Root-like structure bionic high-temperature-resistant protective coating and preparation method thereof

Abstract

The application discloses a root system structure bionic high-temperature-resistant protective coating and a preparation method thereof. The coating comprises a root system structure module and a soil structure module. The root system structure module is a boride-silicon-based ceramic phase, and the soil structure module is a low-melting-point glass phase. The low-melting-point glass phase is stabilized by the boride-silicon-based ceramic phase in the composite coating through bionic root system structure. The preparation method comprises the following steps: mixing raw materials, densification treatment and polishing. Compared with the prior art, the application has the advantages that the low-melting-point glass in the high-temperature-resistant protective coating is effectively compounded, the softening modification effect of the glass phase is utilized, the densification temperature of the coating is reduced, the sealing degree of the oxygen-blocking structure of the coating is further promoted, the oxygen-blocking defect problem of the internal structure of the coating is solved, and the advantages of energy saving and oxygen-blocking strengthening of the coating are achieved.

Description

Technical Field

[0001] This invention relates to the field of coating structure design, specifically to a root-like biomimetic high-temperature resistant protective coating and its preparation method. Background Technology

[0002] Carbon structural materials possess advantages such as high melting point, low density, and excellent high-temperature mechanical properties, making them one of the most promising high-temperature structural materials in industries such as defense and aerospace. However, they are easily oxidized and fail in oxygen-containing environments above 673K, which is a key issue limiting their application. Coating technology is a recognized effective means to address the high-temperature susceptibility of carbon structural materials.

[0003] In recent decades, ultra-high temperature ceramic (UHTC) coatings, represented by ZrB2, have been widely used due to their advantages such as strong covalent bonds, high melting point, high strength, and good thermal and electrical conductivity. However, the strong covalent bond characteristic makes it difficult to achieve densification and sintering during material preparation, leading to oxygen diffusion and penetration at high temperatures, which hinders the improvement of the high-temperature protective coating performance of this type of coating. Furthermore, the high-temperature oxidation of ZrB2, accompanied by the release of gaseous B2O3, creates pores in the coating, providing pathways for oxygen penetration. Refractory metal silicides, represented by MoSi2, exhibit good high-temperature protective coating performance because these silicides generate a silica phase with excellent protective capabilities in high-temperature oxygen-containing environments. Silica is fluid at high temperatures, and as an amorphous phase, oxygen diffusion rates within it are very low, effectively protecting the material from further oxidation and corrosion. Based on this, boride-silicon-based high-temperature protective coatings, represented by ZrB2-MoSi2, show great potential in high-temperature oxidation protection.

[0004] Yang Qingqing et al. (Yang Qingqing. Study on Antioxidant Mechanism of MoSi2-HfB2-SiC Coating [D]. China University of Mining and Technology, 2022) used boride-MoSi2-based coatings on carbon-based surfaces for high-temperature protection, aiming to achieve effective high-temperature oxygen barrier. However, the rapid oxidation of MoSi2 degrades the density of the oxygen barrier structure to a certain extent, causing oxygen penetration. Although Yang Qingqing et al. continued to use a pre-oxidation process to generate a sealing glass layer on the coating surface, this form of film formation is also accompanied by the loss of the components themselves, degrading the oxygen barrier density of the coating structure. Low melting point glass (LMPG), as a special glass that can melt near 900K, is mostly used in the field of surface protection. If LMPG that can resist oxygen erosion is pre-existing inside the coating during the densification process, it can further promote the densification of the coating structure and improve the oxygen barrier effect of the coating structure. However, since the melting point of LMPG is lower than the densification temperature of the coating, and the glass phase is prone to softening and outflow during conventional ultra-high temperature ceramic sintering, it is difficult to ensure the integrity of the target sample. Therefore, feasible methods are urgently needed to solve the current technical problems in order to improve the oxygen barrier effect of the coating structure. Summary of the Invention

[0005] The present invention aims to provide a root-like biomimetic high-temperature resistant protective coating, specifically a coating that utilizes a root-like biomimetic structure to stabilize LMPG and thereby achieve oxygen barrier enhancement.

[0006] To achieve the above objectives, the present invention employs the following technical solution:

[0007] A root-like biomimetic high-temperature resistant protective coating includes a root structure module and a soil structure module; wherein the root structure module is a boride-silicon-based ceramic phase, and the soil structure module is a low-melting-point glass phase; the root structure module and the soil structure module are interwoven within the root-like biomimetic high-temperature resistant protective coating, and the low-melting-point glass phase is stabilized by the boride-silicon-based ceramic phase within the multiphase coating through the biomimetic root structure.

