Solar spectrum total reflection type antistatic thermal control coating and preparation method thereof
阅读说明：本技术 一种太阳光谱全反射型抗静电热控涂层及其制备方法 (Solar spectrum total reflection type antistatic thermal control coating and preparation method thereof ) 是由 吕金鹏 文相宇 陈卓 于 2021-07-05 设计创作，主要内容包括：本发明公开了一种太阳光谱全反射型抗静电热控涂层及其制备方法,属于新材料领域；本发明热控涂层材料主要组成为超宽禁带氧化物颜料、无机水玻璃粘结剂和功能性助剂,本发明中超宽禁带氧化物颜料的涂层宜具有优异的防护粒子辐射稳定性,制备的涂层为水性环保涂料,可空气喷涂、刷涂或刮涂,具有室温固化特性。涂层的太阳吸收比低至0.08～0.09,发射率为0.88～0.92,表面电阻率为10～(5)～10～(7)Ωm,可应用于空间高太阳热流、强粒子辐射、电离层充放电及原子氧环境等复杂苛刻环境协同作用效应下服役的各类航天器的热控系统。(The invention discloses a solar spectrum total reflection type antistatic thermal control coating and a preparation method thereof, belonging to the field of new materials; the thermal control coating material mainly comprises the ultra-wide forbidden band oxide pigment, the inorganic water glass binder and the functional auxiliary agent, the coating of the ultra-wide forbidden band oxide pigment has excellent radiation stability of protective particles, and the prepared coating is an aqueous environment-friendly coating which can be sprayed, brushed or scraped in air and has the characteristic of curing at room temperature. The solar absorption ratio of the coating is as low as 0.08-0.09, the emissivity is 0.88-0.92, and the surface resistivity is 10 5 ~10 7 Omega m, can be applied to space high solar heat flow, strong particle radiation, ionosphere charging and discharging and atomic oxygen cycleAnd the thermal control system of various spacecrafts which are in service under the synergistic effect of complex and harsh environments such as environment and the like.)
1. The solar spectrum total reflection type antistatic thermal control coating is characterized by being prepared from the following raw materials in percentage by mass:
30% -60% of ultra-wide forbidden band oxide pigment;
30% -50% of water glass liquid binder;
2% -10% of functional auxiliary agent;
the balance of distilled water.
2. The solar-spectrum total-reflection antistatic thermal control coating of claim 1, wherein the ultra-wide band-gap oxide pigment is MgO, Ga2O3One or a mixture of both.
3. The solar spectrum total reflection type antistatic thermal control coating according to claim 1, wherein the liquid water glass binder is an inorganic liquid water glass binder, and the inorganic liquid water glass binder is potassium water glass or lithium water glass.
4. The solar spectrum total reflection type antistatic thermal control coating of claim 1, wherein the functional assistant comprises one or more of aluminum phosphate, calcium fluoride, KH560 silane coupling agent.
5. The preparation method of the solar spectrum total reflection type antistatic thermal control coating according to any one of claims 1 to 4, characterized in that the preparation method specifically comprises the following steps:
step one, taking 30% -60% of ultra-wide forbidden band oxide powder pigment, and carrying out ball milling treatment on the pigment; the ultra-wide bandgap oxide powder pigment is MgO and Ga2O3One or a mixture of two of them;
weighing 30-50% of a water glass liquid binder, wherein the water glass liquid binder is potassium water glass or lithium water glass, adding a proper amount of distilled water into the potassium water glass or the lithium water glass for dilution, and forming a silica network structure through hydrolysis so as to form a coating;
step three, uniformly pouring the oxide powder in the step one into the water glass liquid binder solution in the step two, adding a proper amount of distilled water, stirring and dispersing, controlling the rotating speed at 500-2000 r/min, and stirring for 4 hours;
step four, weighing 2-10% of functional auxiliary agent, adding the functional auxiliary agent into the solution obtained in the step three, and fully dispersing and mixing the functional auxiliary agent; the auxiliary agent is one or a mixture of more of aluminum phosphate, calcium fluoride and KH560 silane coupling agent;
and step five, sieving the obtained coating solution by a 200-mesh sieve, preparing a thermal control coating by air spraying, manual brush coating or blade coating, and drying and curing at 80 ℃ for 4 hours or standing for drying and curing at room temperature.
