External heat-resistant coating for quick-drying solid rocket engine and preparation method thereof

Abstract

The present invention relates to the technical field of thermal protection materials, specifically disclosing a fast-drying external thermal protection coating for solid rocket engines and a preparation method thereof. The coating comprises component A and component B. Component A contains, by weight, 40-60 parts of an isocyanate resin, 10-20 parts of a high-temperature resistant filler, 5-8 parts of a modified phenolic resin, 1-2 parts of a modified phenolic resin, and 0.5-1 part of an anti-settling agent; and component B contains 50-60 parts of an amino-terminated polyether, 15-20 parts of a chain extender, 10-20 parts of a high-temperature resistant filler, 5-8 parts of a modified phenolic resin, and 0.5-1 part of an anti-settling agent. The present invention provides a fast-drying external thermal protection coating for solid rocket engines and a preparation method thereof. The coating achieves good adhesion to steel or composite material interfaces and can rapidly cure at room temperature.

Description

Technical Field

[0001] The present invention relates to the technical field of coatings, and in particular to an external heat-resistant coating for a quick-drying solid rocket engine and a preparation method thereof. Background Art

[0002] At present, the country's demand for solid rocket engines is increasing day by day. Propellant charging plants are constantly under the rapidly increasing pressure of engine propellant charging, and in terms of production technology, they are putting forward diverse, fast, efficient and high-quality spraying requirements for external heat protection materials.

[0003] The production process at the charge plant begins with the welded engine casing entering the assembly line, undergoing painting and final assembly, and finally leaving the assembly line as a finished engine casing. During the painting and final assembly process, bumps and collisions are inevitable, and the coating may crack and peel, exposing the sheet metal. To repair and restore the bumped areas, a layer of external heat protection must be applied to the engine casing. Although the existing external heat protection has satisfactory thermal performance, it cannot solve the problems of good adhesion to composite materials and long curing cycle. When applying the external heat protection coating, a topcoat must still be applied, which increases the risk of interface debonding.

[0004] CN115028987A discloses a sprayable polyurethane ablation-resistant material formulation, preparation method, and application. This formulation can be directly applied to solid rocket motor insulation using a sprayer, addressing issues such as debonding caused by weak interfacial bonding strength (steel casing) of solid rocket motor ablation-resistant materials and enabling sprayable ablation-resistant materials. However, when applied to the outer thermal barrier coating (composite casing) for solid rocket motors, this formulation suffers from insufficient bonding strength, easy debonding, and the appearance of fish-scale patterns during application due to the small atomization surface of the spray gun. This degrades the performance of the sprayed material and fails to meet performance requirements.

[0005] The purpose of the present invention is to overcome at least one of the defects of the above-mentioned prior art and to provide a solid rocket engine casing external heat protection having good bonding performance with steel interface and composite material interface and can be quickly cured in room temperature environment, and a preparation method thereof. Summary of the Invention

[0006] The present invention provides an external heat-resistant coating for a quick-drying solid rocket engine and a preparation method thereof. The coating can achieve good adhesion with a steel interface or a composite material interface and can also be quickly cured in a room temperature environment.

[0007] The technical solution of the present invention is to provide a quick-drying solid rocket engine external heat-resistant coating, comprising component A and component B, which are calculated by mass.

[0008] Component A contains 40-60 parts of isocyanate resin, 10-20 parts of high temperature resistant filler, 5-8 parts of modified phenolic resin and 0.5-1 part of anti-settling agent;

[0009] Component B contains 50-60 parts of amino-terminated polyether, 15-20 parts of chain extender, 10-20 parts of high-temperature resistant filler, 5-8 parts of modified phenolic resin and 0.5-1 part of anti-settling agent.

[0010] Optionally, the isocyanate resin is one or more of aromatic isocyanate, aliphatic isocyanate and cycloaliphatic isocyanate.

