A carbon-based composite material surface HfB2-MoSi2-HfSi2 high oxygen barrier coating and a preparation method thereof

Abstract

The present application relates to the field of aerospace structure new material, and particularly relates to a carbon-based composite material surface HfB2-MoSi2-HfSi2 high oxygen barrier coating and a preparation method thereof.The present application utilizes the common element B-Hf-Si-Mo bridging in HfB2-MoSi2-HfSi2 powder, realizes the high oxygen barrier strengthening of the carbon-based composite material surface HfB2-MoSi2-HfSi2 coating, overcomes the problem that the Si element has a long repair path and poor aging for the loose holes of Hf oxide 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 strengthening.The preparation method of the present application comprises the following steps: briquetting, self-propagating combustion, and densification sintering of the coating on the carbon-based material surface by using low-temperature hot pressing technology, and has the characteristics of simple preparation process and short preparation period.

Description

Technical Field

[0001] This invention relates to the field of new materials for aerospace structures, specifically a high oxygen barrier HfB2-MoSi2-HfSi2 coating on the surface of a carbon-based composite material and its preparation method. Background Technology

[0002] Carbon-based structural materials possess excellent properties such as low coefficient of thermal expansion, resistance to thermal shock, and creep resistance, making them widely used as candidate materials for spacecraft thermal protection systems and high-performance aero-engine hot-end components, which are urgently needed for national aerospace strategies. However, when temperatures exceed 400°C, oxidation sensitivity in air reduces service life, significantly limiting the development of carbon-based structural materials. To date, ultra-high temperature ceramic (UHTC) anti-oxidation coatings have proven to be the most reliable method for extending the service life of carbon-based structural materials in air.

[0003] In recent years, HfB2-SiC coatings have attracted considerable attention from researchers due to their excellent high-temperature performance. However, at high temperatures of 1700℃, the oxidation protection process of the coating inevitably involves the oxidation of its components. In particular, the volatilization of gaseous byproducts (such as B2O3) generated during the oxidation of HfB2 leads to a loose coating structure and increases its porosity. Based on the oxidative loosening of HfB2, the dynamic evolution of the oxygen-barrier structure inevitably increases the diffusion path of oxygen within the coating, thereby reducing the oxygen-barrier effect. Therefore, it is urgent to find feasible methods to suppress the loosening of the oxidation structure of HfO2 pinning points at high temperatures.

[0004] Currently, to improve the oxidation resistance of HfB2-SiC coatings, researchers both domestically and internationally have been working to enhance oxygen barrier properties by adding refractory metal silicides for synergistic oxygen barrier enhancement, aiming to improve their protective dynamic stability. Zhang Menglin et al. (Zhang Menglin. Preparation and High Oxygen Barrier Mechanism of Hafnium Boride Coating Modified by Transition Metal Silicates [D]. China University of Mining and Technology, 2022) introduced a second-phase transition metal silicide, MSi2 (M = Ta, Zr, and W), using a mechanical mixing method as a second silicon source. This improved the self-sealing and repair effect of the glass film to some extent and extended the high-temperature protective life of the coating. However, the problem of HfO2 pinning points becoming loose due to the volatilization of the low-melting-point phase after boride oxidation remains unresolved, which inevitably has an adverse effect on optimizing the oxygen barrier performance of the coating. Chen et al. (Chen Yuexing. Study on oxygen barrier performance of ZrB2 coating modified by binary transition metal silicides based on self-propagating combustion synthesis [D]. China University of Mining and Technology, 2023) effectively improved the sealing and repair performance of ZrB2 coatings after oxidation and porosity by utilizing the synergistic effect of binary transition metal silicides. However, due to the segregated distribution of boride and silicide components, the repair path between Si elements released from MoSi2 and TaSi2 and ZrB2 is still relatively long, resulting in poor timeliness in the repair process. Therefore, in order to further improve the long-term stable protection 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, as well as their preparation methods. Summary of the Invention

[0005] This invention aims to provide a high oxygen barrier HfB2-MoSi2-HfSi2 coating on the surface of carbon-based composite materials and its preparation method. By utilizing common element bridging technology, it overcomes the problems of long repair paths and poor aging time of Si element for the loose pores of Hf oxide in the prior art, thereby ensuring the stability of the coating at high temperature and promoting in-situ sealing and oxygen barrier enhancement.