6. The method for preparing the solar spectrum total reflection type antistatic thermal control coating according to claim 5, wherein in the first step, the pigment particle size distribution is controlled to be 100-800 nm by ball milling.
7. The preparation method of the solar spectrum total reflection type antistatic thermal control coating according to claim 5, wherein the water glass binder is prepared by adding analytically pure alkali metal hydroxide and silicon micropowder powder into distilled water according to a molar ratio of 2.5-5, mixing and dispersing, placing into a hydrothermal reaction kettle, and standing for 100 hours at 180 ℃.
8. The method for preparing a solar spectrum total reflection type antistatic thermal control coating according to claim 7, wherein the alkali metal hydroxide is lithium hydroxide or sodium hydroxide.
Technical Field
The invention relates to a solar spectrum total reflection type antistatic thermal control coating and a preparation method thereof, belonging to the field of new materials.
Background
The thermal control coating is an important component of a thermal control subsystem of the spacecraft, is coated on the outer surface of the spacecraft and is applied to the outer surface of the spacecraftThermophysical property of the solar absorption ratio (a)s) And hemispherical emissivity (e)H) To regulate the surface heat balance temperature (T) of a spacecrafts) I.e. Ts∝(as/eH)1/4Thereby achieving the purpose of heat control. The ZnO-based thermal control coating is widely applied to thermal control systems of various types of spacecrafts at home and abroad due to the low absorption and high emission performance and good process characteristics of the ZnO-based thermal control coating. Such as domestic S781 white paint, KSZ white paint, ACR white paint, and AZ Technology in the united states Z-93 white paint, all pigmented with ZnO, correspond to solar absorptance of about 0.20, 0.15, 0.23, and 0.15, respectively. However, the solar spectrum reflectivity of the ZnO coating is low, only about 85%, and there is almost no reflection effect on the high-energy ultraviolet part (200-380 nm) occupying about 6.6% of the total solar radiation energy in the solar radiation spectrum. On the one hand, the thermal protection task of the near-day detector which is in service under high-strength solar irradiation environments such as Venus, Mercury and sun and the like which are developed rapidly is difficult to meet; on the other hand, due to the active photocatalytic activity and the strong absorption of ultraviolet rays of semiconductor pigments such as ZnO and the like in the coating, under the comprehensive environment effects of space particle radiation, vacuum cold and hot alternating circulation and the like, not only is the color center absorption of the coating in a visible light region and the near infrared absorption of free electrons induced, so that the solar heat flow reflection capability of the coating is rapidly reduced, but also the aging degradation of a coating binder and the optical pollution effect are caused. In addition, the common ZnO thermal control coating does not have antistatic capability, and the surface resistivity of the coating can reach 1012Omega m. This results in the deposition of high energy incident electrons on the surface and even inside the coating, resulting in charge and discharge effects due to the potential difference.
Researchers at home and abroad have proposed a series of modification technologies in recent years to improve the solar heat flow reflection capability and the antistatic property of the thermal control coating, but both have the dilemma of trade-off, and the thermal control coating with high solar spectrum reflection and low resistivity cannot be obtained at the same time. For example, the patent (application number CN109439186A a full-illumination-adaptive spacecraft thermal control coating) adopts SiO2Hollow microspheres, BaSO4The low-absorption thermal control white paint is prepared for the pigment, but the surface resistivity of the coating is far larger than GJB 2502 aviation StandardAntistatic thermal control coating in celestial body thermal control coating test method<109And omega m. The patent (New anti-static white thermal control coating with the authorization number CN103666248B and the preparation method thereof) prepares the volume resistivity by adding metal micro-sheets into a ZnO coating<107Omega m, but the solar absorption ratio of the coating is as high as 0.24-0.29.
Therefore, the thermal control coating with solar spectrum total reflection and antistatic property is researched and prepared, the thermophysical property and the application range of the rail environment of the conventional thermal control coating are greatly improved, and the thermal control precision and the service reliability of the spacecraft are improved.
