Thermal control coating with high temperature, high infrared radiation and high solar spectrum reflection performance, coating and preparation method

Abstract

The invention provides a thermal control coating with high temperature, high infrared radiation and high solar spectrum reflection performance, a coating and a preparation method. The thermal control coating comprises a prime coating and a surface coating, the bottom layer coating takes a silica sol modified lithium silicate solution as a bottom layer binder, takes mixed powder of copper chromite and zinc orthotitanate as a bottom layer filler, and takes water as a solvent; and the surface layer coating takes a silica sol modified lithium silicate solution as a surface layer binder, takes mixed powder of zinc orthotitanate and 8YSZ (8mol% Y2O3 doped ZrO2) as a surface layer filler, and takes water as a solvent. The thermal control coating is formed by spraying a thermal control coating, the bottom layer is obtained by spraying the bottom layer coating, and the surface layer is obtained by spraying the surface layer coating on the bottom layer. Through coating structure optimization and ingredient improvement, the high-temperature heat dissipation coating has high high-temperature emissivity and low solar absorptivity, the infrared emissivity at 600 DEG C can reach 0.80-0.85, the solar absorptivity is 0.30-0.40, and the high-temperature heat dissipation coating has a good high-temperature heat dissipation effect.

Description

Technical Field

[0001] This invention belongs to the field of thermal control coatings and coating technology, and relates to high-temperature heat dissipation thermal control coatings for spacecraft, and particularly to a thermal control coating, coating and preparation method that has both high temperature and high infrared radiation and high solar spectrum reflectance performance. Background Technology

[0002] Thermal control coatings are special application coatings prepared on the surface of spacecraft to adjust the thermal and optical properties of the spacecraft, thereby achieving thermal control effects. With the development of aerospace technology, spacecraft face increasingly higher temperatures. For example, new power technologies have enabled the temperature of hot-end components of spacecraft to reach over 600°C; the highest surface temperature on Mercury reaches 427°C; and the highest atmospheric temperature on Venus reaches 500°C. Furthermore, spacecraft operating in orbit are subject to prolonged solar radiation, causing their surface temperature to rise. Therefore, spacecraft surfaces require a high-temperature resistant thermal control coating that also possesses high-temperature, high-infrared radiation and high solar spectral reflectivity to enhance infrared radiation heat dissipation, reduce the absorption of solar radiation energy, and ensure that their temperature remains within a reasonable range.

[0003] According to the laws of blackbody radiation, the peak wavelength of a material's infrared radiation shifts towards shorter wavelengths with increasing temperature. For example, the peak wavelength of blackbody radiation at 600℃ is close to 3μm, falling in the near-infrared band, which overlaps to some extent with the solar absorption spectrum. This overlap increases with increasing temperature. However, achieving high-temperature, high-infrared radiation requires materials with high absorptivity in the near-infrared band, inevitably leading to an increased solar absorptivity and poor solar reflectivity. Currently, common high-emissivity coatings often incorporate oxides such as Fe2O3, MnO2, Cr2O3, and NiO, resulting in a black coating with a high solar absorptivity. Therefore, addressing the issue solely from the perspective of coating materials is insufficient. It is necessary to design a novel thermal control coating that simultaneously satisfies both high-temperature, high-infrared radiation and high solar spectral reflectivity, thereby improving the coating's heat dissipation capacity at high temperatures. Summary of the Invention

[0004] In order to overcome the shortcomings of the existing technology, the inventors have conducted intensive research and provided a thermal control coating, coating and preparation method that have both high temperature and high infrared radiation and high solar spectrum reflectance performance, solving the problem that traditional thermal control coatings cannot achieve high infrared emission and low solar absorptivity at the same time.

[0005] The technical solution provided by this invention is as follows:

[0006] Firstly, a thermal control coating that combines high temperature and high infrared radiation with high solar spectrum reflectance performance includes a base coat and a top coat.

