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Research On Thermal Resistance Coatings With Low Infrared Emissivity In 3~5μm

Posted on:2011-02-19Degree:MasterType:Thesis
Country:ChinaCandidate:C HuFull Text:PDF
GTID:2121330338976470Subject:Physical chemistry
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In recent years, infrared guided weapons have become the main threats to aircrafts.As we know, the coating exterior surface of the aircraft with low emissivity materials can greatly decrease the probability of being detected by infrared detector. However, most of the low emissivity coatings present poor thermal resistance properties and can not be used at the high temperature components of aircraft, such as the exterior surface of the tailpipe, whose working temperature range is 450-700°C. Thus, the preparation of low emissivity coatings with good thermal resistance properties is of great importance for infrared stealth technology applications.In this paper, the thermal resistance coatings with low emissivity were prepared via a simple and convenient process. And the influence of chemical composition, surface structure, roughness and thickness on the emissivity was discussed. The experimental emissivity results are nearly consistent with optical theory analysis for the coatings. Furthermore, thermal ageing and thermal shock resistance of the coatings were also systematically investigated.1. The emissivity of the coating can reach to 0.51 in the 3~5μm and the coating can work at high temperature by solidification process. The condensation reaction and crystal phase change in the solidification process result in the tight structure and the decrease in infrared absorbance, which is the main factor of variable emissivity.2. Thermal resistance coatings with low infrared emissivity can reach to 0.16~0.19 in the 3~5μm. The influence of content of Al powders, roughness and thickness on the emissivity was systematically investigated. Reducing infrared absorption as well as the formation of dense continuous t laminar aluminium structure may account for the lower emissivity of coatings.3. Thermal resistance polysiloxane/Al coatings with low emissivity could be used at 500-600℃. The coatings exhibited favorable thermal ageing and excellent resistance to thermal shocking. The thermal radiation of center cone decreased to 40%.4. The emissivity property of low infrared emissivity coatings was studied during the thermal ageing and thermal shocking. This effect was explained by thermal oxidation of Al particles and polysiloxane degradation in the coatings.5. The thermal resistance property of low emissivity coatings can be enhanced by ZnO.
Keywords/Search Tags:thermal resistance, infrared emissivity, polysiloxane, degradation
PDF Full Text Request
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