Design and preparation method for enhancing bonding strength of surface coating of composite material

Abstract

The invention discloses a design and preparation method for enhancing the bonding strength of a coating on the surface of a composite material, which comprises the following steps: brushing the composite material with slurry formed by mixing resin with Si powder, carbonizing, placing on the surface of the Si powder, and carrying out heat treatment to obtain the composite material of which the surface grows a SiC transition coating covered with SiC nanowires. By means of the method, the nanowire and the transition coating can be prepared at a low temperature, the outer ceramic coating is prepared on the surface of the nanowire and the transition coating, the two effects of nanometer enhancement and transition layer thermal mismatch relieving can be achieved at the same time, the bonding strength between the outer coating and a base body can be effectively enhanced and thermal stress can be effectively reduced under dual-mode cooperation, and the method has the advantages of being easy to operate, low in cost and the like; and the method has low requirements on the shape of the ceramic modified C / C composite material matrix, and is suitable for enhancing the bonding strength of the ceramic coating in industrial production.

Description

Technical Field

[0001] This invention relates to a design and preparation method for enhancing the bonding strength of surface coatings on composite materials, belonging to the field of material preparation technology. Background Technology

[0002] Ceramic matrix composites have attracted widespread attention due to their excellent high-temperature resistance, oxidation resistance, and high specific strength. However, with the rapid development of the aerospace field, these materials still face some key challenges in practical applications, particularly in ablation resistance, which requires the cooperation of coatings to adapt to increasingly harsh service environments. However, thermal mismatch exists between the matrix and the surface coating.

[0003] Currently, researchers mainly employ techniques such as chemical vapor deposition (CVD) and spraying to prepare coatings for composite material surfaces. However, these methods often suffer from weak bonding strength. Furthermore, the significant difference in thermal expansion coefficients between the coating and the substrate easily leads to thermal stress during high-temperature service, causing coating peeling and severely impacting the material's lifespan. Therefore, how to prepare coatings with high bonding strength and effectively mitigate thermal mismatch has become a current research challenge and hot topic. Summary of the Invention

[0004] The technical problem solved by this invention is to overcome the shortcomings of the prior art and propose a design and preparation method for enhancing the bonding strength of the surface coating of composite materials, which significantly improves the bonding strength between the outer coating and the composite material and effectively reduces thermal stress.

[0005] The technical solution of this invention is: A design method for enhancing the bonding strength of a composite material surface coating involves placing nanowires and a transition coating between the composite material surface and an outer ceramic coating. The nanowires are used to nano-enhance the bonding strength between the outer ceramic coating and the composite material, and the transition coating is used to mitigate thermal mismatch.

[0006] Furthermore, the composite material is a ceramic-modified C / C composite material.

[0007] Based on the design method of enhancing the bonding strength of the surface coating of composite materials, a method for preparing nanowires and transition coatings is proposed. A slurry is formed by mixing resin with Si powder, and the slurry is brushed onto the surface of the composite material sample. The composite material sample is then carbonized, placed on the Si powder surface and heat-treated. After cooling, a composite material sample coated with SiC nanowires and a transition coating is obtained.

[0008] Further, phenolic resin, anhydrous ethanol and Si powder are mixed in a ratio of 1:(6-10):(1-4), ultrasonicated and stirred with an electromagnetic stirrer for 30-60 minutes to obtain a slurry.

[0009] Furthermore, the slurry is evenly applied to the surface of the composite material sample with a brush, dried, and then applied again. This process is repeated 3-7 times, and the sample is then dried at 80℃-100℃ for 12-24 hours.

[0010] Further, the sample after being coated with slurry and dried is placed in a corundum crucible and placed in the center of a tubular heat treatment furnace for carbonization under an argon protective atmosphere, i.e., held at 900℃-1000℃ for 30min-60min, and then heated to 1300℃-1600℃ for 30min-60min.

[0011] Furthermore, the carbonized sample was placed on a flat surface of silicon powder and heated to 1300℃-1600℃ under an argon atmosphere and held for 60min-120min.