[0007] The base coat uses a silica sol-modified lithium silicate solution as the base binder, a mixed powder of copper chromite and zinc titanate as the base filler, and water as the solvent.

[0008] The topcoat uses a silica sol-modified lithium silicate solution as the topcoat binder, a mixed powder of zinc titanate and 8YSZ as the topcoat filler, and water as the solvent.

[0009] Secondly, a thermal control coating with both high temperature and high infrared radiation and high solar spectrum reflectance is formed by spraying the thermal control coating with both high temperature and high infrared radiation and high solar spectrum reflectance as described in the first aspect. The bottom layer is formed by spraying the bottom layer coating, and the top layer coating is formed by spraying the top layer coating on the bottom layer coating.

[0010] Thirdly, a method for preparing a thermal control coating that combines high temperature and high infrared radiation with high solar spectral reflectance includes the following steps:

[0011] Add grinding balls, copper chromite, zinc titanate powder, lithium silicate solution, silica sol and water to an alumina ball milling jar, and mix by ball milling. Then filter to remove the grinding balls to obtain a uniformly dispersed base coating.

[0012] Grinding balls, 8YSZ powder, zinc titanate powder, lithium silicate solution, silica sol, and water are added to an alumina ball mill jar and ball-milled to mix them. The grinding balls are then filtered out to obtain a uniformly dispersed surface coating.

[0013] Fourthly, a method for preparing a thermal control coating that combines high temperature and high infrared radiation with high solar spectral reflectance includes the following steps:

[0014] The coating is prepared by air spraying. First, the base coat is stirred evenly and filtered through a filter screen. Then, it is sprayed onto the substrate. After the base coat dries, the stirred and filtered top coat is sprayed onto the base coat. After the top coat dries, it is baked and cured.

[0015] The thermal control coating, coating layer, and preparation method provided by the present invention, which possess both high-temperature, high-infrared radiation, and high solar spectral reflectance properties, have the following beneficial effects:

[0016] This invention provides a thermal control coating, coating material, and preparation method that combines high temperature, high infrared radiation, and high solar spectral reflectance. Through coating structure optimization and material improvement, it achieves high high temperature emissivity while having low solar absorptivity. The infrared emissivity at 600℃ can reach 0.80-0.85, and the solar absorptivity is 0.30-0.40, resulting in good high temperature heat dissipation. Attached Figure Description

[0017] Figure 1 Macroscopic photograph of the coating prepared in Example 1.

[0018] Figure 2 The microstructure of the coating prepared in Example 1 is shown.

[0019] Figure 3 The solar spectral reflectance curve of the coating prepared in Example 1.

[0020] Figure 4 Emissivity curve at 600°C for the coating prepared in Example 1. Detailed Implementation

[0021] The features and advantages of the present invention will become clearer and more explicit from the following detailed description.

[0022] The term “exemplary” as used herein means “serving as an example, embodiment, or illustration.” Any embodiment illustrated herein as “exemplary” is not necessarily to be construed as superior to or better than other embodiments.

[0023] This invention provides a thermal control coating that combines high temperature and high infrared radiation with high solar spectrum reflectance, comprising a base coating and a top coating;

[0024] The base coat uses a silica sol-modified lithium silicate solution as the base binder, a mixed powder of copper chromite and zinc titanate as the base filler, and water as the solvent.

[0025] The topcoat uses a silica sol-modified lithium silicate solution as the topcoat binder, and zinc titanate and 8 mol% Y 3+ Stable ZrO2 (abbreviated as 8YSZ) mixed powder is used as surface filler, and water is used as solvent.

[0026] In the bottom binder, the mass ratio of lithium silicate solution to silica sol is 50:1 to 4:1, and the solid content of lithium silicate solution is 30% to 50%.

[0027] In the surface adhesive, the mass ratio of lithium silicate solution to silica sol is 50:1 to 4:1, and the solid content of lithium silicate solution is 30% to 50%.

