Preparation And Application Research Of Temperature-Controlled Dominant Infrared Stealth Materials

With military technology advanced to a new level,everything from armored clusters to individual personnel outfitted has been equipped with several infrared(IR)thermal imaging systems.The development of IR stealth materials has become the focus of protection research regarding the new situation warfare,where discovery is destruction,and has great importance to national defense and military fields.Traditional IR stealth materials typically use low IR emissivity materials,but temperature control and heat handling in the actual environment continue to be issued.According to current research,the reliable solution for achieving positive and durable IR stealth is to combine heatabsorbing PCMs with conventional low-emissivity materials.First,temperature-controlled double-shell microcapsules(DSMs)with low emissivity were created using in situ polymerization and surface deposition with eicosane as the phase change material(PCM),melamine,urea,and formaldehyde(MUF)as the first shell material,and polyaniline(PANI)as the second shell material.The particle size of the DSMs was 1.484 μm,the latent heat was 155.1 J/g with a core content of 63.25%,and the IR emissivity was 0.722(1-22 μm).The DSMs had good thermal stability in the working temperature range,according to Differential Scanning Calorimeter(DSC)and Thermal Gravimetric Analyzer(TGA).After coating finishing to polyester fabric,the emissivity of the resulting IR stealth fabric was slightly increased to 0.794(1-22 μm),and the IR stealth focal band emissivity was 0.785(8-14μm)and 0.778(3-5 μm),respectively.Furthermore,when compared to untreated fabric,the IR stealth fabric has an outstanding practical temperature control effect.Furthermore,the IR stealth fabric demonstrated a significant IR stealth effect as well as good durability in practical use.Then,to further reduce the surface emissivity,a dual-working module-driven IR stealth fabric was designed based on temperature and emissivity control.It has excellent practical temperature control due to its high latent heat phase change coating of 128.5J/g.Meanwhile,the surface IR emissivity of this IR stealth fabric is as low as 0.692(1-22 μm),0.687(8-14 μm),and 0.655(3-5 μm),because of the metalized surface given by the electroless silver plating.The thermal imager can see the effective shielding and interference of the IR signal clearly by the IR stealth fabric after heating the untreated fabric and the IR stealth fabric on the hot plate at 45°C and 80°C,respectively.According to the related fastness test,it has a high application potential.Finally,considering the application needs of IR stealth materials on high-heat equipment,a low IR emissivity aluminum(Al)-based IR-stealth-gel with temperature regulation via heat absorption was developed.The aerogel prepared by freeze-drying with an Al layer deposited on one side has low emissivity and after adsorption of PCM,it displays strong heat absorption for temperature control.In comparison to pure PCM,the IR-stealth-gel loses only 24.4 J/g while having a skeleton loading of 322.15% and a high latent heat of melting of 140.6 J/g.It has an average emissivity of just 0.478,0.408,and 0.257 in the 1-22 μm,8-14 μm,and 3-5 μm bands,respectively.IR thermography shows that its radiation temperature does not exceed 60°C within 120 min of continuous heating at 100°C,demonstrating a very good IR stealth effect.In addition,several heating-cooling cycle experiments show that the IR-stealth-gel also has distinct shape stability.In sum,this study paves way for the preparation of positive and stable IR stealth materials.