HfB2-MoSi2-HfSi2 high-oxygen-barrier coating on surface of carbon-based composite material and preparation method of HfB2-MoSi2-HfSi2 high-oxygen-barrier coating

Abstract

The invention relates to the field of new materials of aerospace structures, in particular to an HfB2-MoSi2-HfSi2 high-oxygen-barrier coating on the surface of a carbon-based composite material and a preparation method of the HfB2-MoSi2-HfSi2 high-oxygen-barrier coating. According to the invention, the general element B-Hf-Si-Mo in the HfB2-MoSi2-HfSi2 powder is utilized for bridging, so that the high oxygen barrier strengthening of the HfB2-MoSi2-HfSi2 coating on the surface of the carbon-based composite material is realized. The problems that in the prior art, the repairing path of the Si element for loose holes of the Hf oxide is long, and the aging is poor are solved, the stability of the coating at the high temperature is guaranteed, and the advantages of promoting in-situ sealing and oxygen blocking strengthening are achieved. The preparation method comprises the steps of briquetting, self-propagating combustion, coating densification sintering on the surface of the carbon matrix by utilizing a low-temperature hot pressing technology and the like, and has the characteristics of simple preparation process and short preparation period.

Description

Technical Field

[0001] The present invention relates to the field of new aerospace structural materials, and in particular to a HfB2-MoSi2-HfSi2 high oxygen barrier coating on the surface of a carbon-based composite material and a preparation method thereof. Background Art

[0002] Carbon-based structural materials have excellent properties such as low thermal expansion coefficient, resistance to thermal shock, and creep resistance, and are widely used as candidate materials for spacecraft thermal protection systems and high-performance aircraft engine hot end components that are urgently needed in the national aviation strategy. However, when the temperature exceeds 400°C, the oxidation sensitivity in the air reduces the service life, greatly limiting the development of carbon structural materials. So far, ultra-high temperature ceramic (UHTC) anti-oxidation coatings have been proven to be the most reliable way to extend the service life of carbon-based structural materials in air.

[0003] In recent years, HfB2-SiC coatings have attracted the attention of many scholars due to their excellent high-temperature performance. However, under high-temperature environments of 1700°C, the oxidation protection process of the coating is inevitably accompanied by the oxidation of its components. In particular, the volatilization of gas byproducts (such as B2O3) produced during the oxidation of HfB2 leads to a loose coating structure and increases its porosity. Based on the oxidation loosening of HfB2, the dynamic evolution of the oxygen barrier structure inevitably increases the diffusion path of oxygen inside the coating, thereby reducing the oxygen barrier effect. Therefore, it is urgent to find a feasible method to inhibit the loosening of the oxidation structure of HfO2 pinning points at high temperatures.

[0004] At present, in order to improve the antioxidant properties of HfB2-SiC coatings, researchers at home and abroad have added refractory metal silicides to modify them for synergistic oxygen barrier enhancement in order to improve their dynamic stability of protection. Zhang Menglin et al. (Zhang Menglin. Preparation and high oxygen barrier mechanism of transition metal silicide modified hafnium boride coating [D]. China University of Mining and Technology, 2022) introduced the second phase transition metal silicide MSi2 (M = Ta, Zr and W) by mechanical mixing method, and used it as the second silicon source, which improved the self-sealing repair effect of the glass film to a certain extent and extended the high temperature protection life of the coating. However, the problem of loosening of HfO2 pinning points caused by the volatilization of the low melting point phase after boride oxidation has not been effectively solved, which will inevitably have an adverse effect on the optimization of the oxygen barrier performance of the coating. Chen Yuexing et al. (Chen Yuexing. Research on oxygen barrier properties of binary transition metal silicide modified ZrB2 coating based on self-propagating combustion synthesis [D]. China University of Mining and Technology, 2023) effectively improved the sealing and repair performance of ZrB2 coating after oxidation pore formation by utilizing the synergistic effect of binary transition metal silicide. However, due to the segregated distribution of boride and silicide components, the repair path between the Si element released by MoSi2 and TaSi2 and ZrB2 is still relatively long, resulting in poor timeliness during the repair process. Therefore, in order to further improve the long-term stable protection requirements of oxygen barrier coatings at ultra-high temperatures, there is an urgent need for oxygen barrier coatings with strong self-healing timeliness and high protection efficiency and their preparation methods. Summary of the invention