[0011] Optionally, the amino-terminated polyether is one or more of polyethylene oxide diamine, polypropylene oxide diamine, and polypropylene oxide triamine.

[0012] Optionally, the high temperature resistant filler is one or more of iron oxide, talc, mica, and silicon dioxide; and the average particle size of the high temperature resistant filler is 200 μm to 400 μm.

[0013] Optionally, the chain extender is one or more of ethylenediamine, triethylenetetramine, ethanolamine, and diethanolamine.

[0014] Optionally, the anti-settling agent is one or more of sodium dodecylbenzenesulfonate, polyvinyl alcohol, and castor oil derivatives.

[0015] Optionally, the modified phenolic resin is prepared by sequentially adding a NaOH solution and a calcium chloride solution to a thermoplastic phenolic resin to react to obtain the modified phenolic resin. Specifically, the phenolic resin is first dispersed in water, then the NaOH solution is added and reacted at 40-60°C for 1-2 hours. After cooling, CaCl2 is added and mixed, and then centrifuged and filtered to obtain the modified phenolic resin.

[0016] The present invention also relates to a method for preparing the outer heat-resistant coating, comprising the following steps:

[0017] S1. Prepare component A and component B according to the ratio respectively;

[0018] S2. Mix component A and component B and place them in a spraying device. Control the spraying pressure to 1500psi~2000psi, the spraying slurry temperature to 50℃~60℃, the spray gun nozzle diameter to 0.3mm~0.5mm, carry out spraying operation, and finally solidify and shape.

[0019] Optionally, the curing molding temperature is 25°C to 30°C, and the curing time is 48h to 72h.

[0020] The present invention has the following beneficial effects:

[0021] 1. The external heat shield prepared by spraying technology has the advantages of high interface bonding strength, high production efficiency and high dimensional accuracy. It can realize the continuous spraying production of solid engine external heat shield and improve the quality stability and reliability of the insulation layer.

[0022] 2. The external heat protection prepared by the spraying process has the advantages of rapid surface drying and smooth surface. It can be directly transported and assembled after the solid engine external heat protection is sprayed, thereby improving the efficiency of the engine external heat protection production.

[0023] 3. The present invention uses modified phenolic resin as a solid-phase filler and introduces ions to increase the bonding performance between the material and the steel interface and the composite material interface; and by adding modified phenolic resin, the catalytic polyurea reaction rate is accelerated, thereby improving the spray molding efficiency; in addition, the modified phenolic resin has very little effect on the viscosity of the slurry system, which is more conducive to spray construction. DETAILED DESCRIPTION

[0024] The experimental methods in the following examples are conventional methods unless otherwise specified. The raw materials, reagents, etc. used in the following examples are commercially available products unless otherwise specified.

[0025] A quick-drying solid rocket motor outer heat-resistant coating, comprising component A and component B, calculated by mass:

[0026] Component A contains 40-60 parts of isocyanate resin, 10-20 parts of high temperature resistant filler, 5-8 parts of modified phenolic resin and 0.5-1 part of anti-settling agent;

[0027] Component B contains 50-60 parts of amino-terminated polyether, 15-20 parts of chain extender, 10-20 parts of high-temperature resistant filler, 1-2 parts of ablation-resistant resin and 0.5-1 part of anti-settling agent.

[0028] In some embodiments, the isocyanate resin is one or more of aromatic isocyanate, aliphatic isocyanate, and cycloaliphatic isocyanate.

[0029] In some embodiments, the amino-terminated polyether is one or more of polyethylene oxide diamine, polypropylene oxide diamine, and polypropylene oxide triamine.

[0030] In some embodiments, the high temperature resistant filler is one or more of iron oxide, talc, mica, and silicon dioxide; and the average particle size of the high temperature resistant filler is 200 μm to 400 μm.

[0031] In some embodiments, the chain extender is one or more of ethylenediamine, triethylenetetramine, ethanolamine, and diethanolamine.

