Ablation heat-proof coating applicable to high-temperature-resistant base material as well as preparation method and application of ablation heat-proof coating

Abstract

The invention relates to an ablation heat-proof coating suitable for a high-temperature-resistant base material and a preparation method and application of the ablation heat-proof coating, and belongs to the technical field of heat-proof coatings. Coating composition and proportion are optimally designed, and organic silicon resin, a curing agent with a special structure, organic filler and inorganic filler are adopted, so that the ablation heat-proof coating is prepared. The curing agent with a special structure is added and matched for use, so that reliable bonding with a base material at the high temperature of 450 DEG C can be realized, the bonding performance stability of the adhesive in a thermal environment is obviously improved, and the coating is free of bulging, pulverization and peeling after being coated on the surface of the polyimide base material, ablated for 30 minutes at the temperature of 450 DEG C and cooled to the room temperature for 10 times of circulation; in addition, the organic silicon resin prepared by adopting a chemical synthesis method has better heat resistance while keeping higher toughness, the 5% thermal weight loss temperature is 450 DEG C or above, and the bonding performance stability of the organic silicon resin in a thermal environment can be further improved through the cooperation and synergistic effect of the organic silicon resin and a curing agent with a special structure; the high-temperature adhesive force and the temperature impact resistance are more excellent.

Description

Technical Field

[0001] The invention relates to an ablative heat-resistant coating suitable for a high-temperature resistant substrate and a preparation method and application thereof, which can be used for thermal protection of the outer surface of a new generation of aircraft and belongs to the technical field of thermal protection coatings. Background Art

[0002] The new generation of aircraft has the characteristics of long flight time and high flight speed, and the surface aerodynamic heating environment is more demanding. The current aircraft structure generally uses high-temperature resistant materials such as polyimide with an operating temperature of more than 450°C. Ablative thermal protection coating is one of the mainstream solutions for external heat protection and internal heat insulation of aircraft. However, the high-temperature bonding performance of existing thermal protection coatings is only reliable below 400°C. When the substrate temperature reaches 450°C, the coating bonding reliability is greatly reduced, and large-scale debonding occurs during the ablation process. Therefore, the current substrates such as polyimide coated with thermal protection coatings have an operating temperature of no more than 400°C, which fails to give full play to the performance of high-temperature resistant structural materials, resulting in an increase in structural size and weight. Summary of the invention

[0003] The purpose of the present invention is to overcome the above-mentioned shortcomings of the prior art and to provide an ablative heat-resistant coating suitable for high-temperature resistant substrates and a preparation method and application thereof. Through the optimized design of the coating formula, silicone resin and a curing agent with a special structure as well as organic and inorganic fillers are used. The prepared heat-resistant coating is applied to the surface of the substrate and can withstand high temperatures of 450°C and above, and significantly improves the stability of its bonding performance in a hot environment. After continuous heating at 450°C for 30 minutes and 10 cycles, the coating is not powdered or detached.

[0004] The above-mentioned purpose of the present invention is mainly achieved through the following technical solutions:

[0005] An ablative heat-resistant coating suitable for a high-temperature resistant substrate, the raw materials of the coating comprising the following components in parts by mass:

[0006] 100 copies of high temperature resistant heat-proof coating

[0007] 2-5 parts of curing agent

[0008] The high temperature resistant heat-proof coating includes the following components in parts by mass:

[0009]

[0010] The molecular structure of the curing agent is shown below:

[0011]

[0012] In the above-mentioned ablative heat-resistant coating suitable for high-temperature resistant substrates, the preparation method of the curing agent includes: adding 100 parts by mass of octamethylcyclotetrasilazane and 50 to 60 parts by mass of triethoxysilane to a reaction kettle, stirring evenly, raising the temperature to 100 to 120°C, reacting for 22 to 24 hours, and obtaining the curing agent.

