An auxiliary heat-proof and "three-proof" function integrated topcoat and a preparation method thereof

Abstract

The application relates to the technical field of external heat-proof materials, and discloses an integrated topcoat with auxiliary heat-proof and three-proof functions and a preparation method, which comprises the following components in parts by weight: 50 parts of methyl vinyl MQ type silicon resin A, 5-20 parts of methyl vinyl MQ type silicon resin B, 50-70 parts of a base polymer, 1-2 parts of an additive, 15-30 parts of a reinforcing filler, 0-50 parts of a silicon resin color paste, 0.5-3 parts of a mildew inhibitor, 10-20 parts of a hot melt material / phase change material, 4-6 parts of a crosslinking agent, 0.1-0.3 parts of an inhibitor, 0.8-2.0 parts of a platinum gold catalyst and 150-300 parts of a diluent. The integrated topcoat with auxiliary heat-proof and three-proof functions is obtained by mixing and reacting the above components, can effectively improve the ablation resistance of the heat-proof material, has excellent buffering and heat-proof functions, and is widely applied in external heat-proof materials.

Description

Technical Field

[0001] This invention relates to the field of external heat protection materials technology, and in particular to an integrated topcoat with auxiliary heat protection and "three-proof" functions, as well as its preparation method. Background Technology

[0002] Spacecraft experience severe aerodynamic heating upon atmospheric reentry, making thermal protection systems crucial for preventing overheating and burn-up of the spacecraft's surface during flight. Existing thermal protection systems and materials primarily fall into two categories: non-ablative (reusable) and ablation-based. Ablation thermal protection is an active method that uses material to achieve thermal protection, offering advantages such as safety, reliability, high efficiency, and adaptability to changing flow fields. For spacecraft operating under high heat flux conditions or in environments where the thermal environment cannot be accurately predicted, ablation thermal protection is the only feasible option, and its system structure is simple. Currently, resin-based ablation thermal protection is still considered the most effective, reliable, mature, and economical thermal protection method, and it is widely used in spacecraft thermal protection systems. Among them, silicon-based heat-resistant composite materials are an important type of resin-based ablation heat-resistant materials. Most of them use silicone rubber, silicone resin, etc. as the matrix phase, and introduce lightweight functional fillers such as hollow phenolic microspheres, hollow glass microspheres, hollow ceramic microspheres, and reinforcing materials such as short-cut quartz fibers, carbon fibers, and basalt fibers to achieve low density and integrated heat insulation function. In addition, they can be cured at room temperature / heated, have good high and low temperature resistance, simple and easy-to-control molding process, and excellent ablation resistance.

[0003] Conformal coatings, in addition to providing materials with an appearance and marking, also offer protective functions such as moisture resistance, salt spray resistance, and mildew resistance. Broadly speaking, all equipment malfunctions caused by external environmental factors fall under the category of "three-proof" protection. The application of conformal coatings in aerospace vehicles is becoming increasingly widespread. Currently, the six most commonly used conformal coatings domestically and internationally are: parylene conformal coatings, polyurethane conformal coatings, acrylic resin conformal coatings, epoxy resin conformal coatings, synthetic rubber conformal coatings, and silicone conformal coatings. Poly(p-xylene) conformal coatings are mostly applied using plasma spraying, offering excellent protection, but requiring extremely high-quality equipment and raw materials. Polyurethane conformal coatings have poor resistance to yellowing and exhibit aging and embrittlement issues in high-temperature and high-humidity environments. Acrylic resin conformal coatings have high raw material costs, good adhesion, but poor resistance to light aging. Epoxy resin conformal coatings have poor flexibility, high shrinkage, and are difficult to rework. Synthetic rubber conformal coatings form a thin film on the substrate surface through solvent evaporation, providing good protection, but have extremely poor adhesion to the substrate. Silicone conformal coatings use silicone as the base material. The basic structural unit of organosilicon is composed of silicon-oxygen linkages, and the side chains are connected to various other organic groups through silicon atoms. This special composition and molecular structure, which contains both organic groups and inorganic structures, makes conformal coatings resistant to a wide range of high and low temperatures, and have excellent heat resistance, weather resistance, aging resistance, and moisture resistance. In addition, it has strong compatibility with silicone-based heat-resistant coatings (other resin topcoats have extremely poor adhesion to silicone-based heat-resistant coatings), has the best overall performance, and has excellent protective performance, making it very suitable for use in aerospace vehicles and their silicone-based heat-resistant materials.