[0032] In some embodiments, the anti-settling agent is one or more of sodium dodecylbenzenesulfonate, polyvinyl alcohol, and castor oil derivatives.

[0033] In the following examples, a modified phenolic resin was prepared in-house. A NaOH solution and a calcium chloride solution were sequentially added to a thermoplastic novolac resin to react. Specifically, the phenolic resin was first dispersed in water, then the NaOH solution was added and reacted at 50°C for 1 hour. After cooling, CaCl₂ was added, the mixture was stirred at room temperature for 1 hour, and then centrifuged and filtered to obtain the modified phenolic resin.

[0034] The specific preparation of the outer heat-resistant coating includes the following steps:

[0035] S1. Prepare component A and component B respectively according to the ratio; when preparing component A, add the high-temperature resistant filler, modified phenolic resin, anti-settling agent and other additives to the isocyanate resin and mix evenly; when preparing component B, add the high-temperature resistant filler, chain extender, modified phenolic resin and anti-settling agent and other additives to the amino-terminated polyether and mix evenly;

[0036] S2. Mix component A and component B and place them in the barrel of the spray equipment. Control the spraying pressure to 1500psi~2000psi, the spraying slurry temperature to 50℃~60℃, the spray gun nozzle diameter to 0.3mm~0.5mm, and use a pressure pump to transport the slurry to the spray gun mixing chamber for spraying to make the external heat-proof material. Finally, cure it at 25℃~30℃ for 48h~72h to form it.

[0037] The present invention is described in detail below with reference to specific embodiments. This embodiment is implemented based on the technical solution of the present invention, and provides a detailed implementation method and specific operation process, but the protection scope of the present invention is not limited to the following embodiments.

[0038] Example 1:

[0039] Weigh 40 parts of aromatic isocyanate, 10 parts of iron oxide, 5 parts of modified phenolic resin, and 0.5 parts of sodium dodecylbenzene sulfonate, stir and mix evenly, and place the mixed spray slurry in the barrel of spray equipment A; weigh 50 parts of polyethylene oxide, 10 parts of talc, 15 parts of ethylenediamine, 5 parts of modified phenolic resin, and 0.5 parts of sodium dodecylbenzene sulfonate, stir and mix evenly, and place the mixed spray slurry in the barrel of spray equipment B, set the spraying pressure to 1500psi, the spraying temperature to 50°C, the nozzle diameter to 0.3mm, use cross-cross spraying multiple times, and the bottom layer spray outer heat protection thickness is 0.2mm.

[0040] The spray-coated erosion-resistant insulation material was placed at room temperature for curing for 48 hours, and the tensile strength, elongation at break, peel strength with the engine housing, and peel strength with the composite material were tested.

[0041] Example 2:

[0042] Weigh 50 parts of aromatic isocyanate, 15 parts of talc, 6 parts of modified phenolic resin, and 0.5 parts of polyvinyl alcohol, stir and mix evenly, and place the mixed spray slurry in the barrel of spray equipment A; weigh 50 parts of polypropylene oxide diamine, 10 parts of mica, 15 parts of ethylenediamine, 6 parts of modified phenolic resin, and 0.5 parts of polyvinyl alcohol, stir and mix evenly, and place the mixed spray slurry in the barrel of spray equipment B, set the spraying pressure to 1600psi, the spraying temperature to 55°C, the nozzle diameter to 0.4mm, use cross-cross spraying multiple times, and spray the bottom layer with an outer heat-resistant thickness of 0.4mm.

[0043] The spray-coated erosion-resistant insulation material was cured at room temperature for 60 hours, and the tensile strength, elongation at break, peel strength with the engine housing, and peel strength with the composite material were tested.

