A low-absorption and high-emission thermal control coating resistant to high-dose ionizing radiation and its preparation method

Abstract

A low-absorption and high-emission thermal control coating resistant to high-dose ionizing radiation and its preparation method, which relates to the field of spacecraft thermal control coatings. The thermal control coating includes a bottom coating, a middle coating, and a top coating sequentially arranged on the surface of a substrate; the bottom coating includes barium sulfate, cerium oxide, and a binder; the middle coating includes hollow glass microspheres, a binder, and an inorganic dispersant; the top coating includes indium tin oxide and a binder. It greatly increases the scattering ability of different spectral energies of sunlight and the tolerance to vacuum ionizing radiation, enabling it to meet the design requirements of high precision and long life of modern new spacecraft.

Description

Technical Field

[0001] The present invention relates to a preparation method of a thermal control coating with a low solar absorptance and a high infrared emissivity, belonging to the technical field of spacecraft thermal control coatings. Background Technique

[0002] Thermal control coating materials are an important type of thermal management functional materials in spacecraft, and are widely used in products such as thermal radiators, structural plates, electronic units, antennas, electric propulsion systems, and sunshields. They are the most widely used thermal control materials in spacecraft. Their function is to change the surface thermophysical properties of objects by means of coatings, maintain the balance of energy absorption and radiation on the inner and outer surfaces, so as to effectively control the temperature of objects during the radiative heat exchange process, and ensure that the working temperatures of internal instruments and equipment do not exceed the allowable range during the internal and external heat exchange process of the spacecraft. For components, for every 25°C increase in temperature, the failure rate increases by one order of magnitude (for every 2°C increase, the reliability decreases by 10%). Almost all visible inner and outer surfaces of the spacecraft are thermal control coating materials. Among them, spray-type low-absorption and high-emission thermal control coatings are the most widely used, most significant type of thermal control coating materials in spacecraft due to their advantages such as simple construction, wide product adaptability, and low cost. During the on-orbit operation of satellites, they will face harsh space environments. Therefore, it is required that thermal control coatings not only have excellent thermophysical properties, but also have excellent space environmental stability to ensure that the temperature control meets the requirements of each unit and payload during the satellite's life cycle.

[0003] Existing low-absorption and high-emission thermal control coatings are mostly traditional ZnO filler systems. In the past 50-odd years, they have played an important role in the thermal control coating products of low-orbit spacecraft relying on their excellent shielding performance in the ultraviolet band of 200nm to 380nm. However, their characteristics of relatively high solar absorptance (≥0.15) and sensitivity to optical defects of ionizing radiation (the reflectivity at the end of life is reduced to less than 40%) limit their use in the harsh irradiation environments of medium and high orbits and cannot meet the higher performance requirements of subsequent model tasks in China. Summary of the Invention

[0004] The technical problem solved by this application is: overcoming the deficiencies of the prior art, providing a preparation method of a low-absorption, high-emission and high-dose ionizing radiation-resistant thermal control coating, which greatly increases the scattering ability of different spectral energies of sunlight and the tolerance of vacuum ionizing radiation, so as to meet the design requirements of high precision and long life of modern new spacecraft.

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

[0006] A low-absorption, high-emission and high-dose ionizing radiation-resistant thermal control coating includes a primer layer, an intermediate layer and a topcoat layer sequentially provided on the surface of a substrate;

[0007] The bottom coating comprises barium sulfate, cerium oxide, and a binder;

[0008] The middle coating comprises hollow glass microspheres, a binder, and an inorganic dispersant;

[0009] The top coating comprises indium tin oxide and a binder.

[0010] Based on the total volume of the components in the bottom coating being 100%, the volume fraction of barium sulfate in the bottom coating is 40% - 50%, the volume fraction of cerium oxide in the bottom coating is 25% - 35%, and the volume fraction of the binder in the bottom coating is 15% - 35%.

[0011] The binder in the bottom coating comprises potassium silicate and silica sol. Based on the total volume of the components in the bottom coating being 100%, the volume fraction of barium sulfate in the bottom coating is 40% - 50%, the volume fraction of cerium oxide in the bottom coating is 25% - 35%, the volume fraction of potassium silicate is 10% - 20%, and the volume fraction of silica sol is 5% - 15%.

[0012] Based on the total volume of the components in the middle coating being 100%, the volume fraction of hollow glass microspheres is 50% - 70%, the volume fraction of the binder is 30% - 50%, and the volume fraction of the inorganic dispersant is 0.1 - 0.5%.

[0013] The binder in the middle coating comprises potassium silicate and silica sol. Based on the total volume of the components in the middle coating being 100%, the volume fraction of hollow glass microspheres is 50% - 70%, the volume fraction of potassium silicate is 20% - 30%, the volume fraction of silica sol is 10% - 20%, and the volume fraction of the inorganic dispersant is 0.1 - 0.5%.