[0008] As a preferred embodiment, the LMPG low-melting-point glass phase has a volume content of 30-35 vol.%, with the balance being a ZrB2-MoSi2 ceramic phase.

[0009] A method for preparing a root-like biomimetic high-temperature resistant protective coating specifically includes the following steps:

[0010] 1) Mixed raw materials: ZrB2, MoSi2 and LMPG commercial powders are mixed according to volume ratio to obtain biomimetic high temperature resistant protective coating composite precursor powder;

[0011] 2) Densification treatment: The composite precursor powder is wrapped around the carbon matrix and placed into a graphite mold, then placed in a plasma low-temperature hot pressing sintering device to start the coating densification treatment.

[0012] 3) Polishing: After the processing is completed, the sample is taken out and polished to obtain a root-like biomimetic high-temperature resistant protective coating.

[0013] As a preferred embodiment, the volume ratio of ZrB2, MoSi2, and LMPG powder raw materials in step 1) is 32.5–35:32.5–35:30–35.

[0014] As a preferred embodiment, the coating densification treatment temperature range in step 2) is 1250–1300°C.

[0015] As a preferred embodiment, the volume ratio of the components in the root-like biomimetic high-temperature resistant protective coating described in step 3) is ZrB2:MoSi2:LMPG = 32.5~35:32.5~35:30~35.

[0016] The advantages of this invention compared to existing technologies are as follows: Based on the biomimetic concept of a root-like structure, this invention uses the ZrB2 and MoSi2 phases within the coating as the root structure and a high-content LMPG liquid phase as the flowable soil phase. Utilizing the principle of root structure stabilizing flowing soil in a root-like biomimetic structure, and through the staggered curing of the LMPG phase, it effectively achieves the composite of low-melting-point glass within the high-temperature resistant protective coating. Furthermore, based on the softening modification effect of the glass phase, while reducing the coating densification temperature, it further promotes the oxygen barrier sealing degree of the coating structure, solving the problem of oxygen barrier defects in the internal structure of the coating. This has the advantages of saving energy and promoting enhanced oxygen barrier properties in the coating. Attached Figure Description

[0017] Figure 1 This is a cross-sectional microstructure diagram of the root-like biomimetic high-temperature resistant protective coating obtained in Example 1 of the present invention.

[0018] Figure 2 This is a cross-sectional microstructure diagram of the root-like biomimetic high-temperature resistant protective coating obtained in Example 2 of the present invention.

[0019] Figure 3 This is a cross-sectional microstructure diagram of the root-like biomimetic high-temperature resistant protective coating obtained in Example 3 of the present invention.

[0020] Figure 4 This is a cross-sectional microstructure of the conventional high-temperature resistant protective coating obtained in Comparative Example 1 of the present invention.

[0021] Figure 5 This is a cross-sectional microstructure of the biomimetic high-temperature resistant protective coating with an over-quantitative root-like structure obtained in Comparative Example 2 of the present invention.

[0022] Figure 6 The diagram shows the final protective efficiency of the high-temperature resistant protective coatings obtained in Examples 1-3 and Comparative Examples 1-2 of this invention. Detailed Implementation

[0023] To better understand the present invention, the following embodiments further illustrate the content of the present invention, but the content of the present invention is not limited to the following embodiments.

[0024] Example 1:

[0025] This embodiment relates to a root-like biomimetic high-temperature resistant protective coating, wherein the volume content of LMPG glass phase is 30 vol.%, and the balance is ZrB2-MoSi2 ceramic phase.

[0026] This invention provides a method for preparing a root-like biomimetic high-temperature resistant protective coating as described above, which is carried out according to the following steps:

[0027] (1) Using ZrB2, MoSi2 and LMPG commercial powders as raw materials, they are mixed in a volume ratio of 35:35:30 to obtain ZrB2-MoSi2-LMPG biomimetic high temperature protective coating composite precursor powder with a volume ratio of 35:35:30.

[0028] (2) The composite precursor powder is wrapped around the carbon matrix and placed into a graphite mold. The mold is then placed in a plasma low-temperature hot pressing sintering device, and the coating densification treatment is started at a temperature of 1250℃.

[0029] (3) After the processing is completed, the sample is taken out and polished to obtain a ZrB2-MoSi2-LMPG root-like biomimetic high-temperature resistant protective coating with a volume ratio of 35:35:30.

