A primer for aerospace vehicle outer protective coatings, methods of making and using same

Abstract

The application belongs to the field of aerospace coating, and particularly relates to a primer for the outer protective coating of a spacecraft, a preparation method and a use method. The primer comprises the following raw materials in parts by weight: tackifier 2-8 parts, alkyl silicone oil 5-10 parts and diluent 80-90 parts. The primer contains a large amount of inorganic / organic groups, can form a strong chemical bond with the substrate, and improve the adhesion of the coating. Meanwhile, the primer can also have interpenetration synergy with the silicone resin in the coating to form a PIN network structure, further improving the adhesion. In addition, the primer can also be activated to generate silanol under the condition of water molecules, and hydrolysis and bonding with inorganic media to form a firm silicon-oxygen bond. That is, the primer has inorganic / organic dual properties, is applied between organic and inorganic materials, and forms a micro organic-inorganic interface between the two, thereby enhancing the adhesion.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of aerospace coating, and particularly relates to a primer for an outer protective coating of a spacecraft, a preparation method and a use method thereof. BACKGROUND

[0002] The outer protective coating of a spacecraft is usually made of carbon fiber composite material, metal material, ceramic material or thermoplastic resin, and is often a spacecraft outer protective coating mainly made of silicone rubber. During high-speed flight, the spacecraft will generate aerodynamic heating due to air friction, which will cause the outer protective coating of the spacecraft shell to be detached from the shell base material. Therefore, before spraying the outer protective coating of the spacecraft, a primer needs to be sprayed to increase the adhesion strength.

[0003] However, the existing primer has defects in adhesion strength, aging resistance and high temperature resistance. Therefore, the present application is proposed based on the above. SUMMARY

[0004] In order to solve the problems existing in the prior art, the present application provides a primer for an outer protective coating of a spacecraft, which comprises the following raw materials by weight: tackifier 2-8 parts, alkyl silicone oil 5-10 parts and diluent 80-90 parts.

[0005] Preferably, the primer for the outer protective coating of the spacecraft comprises the following raw materials by weight: tackifier 5 parts, alkyl silicone oil 7.5 parts and diluent 85 parts.

[0006] Preferably, the tackifier is a silicon coupling agent, and the silicon coupling agent is one of KH550, KH560 and KH792.

[0007] The structure of the alkyl silicone oil is shown in formula I:

[0008]

[0009] wherein R1 and R2 are hydrocarbon groups or POSS structures, the hydrocarbon groups are branched alkyl groups or aryl groups with 1-18 carbon atoms; n=20-50, and is an integer.

[0010] Preferably, the diluent is one of n-heptane, ethyl acetate, isopropyl alcohol and dimethylbenzene, or a combination of two or more thereof.

[0011] Based on the same technical concept, another scheme of the present application provides a preparation method of a primer for an outer protective coating of a spacecraft, which comprises the following steps:

[0012] The tackifier, the alkyl silicone oil and the diluent are mixed and stirred uniformly.

[0013] Preferably, the stirring speed is 600-800 r / min, and the stirring time is 10-15 min.

[0014] Based on the same technical concept, another aspect of the present application provides a method for using a primer for an outer protective coating of a spacecraft, which comprises the following steps:

[0015] Spraying the primer on the surface of the substrate, waiting for 20-30 min, and then spraying the outer protective coating of the spacecraft.

[0016] The present application has the following advantages:

[0017] The primer for the outer protective coating of the spacecraft contains a large amount of inorganic / organic groups, which can form strong chemical bonds with the substrate, thereby improving the adhesion of the coating. Meanwhile, the primer can also form a PIN network structure with the silicon resin in the coating through interpenetration and synergistic effect, thereby further improving the adhesion. In addition, the primer can also be activated to generate silanol under the condition of water molecules, and the silanol can be hydrolyzed and bonded with inorganic media to form a strong silicon-oxygen bond. That is, the primer has inorganic / organic dual properties, and can be applied between organic and inorganic materials to form a micro organic-inorganic interface between the two, thereby enhancing the adhesion. BRIEF DESCRIPTION OF DRAWINGS

[0018] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed to be used in the embodiments or prior art description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor.