[0013] In the above-mentioned ablation heat-resistant coating suitable for high-temperature resistant substrates, the preparation method of the silicone resin comprises:

[0014] Vacuum and pass nitrogen, add 100 parts by mass of tetramethyldiphenyltrisiloxane and 90-100 parts by mass of vinylborosiloxane into the reactor, stir and raise the temperature to 95°C-100°C, add 1-2 parts by mass of chloroplatinic acid isopropanol solution as a catalyst, react for 5-6 hours, add 30 parts by mass of activated carbon adsorption catalyst after the reaction is completed, filter, and remove the solvent by rotary evaporation to obtain a silicone resin.

[0015] In the above-mentioned ablation heat-resistant coating suitable for high-temperature resistant substrates, the inorganic filler is one or a combination of talcum powder, kaolin powder or glass powder.

[0016] In the above-mentioned ablative heat-resistant coating suitable for high-temperature resistant substrates, the organic filler is one or a combination of phenolic powder or polyimide powder.

[0017] In the above-mentioned ablative heat-resistant coating suitable for high-temperature resistant substrates, the silicon dioxide is fumed silica with a particle size of 15 to 25 nm.

[0018] In the above-mentioned ablative heat-resistant coating suitable for high-temperature resistant substrates, the solvent is one or a combination of xylene, butyl acetate, acetone, ethyl acetate or monofluorodichloroethane.

[0019] In the above-mentioned ablative heat-resistant coating suitable for high-temperature resistant substrates, the operating temperature of the high-temperature resistant substrate is 450° C. and above.

[0020] The method for preparing the ablative heat-resistant coating suitable for high-temperature resistant substrates comprises:

[0021] The organic silicone resin, inorganic filler, organic filler, silicon dioxide and solvent are uniformly mixed, and stirred at a speed of 900 to 1100 rpm or more for more than 30 minutes in a high-speed disperser to obtain a heat-resistant coating;

[0022] The heat-resistant coating is evenly mixed with a curing agent, applied to the surface of a substrate, and cured at room temperature to obtain a heat-resistant coating.

[0023] In the above-mentioned method for preparing the ablative heat-resistant coating suitable for high-temperature resistant substrates, the coating method includes spraying, brushing, roller coating or scraping; the substrate is polyimide or titanium alloy; the coating thickness is 2 to 5 mm.

[0024] The above-mentioned ablative heat-resistant coating suitable for high-temperature resistant substrates is applied to the outer surface of aircraft.

[0025] Compared with the prior art, the present invention has at least the following beneficial effects:

[0026] (1) In the embodiment of the present invention, the composition and proportion of the coating are optimized, and silicone resin, a new structure curing agent, and organic and inorganic fillers are used. By adding the new structure curing agent, reliable bonding with the substrate under high temperature conditions of 450°C can be achieved, and the stability of its bonding performance in a hot environment can be significantly improved. The lightweight degree of the aircraft structure can also be improved and the size of the aircraft structure can be reduced. The heat-resistant coating is resistant to high temperatures above 450°C, has good high-temperature adhesion to the high-temperature resistant composite material substrate, and has good temperature shock resistance. It is coated on the surface of the polyimide substrate, ablated at 450°C for 30 minutes, cooled to room temperature, and the coating has no bulging, powdering, or peeling after 10 cycles.

[0027] (2) Compared with traditional silicone resins, the organic silicone resin prepared by chemical synthesis in the embodiment of the present invention has better heat resistance while maintaining higher toughness, and the 5% thermal weight loss temperature is above 450°C. By cooperating with a new curing agent and acting synergistically, its bonding performance stability in a thermal environment can be further improved, and it has more excellent high-temperature adhesion and temperature shock resistance. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 This is the GPC curve of the curing agent prepared in Example 1 of the present invention;

[0029] Figure 2 This is the GPC curve of the organic silicone resin prepared in Example 1 of the present invention;

[0030] Figure 3 This is the thermal weight loss curve of the high temperature resistant heat-proof coating in Example 1 of the present invention;