[0028] In the bottom packing, the mass ratio of copper chromite to zinc titanate is 10:1 to 1:1.

[0029] In the surface filler, the mass ratio of zinc titanate to 8YSZ is 10:1 to 1:1.

[0030] The powder particle size of copper chromite is 200-1000 nm; the particle size of the bottom layer zinc titanate is 1-10 μm; the particle size of the top layer zinc titanate is 50-200 nm; and the particle size of the top layer 8YSZ is 500-1000 nm.

[0031] The aforementioned thermal control coating, which combines high temperature and high infrared radiation with high solar spectral reflectance, has a gray high-temperature infrared radiation layer as its base coat. It uses black copper chromite with high infrared radiation performance as the main filler and white zinc titanate with high solar spectral reflectance as the auxiliary filler. This improves the infrared emissivity of the coating in the near-infrared band and enhances its infrared radiation performance. The addition of zinc titanate serves two purposes: first, it neutralizes the excessively high solar absorptivity of copper chromite by introducing high solar reflectance fillers, preventing excessively low solar spectral reflectance; second, it introduces large-diameter particles, improving the adhesion of the base coat to the substrate surface.

[0032] The aforementioned thermal control coating, which combines high temperature and high infrared radiation with high solar spectral reflectance, features a white, high solar spectral reflectance topcoat. It uses white zinc titanate with high solar spectral reflectance as the main filler and white 8YSZ with high infrared radiation as the auxiliary filler to enhance the coating's solar spectral reflectance. The auxiliary filler, 8YSZ, is an 8 mol% Y₂O₃-doped ZrO₂ material, with a portion of Zr in its crystal lattice. 4+ By Y 3+ Substitution, due to the difference in valence and ionic radius between the two, introduces oxygen vacancies while causing lattice distortion, reducing lattice symmetry, increasing carrier concentration, broadening the infrared absorption band, and improving the high-temperature emissivity of the material. Furthermore, Y₂O₃, as a high bandgap material, can significantly improve the ultraviolet reflectance and ionizing radiation resistance of the coating when used in thermal control coating systems, reduce the solar absorptivity of the coating, and improve the stability of the space environment. Therefore, the addition of the auxiliary filler 8YSZ improves the low high-temperature emissivity of the main filler, zinc titanate, and enhances the stability of the space environment without severely deteriorating the solar absorptivity of the surface layer. This allows the surface layer to provide a certain degree of high-temperature radiation capability while maintaining high solar reflectance, further enhancing the overall high-temperature heat dissipation capability of the coating.

[0033] This invention also improves a thermal control coating that combines high temperature, high infrared radiation, and high solar spectral reflectance. It is formed by spraying the above-mentioned thermal control coating that combines high temperature, high infrared radiation, and high solar spectral reflectance. The bottom layer is sprayed to form the bottom layer, and the top layer is sprayed on the bottom layer to form the top layer. The thickness of the bottom layer is 40-90 μm, and the thickness of the top layer is 1-20 μm.

[0034] This invention also provides a method for preparing a thermal control coating / coating that combines high temperature and high infrared radiation with high solar spectral reflectance, comprising the following steps:

[0035] (1) Preparation of the base coating: Add alumina grinding balls, copper chromite, zinc titanate powder, lithium silicate solution, silica sol and water to the alumina ball mill jar, and mix them by ball milling. Then filter to remove the grinding balls to obtain a uniformly dispersed base coating.

[0036] In this step, the mass fractions of each component of the base coating are as follows: 100 parts of lithium silicate solution + silica sol, 50-150 parts of copper chromite + zinc titanate, 200-350 parts of water, 300-400 parts of 10mm alumina grinding balls, and 300-400 parts of 5mm alumina grinding balls.

[0037] In this step, the ball mill speed is 40-80 r / min and the ball milling time is 12-24 h.

