Infrared Stealth Nano-doped Indium Tin Oxide Coating Preparation And Performance

This paper summarizes the research actuality of IR stealth technology and the stealth principle of IR stealth coating, and then analyzes the stealth principle of ITO nano-composite coating and puts forward the preparation pathway.Indium tin oxide nano-powder has been prepared InCl₃.5H₂O and SnCl₄.5H₂O as the raw materials, NH₃.H₂O as the co-precipitation agent. The surfactant and organic dehydrating agent are used to prevent the powder reuniting. The structure and properties of the ITO nano-powders such as phase, configuration, particle size and infrared characteristic are also tested by means of XRD, TEM, SEM, BET, and FTIR. The results show that the ITO nano-powders possess a single phase-structure with a good dispersion and a narrow size distribution. Their shapes are similar to the sphere with cubic In2O3 structure, and the nano-powders have a mean size of about 40nm.The IR transmittance of the ITO nano-powders is less than 5 percent in 714～3333cm-1, which indicates that the powders can be used as a good IR absorbable material.The paper studies the stability of the nano-powder in an ethanol solution. The effects of dispersion mode and modification by coating to the nano-powders are mainly researched. The results show that the dispersion effect of ultrasonic dispersion is the best one of the three factors, the ball grinding dispersion is better than the high speed dispersion. Furthermore, the dispersion effect of the ultrasonic dispersion together with the high speed dispersion has a more improvement comparing with only using the ultrasonic dispersion method. The organic coating can be formed on the surface of the ITO nano-powders after modification using silane coupling agent, which reduces the possibility of reuniting and increases the stability of dispersoid. On the base of the experiments, there is no sedimentation in the dispersoid system within 48 hours, which indicated the dispersoid accords with the requirements of the coating preparation.The preparative processes of the ITO nano-composite coating have been investigated.The spectral property in UV/VIS/NIR wave band, the ITO's microcosmic dispersibility in the coating and some part mechanics performances have been characterized. The coating exhibits excellent performances in hardness and adhesion as the content of ITO less than 20 percent. The solidifying temperature with 60℃for two hours and proper slow volatilization solvent are propitious to preparing shining and smooth coating. The nano-scale scattering coating can be fabricated using the coating preparative processes of the ultrasonic dispersion together with the high speed dispersion, and the mean size of ITO is lower than 100nm by means of SEM. The optic testing shows that the coating has a selective transmittance in visible and near IR wave band, but has a strong obstruct function in the UV, middle and far IR. The coating reveals the typical diffuse refection in visible and near IR wave band. The coat's reflectivity is very low, while the emissivity is very high. Furthermore, the coating has the same characteristics even if the thickness is less than 20μm. The results show that the coating can be used as the light IR thermal stealthy material in compatible UV, visible light and near IR wave band, it can also be used in IR radar stealth technology.