Research On Thermal And Artificial Accelerated Aging Of Low Infrared Emissivity Coatings In 8～14μm

With the escalation of infrared threat, a number of infrared suppression technologies were put forward around the world, and the infrared stealth coating occupies an important position in infrared stealth technology due to convenience of manufacturing and low cost. As used under harsh conditions, infrared stealth coating should have good performance of engineering applications besides low emissivity. The topic is mainly in discussion of the thermal properties and artificial accelerated aging properties of the coatings and their improve methods on the basis of preparation of low emissivity coatings.Heat resistance of different low-emissivity coatings was tested by the method of cyclic heating, and the factors which affect heat resistance of the coating involve thermal degradation of the adhesive and high-temperature oxidation of the packing, which leads to the increase of the emissivity of the coating. And high-temperature oxidation of the packing is the most important factor.The degradation evaluation criteria of the low-emissivity coatings was built and the life time and highest endure temperature of the low-emissivity coatings on aircraft skin with different Mach number were predicted. The experimental results were basically consistent to the theoretical analysis, which indicated that this prediction method can be used to predict the low-emissivity coatings service life time in practical applications.High temperature thermal shock resistance of low-emissivity coatings was investigated and compared with their heat resistance. It was shown that the thermal shock resistance of low-emissivity coatings can be obviously improved by introducing a transition layer between the coatings and substrate, and the factors affecting thermal shock resistance of the coating include thermal expansion mismatch between coating and substrate and oxidation protection of coating to substrate.The mechanism of artificial accelerated aging failure of low-emissivity coatings with packing of Cu and Al was investigated. The reason of artificial accelerated aging failure of low-emissivity coatings with packing of Cu is oxidation of the packing, the reason of artificial accelerated aging failure of low-emissivity coatings with packing of Al is degradation of the adhesive, which leads to the state change of the surface of the coating. Moreover, the artificial accelerated aging resistance performance of the coating was improved through adding nano-TiO₂.