[0030] This embodiment provides a preferred formulation and preparation method for a root-like biomimetic high-temperature resistant protective coating, wherein the cross-sectional morphology is as follows: Figure 1 As shown, the protection efficiency after a 100-minute isothermal oxidation high-temperature resistance test at 1700℃ is as follows: Figure 6 As shown in the figure, the high-temperature resistant protective coating provided in this embodiment exhibits a distinct root-like biomimetic morphology and demonstrates good protective effect after a high-temperature resistance test at 1700℃.

[0031] Example 2:

[0032] This embodiment relates to a root-like biomimetic high-temperature resistant protective coating, wherein the volume content of LMPG glass phase is 32.5 vol.%, and the balance is ZrB2-MoSi2 ceramic phase.

[0033] This invention provides a method for preparing a root-like biomimetic high-temperature resistant protective coating as described above, which is carried out according to the following steps:

[0034] (1) Using ZrB2, MoSi2 and LMPG commercial powders as raw materials, they were mixed in a volume ratio of 33.75:33.75:32.5 to obtain a ZrB2-MoSi2-LMPG biomimetic high-temperature protective coating composite precursor powder with a volume ratio of 33.75:33.75:32.5.

[0035] (2) The composite precursor powder is wrapped around the carbon matrix and placed into a graphite mold. The mold is then placed in a plasma low-temperature hot pressing sintering device, and the coating densification treatment is started at a temperature of 1275℃.

[0036] (3) After the processing is completed, the sample is taken out and polished to obtain a ZrB2-MoSi2-LMPG root-like biomimetic high-temperature resistant protective coating with a volume ratio of 33.75:33.75:32.5.

[0037] This embodiment provides a preferred formulation and preparation method for a root-like biomimetic high-temperature resistant protective coating, wherein the cross-sectional morphology is as follows: Figure 2 As shown, the protection efficiency after a 100-minute isothermal oxidation high-temperature resistance test at 1700℃ is as follows: Figure 6 As shown in the figure, the high-temperature resistant protective coating provided in this embodiment exhibits a distinct root-like biomimetic morphology and demonstrates good protective effect after a high-temperature resistance test at 1700℃.

[0038] Example 3:

[0039] This embodiment relates to a root-like biomimetic high-temperature resistant protective coating, wherein the volume content of LMPG glass phase is 35 vol.%, and the balance is ZrB2-MoSi2 ceramic phase.

[0040] This invention provides a method for preparing a root-like biomimetic high-temperature resistant protective coating as described above, which is carried out according to the following steps:

[0041] (1) Using ZrB2, MoSi2 and LMPG commercial powders as raw materials, they were mixed in a volume ratio of 32.5:32.5:35 to obtain ZrB2-MoSi2-LMPG biomimetic high temperature resistant protective coating composite precursor powder with a volume ratio of 32.5:32.5:35.

[0042] (2) The composite precursor powder is wrapped around the carbon matrix and placed into a graphite mold. The mold is then placed in a plasma low-temperature hot pressing sintering device, and the coating densification treatment is started at a temperature of 1300℃.

[0043] (3) After the processing is completed, the sample is taken out and polished to obtain a ZrB2-MoSi2-LMPG root-like biomimetic high-temperature protective coating with a volume ratio of 32.5:32.5:35.

[0044] This embodiment provides a preferred formulation and preparation method for a root-like biomimetic high-temperature resistant protective coating, wherein the cross-sectional morphology is as follows: Figure 3 As shown, the protection efficiency after a 100-minute isothermal oxidation high-temperature resistance test at 1700℃ is as follows: Figure 6 As shown in the figure, the high-temperature resistant protective coating provided in this embodiment exhibits a distinct root-like biomimetic morphology and demonstrates good protective effect after a high-temperature resistance test at 1700℃.

[0045] Comparative Example 1:

[0046] This comparative example relates to a conventional high-temperature resistant protective coating, which does not contain the LMPG glass phase and is entirely composed of the ZrB2-MoSi2 ceramic phase.

[0047] This comparative example provides a method for preparing a conventional high-temperature resistant protective coating as described above, which is carried out according to the following steps:

[0048] (1) Using commercial ZrB2 and MoSi2 powders as raw materials, they are mixed in a volume ratio of 50:50 to obtain ZrB2-MoSi2 high temperature resistant protective coating composite precursor powder with a volume ratio of 50:50.

[0049] (2) The composite precursor powder is wrapped around the carbon matrix and placed into a graphite mold. The mold is then placed in a plasma low-temperature hot pressing sintering device, and the coating densification treatment is started at a temperature of 1300℃.

[0050] (3) After the processing is completed, the sample is taken out and polished to obtain a ZrB2-MoSi2 high temperature resistant protective coating with a volume ratio of 50:50.