[0038] (2) Preparation of topcoat: Add alumina grinding balls, 8YSZ powder, zinc titanate powder, lithium silicate solution, silica sol and water to the alumina ball mill jar, and mix them by ball milling. Then filter to remove the grinding balls to obtain a uniformly dispersed topcoat.

[0039] In this step, the mass fractions of each component of the topcoat are as follows: 100 parts of lithium silicate solution + silica sol, 50-100 parts of 8YSZ + zinc titanate, 200-350 parts of deionized water, 300-400 parts of 10mm alumina grinding balls, and 300-400 parts of 5mm alumina grinding balls.

[0040] In this step, the ball mill speed is 40-80 r / min and the ball milling time is 12-24 h.

[0041] (3) Coating preparation: The coating is prepared by air spraying. First, the base coat is stirred evenly and filtered through a 200-500 mesh screen. Then it is sprayed onto the substrate. After the base coat dries, the evenly stirred and filtered top coat is sprayed onto the base coat. After the top coat dries, it is baked and cured.

[0042] In this step, the ambient temperature during bottom drying is 20-30℃, the relative humidity is 40%-70%, and the drying time is 2-4 hours.

[0043] In this step, the ambient temperature during surface drying is 20-30℃, the relative humidity is 40%-70%, and the drying time is 12-24 hours.

[0044] In this step, the curing temperature of the coating is 150–250℃, and the curing time is 12–24 hours.

[0045] Example

[0046] Unless otherwise specified, the materials used in the following examples and comparative examples shall meet the following requirements:

[0047] The copper chromite powder has a particle size of 200–1000 nm; the bottom layer of zinc titanate has a particle size of 1–10 μm; the top layer of zinc titanate has a particle size of 50–200 nm; the top layer of 8YSZ has a particle size of 500–1000 nm; and the lithium silicate solution has a solid content of 30%–50%.

[0048] Example 1

[0049] A method for preparing a thermal control coating that combines high temperature and high infrared radiation with high solar spectral reflectance includes the following steps:

[0050] (1) Preparation of the base coating: Add 300g of 10mm alumina grinding balls, 300g of 5mm alumina grinding balls, 30g of copper chromite powder, 30g of zinc titanate powder, 80g of lithium silicate solution, 10g of silica sol and 300g of deionized water to an alumina ball mill jar. Set the ball mill speed to 80r / min and ball mill for 16h. Then filter to obtain the base coating.

[0051] (2) Preparation of surface coating: Add 300g of 10mm alumina grinding balls, 300g of 5mm alumina grinding balls, 30g of 8YSZ powder, 60g of zinc titanate powder, 80g of lithium silicate solution, 10g of silica sol and 300g of deionized water to an alumina ball mill jar. Set the ball mill speed to 80r / min and ball mill for 16h. Then filter to obtain the surface coating.

[0052] (3) Coating preparation: After sandblasting, the surface of the aluminum alloy material is first sprayed with 5 coats of primer coating, and then dried for 4 hours in an environment with a temperature of 28-30℃ and a relative humidity of 60%-65%. The appearance is shown in the figure. Figure 1 Left; then spray two coats of topcoat paint onto the base layer, and let it dry for 15 hours in an environment with a temperature of 28-30℃ and a relative humidity of 60%-65%; then cure the coating at 150℃ for 12 hours to obtain the coating appearance. Figure 1 Right, see microscopic image Figure 2 The thickness of the bottom layer is 50-60 μm, and the thickness of the top layer is 10-15 μm.

[0053] like Figure 3 As shown, the coating prepared in Example 1 has high reflectivity in the ultraviolet band and low reflectivity in the near-infrared band, corresponding to a high absorptivity. Figure 4 This further confirms that the coating prepared in Example 1 has a high emissivity in the near-infrared band. Testing showed that the coating prepared in Example 1 has a solar absorptivity of 0.33 and an infrared emissivity of 0.83 at 600℃, exhibiting both high-temperature, high-infrared emissivity and high solar spectral reflectivity, thus demonstrating excellent high-temperature heat dissipation capabilities.

