Bionic high-temperature-resistant protective coating with root-shaped structure and preparation method thereof

Abstract

The invention discloses a bionic high-temperature-resistant protective coating with a root-shaped structure and a preparation method of the bionic high-temperature-resistant protective coating. The bionic high-temperature-resistant protective coating comprises 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 low-melting-point glass phase is stabilized by utilizing a boride-silicon-based ceramic phase in the complex-phase coating through bionic of a root-system-shaped bionic structure. The preparation method comprises the steps of raw material mixing, densification treatment and polishing. Compared with the prior art, the preparation method has the advantages that compounding of low-melting-point glass in the high-temperature-resistant protective coating is effectively achieved, based on the softening modification effect of a glass phase, the densification temperature of the coating is reduced, meanwhile, the oxygen barrier sealing degree of the coating structure is further improved, the oxygen barrier defect problem of the internal structure of the coating is solved, and the preparation method has the advantages of energy saving, environmental protection and the like. And oxygen barrier strengthening of the coating is promoted.

Description

Technical Field

[0001] The invention relates to the field of coating structure design, in particular to a root-like structure bionic high-temperature resistant protective coating and a preparation method thereof. Background Art

[0002] Carbon structural materials have the advantages of high melting point, low density, and excellent high-temperature mechanical properties. They are one of the most promising high-temperature structural materials in the defense, aerospace and other industries. However, they are easily oxidized and fail in oxygen-containing environments above 673K, which is a key issue limiting their application. Coating technology is recognized as an effective means to deal with the high-temperature oxidation 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 points, high strength, good thermal conductivity and electrical conductivity. However, the strong covalent bond characteristics make it difficult to densify and sinter the material during preparation, resulting in oxygen diffusion and penetration at high temperatures, making it difficult to improve the high temperature protective coating performance of such coatings. In addition, the high temperature oxidation of ZrB2 is accompanied by the release of gaseous B2O3, which will form pores in the coating and provide a path for oxygen to penetrate. Refractory metal silicides represented by MoSi2 have good high temperature protective coating performance, because these silicides will generate silicon dioxide phases with excellent protective capabilities in high temperature oxygen-containing environments. Silicon dioxide is in a fluid state at high temperatures. As an amorphous phase, the diffusion rate of oxygen in it is very low, which can effectively protect the material from further oxidation erosion. 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. Research on the Antioxidation 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 in order to achieve effective high-temperature oxygen barrier. However, the rapid oxidation of MoSi2 will deteriorate the density of the oxygen barrier structure to a certain extent, causing oxygen penetration. Although Yang Qingqing et al. continued to use the 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, which deteriorates the 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 can be pre-existed in the coating during the densification process, it can further promote the densification of the coating structure and enhance 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 easy to soften and flow out during the conventional ultra-high temperature ceramic sintering process, it is difficult to ensure the integrity of the target sample. Therefore, feasible methods are urgently needed to solve the problems in current technologies in order to improve the oxygen barrier effect of coating structures. Summary of the invention

[0005] The present invention aims to provide a root-like structure bionic high-temperature resistant protective coating, specifically a coating that utilizes a root-like bionic structure to stabilize LMPG and thereby achieves enhanced oxygen barrier properties of the coating.

[0006] The present invention adopts the following technical solutions to achieve the above-mentioned purpose:

[0007] A root-like structure bionic high-temperature resistant protective coating, comprising 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 in the root-like structure bionic high-temperature resistant protective coating are interlaced with each other, and the low-melting-point glass phase is stabilized by the boride-silicon-based ceramic phase in the composite coating through the bionics of the root-like bionic structure.

[0008] As a preferred solution, the volume content of the LMPG low-melting point glass phase is 30-35 vol.%, and the remainder is ZrB2-MoSi2 ceramic phase.

[0009] A method for preparing a root-like structure bionic high-temperature resistant protective coating comprises the following steps:

[0010] 1) Mixing raw materials: Using ZrB2, MoSi2, and LMPG commercial powder as raw materials, mixing them according to volume ratio to obtain a bionic high temperature resistant protective coating composite precursor powder;

[0011] 2) Densification treatment: The composite precursor powder wrapped carbon matrix is ​​loaded into a graphite mold, placed in a plasma low-temperature hot pressing sintering device, and the coating densification treatment is started;

[0012] 3) Polishing: After the treatment is completed, the sample is taken out and polished to obtain a root-like structure bionic 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 in the range of 32.5-35:32.5-35:30-35.

