Self-reinforcing and self-repairing silicate ablation-resistant heat-insulating coating and preparation method thereof

Abstract

The invention discloses a self-reinforcing and self-repairing silicate ablation-resistant heat-insulating coating and a preparation method thereof. The coating is prepared from the following raw materials: aluminum silicate powder, montmorillonite powder, aluminum silicate fibers, aluminum oxide powder, graphene, silicon oxide, an aluminum silicate solution and a diluent. The high-performance inorganic heat-insulating material is prepared by improving the ceramization reaction level of the silicate coating at high temperature, and compared with a traditional rubber-based heat-insulating material, the high-performance inorganic heat-insulating material is easy to form and lower in cost, and compared with a traditional silicate coating, the high-performance inorganic heat-insulating material is better in ablation resistance and heat-insulating performance.

Description

Technical Field

[0001] The present invention belongs to the technical field of aerospace thermal protection materials, and particularly relates to a self-reinforcing and self-healing silicate ablation-resistant and heat-insulating coating formulation and preparation method. Background Art

[0002] The water ramjet is a new type of power device for underwater vehicles. Its working principle is that a gas generator using solid propellant generates rich-burning gas, which is mixed and burned with vaporized water vapor in a afterburner chamber to generate thrust through a nozzle. The ramjet power device of underwater vehicles usually has a more complex configuration, a longer navigation time, and the afterburner chamber is in an oxidizing atmosphere under high-temperature conditions, which puts forward requirements for thermal protection materials such as good processing performance, easy forming, oxidation resistance, low thermal conductivity, ablation resistance, and lightweight.

[0003] Traditional aerospace vehicle solid rocket engines and ramjet engines often use ethylene propylene diene monomer (EPDM) rubber-based thermal insulation materials or silicone rubber-based thermal insulation materials. However, EPDM rubber-based thermal insulation materials are not oxidation-resistant, silicone rubber-based thermal insulation materials have a large density and a high thermal conductivity, and the processing performance of these two thermal insulation materials is poor, making it difficult to meet the forming problems within complex structures. Compared with aerospace vehicles, there is convective heat transfer and evaporation heat absorption of flowing water on the outer surface of underwater vehicles. Therefore, inorganic coating materials with a smaller heat sink can be considered for thermal protection. Summary of the Invention

[0004] Aiming at the defects or deficiencies of the prior art, the present invention provides a self-reinforcing and self-healing silicate ablation-resistant and heat-insulating coating.

[0005] To this end, the ablation-resistant and heat-insulating coating provided by the present invention is prepared from the following raw materials in parts by mass:

[0006] 50 parts of aluminum silicate powder;

[0007] 50 parts of montmorillonite powder;

[0008] 1 - 20 parts of aluminum silicate fiber;

[0009] 1 - 20 parts of alumina powder;

[0010] 0.01 - 10 parts of graphene;

[0011] 0.5 - 20 parts of silicon oxide;

[0012] Aluminum silicate solution: 50 - 200 parts, and the concentration range of the aluminum silicate solution is: 1 - 2 g / cm 3 ;

[0013] Diluent: 50 - 500 parts, and the diluent is water or ethyl acetate.

[0014] An optional solution is that the aluminum silicate fiber accounts for 10 parts; the aluminum oxide powder accounts for 10 parts.

[0015] An optional solution is that the average particle size of the aluminum silicate powder is 5-20 μm.

[0016] An optional solution is that the average particle size of the montmorillonite powder is 5-20 μm.

[0017] An optional solution is that the aluminum silicate fiber has a diameter of 2-10 μm and a length of ≥50 μm.

[0018] An optional solution is that the average particle size of the aluminum oxide powder is 5-20 μm.

[0019] Optionally, the graphene is multilayer graphene or single layer graphene.

[0020] An optional solution is that the silicon oxide is precipitated silicon dioxide with an average particle size of 5-20 μm.

[0021] The present invention also provides a method for preparing the self-reinforcing and self-repairing silicate ablation-resistant thermal insulation coating. The provided preparation method comprises:

[0022] Step S1, mixing aluminum silicate powder, montmorillonite powder and aluminum oxide powder uniformly to obtain a first matrix;

[0023] Step S2, mixing the aluminum silicate fibers and the first matrix uniformly to obtain a second matrix;

[0024] Step S3, mixing silicon oxide powder and the second matrix to obtain a third matrix;

[0025] Step S4, uniformly mixing the third matrix with a portion of the aluminum silicate solution by mass to obtain a fourth matrix;

[0026] Step S5, uniformly mixing the graphene, the fourth matrix and the remaining parts by mass of the aluminum silicate solution;

[0027] Step S6: Evenly mix the diluent with the mixed solution obtained in step S5 to obtain a coating mixed solution.