[0006] To solve the above-mentioned technical problems, the present invention provides the following technical solution:

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

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

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

[0010] S1. Using Hf, B, Si and Mo as raw materials, they are uniformly mixed and then compacted into blocks by molding.

[0011] S2. Place the bulk material into a self-propagating combustion reactor and prepare HfB2-MoSi2-HfSi2 composite powder using the self-propagating combustion synthesis method;

[0012] S3. Using HfB2-MoSi2-HfSi2 composite powder as the coating powder source, after grinding, it is placed in a graphite mold, and the coating is densified and sintered on the carbon matrix surface using low temperature hot pressing technology to prepare HfB2-MoSi2-HfSi2 high oxygen barrier coating.

[0013] S4. After sintering, the product is removed and polished to obtain HfB2-MoSi2-HfSi2 high oxygen barrier coating.

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

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

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

[0017] 1. This invention utilizes a self-propagating method, using common transition metal elements of borides and silicides as bridging links to bridge the common elements B-Hf-Si-Mo in HfB2-MoSi2-HfSi2 powders. 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 common elements B-Hf-Si-Mo within the HfB2-MoSi2-HfSi2 powder, the intrinsic connections between the components in the coating are strengthened, forming a bridge between HfB2 and Si elements from HfSi2. This represents a microscopic connection between Hf and Si within the system, overcoming the challenges of long repair paths and poor aging time for Si elements in the repair of loose pores in Hf oxides in existing technologies. This ensures the stability of the coating at high temperatures and offers advantages in promoting in-situ sealing and oxygen barrier enhancement. Simultaneously, the B-Hf bridging can increase the coating's melting point, thermal conductivity, and thermal stability; the Mo-Si bridging can improve thermal stability while enhancing the coating's self-healing ability at high temperatures, thus improving the protective effect.

[0019] In summary, this invention utilizes the common element B-Hf-Si-Mo bridging in HfB2-MoSi2-HfSi2 powder to achieve high oxygen barrier strengthening of the HfB2-MoSi2-HfSi2 coating on the surface of carbon-based composite materials. This method is simple, highly effective, and overcomes the problems of long repair paths and poor aging time associated with Si in existing technologies. It ensures the stability of the coating at high temperatures and has the advantages of promoting in-situ sealing and oxygen barrier strengthening. Attached Figure Description

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

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

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

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

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

[0025] Figure 6 The image shows the surface microstructure of the HfB2-MoSi2-HfSi2 high oxygen barrier coating obtained in Example 1 of this invention after high-temperature oxidation at 1700℃.

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

[0027] Figure 8 The image shows the surface microstructure of the HfB2-MoSi2-HfSi2 high oxygen barrier coating obtained in Example 3 of this invention after high-temperature oxidation at 1700℃.

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

[0029] Figure 10The oxidation protection efficiency curves of the HfB2-MoSi2-HfSi2 high oxygen barrier coatings obtained in Examples 1-4 of this invention after high-temperature oxidation at 1700℃ are shown.

[0030] Figure 11 The X-ray diffraction phase analysis results are shown for the conventional HfB2-MoSi2-HfSi2 coatings obtained in Comparative Examples 1 and 2 of this invention.

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

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

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

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

[0035] Figure 16 The oxidation protection efficiency curves of conventional HfB2-MoSi2-HfSi2 coatings obtained in Comparative Examples 1 and 2 of this invention after high-temperature oxidation at 1700℃ are shown. Detailed Implementation

[0036] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are some embodiments of the present invention, but not all embodiments.

[0037] Example 1:

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

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

[0040] S1. Using Hf, B, Si and Mo as raw materials, they are uniformly mixed in a molar ratio of 100:196:45:94 and then compacted into blocks by molding.

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

[0042] S3. Using HfB2-MoSi2-HfSi2 composite powder as the coating powder source (powder source volume ratio of 60:38:2), after grinding, it is placed in a graphite mold, and the coating is densified and sintered on the carbon matrix surface using low temperature hot pressing technology to prepare HfB2-MoSi2-HfSi2 high oxygen barrier coating.