[0014] Based on the total volume of the components in the top coating being 100%, the volume fraction of indium tin oxide is 10% - 20%, and the volume fraction of the binder is 80% - 90%.

[0015] The binder in the top coating comprises potassium silicate and silica sol. Based on the total volume of the components in the top coating being 100%, the volume fraction of indium tin oxide is 10% - 20%, the volume fraction of potassium silicate is 40% - 60%, and the volume fraction of silica sol is 25% - 45%.

[0016] The inorganic dispersant is selected from ethylene glycol, propylene glycol, alcohol ester 12, etc.

[0017] In each coating, by setting that the binder includes potassium silicate and silica sol and setting the corresponding ratios according to different components such as seasonings, the silica sol compensates for the shrinkage stress of the potassium silicate, making the formed coating not easily cracked.

[0018] In the bottom coating, barium sulfate (BaSO4) and cerium oxide (CeO2) are selected as coating fillers. The morphology of barium sulfate is cubic, the particle size is 0.5 μm to 1 μm, and the purity is ≥99.9%. The morphology of cerium oxide is cubic, the particle size is 0.5 μm to 1 μm, and the purity is ≥99.9%. The volume fraction of barium sulfate in the bottom coating is 40% to 50%, and the volume fraction of cerium oxide in the bottom coating is 25% to 35%. Potassium silicate and silica sol are selected as coating binders in the bottom coating. The volume fraction of potassium silicate is 10% to 20%, and the volume fraction of silica sol is 5% to 15%.

[0019] In the intermediate coating, hollow glass microspheres (HGM) are selected as coating fillers. The morphology of HGM is spherical, the particle size is 100 nm to 200 nm, and the purity is ≥99.9%. The volume fraction of HGM is 50% to 70%. Potassium silicate and silica sol are selected as coating binders in the intermediate coating. The volume fraction of potassium silicate is 20% to 30%, and the volume fraction of silica sol is 10% to 20%. The volume fraction of the inorganic dispersant in the intermediate coating is 0.1% to 0.5%.

[0020] In the top coating, indium tin oxide (ITO) is selected as coating filler. The morphology of ITO is spherical, the particle size is 100 to 200 nm, and the purity is ≥99.9%. The volume fraction of ITO is 10% to 20%. Potassium silicate and silica sol are selected as coating binders in the top coating. The volume fraction of potassium silicate is 40% to 60%, and the volume fraction of silica sol is 25% to 45%.

[0021] In the bottom coating, by setting the fillers as a blend of barium sulfate and cerium oxide, barium sulfate has a relatively high reflectivity in the ultraviolet band and good resistance to ionizing radiation. As a rare earth oxide, cerium oxide has variable valence ions and can provide certain ionizing radiation stability through its variable valence characteristics under irradiation conditions. The blending of barium sulfate and cerium oxide in a certain proportion endows the bottom coating with comprehensive characteristics of good solar absorption ratio and insensitivity to ionizing radiation optical defects. In the intermediate coating, the hollow glass microspheres can effectively reflect most of the solar radiation by constructing a multi-layer reflection interface through the refractive index difference property with the binder. In the top coating, the ITO filler with excellent conductivity is used to provide antistatic performance, reduce the surface resistance of the coating system, and provide equipotential ability for the coating.

[0022] By arranging the order of the primer, midcoat, and topcoat, and selecting the filler in the topcoat, the topcoat has a strong antistatic effect. The topcoat is placed on the surface layer, ensuring that the entire thermal control coating has a strong antistatic effect, and the surface resistance of the thermal control coating meets the equipotential requirements of medium and high rails. Ultraviolet and infrared light pass through the primer, midcoat, and topcoat in sequence, and are reflected step by step. The filler in the midcoat is hollow glass microbeads, which have a strong reflective effect on the ultraviolet band. The remaining small amount of ultraviolet radiation is reflected by the primer, while the majority of infrared light is reflected by the primer. The filler in the middle midcoat is transparent hollow glass microbeads, and the radiation reflected by the primer is reflected outward, achieving a strong reflective effect across the entire spectrum. If the midcoat is located on the side of the primer facing away from the topcoat, since the primer is opaque and the midcoat is translucent, the radiation reflected by the midcoat may be reflected back by the primer, resulting in multiple repeated reflections and a reduced solar absorption ratio.

[0023] The barium sulfate is pretreated barium sulfate, and the cerium oxide is pretreated cerium oxide;

[0024] The preparation method of pretreated barium sulfate is:

[0025] BaSO4, potassium silicate and deionized water are mixed, with the volume ratio of BaSO4 to potassium silicate being 1:2-1:4 and the volume ratio of BaSO4 to deionized water being 1:3-1:5. The mixture is stirred for 4-8 hours and then ball-milled for 1-2 hours. The mixture is filtered, washed and dried to obtain pretreated barium sulfate.