[0005] The present invention aims to provide a HfB2-MoSi2-HfSi2 high oxygen barrier coating on the surface of a carbon-based composite material and a preparation method thereof, and utilizes common element bridging technology to overcome the difficulties in the prior art that the Si element has a long repair path and poor aging for the loose pores of Hf oxides, thereby ensuring the stability of the coating at high temperatures and promoting in-situ sealing and oxygen barrier enhancement.

[0006] In order to solve the above technical problems, the technical solutions provided by the present invention are as follows:

[0007] A HfB2-MoSi2-HfSi2 high oxygen barrier coating on the surface of a carbon-based composite material. The coating is a multiphase coating bridged by common elements, and the common elements are bridged in the form of B-Hf-Si-Mo.

[0008] As an improvement, the volume ratio range of HfB2, MoSi2 and HfSi2 in the HfB2-MoSi2-HfSi2 high oxygen barrier coating is: 60:38:2 to 60:32:8.

[0009] The present invention also discloses a method for preparing a HfB2-MoSi2-HfSi2 high oxygen barrier coating on the surface of a carbon-based composite material, comprising the following steps:

[0010] S1. Take Hf, B, Si and Mo as raw materials, mix them evenly and compact them into blocks by molding.

[0011] S2. The block is placed in a self-propagating combustion reactor, and HfB2-MoSi2-HfSi2 composite powder is prepared by self-propagating combustion synthesis method;

[0012] S3. Using HfB2-MoSi2-HfSi2 composite powder as the coating powder source, grinding it into a graphite mold, and using low-temperature hot pressing technology to densify and sinter the coating on the surface of the carbon substrate to prepare HfB2-MoSi2-HfSi2 high oxygen barrier coating;

[0013] S4. After sintering, take out the product and polish it to obtain a HfB2-MoSi2-HfSi2 high oxygen barrier coating.

[0014] As an improvement, the molar ratio range of Hf, B, Si and Mo powders described in step S1 is: 100:196:45:94 to 100:184:36:87.

[0015] As an improvement, the volume ratio range of HfB2, MoSi2, and HfSi2 in the coating powder source described in step S3 is: 60:38:2 to 60:32:8.

[0016] Compared with the prior art, the present invention has the following beneficial effects:

[0017] 1. The present invention utilizes a self-propagating method and uses common transition metal elements of borides and silicides as a bridging link to bridge the common elements B-Hf-Si-Mo in HfB2-MoSi2-HfSi2 powder. The preparation process is simple, the preparation cycle is short, and the prepared coating has a good protective effect.

[0018] 2. Based on the bridging of the common elements B-Hf-Si-Mo in the HfB2-MoSi2-HfSi2 powder, the internal connection between the components in the coating is strengthened, forming a bridge between HfB2 and the Si element from HfSi2, that is, a microscopic connection between Hf-Si in the system, which overcomes the problem of long repair path and poor aging of the loose holes of Hf oxide by Si elements in the prior art, ensures the stability of the coating at high temperatures, and has the advantages of promoting in-situ sealing and oxygen barrier strengthening. At the same time, the bridging of B and Hf can improve the melting point, thermal conductivity and thermal stability of the coating; the bridging of Mo and Si can improve the self-healing ability of the coating at high temperatures while improving thermal stability, thereby improving the protective effect.

[0019] In summary, the present invention utilizes the common elements B-Hf-Si-Mo in HfB2-MoSi2-HfSi2 powders to bridge and achieve high oxygen barrier enhancement of HfB2-MoSi2-HfSi2 coating on the surface of carbon-based composite materials. This method has simple process and significant effect, and overcomes the problem of long repair path and poor aging of loose holes by Si element in the prior art, ensures the stability of the coating at high temperature, and has the advantages of promoting in-situ sealing and oxygen barrier enhancement. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 These are the X-ray diffraction phase analysis results of the HfB2-MoSi2-HfSi2 high oxygen barrier coatings obtained in Examples 1 to 4 of the present invention.

