Research On Low Infrared Emissivity And Resistance To Marine Environment Of Al/Organic Resin Based Coating

With the enhancement of the defense force of China’s maritime air force,the military activities of the aircraft have increased on the offshore platform.When taking off,landing,stopping,and flying on an aircraft carrier,it will be corroded by harsh environments such as salt spray,mold,radiation,high temperature water vapor,etc.The infrared low-emissivity coating applied on the surface of the body will fail,which greatly increases the probability of the aircraft being detected in the 8～14 μm infrared band and reduces the aircraft’s survivability.At present,the research on infrared stealth coatings for carrier-borne aircraft in the harsh marine environment is still in the preliminary stage of exploration.This paper has launched corresponding research work on marine environment resistant infrared stealth coating.In this paper,flake Al powder and organic resin were introduced as the filler and binder respectively.Through analysis and research on all aspects of the properties of fillers,adhesives and auxiliaries,the infrared low-emissivity coating with excellent resistance to the marine environment is finally obtained.The specific work content and results are as follows:1.By selecting and controlling the floating state and addition amount of flake Al powder,the effect of the floating state of Al powder on the balance between the emissivity performance of the coating and the marine environmental resistance was explored.The experimental results show that the coating with an emissivity of less than 0.1 can be obtained when the high-floating flaky Al powder is used as the filler at 20%.After 42 days in the hot salt water test,the emissivity of the coating which still maintained good mechanical properties was 0.271.2.After determining that the filler is a 20% high-floating Al powder,the polyurethane resin and acrylic resin were first studied,and the initial emissivity of the acrylic resin coating was found to be in the range of 0.15-0.2,which has a inherent disadvantage.Based on this,low-viscosity,low VOC,and high NCO/OH values polyurethane resins were further screened in the polyurethane resin system.The experimental results show that the best polyurethane resin coatings have an initial emissivity of0.06-0.08.After 42 d hot salt water corrosion,the emissivity rose to 0.221,after 42 d UV-resistant artificial accelerated aging,the emissivity rose to 0.196,and the emissivity is 0.249 after 1 year exposure to the marine atmosphere.It still maintains good mechanical properties and has excellent weather resistance.It is also verified that the resin’s NCO/OH ratio has a certain effect on the environmental resistance of the coating.3.In order to further improve the arrangement of Al powder,the compatibility of fillers and resins,and the adhesion of the coating to the substrate,appropriate additives have been introduced into low-emissivity coating.The surfactant acetylene glycol is added to improve the dispersibility of aluminum powder and the interface between aluminum powder and resin.The addition of organosilane as an adhesion promoter can significantly enhance the adhesion between the coating and the substrate.The result indicated that when 2% surfactant and 4% organosilane are added,the coating with an emissivity of 0.05 can be obtained,and the mechanical properties are excellent.The emissivity of coating after the hot salt water test for 42 days is 0.147,which remains relatively good mechanical properties.