[0004] With the rapid development of new spacecraft and increasingly higher flight speeds, resin-based ablation heat-resistant materials, subjected to high heat, high enthalpy, and prolonged oxygen exposure in aerobic environments, are prone to cracking, pulverization, and deformation. This leads to a decline in their ablation and shear resistance, a key issue that needs to be addressed. Furthermore, due to the special operating environment, spacecraft and their external heat-resistant coatings may be contaminated, corroded, and prone to mold growth under conditions such as those containing chemicals (e.g., fuel, coolant), vibration, moisture, salt spray, humidity, and high temperatures. Therefore, a protective coating is necessary to cover the surface.

[0005] Therefore, the present invention needs to provide an integrated topcoat with auxiliary heat protection and "three-proof" functions, as well as a preparation method to solve the above problems. Summary of the Invention

[0006] Based on the above, the purpose of this invention is to provide an integrated topcoat with auxiliary heat protection and "three-proof" functions, as well as a preparation method, so that the prepared topcoat can effectively improve the ablation resistance of heat protection materials and at the same time have excellent buffering heat protection function.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] A topcoat with both auxiliary heat protection and "three-proof" functions comprises the following components in parts by weight:

[0009]

[0010]

[0011] The methyl vinyl MQ type silicone resin A has a molecular weight of 4000-8000 g / mol, an M / Q repeating unit ratio of 0.6-1.0, and a vinyl content of 0.7-1.8% by mass; preferably, the methyl vinyl MQ type silicone resin A has a molecular weight of 5000-7000 g / mol, an M / Q repeating unit ratio of 0.8, and a vinyl content of 1.2-1.4% by mass;

[0012] The methyl vinyl MQ type silicone resin B has a molecular weight of 1000-2000 g / mol, an M / Q repeating unit ratio of 0.8-1.2, and a vinyl content of 2-4% by mass; preferably, the methyl vinyl MQ type silicone resin B has a molecular weight of 1000-1500 g / mol, an M / Q repeating unit ratio of 1.0, and a vinyl content of 2.5-3.5% by mass.

[0013] As a preferred embodiment of an integrated topcoat that combines auxiliary heat protection and "three-proof" functions, the base polymer is vinyl-terminated poly(dimethylsiloxane) with a viscosity of 450–2000 mPa·s and a vinyl content of 0.1–0.3% by mass; preferably, the viscosity of the base polymer is 800–1200 mPa·s and the vinyl content is 0.1–0.3% by mass.

[0014] As a preferred solution for an integrated topcoat that combines auxiliary heat protection and "three-proof" functions, the additive includes a silane coupling agent, specifically one or more of γ-glycidoxypropyltrimethoxysilane, γ-methacryloyloxypropyltrimethoxysilane, trimethylethoxysilane, methyltrimethoxysilane, and vinyltriethoxysilane; preferably, the additive is γ-glycidoxypropyltrimethoxysilane.

[0015] As a preferred solution for an integrated topcoat that combines auxiliary heat protection and "three-proof" functions, the reinforcing filler includes one or more of fumed silica and precipitated silica.

[0016] The silicone resin color paste includes one or more of the following: black, white, red, yellow, and blue silicone resin color pastes.

[0017] As a preferred solution for an integrated topcoat that combines auxiliary heat protection and "three-proof" functions, the antifungal agent includes chlorothalonil (chemical name: 2,4,5,6-tetrachloro-1,3-phenylenedionitrile), thiophanate-methyl (chemical name: 1,2-dibromo-2,4-dicyanobutane), 2,4,6-tribromophenol (chemical name: 2,4,6-tribromophenol), and methanesulfonyl tetrachloropyridine (chemical name: 2,3,5,6-tetrachloro-4-methanesulfonyl tetrachloropyridine). The fungicide is one or more of the following: acylpyridine, 2,2′-methylene-bis(4-chlorophenol) [chemical name: 2,2′-methylene-bis(4-chlorophenol)], 5-chloro-2-(2,4-dichlorophenoxy)phenol (2,4,4-trichloro-2-hydroxydiphenyl ether), chloroacetamide (chemical name: 2-chloroacetamide), and benomyl [chemical name: 1-(n-butylaminoformyl)-2-benzimidazole carbamate]; preferably, the fungicide is chlorothalonil or benomyl.