[0026] The preparation method of pretreated cerium oxide is:

[0027] CeO2, potassium silicate and deionized water are mixed, with the volume ratio of CeO2 to potassium silicate being 1:2~1:4 and the volume ratio of CeO2 to deionized water being 1:3~1:5. The mixture is stirred for 4h~8h and then ball-milled for 1~2h. The mixture is filtered, washed and dried to obtain pretreated cerium oxide.

[0028] By using the above-mentioned pretreatment method, SiO2 is pre-coated on the outside of barium sulfate and cerium oxide, so that the primer filler does not need to be dispersed in the ball milling process, thus avoiding the particle size reduction and defect increase caused by excessive grinding of the filler in the ball milling dispersion process.

[0029] Furthermore, the specific thickness of the coating is: the thickness of the base coating is 100 μm to 140 μm, the thickness of the middle coating is 20 to 40 μm, and the thickness of the top coating is 2 to 4 μm.

[0030] Under the thickness limit of the basecoat, the midcoat and the topcoat, the thermal control coating has a smaller weight while meeting the performance required for medium and high rails.

[0031] The present invention provides a method for preparing a low-absorption, high-emission, and large-dose ionizing radiation-resistant thermal control coating, and the steps are as follows:

[0032] (1) Prepare the primer coating paint: First, mix BaSO4, potassium silicate, and deionized water. The volume ratio of BaSO4 to potassium silicate is 1:2 to 1:4, and the volume ratio of BaSO4 to deionized water is 1:3 to 1:5. After high-speed stirring for 4 h to 8 h, then ball-mill for 1 to 2 h, filter, wash, and dry to obtain pretreated barium sulfate. Treat CeO2 according to the same steps and ratios to obtain pretreated cerium oxide. Then, mix the obtained pretreated barium sulfate, pretreated cerium oxide, potassium silicate, silica sol, and diluent, and prepare the primer coating paint after high-speed stirring and uniform dispersion.

[0033] (2) Prepare the intermediate coating paint: Mix HGM, silica sol, potassium silicate, diluent, and inorganic dispersant, and prepare the intermediate coating paint after high-speed stirring and uniform dispersion.

[0034] (3) Prepare the topcoat paint: Mix ITO, silica sol, potassium silicate, and diluent, and prepare the topcoat paint after ball-milling and uniform dispersion.

[0035] (4) Prepare the low-absorption, high-emission, and large-dose ionizing radiation-resistant thermal control coating: Spray deionized water on the surface of the substrate. After surface drying for 0.5 h to 1 h, spray the primer coating. After room-temperature curing for ≥12 h, spray the intermediate coating. After room-temperature curing for ≥12 h, bake at 60 to 100 °C for ≥24 h and then spray the topcoat. After room-temperature curing for ≥12 h, bake at 60 to 100 °C for ≥12 h to obtain the low-absorption, high-emission, and large-dose ionizing radiation-resistant thermal control coating.

[0036] In the preparation method, during the pretreatment process of BaSO4 and CeO2, first high-speed stir for 4 h to 8 h and then ball-mill for 1 to 2 h. By combining high-speed stirring and ball-milling, with a longer high-speed stirring time and a shorter ball-milling time, the ball-milling time of BaSO4 and CeO2 is reduced. During the preparation process of the primer coating, directly perform high-speed stirring on it. Therefore, during the entire preparation process of the primer coating, the ball-milling time of the filler is greatly reduced, and the filler is not easily worn. Moreover, BaSO4 and CeO2 are pretreated separately, further avoiding wear between the two fillers with different hardnesses; avoiding the reduction of particle size and the increase of defects caused by over-grinding of the filler during the ball-milling dispersion process.

[0037] Further, the diluent in steps (1), (2), and (3) is deionized water. The mass of the diluent in step (1) is 20% to 40% of the total mass of other components of the primer coating paint. The mass of the diluent in step (2) is 20% to 40% of the total mass of other components of the intermediate coating paint. The mass of the diluent in step (3) is 20% to 40% of the total mass of other components of the topcoat paint.

[0038] Further, in the steps (1) and (2), the rotation speed of high-speed stirring and dispersion is 1000 rpm to 1600 rpm.

[0039] Further, in the steps (1) and (3), the medium used for ball milling and dispersion is corundum or zirconia, and the volume of the ball milling medium is 1 to 1.5 times the total volume of the coating.

[0040] Further, in the step (4), the substrate is selected from common spacecraft materials such as aluminum alloy, titanium alloy, magnesium alloy, stainless steel, pure iron, ablative material, carbon fiber composite material, etc.

[0041] In summary, the present application at least includes the following beneficial technical effects:

[0042] (1) The low-absorption high-emission large-dose ionizing radiation-resistant thermal control coating of the present invention has excellent solar spectral reflection performance and infrared emission performance, can have a smaller degradation of the solar absorptance after large-dose electron radiation, is applicable to most common spacecraft substrates, has antistatic performance to reduce the risk of electrostatic damage to spacecraft, and plays an important role in the long-term stable in-orbit thermal control performance of long-life spacecraft.