[0031] Figure 4 This is a morphology diagram of the high-temperature ablation-resistant heat-resistant coating in Example 1 of the present invention coated on the surface of a polyimide substrate, ablated at 450° C. for 30 minutes, cooled to room temperature, and cycled 10 times. DETAILED DESCRIPTION

[0032] The present invention is further described in detail below with reference to the accompanying drawings and specific embodiments:

[0033] The present invention provides an ablation heat-resistant coating suitable for a high-temperature resistant substrate. The raw materials of the coating include the following components in parts by mass:

[0034] 100 copies of high temperature resistant heat-proof coating

[0035] 2-5 parts of curing agent

[0036] The high temperature resistant heat-proof coating includes the following components in parts by mass:

[0037]

[0038] The molecular structure of the curing agent is as follows:

[0039]

[0040] In an optional embodiment, the preparation method of the curing agent includes: adding 100 parts by mass of octamethylcyclotetrasilane and 50 to 60 parts by mass of triethoxysilane to a reaction kettle, stirring evenly, raising the temperature to 100 to 120° C., reacting for 22 to 24 hours, and obtaining the curing agent.

[0041] (1) In an optional embodiment, the preparation method of the silicone resin includes: evacuating and passing nitrogen, adding 100 parts by mass of tetramethyldiphenyltrisiloxane and 90-100 parts by mass of vinyl borosiloxane to a reaction kettle, stirring and raising the temperature to 95°C-100°C, adding 1-2 parts by mass of chloroplatinic acid isopropanol solution as a catalyst, reacting for 5-6 hours, adding 30 parts by mass of activated carbon adsorbed platinum catalyst after the reaction, filtering, and removing the solvent by rotary evaporation to obtain a colorless, transparent, viscous liquid. Compared with traditional silicone resins, the silicone resin prepared by chemical synthesis has better heat resistance while maintaining higher toughness, and the 5% thermal weight loss temperature is above 450°C.

[0042] In an optional embodiment, the inorganic filler is one or a combination of talc powder, kaolin powder or glass powder.

[0043] In an optional embodiment, the organic filler is one or a combination of phenolic powder or polyimide powder.

[0044] In an optional embodiment, the silicon dioxide is fumed silica with a particle size of 15 to 25 nm.

[0045] In an optional embodiment, the solvent is one or a combination of xylene, butyl acetate, acetone, ethyl acetate or monofluorodichloroethane.

[0046] The high temperature resistant substrate has an operating temperature of 450°C or above and is a titanium alloy or a resin-based composite material, such as a polyimide.

[0047] The present invention provides a method for preparing an ablation heat-resistant coating suitable for a high-temperature resistant substrate, comprising:

[0048] (1) uniformly mixing an organic silicone resin, an inorganic filler, an organic filler, silicon dioxide and a solvent, stirring the mixture in a high-speed disperser at a speed of 900 to 1100 rpm for more than 30 minutes to obtain a heat-resistant coating resistant to high temperatures of 450° C.;

[0049] (2) The heat-resistant coating and the curing agent are mixed evenly, applied to the surface of the substrate, and cured at room temperature to obtain a heat-resistant coating resistant to 450° C. The coating method includes spraying, brushing, roller coating or scraping; in an optional embodiment, the coating thickness is 2 to 5 mm.

[0050] The 450°C high temperature heat-resistant coating of the present invention has good high temperature adhesion to the high temperature resistant composite material substrate and good temperature shock resistance. It is coated on the surface of the polyimide substrate, ablated at 450°C for 30 minutes, cooled to room temperature, and the coating has no bulging, powdering, or peeling after 10 cycles.

[0051] The above-mentioned ablative heat-resistant coating suitable for high-temperature resistant substrates can be applied to thermal protection of the outer surface of an aircraft.

[0052] Example 1

[0053] Add 100 parts by mass of octamethylcyclotetrasilane and 50 parts by mass of triethoxysilane into the reaction kettle, stir evenly, raise the temperature to 100°C, and react for 22 hours to obtain a curing agent. Figure 1 Shown is the GPC chart of the curing agent prepared in Example 1 of the present invention.

