent; The slurry powder comprises the following components in parts by weight: 25-35 parts of polycarbosilane, 10-15 parts of SiC whiskers, 40-50 parts of SiC ceramic powder, 0.5-3 parts of calcium fluoride, 0.5-2 parts of lanthanum oxide, and 10-25 parts of boron-containing powder; The slurry solvent comprises the following components in parts by weight: Ethanol 60-70 parts, polyurethane binder 20-25 parts, dispersant 1-10 parts and thickener 1-10 parts; The SiC whiskers have a whisker length of 10-20 μm, a diameter of 0.1-0.2 μm, and an aspect ratio of 100:1-200:

1. The SiC whiskers are modified through the following steps: First, SiC whiskers are impregnated in hydrofluoric acid solution and nitric acid solution in sequence, then filtered and dried. Next, they are impregnated in silane coupling agent solution, filtered and dried, and then subjected to high-temperature heat treatment to complete the modification.

2. The rapidly densified ceramic matrix composite slurry according to claim 1, characterized in that, The mass ratio of slurry powder to slurry solvent in the ceramic matrix composite slurry is (1-3):1, and the viscosity is 500-1500 mPa·s.

3. The rapidly densified ceramic matrix composite slurry according to claim 1, characterized in that, The hydrofluoric acid solution has a mass concentration of 5-20%, the nitric acid solution has a mass concentration of 5-20%, the silane coupling agent solution has a concentration of 1-10 g / L, and the silane coupling agent is KH-550. The immersion time in hydrofluoric acid solution is 20-40 min, the immersion time in nitric acid solution is 30-90 min, and the immersion time in silane coupling agent solution is 3-5 h. The conditions for high-temperature heat treatment are as follows: first, heat the temperature to 500-700℃ at a heating rate of 3-7℃ / min, hold for 30-90 min, then heat the temperature to 1400-1600℃ at a heating rate of 8-12℃ / min, hold for 2-4 h, and finally cool naturally to room temperature.

4. The method for preparing the rapidly densified ceramic matrix composite slurry according to any one of claims 1-3, characterized in that, Includes the following steps: First, the slurry powder is mixed and ball-milled. Then, the ball-milled slurry powder is mixed evenly with the slurry solvent. Finally, it is degassed under vacuum to obtain the final product.

5. The method for preparing rapidly densified ceramic matrix composite slurry according to claim 4, characterized in that, The ball milling speed is 200-400 rpm, and the time is 8-12 h; the vacuum degree of the vacuum degassing treatment is -0.08~-0.1 MPa, and the time is 15-30 min.

6. The application of the rapid densification ceramic matrix composite slurry according to any one of claims 1-3 in ceramic densification processing.

7. A method for ceramic densification processing based on the rapid densification ceramic matrix composite slurry according to any one of claims 1-3, characterized in that, Includes the following steps: First, the rapid densification ceramic matrix composite slurry according to any one of claims 1-3 is coated on the surface of the ceramic composite material and penetrates into the interior of the material, then dried and cured, and finally sintered at high temperature.

8. The method for ceramic densification processing based on rapid densification ceramic matrix composite slurry according to claim 7, characterized in that, The drying and curing temperature is 200-300℃, and the time is 20-30 h; The conditions for the high-temperature sintering treatment are as follows: first, heat the temperature to 100-300℃ at a heating rate of 1-3℃ / min, then heat it to 1000-1400℃ at a heating rate of 1-5℃ / min, hold it at that temperature for 1-3 hours, then heat it to 1500-1700℃ at a heating rate of 2-3℃ / min, hold it at that temperature for 1-3 hours, and finally cool it down naturally or at a cooling rate of 1-3℃ / min to room temperature.

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