[0012] The advantages of this invention compared to the prior art are: (1) Synergistic effect of nanowires and transition coating at multiple scales: By simultaneously generating SiC nanowires and SiC transition coating on the surface of C / C-ZrC-SiC composite material, the mechanical locking effect of nanowires and the stress buffering effect of transition layer can be utilized to significantly enhance the bonding strength between the outer coating and the substrate, alleviate the thermal mismatch problem during high-temperature service, thereby significantly reducing the risk of coating peeling and extending the service life of the material.

[0013] (2) Synergistic effect of nanowires and transition coating at multiple scales: By simultaneously generating SiC nanowires and SiC transition coating on the surface of C / C-ZrC-SiC composite material, the mechanical locking effect of nanowires and the stress buffering effect of transition layer can be utilized to significantly enhance the bonding strength between the outer coating and the substrate, alleviate the thermal mismatch problem during high-temperature service, thereby significantly reducing the risk of coating peeling and extending the service life of the material. Attached Figure Description

[0014] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings: Figure 1 This is a flowchart illustrating the design and preparation method for enhancing the bonding strength of surface coatings on composite materials according to the present invention; Figure 2 SEM images of the SiC transition layer and nanowire surface prepared in the embodiments of the present invention; Figure 3 The image shows a cross-sectional BSE view of the SiC transition layer and the coating on the nanowire surface prepared according to an embodiment of the present invention. Detailed Implementation

[0015] Exemplary embodiments of the present disclosure will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.

[0016] This invention proposes a design and preparation method for enhancing the bonding strength of surface coatings on composite materials, such as... Figure 1 As shown, it includes: (1) Phenolic resin, anhydrous ethanol and Si powder are mixed in a ratio of 1:(6-10):(1-4), ultrasonicated and stirred with an electromagnetic stirrer for 30-60 min to obtain Si-containing slurry; (2) Apply the slurry evenly to the surface of the ceramic modified C / C composite material sample, dry it and apply it again, repeat 3-7 times, and then dry it at 80-100℃ for 12-24h. (3) Then place the dried sample into a corundum crucible, place it in the center of a tube heat treatment furnace, and hold it at 900-1000℃ for 30-60 min under an argon protective atmosphere. Then raise the temperature to 1300-1600℃ and hold it for 30-60 min. After cooling, take it out. (4) After removal, place it on a flat surface of silicon powder, heat it to 1300-1600℃ under argon atmosphere protection and hold for 60-120 min. After cooling, remove it to obtain the SiC transition coating with SiC nanowires. SEM images of the SiC transition layer and nanowire surface are shown below. Figure 2 As shown, this improves the bonding strength between the ceramic-modified C / C composite material and the coating, thus alleviating the thermal mismatch problem of the coating.

[0017] The SiC transition coating with SiC nanowires prepared can effectively improve the bonding strength between the ceramic-modified C / C composite material and the coating prepared based on this structure, such as... Figure 3 As shown, this alleviates the problem of thermal mismatch in the coating.

[0018] Example 1 (1) Phenolic resin, anhydrous ethanol and Si powder are mixed in a ratio of 1:6:4, ultrasonicated and stirred with an electromagnetic stirrer for 30 min to obtain Si-containing slurry; (2) Apply slurry S evenly to the surface of C / C-ZrC-SiC composite material sample, dry it and apply it again, repeat 7 times, and then dry it at 80℃ for 24h. (3) Then place it in a corundum crucible, place it in the center of a tubular heat treatment furnace, hold it at 900℃ for 30 minutes under an argon protective atmosphere, then raise the temperature to 1300℃ and hold it for 30 minutes, and take it out after cooling. (4) After taking it out, place it on a flat silicon powder surface, heat it to 1600℃ under argon atmosphere protection and keep it at that temperature for 60 minutes. After cooling, take it out to obtain the SiC transition coating with SiC nanowires.