[0054] Example 2

[0055] A method for preparing a thermal control coating that combines high temperature and high infrared radiation with high solar spectral reflectance includes the following steps:

[0056] (1) Preparation of the base coating: Add 300g of 10mm alumina grinding balls, 300g of 5mm alumina grinding balls, 40g of copper chromite powder, 20g of zinc titanate powder, 80g of lithium silicate solution, 10g of silica sol and 300g of deionized water to the alumina ball mill jar. Set the ball mill speed to 80r / min and ball mill for 16h. Then filter to obtain the base coating.

[0057] (2) Preparation of surface coating: Add 300g of 10mm alumina grinding balls, 300g of 5mm alumina grinding balls, 45g of 8YSZ powder, 45g of zinc titanate powder, 80g of lithium silicate solution, 10g of silica sol and 300g of deionized water to an alumina ball mill jar. Set the ball mill speed to 80r / min and ball mill for 16h. Then filter to obtain the surface coating.

[0058] (3) Coating preparation: After sandblasting, the surface of the aluminum alloy material is first sprayed with 5 coats of base coating and dried for 4 hours at a temperature of 28-30℃ and a relative humidity of 60%-65%; then the base coating is sprayed with 2 coats of top coating and dried for 15 hours at a temperature of 28-30℃ and a relative humidity of 60%-65%; then the coating is cured at 150℃ for 12 hours to obtain the coating, with a base thickness of 50-60μm and a top layer thickness of 10-15μm.

[0059] Tests showed that the coating prepared in Example 2 had a solar absorptivity of 0.38 and an infrared emissivity of 0.85 at 600℃, exhibiting both high-temperature and high-infrared emissivity and high solar spectral reflectivity, thus demonstrating good high-temperature heat dissipation capabilities.

[0060] Comparative Example

[0061] Comparative Example 1

[0062] Comparative Example 1 is the same as Example 1, except that zinc titanate is not added to the base coating, and 60g of copper chromite powder is added.

[0063] Tests showed that the coating prepared in Comparative Example 1 had a solar absorptivity of 0.44 and an infrared emissivity of 0.87 at 600℃. Although it had a high high-temperature emissivity, its solar absorptivity was low, meaning that its solar spectrum reflectivity was weak and its high-temperature heat dissipation capacity was easily weakened by solar radiation.

[0064] Comparative Example 2

[0065] Comparative Example 2 is the same as Example 1, except that 8YSZ is not added to the topcoat, and 90g of zinc titanate powder is added.

[0066] Tests showed that the coating prepared in Comparative Example 2 had a solar absorptivity of 0.28 and an infrared emissivity of 0.77 at 600℃. Although the solar absorptivity was low, the high-temperature emissivity was also low, indicating that the radiative heat dissipation capacity was weak.

[0067] The present invention has been described in detail above with reference to specific embodiments and exemplary examples; however, these descriptions should not be construed as limiting the present invention. Those skilled in the art will understand that various equivalent substitutions, modifications, or improvements can be made to the technical solutions and embodiments of the present invention without departing from the spirit and scope of the invention, and all such modifications and improvements fall within the scope of the present invention. The scope of protection of the present invention is defined by the appended claims.

[0068] The contents not described in detail in this specification are common knowledge to those skilled in the art.

Claims

1. A thermal control coating that combines high temperature and high infrared radiation with high solar spectral reflectance, characterized in that, Includes primer and topcoat; The base coat uses a silica sol-modified lithium silicate solution as the base binder, a mixed powder of copper chromite and zinc titanate as the base filler, and water as the solvent. The topcoat uses a silica sol-modified lithium silicate solution as the topcoat binder, a mixed powder of zinc titanate and 8YSZ as the topcoat filler, and water as the solvent.