[0021] Figure 2 This is a surface microscopic morphology of the HfB2-MoSi2-HfSi2 high oxygen barrier coating obtained in Example 1 of the present invention.

[0022] Figure 3 This is a surface microscopic morphology of the HfB2-MoSi2-HfSi2 high oxygen barrier coating obtained in Example 2 of the present invention.

[0023] Figure 4 This is a surface microscopic morphology of the HfB2-MoSi2-HfSi2 high oxygen barrier coating obtained in Example 3 of the present invention.

[0024] Figure 5 This is a surface microscopic morphology of the HfB2-MoSi2-HfSi2 high oxygen barrier coating obtained in Example 4 of the present invention.

[0025] Figure 6 This is a surface microscopic morphology of the HfB2-MoSi2-HfSi2 high oxygen barrier coating obtained in Example 1 of the present invention after high-temperature oxidation at 1700°C.

[0026] Figure 7 This is a surface microscopic morphology of the HfB2-MoSi2-HfSi2 high oxygen barrier coating obtained in Example 2 of the present invention after high-temperature oxidation at 1700°C.

[0027] Figure 8 This is a surface microscopic morphology of the HfB2-MoSi2-HfSi2 high oxygen barrier coating obtained in Example 3 of the present invention after high-temperature oxidation at 1700°C.

[0028] Fig. 9 This is a surface microscopic morphology of the HfB2-MoSi2-HfSi2 high oxygen barrier coating obtained in Example 4 of the present invention after high-temperature oxidation at 1700°C.

[0029] Fig.10This is the oxidation protection efficiency curve of the HfB2-MoSi2-HfSi2 high oxygen barrier coating obtained in Examples 1 to 4 of the present invention after high-temperature oxidation at 1700°C.

[0030] Fig.11 These are the X-ray diffraction phase analysis results of the conventional HfB2-MoSi2-HfSi2 coatings obtained in Comparative Examples 1 to 2 of the present invention.

[0031] Fig.12 This is a surface microscopic morphology of the conventional HfB2-MoSi2-HfSi2 coating obtained in Comparative Example 1 of the present invention.

[0032] Fig.13 This is a surface microscopic morphology of the conventional HfB2-MoSi2-HfSi2 coating obtained in Comparative Example 2 of the present invention.

[0033] Fig.14 This is a surface microscopic morphology of the conventional HfB2-MoSi2-HfSi2 coating obtained in Comparative Example 1 of the present invention after high-temperature oxidation at 1700°C.

[0034] Fig.15 This is a surface microscopic morphology of the conventional HfB2-MoSi2-HfSi2 coating obtained in Comparative Example 2 of the present invention after high-temperature oxidation at 1700°C.

[0035] Fig.16 This is the oxidation protection efficiency curve of the conventional HfB2-MoSi2-HfSi2 coating obtained in Comparative Examples 1 to 2 of the present invention after high-temperature oxidation at 1700°C. DETAILED DESCRIPTION

[0036] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in combination with the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments.

[0037] Embodiment 1:

[0038] The carbon-based composite material surface HfB2-MoSi2-HfSi2 high oxygen barrier coating involved in this embodiment has a volume ratio of HfB2-MoSi2-HfSi2 system of 60:38:2, and a common element bridging mode of B-Hf-Si-Mo.

[0039] The preparation method of this embodiment comprises the following steps:

[0040] S1. Take Hf, B, Si and Mo as raw materials, mix them evenly in a molar ratio of 100:196:45:94 and compact them into blocks by molding.

[0041] S2. Place the block into a self-propagating combustion reactor, adjust the molybdenum wire access voltage, and prepare HfB2-MoSi2-HfSi2 composite powder using a self-propagating combustion synthesis method.