[0015] As a preferred solution, the coating densification treatment temperature range in step 2) is 1250-1300°C.

[0016] As a preferred embodiment, the volume ratio of the components in the root-like structure bionic high-temperature resistant protective coating described in step 3) is ZrB2:MoSi2:LMPG=32.5~35:32.5~35:30~35.

[0017] The advantages of the present invention compared with the prior art are: based on the bionic idea of ​​root-like structure, the present invention takes ZrB2 and MoSi2 phases in the coating as the root structure, takes the high-content LMPG liquid phase as the flowable soil phase, and utilizes the principle of the root structure in the root-like bionic structure to stabilize the flowable soil, and effectively realizes the compounding of low-melting-point glass in the high-temperature resistant protective coating through the staggered solidification of the LMPG phase. Based on the softening modification effect of the glass phase, while reducing the densification temperature of the coating, the sealing degree of the coating structure to block oxygen is further promoted, and the problem of oxygen blocking defects in the internal structure of the coating is solved, which has the advantages of saving energy and promoting the strengthening of the coating's oxygen blocking. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is a cross-sectional microscopic morphology of the root-like structure bionic high-temperature resistant protective coating obtained in Example 1 of the present invention.

[0019] Figure 2 This is a cross-sectional microscopic morphology of the root-like structure bionic high-temperature resistant protective coating obtained in Example 2 of the present invention.

[0020] Figure 3 This is a cross-sectional microscopic morphology of the root-like structure bionic high-temperature resistant protective coating obtained in Example 3 of the present invention.

[0021] Figure 4 This is a cross-sectional microscopic morphology of a conventional high temperature resistant protective coating obtained in Comparative Example 1 of the present invention.

[0022] Figure 5 This is a cross-sectional microscopic morphology of the excessive root-like structure bionic high-temperature resistant protective coating obtained in Comparative Example 2 of the present invention.

[0023] Figure 6 This is a diagram of the final protection efficiency of the high temperature resistant protective coatings obtained in Examples 1 to 3 of the present invention and Comparative Examples 1 to 2. DETAILED DESCRIPTION

[0024] In order to better understand the present invention, the content of the present invention is further explained below in conjunction with the embodiments, but the content of the present invention is not limited to the following embodiments.

[0025] Embodiment 1:

[0026] The present embodiment relates to a root-like structure bionic high-temperature resistant protective coating, in which the volume content of LMPG glass phase is 30 vol.%, and the balance is ZrB2-MoSi2 ceramic phase.

[0027] The present invention provides a method for preparing the above-mentioned root-like structure bionic high-temperature resistant protective coating, which is carried out according to the following steps:

[0028] (1) ZrB2, MoSi2, and LMPG commercial powders were used as raw materials and mixed in a volume ratio of 35:35:30 to obtain a ZrB2-MoSi2-LMPG bionic high-temperature resistant protective coating composite precursor powder with a volume ratio of 35:35:30.

[0029] (2) The composite precursor powder-wrapped carbon matrix is ​​loaded into a graphite mold, placed in a plasma low-temperature hot pressing sintering device, and the coating densification treatment is started at a densification treatment temperature of 1250°C.

[0030] (3) After the treatment is completed, the sample is taken out and polished to obtain a ZrB2-MoSi2-LMPG root-like structure bionic high-temperature resistant protective coating with a volume ratio of 35:35:30.

[0031] This embodiment provides a preferred ratio of a root-like structure bionic high temperature resistant protective coating and a preparation method thereof, wherein the cross-sectional morphology is as follows Figure 1 As shown in the figure, after a 100-min constant temperature oxidation test at 1700°C, the protection efficiency is as follows: Figure 6 As shown in the figure, it can be seen that the high temperature resistant protective coating provided in this embodiment shows obvious root-like structure bionic morphology, and shows good protective effect after 1700°C high temperature resistance test.