[0043] (2) The low-absorption high-emission large-dose ionizing radiation-resistant thermal control coating of the present invention has the following characteristics:

[0044] 1) Appearance: The overall coating is uniformly white, without phenomena such as bubbles, peeling, cracking, and shedding.

[0045] 2) Solar absorptance: 0.06 to 0.09;

[0046] 3) Hemispherical emissivity: 0.90 to 0.92;

[0047] 4) Surface resistance: 10 5 ~10 7 Ω / □;

[0048] 5) Thermal cycle performance: After the coating on the surface of substrates such as aluminum alloy, titanium alloy, magnesium alloy, stainless steel, pure iron, ablative material, carbon fiber composite material, etc. undergoes 100 times of thermal cycle tests at -196°C to +200°C according to the standard, there are no phenomena such as bubbles, peeling, cracking, and shedding in the coating.

[0049] 6) Radiation resistance performance: After experiencing the ionizing radiation dose of 15 years in the GEO orbit, the change in the solar absorptance of the coating is ≤0.20, the change in the hemispherical emissivity is ≤0.02, and the thermal cycle performance meets the requirements. Specific embodiments

[0050] As used herein, the term "exemplary" means "serving as an example, instance, or illustration". Any embodiment described herein as "exemplary" is not necessarily to be construed as superior or better than other embodiments.

[0051] Example 1

[0052] (1) Preparation of the bottom coating: First, mix 0.5 μm BaSO4, potassium silicate, and deionized water. The volume ratio of BaSO4 to potassium silicate is 1:2, and the volume ratio of BaSO4 to deionized water is 1:3. After high-speed stirring for 4 h, ball mill for 1 h. The ball milling medium is corundum, and the volume of the ball milling medium is 1 times the total volume of the coating. Filter, wash, and dry to obtain pretreated BaSO4. Treat 0.5 μm CeO2 according to the same steps and ratio to obtain pretreated CeO2. Then mix the pretreated BaSO4, pretreated CeO2, potassium silicate, silica sol, and diluent. The volume fraction of barium sulfate is 40%, the volume fraction of cerium oxide in the bottom coating is 25%, the volume fraction of potassium silicate is 20%, and the volume fraction of silica sol is 15%. The diluent is 20% of the total mass of the pretreated BaSO4, pretreated CeO2, potassium silicate, and silica sol. After high-speed stirring and dispersing evenly at 1200 rpm, the bottom coating is prepared.

[0053] (2) Preparation of the intermediate coating: Mix 100 nm HGM, silica sol, potassium silicate, diluent, and inorganic dispersant. The volume fraction of HGM is 50%, the volume fraction of potassium silicate is 30%, and the volume fraction of silica sol is 19.9%. The volume fraction of the inorganic dispersant in the intermediate coating is 0.1%. The diluent is 20% of the total mass of HGM, silica sol, and potassium silicate. After high-speed stirring and dispersing evenly at 1200 rpm, the intermediate coating is prepared.

[0054] (3) Preparation of the top coating: Mix ITO, silica sol, potassium silicate, and diluent. The volume fraction of ITO is 10%, the volume fraction of potassium silicate is 60%, and the volume fraction of silica sol is 30%. The diluent is 20% of the total mass of ITO, silica sol, and potassium silicate. After ball milling and dispersing evenly, the top coating is prepared.

[0055] (4) Preparation of the low-absorption, high-emission, high-dose ionization radiation-resistant thermal control coating: Spray deionized water on the substrate surface. After the surface is dry for 0.5 h, spray the bottom coating of 100 μm. After curing at room temperature for 12 h, spray the intermediate coating of 20 μm. After curing at room temperature for 12 h, bake at 60 °C for 36 h and then spray the top coating of 2 μm. After curing at room temperature for 12 h and baking at 60 °C for 24 h, the low-absorption, high-emission, high-dose ionization radiation-resistant thermal control coating is prepared.

[0056] The low-absorption, high-emission, high-dose ionization radiation-resistant thermal control coating prepared in this example has the following characteristics:

[0057] 1) Appearance: The coating is uniformly white as a whole, without phenomena such as bubbles, peeling, cracking, and shedding.

[0058] 2) Solar absorptance: 0.09;

[0059] 3) Hemispherical emissivity: 0.90;

[0060] 4) Sheet resistance: 10 5 ~10 7 Ω / □;

[0061] 5) Thermal cycling performance: After the coating on the surfaces of substrates such as aluminum alloy, titanium alloy, magnesium alloy, stainless steel, pure iron, ablative materials, and carbon fiber composite materials undergoes 100 thermal cycling tests at -196°C to +200°C according to the standard, there are no phenomena such as bubbles, peeling, cracking, and shedding on the coating.