[0018] As a preferred solution for an integrated topcoat that combines auxiliary heat protection and "three-proof" functions, the hot-melt material / phase change material includes one or more of the following: glass powder that melts at 350-1000℃, quartz sand, Na2SO4 / SiO2 ceramic matrix molten salt, NaCl / SiC foam ceramic composite phase change material, low-melting-point glass powder D255 and NaCl molten salt, 4Cu-Si alloy, and silicon-aluminum eutectic alloy.

[0019] The glass powder includes one or more of molten glass powder D40, molten glass powder D45, molten glass powder D50, molten glass powder D58, molten glass powder D70, and molten glass powder D75.

[0020] The Na2SO4 content in the Na2SO4 / SiO2 ceramic-based molten salt is 50%.

[0021] The silicon-aluminum eutectic alloy includes one or more of the following: 3Al-Si, Al-8Si, Al-12Si, Al-12.5Si, Al-12.6Si, Al-13Si, Al-20Si, Al-5Si-30Cu, Al-Si-Mg, Al-11.7Si-5.16Mg, Al-26.5Cu-5Si, Al-5.2Si-28Cu-2.2Mg, Al-5.25Si / 27Cu, Al-5Si / 30Cu, and Al-13.2Si / 5Mg.

[0022] As a preferred solution for an integrated topcoat that combines auxiliary heat protection and "three-proof" functions, the platinum catalyst includes PT-5000 platinum catalyst; the diluent includes one or more of No. 120 solvent oil, ethyl acetate, and butyl acetate.

[0023] As a preferred solution for an integrated topcoat that combines auxiliary heat protection and "three-proof" functions, the crosslinking agent includes a hydrogen-containing silicone oil with a viscosity of 30-40 mPa.s and a hydrogen mass of 0.73-0.82%; the inhibitor includes one or more of methylbutyninol, ethynylcyclohexanol and 3,5-dimethyl-1-hexyn-3-ol.

[0024] A method for preparing an integrated topcoat with auxiliary heat protection and "three-proof" functions includes the following steps:

[0025] Methyl vinyl MQ type silicone resin A and methyl vinyl MQ type silicone resin B are added to the vinyl-terminated poly(dimethylsiloxane), and heated and stirred to make it a uniformly dispersed liquid.

[0026] Additives, reinforcing fillers, color paste, mildew inhibitors, and phase change materials / hot melt fillers are added in sequence, premixed and ground to disperse, and then platinum catalyst and diluent are added to obtain component A;

[0027] The inhibitor and cross-linking agent are mixed evenly to obtain component B;

[0028] Mix component A and component B evenly to obtain an integrated topcoat that combines auxiliary heat protection and "three-proof" functions.

[0029] As a preferred embodiment of the preparation method of a topcoat that integrates auxiliary heat protection and "three-proof" functions, the heating and stirring temperature is not lower than 100℃.

[0030] The beneficial effects of this invention are as follows:

[0031] The organosilicon conformal coating of the present invention is integrated with the silicon-based heat-resistant material through processes such as spraying and brushing. It can be regarded as a special continuous functional gradient composite material. The structure of the silicon-based heat-resistant composite material is designed to achieve functional zoning. Functional units such as ablation resistance, erosion resistance and oxidation resistance are introduced into the ablation surface layer of the organosilicon conformal coating, which greatly improves the heat-resistant performance of the heat-resistant material surface, realizes the continuous gradient transition of functions and the matching of material interfaces, and maximizes the role of each functional zone.

[0032] Firstly, by coordinating the oxidizing properties of each component in the conformal coating, the differences in the antioxidant properties of each component phase are controlled within a certain range. This reduces the surface roughness of the heat-resistant material during the ablation process caused by differences in the antioxidant properties of each component phase, different micro-ablation behaviors, and uneven ablation retreat, thereby improving the overall antioxidant properties of the heat-resistant material.

[0033] Secondly, the matrix at the ablation surface is a porous material. The higher the porosity of the matrix, the larger the effective contact area between the material and the oxidizing gas, and the worse the oxidation resistance of the material. Therefore, in the design of ablation composite materials, the porosity of the matrix at the ablation surface should be minimized to obtain better oxidation resistance. The organosilicon conformal coating of this invention adds silica-based quartz, low-melting-point glass powder, or silicon-containing phase change materials (PCMs) (mainly referring to silicon-containing medium-high temperature solid-liquid phase change materials, including molten salts, metals and alloys, or inorganic composites) to the matrix. Under a certain medium-high temperature range (350℃~1600℃), it changes from a solid phase to a liquid phase and flows into the pores of the ablation surface matrix, reducing the porosity and the contact area between each component phase and the oxidizing gas, thus giving the heat-resistant material better oxidation resistance. The specific mechanism of action is as follows: Figure 1 As shown.