[0032] Embodiment 2:

[0033] The present embodiment relates to a root-like structure bionic high-temperature resistant protective coating, in which the volume content of LMPG glass phase is 32.5 vol.%, and the balance is ZrB2-MoSi2 ceramic phase.

[0034] The present invention provides a method for preparing the above-mentioned root-like structure bionic high-temperature resistant protective coating, which is carried out according to the following steps:

[0035] (1) ZrB2, MoSi2, and LMPG commercial powders were used as raw materials and mixed in a volume ratio of 33.75:33.75:32.5 to obtain a ZrB2-MoSi2-LMPG bionic high-temperature resistant protective coating composite precursor powder with a volume ratio of 33.75:33.75:32.5.

[0036] (2) The composite precursor powder-wrapped carbon matrix is ​​loaded into a graphite mold, placed in a plasma low-temperature hot pressing sintering device, and the coating densification treatment is started at a densification treatment temperature of 1275°C.

[0037] (3) After the treatment is completed, the sample is taken out and polished to obtain a ZrB2-MoSi2-LMPG root-like structure bionic high-temperature resistant protective coating with a volume ratio of 33.75:33.75:32.5.

[0038] This embodiment provides a preferred ratio of a root-like structure bionic high temperature resistant protective coating and a preparation method thereof, wherein the cross-sectional morphology is as follows Figure 2 As shown in the figure, after a 100-min constant temperature oxidation test at 1700°C, the protection efficiency is as follows: Figure 6 As shown in the figure, it can be seen that the high temperature resistant protective coating provided in this embodiment shows obvious root-like structure bionic morphology, and shows good protective effect after 1700°C high temperature resistance test.

[0039] Embodiment 3:

[0040] The present embodiment relates to a root-like structure bionic high-temperature resistant protective coating, in which the volume content of LMPG glass phase is 35 vol.%, and the balance is ZrB2-MoSi2 ceramic phase.

[0041] The present invention provides a method for preparing the above-mentioned root-like structure bionic high-temperature resistant protective coating, which is carried out according to the following steps:

[0042] (1) ZrB2, MoSi2, and LMPG commercial powders were used as raw materials and mixed in a volume ratio of 32.5:32.5:35 to obtain a ZrB2-MoSi2-LMPG bionic high-temperature resistant protective coating composite precursor powder with a volume ratio of 32.5:32.5:35.

[0043] (2) The composite precursor powder-wrapped carbon matrix is ​​loaded into a graphite mold, placed in a plasma low-temperature hot pressing sintering device, and the coating densification treatment is started at a densification treatment temperature of 1300°C.

[0044] (3) After the treatment is completed, the sample is taken out and polished to obtain a ZrB2-MoSi2-LMPG root-like structure bionic high-temperature resistant protective coating with a volume ratio of 32.5:32.5:35.

[0045] This embodiment provides a preferred ratio of a root-like structure bionic high temperature resistant protective coating and a preparation method thereof, wherein the cross-sectional morphology is as follows Figure 3 As shown in the figure, after a 100-min constant temperature oxidation test at 1700°C, the protection efficiency is as follows: Figure 6 As shown in the figure, it can be seen that the high temperature resistant protective coating provided in this embodiment shows obvious root-like structure bionic morphology, and shows good protective effect after 1700°C high temperature resistance test.

[0046] Comparative Example 1:

[0047] This comparative example relates to a conventional high temperature resistant protective coating, which does not contain LMPG glass phase and is composed entirely of ZrB2-MoSi2 ceramic phase.

[0048] This comparative example provides a method for preparing the conventional high temperature resistant protective coating as described above, which is carried out according to the following steps:

[0049] (1) Using ZrB2 and MoSi2 commercial powders as raw materials, they were mixed in a volume ratio of 50:50 to obtain a ZrB2-MoSi2 high temperature resistant protective coating composite precursor powder with a volume ratio of 50:50.

[0050] (2) The composite precursor powder-wrapped carbon matrix is ​​loaded into a graphite mold, placed in a plasma low-temperature hot pressing sintering device, and the coating densification treatment is started at a densification treatment temperature of 1300°C.

[0051] (3) After the treatment 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.