[0028] The thermal insulation material formula of the present invention uses raw materials such as aluminum silicate, graphene and silicon oxide, which enhances the ceramic reaction during the coating ablation process and the synergistic effect with aluminum silicate, so that the steel products have better ablation resistance and thermal insulation properties, and are formed by spraying to meet the thermal protection needs of complex configurations. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 This is a broken line graph of the ablation rate of the embodiment of the present application and the comparative example;

[0030] Figure 2 This is the line graph of the mass loss rate of the embodiments and comparative examples of this application;

[0031] Figure 3 This is the line graph of the back temperature of the embodiments and comparative examples of this application;

[0032] Figure 4 This is the morphology after ablation of Comparative Example 3 of this application;

[0033] Figure 5 This is the morphology after ablation of Comparative Example 4 of this application;

[0034] Figure 6 This is the morphology after ablation of Embodiment 1 of this application. Detailed implementation manners

[0035] Unless otherwise specified, the scientific and technical terms in this article are understood according to the knowledge of those of ordinary skill in the relevant fields. The present invention will be described in detail below with reference to specific embodiments. All materials used in the following embodiments are commercially available products.

[0036] Embodiment 1:

[0037] The silicate ablation-resistant and heat-insulating coating of this embodiment is prepared from the following raw materials in parts by mass:

[0038] 50 parts of aluminum silicate powder; 50 parts of montmorillonite powder; 10 parts of aluminum silicate fiber; 10 parts of alumina powder; 1 part of graphene; 4 parts of silicon oxide; 200 parts of aluminum silicate solution; 200 parts of diluent;

[0039] Among them, the average particle size of the aluminum silicate powder is 10um; the average particle size of the montmorillonite powder is 10um; the average diameter of the aluminum silicate fiber is 3um and the length is about 50um; the average particle size of the alumina powder is 10um; the graphene is multi-layer graphene; the silicon oxide is precipitated silicon dioxide with an average particle size of 10um; the concentration of the aluminum silicate solution is: 1.2g / cm 3 ; the diluent is ethyl acetate.

[0040] The preparation method of the silicate ablation-resistant and heat-insulating coating in this embodiment is as follows:

[0041] Step S1, mix the aluminum silicate powder, montmorillonite powder and alumina powder evenly to obtain a first matrix;

[0042] Step S2, add the aluminum silicate fiber to the first matrix and mix evenly to obtain a second matrix;

[0043] Step S3, add the silicon oxide powder to the second matrix and mix evenly to obtain a third matrix;

[0044] Step S4: Add the third matrix into 100 parts by mass of the aluminosilicate solution, and stir evenly until there is no powder agglomeration to obtain the fourth matrix;

[0045] Step S5: Gradually add graphene into the fourth matrix, and at the same time gradually add 100 parts by weight of the aluminosilicate solution, and stir evenly until there is no graphene agglomeration on the liquid surface;

[0046] Step S6: Add the diluent into the mixture obtained in Step S5, and stir evenly to obtain the coating mixture of this example.

[0047] Comparative Example 1:

[0048] This example is different from Example 1 in that it does not contain graphene and silicon oxide.

[0049] Comparative Example 2:

[0050] This example is different from Example 1 in that it does not contain graphene.

[0051] Comparative Example 3:

[0052] This example is different from Example 1 in that it does not contain silicon oxide.

[0053] Comparative Example 4:

[0054] This comparative example is different from Example 1 in that the aluminosilicate powder and aluminosilicate fiber therein are replaced with aluminum phosphate, and the aluminosilicate solution is replaced with an aluminum phosphate solution of the same concentration.

[0055] Example 2:

[0056] This example is different from Example 1 in that the graphene content is 0.1 part.

[0057] Example 3:

[0058] This example is different from Example 1 in that the graphene content is 5 parts.

[0059] Example 4:

[0060] This example is different from Example 1 in that the silicon oxide content is 1 part.

[0061] Example 5:

[0062] This example is different from Example 1 in that the silicon oxide content is 8 parts.

[0063] Furthermore, use the coating mixtures obtained from the above examples and comparative examples respectively to prepare coatings on the metal surface:

[0064] Specifically, a sandblasting machine is used to perform sandblasting treatment on the surface of steel (such as high-temperature alloy steel, 45# steel, etc., 45# steel in this embodiment); then alcohol is used to clean the metal surface and then dried; then an epoxy adhesive is brushed on the metal surface and dried; finally, a corresponding coating mixture is sprayed on the metal surface using a spraying machine, fully dried and then sprayed again, repeating the spraying / drying process until the coating thickness reaches the required thickness of 5 mm.

[0065] In this application, ablation performance tests were carried out on the metal surface coatings prepared in the above-mentioned examples and comparative examples. The experiment was carried out using an oxyacetylene ablation experimental device based on GJB 323A / 96; the back temperature of the metal was measured simultaneously during the ablation process. The test results are shown in Table 1 below:

[0066] Table 1

[0067] Linear ablation rate mm / s Mass ablation rate g / s Back temperature (°C) Comparative example 1 0.3127 4.709 92.2 Comparative example 2 0.285 2.289 75 Comparative example 3 0.2050 2.151 68.9 Comparative example 4 0.5012 6.7492 121.6 Example 1 0.147 1.841 58.2 Example 2 0.1787 2.093 63.9 Example 3 0.202 1.92 69.6 Example 4 0.1723 2.009 62.1 Example 5 0.1905 2.090 64.7

[0068] From Figure 1 and Figure 2 it can be clearly seen that the ablation resistance performance of the enhanced coating formulation in the example is significantly better than that of the comparative example coating formulations that do not add graphene and silica, add graphene and silica alone, and add other components of graphene and silica. Figure 3 The reflected back temperature curve and Figure 2 , Figure 3 have the same distribution trend as the ablation rate curve.