[0034] Finally, by coordinating the oxidizing properties of each component of the conformal coating and introducing hot-melt materials or phase change materials, the two are organically combined. By utilizing the design thinking of continuous functional gradient materials, the ablation resistance of the heat-resistant material is effectively improved.

[0035] Furthermore, the presence of non-polar groups on the surface of addition-type silicone coatings results in relatively poor adhesion to the substrate, which is an inherent defect. The tackiness of the topcoat is essentially determined by the morphology of the two-phase system of the base adhesive. Before curing, a resin dispersion of appropriate molecular weight forms a very thin tack layer at the bonding interface. This tack layer can undergo viscous flow under external force, wetting the bonded layer and thus increasing the initial tack. After curing, the topcoat forms a monolithic polymer network. The relatively highly cross-linked short-chain polymer network provides overall elasticity, while the relatively loosely cross-linked long-chain polymer network provides tackiness at the interface. The silicone conformal coating of this invention also belongs to the category of flexible conformal materials. Utilizing the high strain and deformability of such materials, the silicone conformal coating is directly applied to the heat-resistant material according to an aerodynamic shape, allowing it to fully deploy during high-speed flight of a spacecraft and exert its buffering and heat-resistant function.

[0036] Based on the above mechanism, this invention, by rationally setting the ratio of high and low molecular weight silicone resins, allows these resins to work synergistically to fully wet the heat-resistant coating, increasing initial tack. Simultaneously, the coating exhibits suitable elasticity and tack, ensuring the adhesion between the topcoat and the heat-resistant coating. This achieves the integration of multiple functions and its application in resin-based ablation-type external heat-resistant materials aligns with the ongoing pursuit of lightweight heat-resistant structures in aerospace vehicles. Attached Figure Description

[0037] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments of the present invention will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the content of the embodiments of the present invention and these drawings without creative effort.

[0038] Figure 1 This is a schematic diagram of the cross-sectional process of the conformal coating ablation.

[0039] Figure 2 This is an image of the arc micro-wind tunnel ablation appearance of the sprayed topcoat test panel in Embodiment 1 of the present invention;

[0040] Figure 3 This is a view of the test plate after the ablation layer has been removed in Embodiment 1 of the present invention;

[0041] Figure 4 This is an image of the arc micro-wind tunnel ablation appearance of the sprayed topcoat test panel in Embodiment 2 of the present invention;

[0042] Figure 5 This is a view of the test plate after the ablation layer has been removed in Embodiment 2 of the present invention;

[0043] Figure 6 This is an image of the arc micro-wind tunnel ablation appearance of the sprayed topcoat test panel in Embodiment 3 of the present invention;

[0044] Figure 7 This is a view of the test plate after the ablation layer has been removed in Embodiment 3 of the present invention;

[0045] Figure 8 This is a diagram of the surface of the test panel without topcoat in the electric arc micro-wind tunnel ablation of Comparative Example 1 of this invention;

[0046] Figure 9 This is a diagram of the surface of the test panel without topcoat in the electric arc micro-wind tunnel, which is ablation surface of the test panel of Comparative Example 2 of this invention. Detailed Implementation

[0047] To facilitate understanding of the present invention, a more comprehensive description will be provided below. The present invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a thorough and complete understanding of the disclosure of the present invention. Unless otherwise defined, all technical and scientific terms used in this invention pertain to the technical field of the invention.

[0048] MQ silicone resin is an organosilicon resin composed of two types of siloxane linkages: M-linkages and Q-linkages. The M-linkage is an organic group, typically a monofunctional siloxane linkage (R3SiO2). 1 / 2One oxygen atom is shared by two silicon atoms; while the Q-unit is an inorganic group, usually a tetrafunctional siloxane unit (SiO2). 4 / 2 (One silicon atom is linked to four oxygen atoms, and each of these four oxygen atoms is in turn linked to a silicon atom.) These two types of linkages generate a three-dimensional spherical silicone ester through a co-hydrolysis-condensation reaction.