[0052] This comparative example provides a conventional high temperature resistant protective coating preferred ratio and preparation method thereof, that is, compared with Example 3, this comparative example removes the glass phase. Figure 4 As shown in the figure, after a 100-min constant temperature oxidation test at 1700°C, the protection efficiency is as follows: Figure 6 As shown in the figure, it can be seen that the high temperature resistant protective coating provided in this comparative example does not show the bionic morphology of the root-like structure. Since it does not contain a glass phase, the densification temperature of 1300°C cannot meet the effective densification sintering of the ZrB2-MoSi2 coating. The densification degree of the coating is not enough, so there are many defective holes in the morphology; compared with Example 3, the protective effect after the 1700°C high temperature test is poor.

[0053] Comparative Example 2:

[0054] This comparative example relates to an excessive root-like structure bionic high-temperature resistant protective coating, in which the volume content of LMPG glass phase is 50 vol.%, and the balance is ZrB2-MoSi2 ceramic phase.

[0055] This comparative example provides a method for preparing the above-mentioned root-like structure bionic high-temperature resistant protective coating, which is carried out according to the following steps:

[0056] (1) ZrB2, MoSi2, and LMPG commercial powders were used as raw materials and mixed in a volume ratio of 25:25:50 to obtain a ZrB2-MoSi2-LMPG bionic high-temperature resistant protective coating composite precursor powder with a volume ratio of 25:25:50.

[0057] (2) The composite precursor powder-wrapped carbon matrix is ​​loaded into a graphite mold, placed in a plasma low-temperature hot pressing sintering device, and the coating densification treatment is started at a densification treatment temperature of 1300°C.

[0058] (3) After the treatment is completed, the sample is taken out and polished to obtain a ZrB2-MoSi2-LMPG root-like structure bionic high-temperature resistant protective coating with a volume ratio of 25:25:50.

[0059] This comparative example provides a preferred ratio of an excessive root-like structure bionic high-temperature resistant protective coating and a preparation method thereof, that is, compared with Example 3, the glass phase content in this comparative example is excessive. Figure 5 As shown in the figure, after a 100-min constant temperature oxidation test at 1700°C, the protection efficiency is as follows: Figure 6 As shown in the figure, although the high temperature resistant protective coating provided in this comparative example shows a significant root-like structure bionic morphology, due to the excessive glass phase content, the glass phase is easy to soften, squeeze and overflow during the densification process of the coating, thereby causing the coating quality to deteriorate; compared with Example 3, the protective effect after the 1700°C high temperature resistance test is poor.

[0060] The present invention and its embodiments are described above, which is not restrictive. The drawings show only one embodiment of the present invention, and the actual structure is not limited thereto. In short, if ordinary technicians in the field are inspired by it and do not deviate from the purpose of the invention, they can creatively design a structure and embodiment similar to the technical solution, which should fall within the protection scope of the present invention.

Claims

1. A root-like structure bionic high temperature resistant protective coating, characterized in that: It 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 LMPG low-melting point glass phase.

2. The root-like structure bionic high temperature resistant protective coating according to claim 1, characterized in that: The volume content of the LMPG low melting point glass phase is 30-35 vol.%, and the balance is ZrB2-MoSi2 ceramic phase.

3. A method for preparing a root-like structure bionic high-temperature resistant protective coating, characterized in that: The specific steps include: 1) Mixing raw materials: Using ZrB2, MoSi2, and LMPG commercial powder as raw materials, mixing them according to volume ratio to obtain a bionic high temperature resistant protective coating composite precursor powder; 2) Densification treatment: The composite precursor powder wrapped carbon matrix is ​​loaded into a graphite mold, placed in a plasma low-temperature hot pressing sintering device, and the coating densification treatment is started; 3) Polishing: After the treatment is completed, the sample is taken out and polished to obtain a root-like structure bionic high-temperature resistant protective coating.

4. The method for preparing a root-like structure bionic high temperature resistant protective coating according to claim 3, characterized in that: In the step 1), the volume ratio of ZrB2, MoSi2 and LMPG powder raw materials is in the range of 32.5-35:32.5-35:30-35.

5. The method for preparing a root-like structure bionic high temperature resistant protective coating according to claim 3, characterized in that: The coating densification treatment temperature range in step 2) is 1250-1300°C.

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

Images