[0062] Radiation resistance performance: After experiencing the ionization radiation with a dose of 15 years in the GEO orbit, the change in the solar absorptance of the coating is 0.16, the change in the hemispherical emissivity is 0.01, and the thermal cycling performance meets the requirements.

[0063] Example 2

[0064] (1) Preparation of the bottom coating paint: First, mix 1μm BaSO4, potassium silicate, and deionized water. The volume ratio of BaSO4 to potassium silicate is 1:3, and the volume ratio of BaSO4 to deionized water is 1:4. After high-speed stirring for 6h, then ball-mill for 2h. The ball-milling medium is zirconia, and the volume of the ball-milling medium is 1.5 times the total volume of the paint. Filter, wash, and dry, and process 1μm CeO2 according to the same steps and ratios. Then mix the BaSO4, CeO2, potassium silicate, silica sol, and diluent processed according to the above steps. The volume fraction of barium sulfate is 50%, the volume fraction of cerium oxide in the bottom coating is 30%, the volume fraction of potassium silicate is 15%, the volume fraction of silica sol is 5%, and the diluent is 30% of the total mass of the pre-treated BaSO4, pre-treated CeO2, potassium silicate, and silica sol; After high-speed stirring and dispersing evenly at 1600rpm, the bottom coating paint is prepared.

[0065] (2) Preparation of the intermediate coating paint: Mix 200nm HGM, silica sol, potassium silicate, diluent, and inorganic dispersant. The volume fraction of HGM is 69.9%, the volume fraction of potassium silicate is 20%, and the volume fraction of silica sol is 10%. The volume fraction of the inorganic dispersant in the intermediate coating is 0.1%, and the diluent is 30% of the total mass of HGM, silica sol, and potassium silicate; After high-speed stirring and dispersing evenly at 1600rpm, the intermediate coating paint is prepared.

[0066] (3) Preparation of the surface coating paint: Mix ITO, silica sol, potassium silicate, and diluent. The volume fraction of ITO is 15%, the volume fraction of potassium silicate is 55%, the volume fraction of silica sol is 30%, and the diluent is 30% of the total mass of ITO, silica sol, and potassium silicate. After ball milling and uniform dispersion, the surface coating paint is obtained.

[0067] (4) Preparation of the low-absorption high-emission heat control coating resistant to high-dose ionizing radiation: Spray deionized water on the surface of the substrate. After the surface is dry for 1 h, spray the bottom coating with a thickness of 140 μm, cure at room temperature for 12 h, then spray the middle coating with a thickness of 40 μm, cure at room temperature for 12 h, bake at 80 °C for 24 h, and then spray the surface coating with a thickness of 4 μm. After curing at room temperature for 12 h and baking at 80 °C for 12 h, the low-absorption high-emission heat control coating resistant to high-dose ionizing radiation is obtained.

[0068] The low-absorption high-emission heat control coating resistant to high-dose ionizing radiation prepared in this example has the following properties:

[0069] 1) Appearance: The overall coating is uniformly white, without phenomena such as bubbles, peeling, cracking, and falling off.

[0070] 2) Solar absorptance: 0.06;

[0071] 3) Hemispherical emissivity: 0.92;

[0072] 4) Sheet resistance: 10 5 ~ 10 [[ID=2I]] 7 Ω / □;

[0073] 5) Thermal cycling performance: After the coating on the surfaces of substrates such as aluminum alloy, titanium alloy, magnesium alloy, stainless steel, pure iron, ablative material, and carbon fiber composite material undergoes 100 thermal cycling tests at -196 °C to +200 °C according to the standard, there are no phenomena such as bubbles, peeling, cracking, and falling off of the coating.

[0074] Radiation resistance performance: After experiencing the ionizing radiation dose of 15 years in the GEO orbit, the change in the solar absorptance of the coating is 0.20, the change in the hemispherical emissivity is 0.01, and the thermal cycling performance meets the requirements.

[0075] Example 3

[0076] (1) Preparation of the bottom coating: First, mix 0.5μm BaSO4, potassium silicate, and deionized water. The volume ratio of BaSO4 to potassium silicate is 1:4, and the volume ratio of BaSO4 to deionized water is 1:5. After high-speed stirring for 4h, ball mill for 1h. The ball milling medium is zirconia, and the volume of the ball milling medium is 1.3 times the total volume of the coating. Filter, wash, and dry. Treat 0.5μm CeO2 according to the same steps and ratios. Then mix the BaSO4, CeO2, potassium silicate, silica sol, and diluent treated according to the above steps. The volume fraction of barium sulfate is 45%, the volume fraction of cerium oxide in the bottom coating is 30%, the volume fraction of potassium silicate is 15%, and the volume fraction of silica sol is 10%. The diluent is 40% of the total mass of pretreated BaSO4, pretreated CeO2, potassium silicate, and silica sol. After high-speed stirring and dispersing evenly at 1400rpm, the bottom coating is obtained.