[0049] The M / Q chain segment ratio refers to the proportion of M chain segments to Q chain segments in MQ silicone resin. This ratio has a significant impact on the properties of MQ silicone resin because it determines the relative content of organic and inorganic groups, thereby affecting the mechanical strength, flexibility, weather resistance, and other physicochemical properties of MQ silicone resin.

[0050] In practical applications, the M / Q ratio is typically determined based on specific usage requirements and environmental conditions. For example, if higher mechanical strength is needed, the number of M links may be increased; if better weather resistance is required, the number of Q links may be increased. Therefore, the M / Q ratio is a very important parameter, as it directly affects the application performance and scope of MQ silicone resin.

[0051] In this invention, the ablation resistance performance test is conducted using a vinyl silicone resin-based external heat-resistant material test plate through an arc micro-wind tunnel ablation test. The test standard is GJB-7050, the micro-wind tunnel ablation time for the heat-resistant coating is 620 seconds, and the highest surface temperature is 1300 degrees Celsius. The vinyl silicone resin-based external heat-resistant material refers to an addition-type silicone resin-based external heat-resistant material. The preparation process includes selecting vinyl silicone resin, adding silane coupling agent, carbon fiber, hollow microspheres, and silicate filler, mixing them evenly, coating them on the surface of equipment or components, and then drying and curing to obtain the vinyl silicone resin-based external heat-resistant material test plate.

[0052] The present invention will be further described below through specific embodiments.

[0053] Example 1

[0054] 35 parts of methyl vinyl MQ type silicone resin A (molecular weight 6000 g / mol, M / Q repeating ratio 0.8, vinyl content 1.2%) and 15 parts of methyl vinyl MQ type silicone resin B (molecular weight 1500 g / mol, M / Q repeating ratio 1.0, vinyl content 3%) were added to 50 parts of vinyl-terminated poly(dimethylsiloxane) (viscosity 1200 mPa.s, vinyl content 0.2%), and the mixture was heated to above 100°C and stirred to form a uniformly dispersed liquid.

[0055] 1 part of γ-glycidoxypropyltrimethoxysilane, 20 parts of fumed silica, 12 parts of green silicone resin color paste, 0.2 parts of yellow silicone resin color paste, 3 parts of chlorothalonil, and 20 parts of molten glass powder D45 were added sequentially and mixed evenly. Then, the mixture was ground using a three-roll mill. Finally, 1 part of PT-5000 platinum catalyst and an appropriate amount of butyl acetate were added and dispersed evenly using a mixer to prepare component A.

[0056] Mix 0.2 parts of acetylenecyclohexanol and 4 parts of hydrogen-containing silicone oil with a viscosity of 30 mPa·s and a hydrogen content of 0.8% evenly to prepare component B;

[0057] Mix components A and B evenly to obtain an integrated topcoat with auxiliary heat protection and "three-proof" functions. When the viscosity reaches 12S using a Coat 4 cup, it can be sprayed.

[0058] Test panels were prepared by spraying with a small-scale automated spraying equipment. After curing at room temperature for 7 days, arc micro-wind tunnel ablation tests were conducted. The surface morphology is shown in the figure. Figure 2 and Figure 3 As shown.

[0059] Example 2

[0060] 35 parts of methyl vinyl MQ type silicone resin A (molecular weight 4000 g / mol, M / Q repeating ratio 0.6, vinyl content 0.7%) and 5 parts of methyl vinyl MQ type silicone resin B (molecular weight 1000 g / mol, M / Q repeating ratio 0.8, vinyl content 2%) were added to 60 parts of vinyl-terminated poly(dimethylsiloxane) (viscosity 450 mPa.s, vinyl content 0.1%), and the mixture was heated to above 100°C and stirred to form a uniformly dispersed liquid.

[0061] 2 parts of trimethylethoxysilane, 15 parts of fumed silica, 28 parts of titanium dioxide, 1.5 parts of styrax, 5 parts of molten glass powder D40, and 8 parts of low-melting-point glass powder D255 were added sequentially and initially mixed with NaCl molten salt. Then, the mixture was ground using a three-roll mill. Finally, 2 parts of PT-5000 platinum catalyst and an appropriate amount of No. 120 solvent oil were added and dispersed evenly using a mixer to prepare component A.