Disclosure of Invention
The invention aims to overcome the defects of low solar heat flow reflectivity, large surface potential difference, poor radiation stability of a space environment and the like of the current active thermal control white paint, and provides a solar spectrum total reflection type antistatic thermal control white paint and a preparation method thereof based on spectrum design and an energy band regulation principle so as to obtain a thermal control coating with high solar heat flow reflectivity and antistatic property at the same time, and the solar spectrum total reflection type antistatic thermal control white paint can be applied to the fields of surface thermal protection, industrial passive radiation refrigeration and the like of various spacecrafts in service in an extreme space environment.
The invention is realized by the following steps:
the solar spectrum total reflection type antistatic thermal control coating is characterized by being prepared from the following raw materials in percentage by mass: 30% -60% of ultra-wide forbidden band oxide pigment; 30% -50% of water glass liquid binder; 2% -10% of functional auxiliary agent; the balance of distilled water. The coating of the ultra-wide forbidden band oxide pigment is suitable for having excellent radiation stability of protective particles, and the prepared coating is water-based environment-friendly paint which can be sprayed, brushed or scraped in air and has the characteristic of curing at room temperature.
Furthermore, the ultra-wide bandgap oxide pigment is MgO and Ga2O3One or a mixture of both.
Further, the liquid sodium silicate binder is an inorganic liquid sodium silicate binder, and the inorganic liquid sodium silicate binder is potassium sodium silicate or lithium sodium silicate.
Further, the functional auxiliary agent comprises one or a mixture of more of aluminum phosphate, calcium fluoride and KH560 silane coupling agent.
The invention discloses a preparation method of a solar spectrum total reflection type antistatic thermal control coating, which is characterized by comprising the following steps:
step one, taking 30% -60% of ultra-wide forbidden band oxide powder pigment, and carrying out ball milling treatment on the pigment; the ultra-wide bandgap oxide powder pigment is MgO and Ga2O3One or a mixture of two of them;
weighing 30-50% of a water glass liquid binder, wherein the water glass liquid binder is potassium water glass or lithium water glass, adding a proper amount of distilled water into the potassium water glass or the lithium water glass for dilution, and forming a silica network structure through hydrolysis so as to form a coating;
step three, uniformly pouring the oxide powder in the step one into the water glass liquid binder solution in the step two, adding a proper amount of distilled water, stirring and dispersing, controlling the rotating speed at 500-2000 r/min, and stirring for 4 hours;
step four, weighing 2-10% of functional auxiliary agent, adding the functional auxiliary agent into the solution obtained in the step three, and fully dispersing and mixing the functional auxiliary agent; the auxiliary agent is one or a mixture of more of aluminum phosphate, calcium fluoride and KH560 silane coupling agent;
and step five, sieving the obtained coating solution by a 200-mesh sieve, preparing a thermal control coating by air spraying, manual brush coating or blade coating, and drying and curing at 80 ℃ for 4 hours or standing for drying and curing at room temperature.
Further, in the first step, the particle size distribution of the pigment is controlled to be 100-800 nm through ball milling.
Further, the sodium silicate binder is prepared by adding analytically pure alkali metal hydroxide and silicon micropowder powder into distilled water according to a molar ratio of 2.5-5, mixing and dispersing, and placing into a hydrothermal reaction kettle to stand for 100 hours at 180 ℃.
Further, the alkali metal hydroxide is lithium hydroxide or sodium hydroxide.
The beneficial effects of the invention and the prior art are as follows:
the invention not only realizes the total reflection of solar radiation heat flow occupying more than 99% of solar radiation energy through spectral design and energy band regulation, but also obtains the antistatic performance of the coating based on the semi-conductive characteristics of the inorganic oxide semiconductor and the ionic compound binder.
The coating has extremely high solar spectrum full-spectrum reflection capability, low surface resistivity and excellent space environment irradiation stability, the solar absorption ratio of the coating is as low as 0.08-0.09, the emissivity is 0.88-0.92, and the surface resistivity is 105~107Omega m. The device can be widely applied to the fields of spacecraft outer surface heat balance control with harsh temperature control precision and energy conservation and emission reduction of buildings, large oil and gas tanks, industrial pipelines, weapon and war chariot radiation refrigeration and the like, and is particularly suitable for service requirements of stratospheric detectors and near-earth orbit spacecrafts which are in service in environments of strong space illumination, radiation, atomic oxygen and the like. The coating has the advantages of simple preparation process, water-based environmental protection, short period, low cost and easy large-scale production.