[0077] (2) Preparation of the intermediate coating: Mix 100nm HGM, silica sol, potassium silicate, diluent, and inorganic dispersant. The volume fraction of HGM is 59.9%, the volume fraction of potassium silicate is 25%, and the volume fraction of silica sol is 15%. The volume fraction of the inorganic dispersant in the intermediate coating is 0.1%, and the diluent is 40% of the total mass of HGM, silica sol, and potassium silicate. After high-speed stirring and dispersing evenly at 1400rpm, the intermediate coating is obtained.

[0078] (3) Preparation of the top coating: Mix ITO, silica sol, potassium silicate, and diluent. The volume fraction of ITO is 15%, the volume fraction of potassium silicate is 55%, and the volume fraction of silica sol is 30%. The diluent is 40% of the total mass of ITO, silica sol, and potassium silicate. After ball milling and dispersing evenly, the top coating is obtained.

[0079] (4) Preparation of the low-absorption high-emission heat control coating resistant to high-dose ionizing radiation: Spray deionized water on the substrate surface. After the surface is dry for 0.5h, spray the bottom coating of 110μm. After curing at room temperature for 12h, spray the intermediate coating of 30μm. After curing at room temperature for 12h, bake at 100℃ for 24h and then spray the top coating of 3μm. After curing at room temperature for 12h, bake at 100℃ for 12h to obtain the low-absorption high-emission heat control coating resistant to high-dose ionizing radiation.

[0080] The low-absorption high-emission heat control coating resistant to high-dose ionizing radiation prepared in this example has the following characteristics:

[0081] 1) Appearance: The coating is uniformly white as a whole, without phenomena such as bubbles, peeling, cracking, and shedding.

[0082] 2) Solar absorptance: 0.08;

[0083] 3) Hemispherical emissivity: 0.91;

[0084] 4) Sheet resistance: 10 5 ~10 7 Ω / sq;

[0085] 5) Thermal cycle performance: After the surface coatings of substrates such as aluminum alloy, titanium alloy, magnesium alloy, stainless steel, pure iron, ablative material, carbon fiber composite material, etc. are subjected to 100 thermal cycle tests at -196°C to +200°C according to the standard, there are no phenomena such as bubbles, peeling, cracking, and shedding on the coatings.

[0086] Irradiation resistance performance: After experiencing the ionization irradiation of the GEO orbit for 15 years of dose, the solar absorptance of the coating changes by 0.18, the hemispherical emittance changes by 0.01, and the thermal cycle performance meets the requirements.

[0087] Example 4

[0088] The difference from Example 3 is that in the bottom coating, the volume fraction of barium sulfate is 30%, and the volume fraction of cerium oxide is 45%.

[0089] The low-absorption high-emission large-dose ionization irradiation-resistant thermal control coating prepared in this example has the following characteristics:

[0090] 1) Appearance: The whole coating is uniformly white, without phenomena such as bubbles, peeling, cracking, and shedding;

[0091] 2) Solar absorptance: 0.12;

[0092] 3) Hemispherical emittance: 0.90;

[0093] 4) Sheet resistance: 10 5 ~10 7 Ω / sq;

[0094] 5) Thermal cycle performance: After the surface coatings of substrates such as aluminum alloy, titanium alloy, magnesium alloy, stainless steel, pure iron, ablative material, carbon fiber composite material, etc. are subjected to 100 thermal cycle tests at -196°C to +200°C according to the standard, there are no phenomena such as bubbles, peeling, cracking, and shedding on the coatings.

[0095] Irradiation resistance performance: After experiencing the ionization irradiation of the GEO orbit for 15 years of dose, the solar absorptance of the coating changes by 0.19, the hemispherical emittance changes by 0.01, and the thermal cycle performance meets the requirements.

[0096] Example 5

[0097] The difference from Example 3 is that in the bottom coating, the volume fraction of barium sulfate is 60%, and the volume fraction of cerium oxide is 15%.

[0098] The low-absorption high-emission large-dose ionization irradiation-resistant thermal control coating prepared in this example has the following characteristics:

[0099] 1) Appearance: The coating is uniformly white as a whole, without phenomena such as bubbles, peeling, cracking, and shedding.

[0100] 2) Solar absorptance: 0.10;

[0101] 3) Hemispherical emittance: 0.90;

[0102] 4) Sheet resistance: 10 5 ~10 7 Ω / □;

[0103] 5) Thermal cycle performance: After the coating on the surfaces of substrates such as aluminum alloy, titanium alloy, magnesium alloy, stainless steel, pure iron, ablative material, and carbon fiber composite material undergoes 100 thermal cycle tests at -196°C to +200°C according to the standard, there are no phenomena such as bubbles, peeling, cracking, and shedding in the coating.