[0019] Example 2 (1) Phenolic resin, anhydrous ethanol and Si powder are mixed in a ratio of 1:6:4, ultrasonicated and stirred with an electromagnetic stirrer for 30 min to obtain Si-containing slurry; (2) Apply slurry S evenly to the surface of C / C-ZrC-SiC composite material sample, dry it and apply it again, repeat 7 times, and then dry it at 80℃ for 12h. (3) Then place it in a corundum crucible, place it in the center of a tube heat treatment furnace, and hold it at 1000℃ for 30 minutes under an argon protective atmosphere. Then raise the temperature to 1600℃ and hold it for 30 minutes. After cooling, take it out. (4) After taking it out, place it on a flat silicon powder surface, heat it to 1600℃ under argon atmosphere protection and keep it at that temperature for 60 minutes. After cooling, take it out to obtain the SiC transition coating with SiC nanowires.

[0020] Example 3 (1) Phenolic resin, anhydrous ethanol and Si powder are mixed in a ratio of 1:10:2, ultrasonicated and stirred with an electromagnetic stirrer for 60 min to obtain Si-containing slurry; (2) Apply slurry S evenly to the surface of C / C-ZrC-SiC composite material sample, dry it and apply it again, repeat 7 times, and then dry it at 80℃ for 24h. (3) Then place it in a corundum crucible, place it in the center of a tube heat treatment furnace, and hold it at 1000℃ for 60 minutes under an argon protective atmosphere, then raise the temperature to 1500℃ and hold it for 30 minutes, and take it out after cooling. (4) After taking it out, place it on a flat silicon powder surface, heat it to 1500℃ under argon atmosphere protection and keep it at that temperature for 120 minutes. After cooling, take it out to obtain the SiC transition coating with SiC nanowires.

[0021] This invention proposes a design and preparation method for enhancing the bonding strength of coatings on composite materials. By simultaneously preparing SiC nanowires and a SiC transition coating on the composite material surface, and combining the synergistic effect of nano-reinforcement and the transition layer in mitigating thermal mismatch, the bonding strength between the outer coating and the substrate is significantly improved, and thermal stress is effectively reduced. This method has advantages such as simple operation, low cost, and minimal requirements on substrate shape, making it particularly suitable for industrial production. This innovation not only provides a new approach to the surface modification of high-performance composite materials but also offers an effective solution to the problem of thermal mismatch between the coating and the substrate, possessing significant theoretical and practical application value.

[0022] The embodiments described above are merely preferred embodiments of the present invention. Ordinary variations and substitutions made by those skilled in the art within the scope of the technical solution of the present invention should be included within the protection scope of the present invention.

Claims

1. A design method for enhancing the bond strength of a surface coating of a composite material, characterized by, Nanowires are arranged between the surface of the composite material and the outer ceramic coating, the nanowires are used to nano-reinforce the bonding strength between the outer ceramic coating and the composite material, and a transition coating is arranged to relieve thermal mismatch.

2. The method of claim 1, wherein the method is characterized by: The composite material is a ceramic modified C / C composite material.

3. The method for designing the surface coating bonding strength of the reinforced composite material according to claim 1, the method for preparing the nanowire and the transition coating, characterized in that, A slurry is formed by mixing Si powder with resin, the slurry is brushed on the surface of the composite material sample, and then the composite material sample is carbonized, placed on the surface of Si powder and heat treated, and after cooling, a composite material sample coated with a transition coating of SiC nanowires is obtained.

4. The method of claim 3, wherein the method further comprises: Phenolic resin, anhydrous ethanol and Si powder are mixed in a ratio of 1: (6-10): (1-4), after ultrasonic treatment, the mixture is stirred with an electromagnetic stirrer for 30-60 minutes to obtain a slurry.

5. The method of claim 3, wherein the method further comprises: The slurry is evenly brushed on the surface of the composite material sample with a brush, and after drying, it is brushed again, repeated 3-7 times, and then dried at 80-100°C for 12-24 hours.

6. The method of claim 5, wherein the method further comprises: The sample after brushing the slurry and drying is placed in a corundum crucible and placed in the center of a tube furnace, and carbonized in an argon protective atmosphere, i.e. heated to 900-1000°C for 30-60 minutes, and then heated to 1300-1600°C for 30-60 minutes.

7. The method of claim 1, wherein the method further comprises: The carbonized sample is placed on the surface of the silicon powder laid flat and heated to 1300-1600°C for 60-120 minutes in an argon atmosphere.

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