[0062] Mix 0.1 parts of methylbutyninol and 5 parts of hydrogen-containing silicone oil with a viscosity of 35 mPa·s and a hydrogen content of 0.73% evenly to prepare component B;

[0063] Mix components A and B evenly to obtain an integrated topcoat with auxiliary heat protection and "three-proof" functions. When the viscosity reaches 12S using a Coat 4 cup, it can be sprayed.

[0064] Test panels were prepared by spraying with a small-scale automated spraying equipment. After curing at room temperature for 7 days, arc micro-wind tunnel ablation tests were conducted. The surface morphology is shown in the figure. Figure 4 and Figure 5 As shown.

[0065] Example 3

[0066] 35 parts of methyl vinyl MQ type silicone resin A (molecular weight 8000 g / mol, M / Q repeating unit ratio 1, vinyl content 1.8%) and 20 parts of methyl vinyl MQ type silicone resin B (molecular weight 2000 g / mol, M / Q repeating unit ratio 1.2, vinyl content 4%) were added to 70 parts of vinyl-terminated poly(dimethylsiloxane) (viscosity 2000 mPa.s, vinyl content 0.3%), and the mixture was heated to above 100°C and stirred to form a uniformly dispersed liquid.

[0067] 1.5 parts of vinyltriethoxysilane, 30 parts of precipitated silica, 50 parts of rutile titanium dioxide, 0.5 parts of antifungal phenol, 3 parts of molten glass powder D45, and 7 parts of 3Al-Si eutectic alloy were added sequentially and mixed evenly. Then, the mixture was ground using a three-roll mill. Finally, 0.8 parts of PT-5000 platinum catalyst and an appropriate amount of ethyl acetate were added and dispersed evenly using a stirrer to prepare component A.

[0068] Mix 0.3 parts of 3,5-dimethyl-1-hexyn-3-ol and 6 parts of hydrogen-containing silicone oil with a viscosity of 40 mPa·s and a hydrogen content of 0.82% evenly to prepare component B;

[0069] Mix components A and B evenly to obtain an integrated topcoat with auxiliary heat protection and "three-proof" functions. When the viscosity reaches 12S using a Coat 4 cup, it can be sprayed.

[0070] Test panels were prepared by spraying with a small-scale automated spraying equipment. After curing at room temperature for 7 days, arc micro-wind tunnel ablation tests were conducted. The surface morphology is shown in the figure. Figure 6 and Figure 7 As shown.

[0071] To further illustrate the key aspects of this patent, comparative examples are provided.

[0072] Comparative Example 1

[0073] Using test panels without topcoat, the arc micro-wind tunnel ablation morphology is shown below. Figure 8 As shown.

[0074] Comparative Example 2

[0075] Using test panels without topcoat, the arc micro-wind tunnel ablation morphology is shown below. Figure 9 As shown.

[0076] like Figure 8 , Figure 9 As shown, the test panel without topcoat in the comparative example exhibited deeper cracks and larger fissures on its surface after micro-wind tunnel ablation, indicating a risk of deep cracking, blistering, and even large-scale erosion of the surface ablation layer. Furthermore, the surface morphology of the two comparative examples differed significantly after micro-wind tunnel ablation. This is because the external heat-resistant material without topcoat has poor stability or limited applicability tolerance, while topcoat improves stability or increases applicability tolerance. For example... Figure 2 , Figure 3 , Figure 6 As shown, in Examples 1, 2, and 3, the test panels using the topcoat exhibited uniformly distributed fine cracks on the micro-wind tunnel ablation surface. Through these fine cracks, the stress on the ablation surface of the heat-insulating layer was released relatively evenly, which to some extent eliminated the risk of large-scale peeling that could be caused by stress concentration. This effectively utilized the buffering and heat-insulating function of the topcoat and solved the problem of insufficient high-temperature shear resistance of the external heat-insulating material.

[0077] And as Figure 3 , Figure 5 , Figure 7 As shown, the appearance of the test plates of the three embodiments after the surface ablation layer was removed is almost without any deep cracks. This is because the presence of the three-proof functional topcoat reduces the porosity of the surface substrate, reduces the contact area between the various components of the heat-proof coating and the oxidizing gas, increases its adhesion performance, and fully verifies its buffering and heat-proofing function.

[0078] By combining the two organically, the conformal coating effectively improves the ablation resistance of heat-resistant materials and has excellent buffering and heat-resistant functions.

