The Prepared Method And Radiation Properties Of Perovskite Smart Thermal Control Devices

With the development of miniaturization and lightweight of spacecraft,the internal electronic components are highly integrated,and the local high temperature is easy to form.Traditional thermal shutter devices are not suitable for small satellites due to their large size,high energy consumption,and high quality.Therefore,the application of the heat radiation surface is proposed,and the common heat radiation surface has the defect that it cannot automatically adjust the heat radiation characteristics according to the change of the device temperature and the external heat flow,so it cannot meet the requirements of satellite autonomous heat control.The variable emissivity intelligent thermal control device based on perovskite manganese oxide can change its own thermal radiation performance according to the change of the external environment temperature,and realize the role of active intelligent thermal control,which has great development prospects in the application of spacecraft.In this paper,based on(La,Ca,K)Mn O3 perovskite-type manganese oxide,a smart thermal control device was prepared by solid-phase reaction method,the crystal structure,and micromorphology were studied,the factors affecting the heat radiation performance were explored,and the radiation was improved.Performance and testing its environmental stability have important application significance for improving satellite thermal control technology.The main research contents of the paper are as follows:(1)Preparation and characterization of perovskite-type manganese oxide In this paper,a series of La0.7Ca1-x Kx MnO3(x = 0,0.05,0.10,0.15,0.20)thermochromic materials were prepared from lanthanum oxide,calcium carbonate,potassium carbonate and manganese dioxide by solid-phase reaction.Optimize the production preparation process.XRD,SEM,and XPS were used to study the micro-morphology,phase structure,and composition of the material samples.The results show that the prepared thermal control device crystallizes well,no miscellaneous phase exists,and all exhibit a single perovskite structure.The doping of K ions causes the main diffraction peak to split and the perovskite structure is distorted.(2)Research on thermal radiation characteristics of variable emissivity thermal control devices Taking thermochromic materials as the research object,the spectral reflectance was tested at different temperatures in a vacuum and the emissivity and solar radiance were analyzed and calculated.Study the relationship between reflectivity,emissivity,and solar absorption rate with different element composition and different doping concentration,and try to reduce the solar absorption rate of the material.At the same time,the influence of the magnetic field on the radiation characteristics of the thermal control device was studied,and the infrared temperature imaging technology was used to demonstrate the temperature control capability of the device.The results show that the solar absorption rate of the thermal control device is higher,but it can be reduced from 0.81 to 0.20 by coating.In the temperature range of 173 K to 373 K,the doping of K ions increases the high and low-temperature emissivity of the thermal control device,the emissivity adjustability decreases,and the phase transition temperature increases.When K =0.20,the phase transition temperature is 280 K,which is in the room temperature range,which meets the actual application requirements.The external magnetic field experiment found that the radiation performance of the thermal control device is basically not affected by the magnetic field.Infrared thermal imaging demonstrates the good temperature control capabilities of the material.(3)The environmental experiment of the thermal control device Using laboratory conditions,conduct environmental experimental research on thermal control devices,vacuum volatility,electrostatic protection and thermal cycling to explore its stability and reliability when working in a space environment.The experimental results show that the vacuum outgassing of the thermal control device is 0.00225%,which is better than the expected value of the application;the surface resistance is about 40Ω,which has a certain antistatic ability,but the insulation effect of the coating layer makes the device lose its antistatic Electrostatic capability;thermal control device ruptures under extreme conditions(-196℃～100℃,temperature changing time 10s),slowing down temperature changing conditions(-20℃～ 100℃,12h)can maintain the integrity and has certain thermal adaptability.