[0042] S3. Use HfB2-MoSi2-HfSi2 composite powder as the coating powder source (the powder source volume ratio is 60:38:2), grind it and put it into a graphite mold, use low-temperature hot pressing technology to densify and sinter the coating on the surface of the carbon matrix, and prepare HfB2-MoSi2-HfSi2 high oxygen barrier coating.

[0043] S4. After sintering, take out the product and polish it to obtain a HfB2-MoSi2-HfSi2 high oxygen barrier coating.

[0044] This embodiment provides a preferred ratio of HfB2-MoSi2-HfSi2 high oxygen barrier coating on the surface of carbon-based composite material and a preparation method thereof, wherein the phase structure, surface morphology, surface morphology after oxidation, and oxidation protection efficiency curve are respectively as follows: Figure 1 , Figure 5 , Fig. 9 , Fig.10 As shown in the figure, it can be seen that the HfB2-MoSi2-HfSi2 high oxygen barrier coating on the surface of the carbon-based composite material provided in this embodiment shows a good protective effect in the 1700°C high temperature oxidation protection process.

[0045] Embodiment 2:

[0046] The carbon-based composite material surface HfB2-MoSi2-HfSi2 high oxygen barrier coating involved in this embodiment has a volume ratio of HfB2-MoSi2-HfSi2 system of 60:36:4, and the common element bridging mode is B-Hf-Si-Mo.

[0047] The preparation method of this embodiment comprises the following steps:

[0048] S1. Take Hf, B, Si and Mo as raw materials, mix them evenly in a molar ratio of 100:192:42:92 and compact them into blocks by molding.

[0049] S2. Place the block into a self-propagating combustion reactor, adjust the molybdenum wire access voltage, and prepare HfB2-MoSi2-HfSi2 composite powder using a self-propagating combustion synthesis method.

[0050] S3. Use HfB2-MoSi2-HfSi2 composite powder as the coating powder source (the powder source volume ratio is 60:36:4), grind it and put it into a graphite mold, use low-temperature hot pressing technology to densify and sinter the coating on the surface of the carbon matrix, and prepare HfB2-MoSi2-HfSi2 high oxygen barrier coating.

[0051] S4. After sintering, take out the product and polish it to obtain a HfB2-MoSi2-HfSi2 high oxygen barrier coating.

[0052] This embodiment provides a preferred ratio of HfB2-MoSi2-HfSi2 high oxygen barrier coating on the surface of carbon-based composite material and a preparation method thereof, wherein the phase structure, surface morphology, surface morphology after oxidation, and oxidation protection efficiency curve are respectively as follows: Figure 1 , Figure 4 , Figure 8 , Fig.10 As shown in the figure, it can be seen that the HfB2-MoSi2-HfSi2 high oxygen barrier coating on the surface of the carbon-based composite material provided in this embodiment shows a good protective effect in the 1700°C high temperature oxidation protection process.

[0053] Embodiment 3:

[0054] The carbon-based composite material surface HfB2-MoSi2-HfSi2 high oxygen barrier coating involved in this embodiment has a volume ratio of HfB2-MoSi2-HfSi2 system of 60:34:6, and the common element bridging mode is B-Hf-Si-Mo.

[0055] The preparation method of this embodiment comprises the following steps:

[0056] S1. Take Hf, B, Si and Mo as raw materials, mix them evenly in a molar ratio of 100:188:39:89 and compact them into blocks by molding.

[0057] S2. Place the block into a self-propagating combustion reactor, adjust the molybdenum wire access voltage, and prepare HfB2-MoSi2-HfSi2 composite powder using a self-propagating combustion synthesis method.

[0058] S3. Use HfB2-MoSi2-HfSi2 composite powder as the coating powder source (the powder source volume ratio is 60:34:6), grind it and put it into a graphite mold, use low-temperature hot pressing technology to densify and sinter the coating on the surface of the carbon matrix, and prepare HfB2-MoSi2-HfSi2 high oxygen barrier coating.

[0059] S4. After sintering, take out the product and polish it to obtain a HfB2-MoSi2-HfSi2 high oxygen barrier coating.