[0069] Comparing Figure 4 , Figure 5 and Figure 6 after ablation, it can be seen that materials without graphene and silica ceramization reaction are difficult to resist the gas erosion. The surface attachments are blown off by the gas in a large area, and the surface layer is very seriously damaged; while materials with less graphene and silica are also blown away to a certain extent, but the surface layer still maintains a relatively intact profile. The material of the present invention not only has the surface attachments intact without signs of being blown off after ablation, but also the surface layer is intact without being damaged by the high-speed airflow. On the one hand, silica from silicate can undergo a ceramization reaction with graphene, and on the other hand, this molten state substance can greatly strengthen the adhesion and bonding toughness of the ablation layer surface ( Figure 4 The projected area of the molten attachments on the surface of the material in Comparative Example 3 is about 37.2%, Figure 5 The projected area of the molten attachments on the surface of the material in Comparative Example 4 is about 58.3%, Figure 6 The projected area of the molten attachments on the surface of the material in Example 1 is about 84.7%). It can not only form a flexible protective layer through the molten state substance to avoid direct contact between the airflow, particles, etc. and the ablation surface layer, but also self-repair surface cracks to prevent the generation of larger cracks.

[0070] The preferred embodiments of the present disclosure have been described in detail above in conjunction with the accompanying drawings. However, the present disclosure is not limited to the specific details in the above embodiments. Within the scope of the technical concept of the present disclosure, various simple modifications can be made to the technical solutions of the present disclosure, and these simple modifications all fall within the protection scope of the present disclosure.

[0071] In addition, it should be noted that, in the various specific technical features described in the above specific embodiments, they can be combined in any suitable manner without conflict. To avoid unnecessary repetition, the present disclosure will not separately describe various possible combination manners.

[0072] Furthermore, any combination can be made between various different embodiments of the present disclosure, as long as it does not violate the idea of the present disclosure, and it should also be regarded as the content disclosed by the present disclosure.

Claims

1. A self-strengthening and self-healing silicate ablative heat-insulating coating, characterized in that, It is prepared from the following raw materials in parts by weight: 50 parts of aluminum silicate powder; 50 parts of montmorillonite powder; 1-20 parts of aluminum silicate fiber; 1-20 parts of aluminum oxide powder; 0.01 to 10 parts of graphene; 0.5-20 parts of silicon oxide; Aluminum silicate solution: 50-200 parts, the concentration range of the aluminum silicate solution is: 1-2g / cm 3 ; Diluent: 50-500 parts, the diluent is water or ethyl acetate.

2. The self-strengthening and self-repairing silicate ablation-resistant and heat-insulating coating according to claim 1, wherein The aluminum silicate fiber accounts for 10 parts; the aluminum oxide powder accounts for 10 parts.

3. The self-strengthening and self-repairing silicate ablation-resistant and heat-insulating coating according to claim 1, characterized in that, The average particle size of the aluminum silicate powder is 5-20 μm.

4. The self-strengthening and self-repairing silicate ablation-resistant and heat-insulating coating according to claim 1, characterized in that The average particle size of the montmorillonite powder is 5-20 μm.

5. The self-strengthening and self-repairing silicate ablation-resistant and heat-insulating coating according to claim 1, characterized in that, The aluminum silicate fiber has a diameter of 2-10 μm and a length of ≥50 μm.

6. The self-strengthening and self-repairing silicate ablation-resistant and heat-insulating coating according to claim 1, wherein The average particle size of the alumina powder is 5-20 μm.

7. The self-strengthening and self-repairing silicate ablation-resistant thermal insulation coating according to claim 1, characterized in that, The graphene is multilayer graphene or single layer graphene.

8. The self-strengthening and self-healing silicate ablation-resistant thermal insulation coating according to claim 1, characterized in that, The silicon oxide is precipitated silicon dioxide with an average particle size of 5-20 μm.

9. The method for preparing the self-reinforced and self-repairing silicate ablation-resistant thermal insulation coating according to claim 1, characterized in that: The preparation method comprises: Step S1, mixing aluminum silicate powder, montmorillonite powder and aluminum oxide powder uniformly to obtain a first matrix; Step S2, mixing the aluminum silicate fibers and the first matrix uniformly to obtain a second matrix; Step S3, mixing silicon oxide powder and the second matrix uniformly to obtain a third matrix; Step S4, uniformly mixing the third matrix with a portion of the aluminum silicate solution by mass to obtain a fourth matrix; Step S5, uniformly mixing the graphene, the fourth matrix and the remaining parts by mass of the aluminum silicate solution; Step S6: Evenly mix the diluent with the mixed solution obtained in step S5 to obtain a coating mixed solution.

10. Use of the coating according to claim 1 as an ablation-resistant heat-insulating coating on the surface of steel products.

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