Drawings
FIG. 1 is an SEM photograph of the surface morphology of a thermal control coating prepared in example 1 of a solar spectrum total reflection type antistatic thermal control coating and a preparation method thereof according to the present invention;
FIG. 2 is a spectral reflection curve of a coating sample prepared in example 1 of a solar spectrum total reflection type antistatic thermal control coating and a preparation method thereof in a range of 200nm to 2500 nm.
Detailed Description
In order to make the objects, technical solutions and effects of the present invention more clear, the present invention is further described in detail by the following examples. It should be noted that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
Example 1
(1) Weighing 40% of ultra-wide forbidden band Ga according to mass percentage2O3Powder pigment, wherein the particle size distribution of the pigment is controlled to be 100-800 nm through ball milling; the Ga is2O3The powder pigment is analytically pure and has the purity above.
(2) 40% of potassium water glass binder is weighed and diluted by adding 10% of distilled water. The preparation method of the potassium water glass binder comprises the following steps: adding 5 percent distilled water into analytically pure potassium hydroxide and silicon micropowder powder according to the molar ratio of 3, mixing and dispersing, and placing the mixture into a hydrothermal reaction kettle to stand for 100 hours at 180 ℃.
(3) Uniformly pouring the gallium oxide powder pigment ground and dried in the step (1) into a potassium silicate binder solution, adding 5% of distilled water, stirring and dispersing, controlling the rotating speed at 1000r/min, and stirring for 4 hours;
(4) and (3) weighing 5% of functional auxiliary agent, adding the functional auxiliary agent into the solution in the step (3), and fully dispersing and mixing. The auxiliary agent is aluminum phosphate.
(5) The obtained coating solution is sieved by a 200-mesh sieve, and a thermal control coating is prepared by air spraying and is dried and cured for 4 hours at 80 degrees. The coating prepared in this example was examined, and fig. 1 is a photograph of the surface topography of the thermal control coating, it can be seen that the pigment was completely coated with the binder, and the surface topography of the coating was uniform and flat. FIG. 2 is the spectral reflectance of a solar spectrum total reflection antistatic thermal control coating, with the lower curve in the graph being the standard solar irradiance spectrum outside the earth's atmosphere. The coating has a solar spectral reflectivity of 95% in a 200-1200 nm wave band with concentrated solar radiation energy, and the coating prepared by the method has excellent solar heat flow reflection performance. The thickness of the prepared coating is 200 mu m, the solar absorption ratio of the coating is 0.088, the emissivity is 0.086, and the surface resistivity of the coating is 107Omega m, after electron irradiation fluence of 10 years of simulated GEO orbit, asAbout a degradation amount of less than 0.09.
Example 2
(1) Weighing 30 percent of ultra-wide forbidden band Ga according to mass percentage2O3Powder pigment, wherein the particle size distribution of the pigment is controlled to be 100-800 nm through ball milling; the Ga is2O3The powder pigment is analytically pure and has the purity above.
(2) 50% of lithium water glass binder is weighed and diluted by adding 8% of distilled water. The lithium water glass adhesive is prepared by adding analytically pure lithium hydroxide and silicon micropowder powder into 4 percent of distilled water according to the molar ratio of 2.5, mixing and dispersing, and placing into a hydrothermal reaction kettle to stand for 100 hours at 180 ℃.
(3) Uniformly pouring the gallium oxide powder pigment ground and dried in the step (1) into a lithium water glass binder solution, adding 4% distilled water, stirring and dispersing, controlling the rotating speed at 1000r/min, and stirring for 4 hours;
(4) and (3) weighing 8% of functional auxiliary agent, adding the functional auxiliary agent into the solution in the step (3), and fully dispersing and mixing. The auxiliary agent is KH 560.