[0060] This embodiment provides a preferred ratio of HfB2-MoSi2-HfSi2 high oxygen barrier coating on the surface of carbon-based composite material and a preparation method thereof, wherein the phase structure, surface morphology, surface morphology after oxidation, and oxidation protection efficiency curve are respectively as follows: Figure 1 , Figure 3 , Figure 7 , Fig.10 As shown in the figure, it can be seen that the HfB2-MoSi2-HfSi2 high oxygen barrier coating on the surface of the carbon-based composite material provided in this embodiment shows a good protective effect in the 1700°C high temperature oxidation protection process.

[0061] Embodiment 4:

[0062] The carbon-based composite material surface HfB2-MoSi2-HfSi2 high oxygen barrier coating involved in this embodiment has a volume ratio of HfB2-MoSi2-HfSi2 system of 60:32:8, and the common element bridging mode is B-Hf-Si-Mo.

[0063] The preparation method of this embodiment comprises the following steps:

[0064] S1. Take Hf, B, Si and Mo as raw materials, mix them evenly in a molar ratio of 100:184:36:87 and compact them into blocks by molding.

[0065] S2. Place the block into a self-propagating combustion reactor, adjust the molybdenum wire access voltage, and prepare HfB2-MoSi2-HfSi2 composite powder using a self-propagating combustion synthesis method.

[0066] S3. Use HfB2-MoSi2-HfSi2 composite powder as the coating powder source (the powder source volume ratio is 60:32:8), grind it and put it into a graphite mold, use low-temperature hot pressing technology to densify and sinter the coating on the surface of the carbon matrix, and prepare HfB2-MoSi2-HfSi2 high oxygen barrier coating.

[0067] S4. After sintering, take out the product and polish it to obtain a HfB2-MoSi2-HfSi2 high oxygen barrier coating.

[0068] This embodiment provides a preferred ratio of HfB2-MoSi2-HfSi2 high oxygen barrier coating on the surface of carbon-based composite material and a preparation method thereof, wherein the phase structure, surface morphology, surface morphology after oxidation, and oxidation protection efficiency curve are respectively as follows: Figure 1 , Figure 2 , Figure 6 , Fig.10 As shown in the figure, it can be seen that the HfB2-MoSi2-HfSi2 high oxygen barrier coating on the surface of the carbon-based composite material provided in this embodiment shows a good protective effect in the 1700°C high temperature oxidation protection process.

[0069] Comparative Example 1:

[0070] The HfB2-MoSi2-HfSi2 coating on the surface of the carbon-based composite material involved in this comparative example is a conventional HfB2-MoSi2-HfSi2 coating that is not bridged by common elements, and the volume ratio of the HfB2-MoSi2-HfSi2 system is 60:38:2.

[0071] The preparation method of this comparative example comprises the following steps:

[0072] (1) Commercial powders of HfB2, MoSi2, and HfSi2 were used as coating powder sources (the powder source volume ratio was 60:38:2). After the mixed materials were ground, they were placed in a graphite mold. The coating was densified and sintered on the surface of the carbon matrix using low-temperature hot pressing technology to prepare a conventional HfB2-MoSi2-HfSi2 coating.

[0073] (2) After sintering, the product is taken out and polished to obtain a conventional HfB2-MoSi2-HfSi2 coating.

[0074] This comparative example provides a comparative example of a conventional HfB2-MoSi2-HfSi2 coating on the surface of a carbon-based composite material without common element bridging. That is, compared with Example 1, the system ratio is the same, but there is no common element bridging inside the coating. Among them, the phase structure, surface morphology, surface morphology after oxidation, and oxidation protection efficiency curve are shown as follows: Fig.11 , Fig.12 , Fig.14 , Fig.16 shown.

[0075] It can be seen from the figure that the sample obtained in comparative example 1 has pores and many defects in the oxygen barrier structure, which provides a channel for oxygen diffusion. Compared with Example 1, since the HfB2-MoSi2-HfSi2 composite powder lacks the common element bridge of B-Hf-Si-Mo at the chemical level, that is, when Hf-B is loosened, there is no Si element nearby for oxidation repair in the first time, that is, the repair path of the loose holes by the Si element is long, which leads to poor repair time, which is manifested as more surface holes after oxidation and lower oxidation protection efficiency.