[0019] Figure 1 is a photograph of the test piece before heating in the muffle furnace in the muffle furnace heating test.

[0020] Figure 2 is a photograph of the test piece after heating in the muffle furnace in the muffle furnace heating test.

[0021] Figure 3 is a photograph of test 1 in the flight test of the outer protective coating of the spacecraft.

[0022] Figure 4 is a photograph of test 3 in the flight test of the outer protective coating of the spacecraft. DETAILED DESCRIPTION

[0023] In order to make the objects, technical solutions and advantages of the present application clearer, the technical solutions of the present application will be described in detail below. Obviously, the described embodiments are only some of the embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work belong to the scope of protection of the present application.

[0024] Embodiment 1

[0025] The present embodiment provides a preparation method and a use method of a primer for an outer protective coating of a spacecraft, and the preparation method is as follows:

[0026] Mix 20g of KH550, 100g of alkyl silicone oil and 800g of n-heptane, and stir at a rotating speed of 600r / min for 15min.

[0027] The use method is as follows:

[0028] Spray the above primer on the surface of the substrate, wait for 20min, and then spray the outer protective coating of the spacecraft.

[0029] Embodiment 2

[0030] The present embodiment provides a preparation method and a use method of a primer for an outer protective coating of a spacecraft, and the preparation method is as follows:

[0031] Mix 80g of KH560, 50g of alkyl silicone oil and 900g of isopropyl alcohol, and stir at a rotating speed of 800r / min for 10min.

[0032] The use method is as follows:

[0033] Spray the above primer on the surface of the substrate, wait for 30min, and then spray the outer protective coating of the spacecraft.

[0034] Embodiment 3

[0035] The present embodiment provides a preparation method and a use method of a primer for an outer protective coating of a spacecraft, and the preparation method is as follows:

[0036] Mix 50g of KH792, 75g of alkyl silicone oil and 850g of dimethylbenzene, and stir at a rotating speed of 700r / min for 12min.

[0037] The use method is as follows:

[0038] Spray the above primer on the surface of the substrate, wait for 25min, and then spray the outer protective coating of the spacecraft.

[0039] Verification comparative example

[0040] To show the effect of the primer for silicon-based outer protective coating according to the present application, the following tests were conducted (mechanical properties refer to QJ 2038.2-1991, flight test refer to GJB 7050-2010) :

[0041] (1) Mechanical property test

[0042] The tensile shear test sample was prepared according to the national standard QJ 2038.2-1991, and the mechanical properties of the sample were determined by using a microcomputer-controlled electronic universal testing machine with a specification of CMT4104.

[0043] The test piece for preparing the tensile shear test sample was an aluminum alloy test piece of model 2A12-T4 and a carbon fiber composite test piece.

[0044] Test 1 was without primer between the silicon-based outer protective coating and the aluminum alloy test piece; test 2 was without primer between the silicon-based outer protective coating and the carbon fiber composite test piece; test 3 was with primer (prepared in Example 3) between the silicon-based outer protective coating and the aluminum alloy test piece; and test 4 was with primer (prepared in Example 3) between the silicon-based outer protective coating and the carbon fiber composite test piece.

[0045] The test results are shown in Table 1:

[0046] Table 1

[0047] Group Tensile Shear Strength / MPa Mode of Failure Test 1 0.7 Interfacial Failure Test 2 0.62 Interfacial Failure Test 3 1.67 Bulk Failure Test 4 1.5 Bulk Failure

[0048] As shown in Table 1, the primer for silicon-based outer protective coating prepared according to the present application greatly improves the bonding strength compared with the silicon-based outer protective coating without primer, and can meet the performance requirements of the bonding between the outer protective coating of a spacecraft and the substrate.