[0104] Irradiation resistance performance: After experiencing the ionization irradiation with a dose of 15 years in the GEO orbit, the change in the solar absorptance of the coating is 0.24, the change in the hemispherical emittance is 0.01, and the thermal cycle performance meets the requirements.

[0105] Comparative Example 1

[0106] The difference from Example 3 is that: the spraying sequence in step (4) is: first spray the intermediate coating on the substrate surface, then spray the bottom coating, and finally spray the top coating.

[0107] The low-absorption high-emission thermal control coating with high-dose ionization irradiation resistance prepared in this example has the following characteristics:

[0108] 1) Appearance: The coating is uniformly white as a whole, without phenomena such as bubbles, peeling, cracking, and shedding.

[0109] 2) Solar absorptance: 0.15;

[0110] 3) Hemispherical emittance: 0.89;

[0111] 4) Sheet resistance: 10 5 ~10 7 Ω / □; <able>

[0112] 5) Thermal cycle performance: After the coating on the surfaces of substrates such as aluminum alloy, titanium alloy, magnesium alloy, stainless steel, pure iron, ablative material, and carbon fiber composite material undergoes 100 thermal cycle tests at -196°C to +200°C according to the standard, there are no phenomena such as bubbles, peeling, cracking, and shedding in the coating.

[0113] Irradiation resistance performance: After experiencing the ionization irradiation with a dose of 15 years in the GEO orbit, the change in the solar absorptance of the coating is 0.23, the change in the hemispherical emittance is 0.01, and the thermal cycle performance meets the requirements.

[0114] Comparative Example 2

[0115] The difference from Example 3 is that the spraying sequence in step (4) is as follows: first spray the top coat on the surface of the substrate, then spray the bottom coat, and finally spray the middle coat.

[0116] The low-absorption high-emission large-dose ionizing radiation-resistant thermal control coating prepared in this example has the following properties:

[0117] 1) Appearance: The overall coating is uniformly white, without phenomena such as bubbles, peeling, cracking, and shedding.

[0118] 2) Solar absorptance: 0.08;

[0119] 3) Hemispherical emittance: 0.91;

[0120] 4) Sheet resistance: 10 9 ~10 11 Ω / □;

[0121] 5) Thermal cycle performance: After the coating on the surfaces of substrates such as aluminum alloy, titanium alloy, magnesium alloy, stainless steel, pure iron, ablative materials, and carbon fiber composite materials undergoes a thermal cycle test of 100 times at -196°C to +200°C according to the standard, there are no phenomena such as bubbles, peeling, cracking, and shedding in the coating.

[0122] Irradiation resistance performance: After undergoing the ionizing radiation of the GEO orbit for 15 years of dose, the change in the solar absorptance of the coating is 0.19, the change in the hemispherical emittance is 0.01, and the thermal cycle performance meets the requirements.

[0123] Comparative Example 3

[0124] The difference from Example 3 is that:

[0125] In the preparation method, the barium sulfate and cerium oxide fillers are not pretreated, and the bottom coat paint is directly prepared by ball milling and dispersing for 12 hours.

[0126] The low-absorption high-emission large-dose ionizing radiation-resistant thermal control coating prepared in this example has the following properties:

[0127] 1) Appearance: The overall coating is uniformly white, without phenomena such as bubbles, peeling, cracking, and shedding.

[0128] 2) Solar absorptance: 0.13;

[0129] 3) Hemispherical emittance: 0.90;

[0130] 4) Sheet resistance: 10 5 ~10 7 Ω / □;

[0131] 5) Thermal cycling performance: After the surface coatings of substrates such as aluminum alloy, titanium alloy, magnesium alloy, stainless steel, pure iron, ablative materials, and carbon fiber composite materials are subjected to 100 thermal cycling tests at -196°C to +200°C according to the standard, there are no phenomena such as bubbles, peeling, cracking, and shedding of the coatings.

[0132] Irradiation resistance performance: After experiencing the ionization irradiation dose of 15 years in the GEO orbit, the solar absorptance of the coating changes by 0.22, the hemispherical emissivity changes by 0.01, and the thermal cycling performance meets the requirements.

[0133] The content not described in detail in the specification of the present invention belongs to the well-known technology in the art.

[0134] The present application has been described in detail above in combination with specific embodiments and exemplary examples. However, these descriptions should not be construed as limiting the present application. Those skilled in the art understand that without departing from the spirit and scope of the present application, various equivalent substitutions, modifications, or improvements can be made to the technical solutions and their implementation manners of the present application, and these all fall within the scope of the present application. The protection scope of the present application is subject to the appended claims.