[0079] The above description is merely a preferred embodiment of the present invention and the technical principles employed. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described herein, and various obvious changes, readjustments, and substitutions can be made without departing from the scope of protection of the present invention. Therefore, although the present invention has been described in detail through the above embodiments, the present invention is not limited to the above embodiments. Many other equivalent embodiments may be included without departing from the concept of the present invention, and the scope of the present invention is determined by the scope of the appended claims.

Claims

1. A topcoat that combines auxiliary heat protection and "three-proof" functions, characterized in that, The components include the following parts by weight: 35 parts of methyl vinyl MQ type silicone resin A Methyl vinyl MQ type silicone resin B 5-20 parts 50-70 parts of base polymer 1-2 parts of auxiliary agent 15-30 parts of reinforcing filler Silicone resin color paste 0-50 parts 0.5-3 parts of antifungal agent 10-20 parts of hot melt material / phase change material 4-6 parts of crosslinking agent Inhibitor 0.1-0.3 parts Platinum catalyst 0.8-2.0 parts 150-300 parts of diluent; The methyl vinyl MQ type silicone resin A has a molecular weight of 4000~8000 g / mol, an M / Q repeating unit ratio of 0.6~1.0, and a vinyl content of 0.7~1.8% by mass. The methyl vinyl MQ type silicone resin B has a molecular weight of 1000~2000 g / mol, an M / Q repeating unit ratio of 0.8~1.2, and a vinyl content of 2~4% by mass. The hot-melt material / phase change material includes one or more of the following: glass powder molten at 350~1000℃, Na2SO4 / SiO2 ceramic-based molten salt, NaCl / SiC foam ceramic composite phase change material, low-melting-point glass powder D255 and NaCl molten salt, and silicon-aluminum eutectic alloy. The Na2SO4 content in the Na2SO4 / SiO2 ceramic-based molten salt is 50%. The base polymer is vinyl-terminated poly(dimethylsiloxane) with a viscosity of 450~2000 mPa·s and a vinyl content of 0.1~0.3% by mass.

2. The integrated topcoat with auxiliary heat protection and "three-proof" functions as described in claim 1, characterized in that, The adjuvant includes one or more of γ-glycidoxypropyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane, trimethylethoxysilane, methyltrimethoxysilane, and vinyltriethoxysilane.

3. The integrated topcoat with auxiliary heat protection and "three-proof" functions as described in claim 1, characterized in that, The reinforcing filler includes one or more of fumed silica and precipitated silica. The silicone resin color paste includes one or more of black, white, red, yellow, and blue silicone resin color pastes.

4. The integrated topcoat with auxiliary heat protection and "three-proof" functions as described in claim 1, characterized in that, The antifungal agent includes one or more of the following: chlorothalonil, thiophanate-methyl, 2,4,6-tribromophenol, methanesulfonyltetrachloropyridine, antifungal phenol, chloroacetamide, and benomyl.

5. The integrated topcoat with auxiliary heat protection and "three-proof" functions as described in claim 1, characterized in that, The platinum catalyst includes PT-5000 platinum catalyst; the diluent includes one or more of No. 120 solvent oil, ethyl acetate, and butyl acetate.

6. The integrated topcoat with auxiliary heat protection and "three-proof" functions as described in claim 1, characterized in that, The crosslinking agent includes a hydrogen-containing silicone oil with a viscosity of 30-40 mPa·s and a hydrogen content of 0.73-0.82%; the inhibitor includes one or more of methylbutynol, ethynylcyclohexanol and 3,5-dimethyl-1-hexyn-3-ol.

7. The method for preparing the integrated topcoat with auxiliary heat protection and "three-proof" functions as described in any one of claims 1 to 6, characterized in that, Includes the following steps: Methyl vinyl MQ type silicone resin A and methyl vinyl MQ type silicone resin B are added to the base polymer and heated and stirred to make it a uniformly dispersed liquid. Additives, reinforcing fillers, silicone resin color paste, mildew inhibitor, and phase change material / hot melt filler are added in sequence, premixed and ground to disperse, and then platinum catalyst and diluent are added to obtain component A; The inhibitor and cross-linking agent are mixed evenly to obtain component B; Mix component A and component B evenly to obtain an integrated topcoat that combines auxiliary heat protection and "three-proof" functions.

8. The preparation method of the integrated topcoat with auxiliary heat protection and "three-proof" functions according to claim 7, characterized in that, The heating and stirring temperature is not lower than 100℃.

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