[0043] S4. After sintering, the product is removed and polished to obtain HfB2-MoSi2-HfSi2 high oxygen barrier coating.

[0044] This embodiment provides an optimal formulation and preparation method for a high oxygen barrier HfB2-MoSi2-HfSi2 coating on a carbon-based composite material surface. The phase structure, surface morphology, post-oxidation surface morphology, and oxidation protection efficiency curves are shown below. Figure 1 , Figure 5 , Figure 9 , Figure 10 As shown in the figure, the HfB2-MoSi2-HfSi2 high oxygen barrier coating on the surface of the carbon-based composite material provided in this embodiment exhibits good protective effect during high-temperature oxidation protection at 1700℃.

[0045] Example 2:

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

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

[0048] S1. Using Hf, B, Si and Mo as raw materials, they are uniformly mixed in a molar ratio of 100:192:42:92 and then compacted into blocks by molding.

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

[0050] S3. Using HfB2-MoSi2-HfSi2 composite powder as the coating powder source (powder source volume ratio of 60:36:4), after grinding, it is placed in a graphite mold, and the coating is densified and sintered on the carbon matrix surface using low temperature hot pressing technology to prepare HfB2-MoSi2-HfSi2 high oxygen barrier coating.

[0051] S4. After sintering, the product is removed and polished to obtain HfB2-MoSi2-HfSi2 high oxygen barrier coating.

[0052] This embodiment provides an optimal formulation and preparation method for a high oxygen barrier HfB2-MoSi2-HfSi2 coating on a carbon-based composite material surface. The phase structure, surface morphology, post-oxidation surface morphology, and oxidation protection efficiency curves are shown below. Figure 1 , Figure 4 , Figure 8 , Figure 10 As shown in the figure, the HfB2-MoSi2-HfSi2 high oxygen barrier coating on the surface of the carbon-based composite material provided in this embodiment exhibits good protective effect during high-temperature oxidation protection at 1700℃.

[0053] Example 3:

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

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

[0056] S1. Using Hf, B, Si and Mo as raw materials, they are uniformly mixed in a molar ratio of 100:188:39:89 and then compacted into blocks by molding.

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

[0058] S3. Using HfB2-MoSi2-HfSi2 composite powder as the coating powder source (powder source volume ratio of 60:34:6), after grinding, it is placed in a graphite mold, and the coating is densified and sintered on the carbon matrix surface using low temperature hot pressing technology to prepare HfB2-MoSi2-HfSi2 high oxygen barrier coating.

[0059] S4. After sintering, the product is removed and polished to obtain HfB2-MoSi2-HfSi2 high oxygen barrier coating.

[0060] This embodiment provides an optimal formulation and preparation method for a high oxygen barrier HfB2-MoSi2-HfSi2 coating on a carbon-based composite material surface. The phase structure, surface morphology, post-oxidation surface morphology, and oxidation protection efficiency curves are shown below. Figure 1 , Figure 3 , Figure 7 , Figure 10 As shown in the figure, the HfB2-MoSi2-HfSi2 high oxygen barrier coating on the surface of the carbon-based composite material provided in this embodiment exhibits good protective effect during high-temperature oxidation protection at 1700℃.

[0061] Example 4:

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

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

[0064] S1. Using Hf, B, Si and Mo as raw materials, they are uniformly mixed in a molar ratio of 100:184:36:87 and then compacted into blocks by molding.

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

[0066] S3. Using HfB2-MoSi2-HfSi2 composite powder as the coating powder source (powder source volume ratio of 60:32:8), after grinding, it is placed in a graphite mold, and the coating is densified and sintered on the carbon matrix surface using low temperature hot pressing technology to prepare HfB2-MoSi2-HfSi2 high oxygen barrier coating.

[0067] S4. After sintering, the product is removed and polished to obtain HfB2-MoSi2-HfSi2 high oxygen barrier coating.