[0051] This comparative example provides a preferred formulation and preparation method for a conventional high-temperature resistant protective coating. Compared with Example 3, this comparative example removes the glass phase. The cross-sectional morphology is as follows: Figure 4 As shown, the protection efficiency after a 100-minute isothermal oxidation high-temperature resistance test at 1700℃ is as follows: Figure 6 As shown in the figure, the high-temperature protective coating provided in this comparative example does not exhibit a root-like biomimetic morphology. Due to the absence of a glass phase, the densification temperature of 1300℃ is insufficient for the effective densification sintering of the ZrB2-MoSi2 coating, resulting in insufficient densification and a large number of defects and pores in the morphology. Compared to Example 3, the protective effect is worse after the high-temperature resistance test at 1700℃.

[0052] Comparative Example 2:

[0053] This comparative example relates to an over-quantitative root-like biomimetic high-temperature resistant protective coating, wherein the volume content of the LMPG glass phase is 50 vol.%, and the balance is the ZrB2-MoSi2 ceramic phase.

[0054] This comparative example provides a method for preparing a root-like biomimetic high-temperature resistant protective coating as described above, which is carried out according to the following steps:

[0055] (1) Using ZrB2, MoSi2 and LMPG commercial powders as raw materials, they are mixed in a volume ratio of 25:25:50 to obtain ZrB2-MoSi2-LMPG biomimetic high temperature resistant protective coating composite precursor powder with a volume ratio of 25:25:50.

[0056] (2) The composite precursor powder is wrapped around the carbon matrix and placed into a graphite mold. The mold is then placed in a plasma low-temperature hot pressing sintering device, and the coating densification treatment is started at a temperature of 1300℃.

[0057] (3) After the processing is completed, the sample is taken out and polished to obtain a ZrB2-MoSi2-LMPG root-like biomimetic high-temperature resistant protective coating with a volume ratio of 25:25:50.

[0058] This comparative example provides an optimal formulation and preparation method for an over-quantified root-like biomimetic high-temperature resistant protective coating, specifically, compared to Example 3, the glass phase content in this comparative example is excessive. The cross-sectional morphology is as follows: Figure 5 As shown, the protection efficiency after a 100-minute isothermal oxidation high-temperature resistance test at 1700℃ is as follows: Figure 6 As shown in the figure, although the high-temperature protective coating provided in this comparative example exhibits a significant root-like biomimetic morphology, the excessive glass phase content causes the glass phase to soften and overflow during the coating densification process, leading to a deterioration in coating quality. Compared to Example 3, the protective effect is worse after the 1700℃ high-temperature test.

[0059] The present invention and its embodiments have been described above. This description is not restrictive, and the accompanying drawings are only one embodiment of the present invention; the actual structure is not limited thereto. In conclusion, if those skilled in the art are inspired by this description and design similar structures and embodiments without departing from the spirit of the invention, such designs should fall within the protection scope of the present invention.

Claims

1. A method for preparing a root-like biomimetic high-temperature resistant protective coating, characterized in that, Specifically, the following steps are included: 1) Mixed raw materials: ZrB2, MoSi2 and LMPG commercial powders are mixed in volume ratio to obtain biomimetic high temperature resistant protective coating composite precursor powder. The volume ratio of ZrB2, MoSi2 and LMPG powder raw materials is 32.5~35:32.5~35:30~35. 2) Densification treatment: The composite precursor powder is wrapped around the carbon matrix and placed into a graphite mold, then placed in a plasma low-temperature hot pressing sintering device to start the coating densification treatment. 3) Polishing: After the processing is completed, the sample is taken out and polished to obtain a root-like biomimetic high-temperature resistant protective coating.

2. The method for preparing a root-like biomimetic high-temperature resistant protective coating according to claim 1, characterized in that: The temperature range for the coating densification treatment in step 2) is 1250 ~ 1300 °C.

3. The method for preparing a root-like biomimetic high-temperature resistant protective coating according to claim 1, characterized in that: The volume ratio range of the components in the root-like biomimetic high-temperature resistant protective coating described in step 3) is ZrB2:MoSi2:LMPG = 32.5~35:32.5~35:30~35.

4. A root-like biomimetic high-temperature resistant protective coating prepared by the method according to claim 1, characterized in that: It includes a root structure module and a soil structure module. The root structure module is a boride-silicon-based ceramic phase, and the soil structure module is an LMPG low-melting-point glass phase.

5. The root-like biomimetic high-temperature resistant protective coating according to claim 4, characterized in that: The LMPG low-melting-point glass phase has a volume content of 30~35 vol.%, with the balance being ZrB2-MoSi2 ceramic phase.

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