[0076] Comparative Example 2:

[0077] The HfB2-MoSi2-HfSi2 coating on the surface of the carbon-based composite material involved in this comparative example is a conventional HfB2-MoSi2-HfSi2 coating that is not bridged by common elements, and the volume ratio of the HfB2-MoSi2-HfSi2 system is 60:36:4.

[0078] The preparation method of this comparative example comprises the following steps:

[0079] (1) Using HfB2, MoSi2, and HfSi2 commercial powders as coating powder sources (the powder source volume ratio is 60:36:4), the mixed materials are ground and placed in a graphite mold, and the coating is densified and sintered on the surface of the carbon matrix using low-temperature hot pressing technology to prepare a conventional HfB2-MoSi2-HfSi2 coating;

[0080] (2) After sintering, the product is taken out and polished to obtain a conventional HfB2-MoSi2-HfSi2 coating.

[0081] This comparative example provides a comparative example of a conventional HfB2-MoSi2-HfSi2 coating on the surface of a carbon-based composite material without common element bridging. That is, compared with Example 2, the system ratio is the same, but there is no common element bridging inside the coating. Among them, the phase structure, surface morphology, surface morphology after oxidation, and oxidation protection efficiency curve are shown as follows: Fig.11 , Fig.13 , Fig.15 , Fig.16 shown.

[0082] It can be seen from the figure that the sample obtained in comparative example 2 has pores and many defects in the structural oxygen barrier, which provides a channel for oxygen diffusion. Compared with Example 2, since the HfB2-MoSi2-HfSi2 composite powder lacks the common element bridge of B-Hf-Si-Mo at the chemical level, that is, when Hf-B is loosened, there is no Si element nearby for oxidation repair in the first time, that is, the repair path of the loose holes by the Si element is long, which leads to poor repair time, which is manifested as more surface holes after oxidation and lower oxidation protection efficiency.

[0083] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A HfB2-MoSi2-HfSi2 high oxygen barrier coating on the surface of a carbon-based composite material, characterized in that: The coating is a multiphase coating bridged by common elements, and the common elements are bridged in the form of B-Hf-Si-Mo.

2. The HfB2-MoSi2-HfSi2 high oxygen barrier coating on the surface of a carbon-based composite material according to claim 1, characterized in that: The volume ratio range of HfB2, MoSi2 and HfSi2 in the HfB2-MoSi2-HfSi2 high oxygen barrier coating is: 60:38:2 to 60:32:

8.

3. A method for preparing a HfB2-MoSi2-HfSi2 high oxygen barrier coating on the surface of a carbon-based composite material according to claim 1, characterized in that: The steps include: S1. Take Hf, B, Si and Mo as raw materials, mix them evenly and compact them into blocks by molding. S2. The block is placed in a self-propagating combustion reactor, and HfB2-MoSi2-HfSi2 composite powder is prepared by self-propagating combustion synthesis method; S3. Using HfB2-MoSi2-HfSi2 composite powder as the coating powder source, grinding it into a graphite mold, and using low-temperature hot pressing technology to densify and sinter the coating on the surface of the carbon substrate to prepare HfB2-MoSi2-HfSi2 high oxygen barrier coating; S4. After sintering, take out the product and polish it to obtain a HfB2-MoSi2-HfSi2 high oxygen barrier coating.

4. The method for preparing a HfB2-MoSi2-HfSi2 high oxygen barrier coating on the surface of a carbon-based composite material according to claim 3, characterized in that: The molar ratio of each component in the Hf, B, Si, and Mo powders described in step S1 is in the range of 100:196:45:94 to 100:184:36:

87.

5. The method for preparing a HfB2-MoSi2-HfSi2 high oxygen barrier coating on the surface of a carbon-based composite material according to claim 3, characterized in that: The volume ratio range of HfB2, MoSi2 and HfSi2 in the coating powder source described in step S3 is: 60:38:2 to 60:32:8.

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