[0068] This embodiment provides an optimal formulation and preparation method for a high oxygen barrier HfB2-MoSi2-HfSi2 coating on a carbon-based composite material surface. The phase structure, surface morphology, post-oxidation surface morphology, and oxidation protection efficiency curves are shown below. Figure 1 , Figure 2 , Figure 6 , Figure 10 As shown in the figure, the HfB2-MoSi2-HfSi2 high oxygen barrier coating on the surface of the carbon-based composite material provided in this embodiment exhibits good protective effect during high-temperature oxidation protection at 1700℃.

[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 does not utilize common element bridging. The volume ratio of the HfB2-MoSi2-HfSi2 system is 60:38:2.

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

[0072] (1) Using commercial HfB2, MoSi2 and HfSi2 powders as coating powder sources (powder source volume ratio of 60:38:2), the powders were mixed and ground and then placed in a graphite mold. The coating was densified and sintered on the carbon matrix surface 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 case study of a conventional HfB2-MoSi2-HfSi2 coating on a carbon-based composite material surface that does not utilize common element bridging. Compared to Example 1, the system composition is the same, but the coating lacks common element bridging. The phase structure, surface morphology, post-oxidation surface morphology, and oxidation protection efficiency curves are shown below. Figure 11 , Figure 12 , Figure 14 , Figure 16 As shown.

[0075] As can be seen from the figure, the sample obtained in Comparative Example 1 has pores and many defects in its oxygen barrier structure, providing channels for oxygen diffusion. Compared with Example 1, the HfB2-MoSi2-HfSi2 composite powder lacks the common element bridging of B-Hf-Si-Mo at the chemical level. That is, when Hf-B becomes porous, Si elements are not available nearby for immediate oxidation repair. In other words, the repair path for Si elements to porous pores is long, resulting in poor repair efficiency. This manifests as more pores on the surface 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 does not utilize common element bridging. The volume ratio of the HfB2-MoSi2-HfSi2 system is 60:36:4.

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

[0079] (1) Using commercial HfB2, MoSi2 and HfSi2 powders as coating powder sources (powder source volume ratio of 60:36:4), the mixtures were ground and placed in a graphite mold. Low-temperature hot pressing technology was used to densify and sinter the coating on the carbon matrix to prepare 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 case study of a conventional HfB2-MoSi2-HfSi2 coating on a carbon-based composite material surface that does not utilize common element bridging. Compared to Example 2, the system composition is the same, but the coating lacks common element bridging. The phase structure, surface morphology, post-oxidation surface morphology, and oxidation protection efficiency curves are shown below. Figure 11 , Figure 13 , Figure 15 , Figure 16 As shown.

[0082] As can be seen from the figure, the sample obtained in Comparative Example 2 has pores and many defects in its oxygen barrier structure, providing channels for oxygen diffusion. Compared with Example 2, the HfB2-MoSi2-HfSi2 composite powder lacks the common element bridging of B-Hf-Si-Mo at the chemical level. That is, when Hf-B becomes porous, Si elements are not available nearby for immediate oxidation repair. In other words, the repair path for Si elements to porous pores is long, resulting in poor repair efficiency. This manifests as more pores on the surface after oxidation and lower oxidation protection efficiency.

[0083] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A high oxygen barrier HfB2-MoSi2-HfSi2 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 bridging method of the common elements is: B-Hf-Si-Mo; The volume ratio of HfB2, MoSi2, and HfSi2 in the HfB2-MoSi2-HfSi2 high oxygen barrier coating is in the range of 60:38:2 to 60:32:

8. Its preparation includes the following steps: S1. Using Hf, B, Si, and Mo as raw materials, they are uniformly mixed and then compacted into blocks by molding; S2. Place the bulk material into a self-propagating combustion reactor and prepare HfB2-MoSi2-HfSi2 composite powder using the self-propagating combustion synthesis method; S3. Using HfB2-MoSi2-HfSi2 composite powder as the coating powder source, after grinding, it is placed in a graphite mold, and the coating is densified and sintered on the carbon matrix surface using low temperature hot pressing technology to prepare HfB2-MoSi2-HfSi2 high oxygen barrier coating. S4. After sintering, the product is removed and polished to obtain the HfB2-MoSi2-HfSi2 high oxygen barrier coating.

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 molar ratio range of each component in the Hf, B, Si, and Mo powders mentioned in step S1 is 100:196:45:94 to 100:184:36:87.

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