[0044] Example 3:

[0045] Weigh 50 parts of aliphatic isocyanate, 15 parts of talc, 7 parts of modified phenolic resin, and 1 part of polyvinyl alcohol, stir and mix evenly, and place the mixed spray slurry in the barrel of spray equipment A; weigh 60 parts of polypropylene oxide triamine, 10 parts of mica, 20 parts of diethanolamine, 7 parts of modified phenolic resin, and 0.5 parts of polyvinyl alcohol, stir and mix evenly, and place the mixed spray slurry in the barrel of spray equipment B, set the spraying pressure to 1800psi, the spraying temperature to 55°C, the nozzle diameter to 0.5mm, use cross-cross spraying multiple times, and the bottom layer spray outer heat protection thickness is 0.6mm.

[0046] The spray-coated erosion-resistant insulation material was cured at room temperature for 60 hours, and the tensile strength, elongation at break, peel strength with the engine housing, and peel strength with the composite material were tested.

[0047] Example 4:

[0048] Weigh 50 parts of cycloaliphatic isocyanate, 15 parts of silica, 8 parts of modified phenolic resin, and 1 part of polyvinyl alcohol, stir and mix evenly, and place the mixed spray slurry in the barrel of spray equipment A; weigh 55 parts of polypropylene oxide triamine, 10 parts of silica, 15 parts of ethanolamine, 8 parts of modified phenolic resin, and 0.5 parts of polyvinyl alcohol, stir and mix evenly, and place the mixed spray slurry in the barrel of spray equipment B, set the spraying pressure to 2000psi, the spraying temperature to 60℃, the nozzle diameter to 0.5mm, use cross-cross spraying for multiple times, and the bottom layer spray outer heat protection thickness is 0.6mm.

[0049] The spray-coated erosion-resistant insulation material was cured at room temperature for 72 hours, and the tensile strength, elongation at break, peel strength with the engine housing, and peel strength with the composite material were tested.

[0050] Example 5:

[0051] Weigh 50 parts of cycloaliphatic isocyanate, 15 parts of silica, and 1 part of polyvinyl alcohol, stir and mix evenly, and place the mixed spray slurry in the barrel of spray equipment A; weigh 55 parts of polypropylene oxide triamine, 10 parts of silica, 15 parts of ethanolamine, and 0.5 parts of polyvinyl alcohol, stir and mix evenly, and place the mixed spray slurry in the barrel of spray equipment B, set the spraying pressure to 2000psi, the spraying temperature to 60℃, the nozzle diameter to 0.5mm, use cross-cross spraying for multiple times, and the bottom layer spray outer heat protection thickness is 0.6mm.

[0052] The spray-coated erosion-resistant insulation material was cured at room temperature for 72 hours, and the tensile strength, elongation at break, peel strength with the engine housing, and peel strength with the composite material were tested.

[0053] Example 6:

[0054] Weigh 50 parts of cycloaliphatic isocyanate, 15 parts of silica, 8 parts of thermoplastic phenolic resin, and 1 part of polyvinyl alcohol, stir and mix evenly, and place the mixed spray slurry in the barrel of spray equipment A; weigh 55 parts of polypropylene oxide triamine, 10 parts of silica, 15 parts of ethanolamine, 8 parts of thermoplastic phenolic resin, and 0.5 parts of polyvinyl alcohol, stir and mix evenly, and place the mixed spray slurry in the barrel of spray equipment B, set the spraying pressure to 2000psi, the spraying temperature to 60℃, the nozzle diameter to 0.5mm, use cross-cross spraying multiple times, and the bottom layer spray outer heat protection thickness is 0.6mm.

[0055] The spray-coated erosion-resistant insulation material was cured at room temperature for 72 hours, and the tensile strength, elongation at break, peel strength with the engine housing, and peel strength with the composite material were tested.

[0056] The test conditions for the tensile strength, elongation at break, surface drying time, peel strength with the engine steel housing, and peel strength with the composite material of the spray-coated external heat-resistant materials of the above embodiments and comparative examples are shown in Table 1, and the test results are shown in Table 2.