[0049] (2) Muffle furnace heating test

[0050] In this test, a 100mm x 100mm carbon fiber test piece was used, the thickness of the outer protective coating of a spacecraft was 4.0mm, the test temperature of the test piece in the muffle furnace was 200℃, the heating time was 2h (the timing started when the muffle furnace reached 200℃), and after the test, a shovel knife was used to detect the bonding condition at the interface after using the primer, and the results are shown in Table 2.

[0051] Table 2

[0052] Test Piece Before Muffle Heating Test Piece After Muffle Heating See Figure 1 See Figure 2

[0053] From Figure 1 , Figure 2 The results show that the test piece surface has coating and no debonding phenomenon occurs.

[0054] (3) Flight test of outer protective coating of a spacecraft

[0055] According to the national military standard GJB 7050-2010 "Spacecraft heat protection material electric arc heater turbulent flat test method", the electric arc micro-wind tunnel test is carried out. The size of the test piece is 100mm*100mm, and the aluminum alloy base material is used.

[0056] Table 3

[0057] Test 1 Test 3 See Figure 3 See Figure 4

[0058] By Figure 3 , Figure 4 The results show that the interface of test 1 without primer debonding, the interface of test 3 with primer does not debond, and the use of primer can greatly improve the adhesion of spacecraft outer protective coating and substrate.

[0059] (4) Aging test

[0060] The air aging test box with specification model RLH-500 is used, the test parameter temperature is 180℃, the air exchange frequency of the box is 3 times per hour, and the shear strength of the tensile shear test piece monitored in the aging box for three months is shown in Table 4.

[0061] Table 4

[0062]

[0063] As shown in Table 4, after the spacecraft outer protective coating under the action of primer experiences a 3-month heat and oxygen aging process at 180℃, the adhesion strength does not show a downward trend, which shows that the primer provides reliable adhesion for the spacecraft outer protective coating, and has excellent aging resistance.

[0064] The above is only a specific embodiment of the present application, but the protection scope of the present application is not limited to this. Any skilled person in the art can easily think of changes or replacements within the technical range disclosed by the present application, which should be covered within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A primer for aerospace vehicle outer protective coatings, characterized in that, The raw materials include the following weight parts: tackifier 2-8 parts, alkyl silicone oil 5-10 parts and diluent 80-90 parts; The tackifier is a silicon coupling agent, and the silicon coupling agent is one of KH550, KH560 and KH792; The structure of the alkyl silicone oil is shown in formula I: Formula I R1, R2 are hydrocarbon groups or POSS structures, the hydrocarbon groups are branched alkyl groups or aryl groups with 1-18 carbon atoms, n=20-50 and is an integer.

2. The primer for a space vehicle outer protective coating according to claim 1, wherein The raw materials include the following weight parts: tackifier 5 parts, alkyl silicone oil 7.5 parts and diluent 85 parts.

3. The primer coating for aerospace vehicle outer protective coating according to claim 1, wherein The diluent is one of n-heptane, ethyl acetate, isopropyl alcohol and xylene, or a combination of two or more thereof.

4. The process for the production of a primer for the outer protective coating of a spacecraft according to any one of claims 1 to 3, characterized in that, The preparation method is: The tackifier, the alkyl silicone oil and the diluent are mixed and stirred uniformly.

5. The method of claim 4, wherein the primer for the outer protective coating of a spacecraft is prepared by adding 0.1 to 10 parts by weight of the compound of claim 1 to 100 parts by weight of a solvent. The stirring speed is 600-800 r / min, and the stirring time is 10-15 min.

6. The method of using the primer of any one of claims 1 to 3 for an outer protective coating of a spacecraft, characterized in that, The use method is: The primer is sprayed on the surface of the substrate, and the spacecraft outer protective coating is sprayed after waiting for 20-30 min.

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