Claims

1. A low-absorption, high-emission thermal control coating resistant to high-dose ionizing radiation, characterized in that: It includes a primer coat, an intermediate coat, and a top coat sequentially provided on the substrate surface; The primer coat includes barium sulfate, cerium oxide, and a binder; The intermediate coat includes hollow glass microspheres, a binder, and an inorganic dispersant; The top coat includes indium tin oxide and a binder; Based on the total volume of each component in the primer coat being 100%, the volume fraction of barium sulfate in the primer coat is 40% - 50%, the volume fraction of cerium oxide in the primer coat is 25% - 35%, and the volume fraction of the binder in the primer coat is 15% - 35%.

2. The low-absorption and high-emission thermal control coating resistant to high-dose ionizing radiation according to claim 1, wherein: The binder in the primer coat includes potassium silicate and silica sol. Based on the total volume of each component in the primer coat being 100%, the volume fraction of barium sulfate in the primer coat is 40% - 50%, the volume fraction of cerium oxide in the primer coat is 25% - 35%, the volume fraction of potassium silicate is 10% - 20%, and the volume fraction of silica sol is 5% - 15%.

3. A low-absorption and high-emission thermal control coating resistant to high-dose ionizing radiation according to claim 1, characterized in that: Based on the total volume of each component in the intermediate coat being 100%, the volume fraction of hollow glass microspheres is 50% - 70%, the volume fraction of the binder is 30% - 50%, and the volume fraction of the inorganic dispersant is 0.1 - 0.5%.

4. The low-absorption and high-emission thermal control coating resistant to high-dose ionizing radiation according to claim 1, wherein: Based on the total volume of each component in the top coat being 100%, the volume fraction of indium tin oxide is 10% - 20%, and the volume fraction of the binder is 80% - 90%.

5. A low-absorption high-emission thermal control coating resistant to high-dose ionizing radiation according to claim 1, characterized in that: The barium sulfate has a cubic shape, a particle size of 0.5μm - 1μm, and a purity of ≥99.9%; the cerium oxide has a cubic shape, a particle size of 0.5μm - 1μm, and a purity of ≥99.9%; The hollow glass microspheres have a spherical shape, a particle size of 100nm - 200nm, and a purity of ≥99.9%; The indium tin oxide has a spherical shape, a particle size of 100 - 200nm, and a purity of ≥99.9%.

6. The low-absorption and high-emission thermal control coating resistant to high-dose ionizing radiation according to claim 1, characterized in that: The thickness of the primer coat is 100μm - 140μm, the thickness of the intermediate coat is 20 - 40μm, and the thickness of the top coat is 2 - 4μm.

7. A low-absorption high-emission large-dose ionization radiation-resistant thermal control coating according to claim 1, characterized in that: The barium sulfate is pretreated barium sulfate, and the cerium oxide is pretreated cerium oxide; The preparation method of the pretreated barium sulfate is: Mix BaSO4, potassium silicate, and deionized water. The volume ratio of BaSO4 to potassium silicate is 1:2 - 1:4, and the volume ratio of BaSO4 to deionized water is 1:3 - 1:

5. After stirring for 4h - 8h and then ball milling for 1 - 2h, filter, wash, and dry to obtain the pretreated barium sulfate.

8. The preparation method of a low-absorption high-emission large-dose ionization radiation-resistant thermal control coating according to any one of claims 1-7, characterized in that, It includes: S1: Prepare the primer coat paint: First, pretreat BaSO4 and CeO2 to obtain pretreated barium sulfate and pretreated cerium oxide; Then mix the pretreated BaSO4, pretreated CeO2, potassium silicate, silica sol, and a diluent, and stir and disperse evenly to prepare the primer coat paint; S2: Prepare the intermediate coat paint: Mix hollow glass microspheres, a binder, a diluent, and an inorganic dispersant, and stir and disperse evenly to prepare the intermediate coat paint; S3: Prepare the top coat paint: Mix indium tin oxide, a binder, and a diluent, and ball mill and disperse evenly to prepare the top coat paint; S4: Preparation of a low-absorption and high-emission thermal control coating resistant to high-dose ionizing radiation: Spray deionized water on the surface of the substrate. After the surface is dry for 0.5 h to 1 h, spray the bottom coating. After curing at room temperature for ≥12 h, spray the middle coating. After curing at room temperature for ≥12 h, bake at 60 to 100 °C for ≥24 h and then spray the top coating. After curing at room temperature for ≥12 h, bake at 60 to 100 °C for ≥12 h to obtain the low-absorption and high-emission thermal control coating resistant to high-dose ionizing radiation.

9. The preparation method of a low-absorption high-emission thermal control coating resistant to high-dose ionizing radiation according to claim 8, characterized in that: The diluent in the steps S1, S2 and S3 is deionized water. The mass of the diluent in step S1 is 20% to 40% of the total volume of the other components of the bottom coating paint. The mass of the diluent in step S2 is 20% to 40% of the total volume of the other components of the middle coating paint. The mass of the diluent in step S3 is 20% to 40% of the total volume of the other components of the top coating paint.