[0057] Table 1 Test standards and methods

[0058]

[0059] Table 2 Test results

[0060]

[0061] As can be seen from Table 2, when not adding modified phenolic resin among embodiment 5, material mechanical property and steel interface bonding performance do not have detailed variation, but itself and composite material bonding performance descend, and tack free time also increases.When using modified phenolic resin precursor thermoplastic novolac resin, material mechanical property and steel interface bonding performance do not have almost variation, but itself and composite material bonding performance descend, and tack free time also increases.The modified phenolic resin that the present invention improves also shortened its tack free time when increasing and composite material interface bonding strength, for solid rocket motor exothermic material serialization, automation spraying provide solution.

[0062] The above embodiments describe preferred embodiments of the present invention, but the present invention is not limited thereto. Within the technical concept of the present invention, various simple variations of the technical solution of the present invention may be made, including combining the various technical features in any other manner. These simple variations and combinations should also be regarded as disclosed in the present invention and fall within the scope of protection of the present invention. Therefore, the scope of protection of the patent of the present invention shall be based on the appended claims.

Claims

1. A quick-drying solid rocket engine outer thermal protection coating, characterized in that: Including component A and component B, calculated by mass: Component A contains 40-60 parts of isocyanate resin, 10-20 parts of high temperature resistant filler, 5-8 parts of modified phenolic resin and 0.5-1 part of anti-settling agent; Component B contains 50-60 parts of amino-terminated polyether, 15-20 parts of chain extender, 10-20 parts of high-temperature resistant filler, 5-8 parts of modified phenolic resin and 0.5-1 part of anti-settling agent; The modified phenolic resin is prepared by using thermoplastic phenolic resin as raw material, and NaOH solution and calcium chloride solution are added in sequence for reaction to obtain the modified phenolic resin.

2. The quick-drying solid rocket motor outer thermal protection coating according to claim 1, characterized in that: The isocyanate resin is one or more of aromatic isocyanate, aliphatic isocyanate and cycloaliphatic isocyanate.

3. The quick-drying solid rocket motor outer thermal protection coating according to claim 1, characterized in that: The amino-terminated polyether is one or more of polyethylene oxide diamine, polypropylene oxide diamine, and polypropylene oxide triamine.

4. The quick-drying solid rocket motor outer thermal protection coating according to claim 1, characterized in that: The high temperature resistant filler is one or more of iron oxide, talc, mica, and silicon dioxide; the average particle size of the high temperature resistant filler is 200 μm to 400 μm.

5. The quick-drying solid rocket motor outer thermal protection coating according to claim 1, characterized in that: The chain extender is one or more of ethylenediamine, triethylenetetramine, ethanolamine and diethanolamine.

6. The quick-drying solid rocket motor outer thermal protection coating according to claim 1, characterized in that: The anti-settling agent is one or more of sodium dodecylbenzene sulfonate, polyvinyl alcohol, and castor oil derivatives.

7. The quick-drying solid rocket motor outer thermal protection coating according to claim 6, characterized in that: The phenolic resin is first dispersed by adding water, and then NaOH solution is added and reacted at 40-60°C for 1-2 hours; after cooling, CaCl2 is added and mixed, and then centrifugal filtration is performed to obtain the modified phenolic resin.

8. The method for preparing the quick-drying solid rocket engine outer thermal protection coating according to any one of claims 1 to 7, characterized in that: The following steps are involved: S1. Prepare component A and component B according to the ratio respectively; S2. Mix component A and component B and place them in a spraying device. Control the spraying pressure to 1500psi~2000psi, the spraying slurry temperature to 50℃~60℃, the spray gun nozzle diameter to 0.3mm~0.5mm, carry out spraying operation, and finally solidify and shape.

9. The method for preparing the outer thermal protection coating for a quick-drying solid rocket engine according to claim 8, characterized in that: The curing temperature is 25℃~30℃, and the curing time is 48h~72h.

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