(5) The obtained coating solution is sieved by a 200-mesh sieve, and a thermal control coating is prepared by air spraying and is dried and cured for 4 hours at 80 degrees. The thickness of the prepared coating is 180 mu m, the solar absorption ratio of the coating is 0.080, the emissivity is 0.088, and the surface resistivity of the coating is 105Ωm。
Example 3
(1) Weighing 50% of ultra-wide forbidden band MgO powder pigment by mass percent, and controlling the particle size distribution of the pigment to be 100-800 nm by ball milling; the MgO powder pigment has the purity of analytical grade and above.
(2) 40% of potassium water glass binder is weighed and diluted by adding 2% of distilled water. The potassium silicate binder is prepared by adding analytically pure potassium hydroxide and silicon micropowder powder into 2 percent of distilled water according to the molar ratio of 4, mixing and dispersing, and placing into a hydrothermal reaction kettle to stand for 100 hours at 180 ℃.
(3) Uniformly pouring the MgO powder pigment ground and dried in the step (1) into a potassium water glass binder solution, adding 3% of distilled water, stirring and dispersing, controlling the rotating speed at 800r/min, and stirring for 4 hours;
(4) and (3) weighing 5% of functional auxiliary agent, adding the functional auxiliary agent into the solution in the step (3), and fully dispersing and mixing. The auxiliary agent is 2% of aluminum phosphate and 3% of calcium fluoride.
(5) The resulting coating solution was sieved through a 200 mesh sieve, and a thermal control coating was prepared by manual brush coating, followed by room temperature standing and curing. The thickness of the prepared coating is 350 mu m, the solar absorption ratio of the coating is 0.088, the emissivity is 0.92, and the surface resistivity of the coating is 107Ωm。
Example 4
(1) Weighing 60% of ultra-wide forbidden band MgO powder pigment by mass percent, and controlling the particle size distribution of the pigment to be 100-800 nm by ball milling; the MgO powder pigment has the purity of analytical grade and above.
(2) 30 percent of potassium water glass binder is weighed and diluted by adding 6 percent of distilled water. The potassium silicate binder is prepared by adding analytically pure potassium hydroxide and silicon micropowder powder into 3 percent of distilled water according to the molar ratio of 2.5, mixing and dispersing, and placing into a hydrothermal reaction kettle to stand for 100 hours at 180 ℃.
(3) Uniformly pouring the MgO powder pigment ground and dried in the step (1) into a potassium water glass binder solution, adding 2% of distilled water, stirring and dispersing, controlling the rotating speed at 800r/min, and stirring for 4 hours;
(4) and (3) weighing 2% of functional auxiliary agent, adding the functional auxiliary agent into the solution in the step (3), and fully dispersing and mixing. The auxiliary agent is 2% of aluminum phosphate and 3% of calcium fluoride.
(5) The resulting coating solution was sieved through a 200 mesh sieve, and a thermal control coating was prepared by manual brush coating, followed by room temperature standing and curing.
Example 5
(1) Weighing 40% of ultra-wide forbidden band Ga according to mass percentage2O3Powder pigment, wherein the particle size distribution of the pigment is controlled to be 100-800 nm through ball milling; the Ga is2O3The powder pigment is analytically pure and has the purity above.
(2) 40% of potassium water glass binder is weighed and diluted by adding 8% of distilled water. The potassium silicate binder is prepared by adding analytically pure potassium hydroxide and silicon micropowder powder into 4 percent of distilled water according to the molar ratio of 5, mixing and dispersing, and placing into a hydrothermal reaction kettle to stand for 100 hours at 180 ℃.
(3) Uniformly pouring the gallium oxide powder pigment ground and dried in the step (1) into a potassium silicate binder solution, adding 2% distilled water, stirring and dispersing, controlling the rotating speed at 1000r/min, and stirring for 4 hours;
(4) and (3) weighing 10% of functional auxiliary agent, adding the functional auxiliary agent into the solution in the step (3), and fully dispersing and mixing. The auxiliary agent is aluminum phosphate.
(5) The obtained coating solution is sieved by a 200-mesh sieve, and a thermal control coating is prepared by air spraying and is dried and cured for 4 hours at 80 degrees.
The foregoing is only a preferred embodiment of the present invention, and it should be noted that modifications can be made by those skilled in the art without departing from the principle of the present invention, and these modifications should also be construed as the protection scope of the present invention.
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