[0054] Vacuum and pass nitrogen, add 100 parts by mass of tetramethyldiphenyltrisiloxane and 100 parts by mass of vinyl borosiloxane to the reactor, stir and raise the temperature to 95°C, add 1 part by mass of chloroplatinic acid isopropanol solution, react for 6 hours, add 30 parts by mass of activated carbon adsorbed platinum catalyst after the reaction, filter, and remove the solvent by rotary evaporation to obtain a colorless, transparent, viscous liquid. Figure 2 Shown is the GPC curve of thermal weight loss of the silicone resin prepared in Example 1 of the present invention.

[0055] 100 g of silicone resin, 30 g of talcum powder, 30 g of phenolic powder, 30 g of silicon dioxide and 110 g of solvent were added into a high-speed disperser and stirred at a speed of 1000 rpm for 30 min to prepare a 450° C. high-temperature resistant heat-resistant coating.

[0056] Mix 200g of 450℃ heat-resistant coating with 8g of curing agent, apply it on the surface of polyimide substrate by spraying, and cure it at room temperature for more than 96h. The density of heat-resistant coating is 0.6g / m 3 , tensile strength 1.2MPa, elongation at break 15%, thermal conductivity 0.18W / mK.

[0057] like Figure 3The thermal weight loss curve of the high temperature resistant heat-resistant coating in Example 1 of the present invention is shown; there is no mass loss below 450°C. Figure 4 As shown, in this embodiment, the 450°C high temperature resistant heat-resistant coating is coated on the surface of the polyimide substrate, ablated at 450°C for 30 minutes, cooled to room temperature, and the coating has no bulging, powdering, or peeling after 10 cycles.

[0058] Example 2

[0059] 100 parts by mass of octamethylcyclotetrasilane and 55 parts by mass of triethoxysilane were added to the reaction kettle, stirred evenly, the temperature was raised to 110° C., and the reaction was carried out for 23 hours to obtain a curing agent.

[0060] Vacuum and pass nitrogen, add 100 parts by mass of tetramethyldiphenyltrisiloxane and 95 parts by mass of vinyl borosiloxane to the reactor, stir and raise the temperature to 95°C, add 1 part by mass of chloroplatinic acid isopropanol solution, react for 6 hours, add 30 parts by mass of activated carbon adsorbed platinum catalyst after the reaction, filter, and remove the solvent by rotary evaporation to obtain a colorless, transparent, viscous liquid

[0061] 100 g of silicone resin, 20 g of talcum powder, 20 g of phenolic powder, 20 g of silicon dioxide and 110 g of solvent were added into a high-speed disperser and stirred at a speed of 1000 rpm for 30 min to prepare a 450° C. high-temperature heat-resistant coating.

[0062] Mix 200g of 450℃ heat-resistant coating with 8g of curing agent, apply it on the surface of polyimide substrate by spraying, and cure it at room temperature for more than 96h. The density of heat-resistant coating is 0.58g / m 3 , tensile strength 1.25MPa, elongation at break 18%, thermal conductivity 0.17W / mK.

[0063] Example 3

[0064] 100 parts by mass of octamethylcyclotetrasilane and 60 parts by mass of triethoxysilane were added into the reaction kettle, stirred evenly, the temperature was raised to 120° C., and the reaction was carried out for 24 hours to obtain a curing agent.

[0065] Vacuum and pass nitrogen, add 100 parts by mass of tetramethyldiphenyltrisiloxane and 100 parts by mass of vinyl borosiloxane to the reactor, stir and raise the temperature to 95°C, add 1 part by mass of chloroplatinic acid isopropanol solution, react for 5 hours, add 30 parts by mass of activated carbon adsorbed platinum catalyst after the reaction, filter, and remove the solvent by rotary evaporation to obtain a colorless, transparent, viscous liquid

[0066] 100 g of silicone resin, 30 g of kaolin powder, 30 g of polyimide powder, 30 g of silicon dioxide and 110 g of solvent were added into a high-speed disperser and stirred at a speed of 1000 rpm for 30 min to prepare a 450° C. high-temperature resistant heat-resistant coating.