2. The thermal control coating with both high temperature and high infrared radiation and high solar spectral reflectance properties according to claim 1, characterized in that, In the underlying adhesive, the mass ratio of lithium silicate solution to silica sol is 50:1 to 4:1, and the solid content of the lithium silicate solution is 30% to 50%.

3. The thermal control coating with both high temperature and high infrared radiation and high solar spectral reflectance properties according to claim 1, characterized in that, In the surface adhesive, the mass ratio of lithium silicate solution to silica sol is 50:1 to 4:1, and the solid content of lithium silicate solution is 30% to 50%.

4. The thermal control coating with both high temperature and high infrared radiation and high solar spectral reflectance properties according to claim 1, characterized in that, In the bottom filler, the mass ratio of copper chromite to zinc titanate is 10:1 to 1:

1.

5. The thermal control coating with both high temperature and high infrared radiation and high solar spectral reflectance properties according to claim 1, characterized in that, The mass ratio of zinc titanate to 8YSZ is 10:1 to 1:

1.

6. The thermal control coating with both high temperature and high infrared radiation and high solar spectral reflectance properties according to claim 1, characterized in that, The copper chromite powder has a particle size of 200–1000 nm; the bottom layer of zinc titanate has a particle size of 1–10 μm; the top layer of zinc titanate has a particle size of 50–200 nm; and the top layer of 8YSZ has a particle size of 500–1000 nm.

7. A thermal control coating that combines high temperature and high infrared radiation with high solar spectral reflectance, characterized in that, The coating is formed by spraying a thermal control coating with high temperature, high infrared radiation and high solar spectrum reflectance as described in any one of claims 1 to 6. The bottom layer is formed by spraying a base coating, and the top layer is formed by spraying a top coating on the bottom layer.

8. The thermal control coating with both high temperature and high infrared radiation and high solar spectral reflectance properties according to claim 7, characterized in that, The thickness of the bottom layer is 40–90 μm, and the thickness of the top layer is 1–20 μm.

9. A method for preparing a thermal control coating with both high temperature and high infrared radiation and high solar spectral reflectance properties as described in any one of claims 1 to 6, characterized in that, Includes the following steps: Add grinding balls, copper chromite, zinc titanate powder, lithium silicate solution, silica sol and water to an alumina ball milling jar, and mix by ball milling. Then filter to remove the grinding balls to obtain a uniformly dispersed base coating. Grinding balls, 8YSZ powder, zinc titanate powder, lithium silicate solution, silica sol, and water are added to an alumina ball mill jar and ball-milled to mix them. The grinding balls are then filtered out to obtain a uniformly dispersed surface coating.

10. The method for preparing the thermal control coating with both high temperature and high infrared radiation and high solar spectral reflectance properties according to claim 9, characterized in that, The mass fractions of each component in the base coat are as follows: 100 parts lithium silicate solution and silica sol, 50-150 parts copper chromite and zinc titanate, and 200-350 parts water. The mass fractions of each component of the topcoat are as follows: 100 parts lithium silicate solution and silica sol, 50-100 parts 8YSZ and zinc titanate, and 200-350 parts deionized water.

11. A method for preparing a thermal control coating with both high temperature and high infrared radiation and high solar spectral reflectance properties as described in claim 7 or 8, characterized in that, Includes the following steps: The coating is prepared by air spraying. First, the base coat is stirred evenly and filtered through a filter screen. Then, it is sprayed onto the substrate. After the base coat dries, the stirred and filtered top coat is sprayed onto the base coat. After the top coat dries, it is baked and cured.

12. The method for preparing a thermal control coating with both high temperature and high infrared radiation and high solar spectral reflectance properties according to claim 11, characterized in that, The ambient temperature for bottom drying is 20–30℃, the relative humidity is 40%–70%, and the drying time is 2–4 hours; and / or The ambient temperature for surface drying is 20–30℃, the relative humidity is 40%–70%, and the drying time is 12–24 hours; and / or The curing temperature of the coating is 150–250℃, and the curing time is 12–24 hours.

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