[0067] Mix 200g of 450℃ heat-resistant coating with 8g of curing agent, apply it on the surface of polyimide substrate by spraying, and cure it at room temperature for more than 96h. The density of heat-resistant coating is 0.56g / m 3 , tensile strength 1.1MPa, elongation at break 16%, thermal conductivity 0.17W / mK.

[0068] The above description is only the best specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by any technician familiar with the technical field within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention.

[0069] The contents not described in detail in the specification of the present invention belong to the common knowledge of the professionals in this field.

Claims

1. An ablative heat-resistant coating suitable for a high-temperature resistant substrate, characterized in that: The raw materials of the coating include the following components in parts by weight: 100 copies of high temperature resistant heat-proof coating 2-5 parts of curing agent The high temperature resistant heat-proof coating includes the following components in parts by mass: The molecular structure of the curing agent is shown below:

2. The ablative heat-resistant coating suitable for high-temperature resistant substrates according to claim 1, characterized in that: The preparation method of the curing agent comprises: adding 100 parts by mass of octamethylcyclotetrasilane and 50-60 parts by mass of triethoxysilane into a reaction kettle, stirring evenly, raising the temperature to 100-120° C., reacting for 22-24 hours, and obtaining the curing agent.

3. The ablative heat-resistant coating suitable for a high-temperature resistant substrate according to claim 1, characterized in that: The preparation method of the silicone resin comprises: Vacuum and pass nitrogen, add 100 parts by mass of tetramethyldiphenyltrisiloxane and 90-100 parts by mass of vinylborosiloxane into the reactor, stir and raise the temperature to 95°C-100°C, add 1-2 parts by mass of chloroplatinic acid isopropanol solution as a catalyst, react for 5-6 hours, add 30 parts by mass of activated carbon adsorption catalyst after the reaction is completed, filter, and remove the solvent by rotary evaporation to obtain a silicone resin.

4. The ablative heat-resistant coating suitable for a high-temperature resistant substrate according to claim 1, characterized in that: The inorganic filler is one or a combination of talcum powder, kaolin powder or glass powder.

5. The ablative heat-resistant coating suitable for high-temperature resistant substrates according to claim 1, characterized in that: The organic filler is one or a combination of phenolic powder and polyimide powder.

6. The ablative heat-resistant coating suitable for high-temperature resistant substrates according to claim 1, characterized in that: The silicon dioxide is fumed white carbon black with a particle size of 15 to 25 nm.

7. The ablative heat-resistant coating suitable for a high-temperature resistant substrate according to claim 1, characterized in that: The solvent is one or a combination of xylene, butyl acetate, acetone, ethyl acetate or monofluorodichloroethane.

8. The ablative heat-resistant coating suitable for a high-temperature resistant substrate according to claim 1, characterized in that: The high temperature resistant substrate has an operating temperature of 450° C. or above.

9. The method for preparing the ablation heat-resistant coating suitable for high-temperature resistant substrates according to any one of claims 1 to 8, characterized in that: include: The organic silicone resin, inorganic filler, organic filler, silicon dioxide and solvent are uniformly mixed, and stirred at a speed of 900 to 1100 rpm or more for more than 30 minutes in a high-speed disperser to obtain a heat-resistant coating; The heat-resistant coating is evenly mixed with a curing agent, applied to the surface of a substrate, and cured at room temperature to obtain a heat-resistant coating.

10. The method for preparing the ablative heat-resistant coating suitable for high-temperature resistant substrates according to claim 9, characterized in that: The coating method includes spraying, brushing, roller coating or scraping; The substrate is polyimide or titanium alloy; The coating thickness is 2 to 5 mm.

11. Use of the ablative heat-resistant coating suitable for high-temperature resistant substrates as claimed in any one of claims 1 to 8 on the outer surface of an aircraft.

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