Preparation Of Water-Based Polyurethane Composite Infrared Stealth Material And Its Performance Analysis

Nowadays,countries are actively developing detection equipment for security reasons.With the widespread use and popularity of infrared detection equipment in warfare,the reciprocal development of infrared stealth materials to protect important targets from destruction has become a key focus of national protective research.Low emissivity is usually the only focus in the previous research of infrared stealth materials,but in the real world of battle,it alone plays a limited role,and the heat sources generated by equipment operating in environments are the most significant problem with infrared radiation.According to the Stefan Boltzmann law,the intensity of infrared radiation is mainly determined by the infrared emissivity of the surface of an object and the temperature of the surface of the object.Based on this,a new infrared stealth composite material combining low infrared emissivity SiO₂@ZnO with insulating WPU aerogel is designed and prepared.A number of silica microspheres with concentrated particle size were first prepared by a modified St?ber method using tetraethyl orthosilicate（TEOS）as the silica source.The silica was then used as a core material and the surface was modified with polyvinylpyrrolidone（PVP）as a guide to produce sites.Zinc oxide was prepared by hydrothermal decomposition of zinc acetate,and its precipitation and growth on the surface of silica were obtained,and finally a SiO₂@ZnO with infrared low emissivity properties was obtained.The average particle size distribution of SiO₂@ZnO was found to be in the range of 2-3μm.The apparent morphology of the SiO₂@ZnO was observed by scanning electron microscopy（SEM）and transmission electron microscopy（TEM）,which revealed that the ZnO was well coated on the SiO₂.Analysis of the bonding bonds and diffraction peaks by infrared spectroscopy（FT-IR）and X-ray diffractometry（XRD）confirmed the bonding form of our synthesized SiO₂@ZnO.Their surface emissivity was tested by IR emissivity down to 0.71（3-5μm）and 0.79（8-14μm）.The SiO₂@ZnO/WPU aerogel composites were prepared by gravity-driven filler separation and freeze-drying using water polyurethane（WPU）as the main material and SiO₂@ZnO as the filler material and supporting the entire structure.The composites achieved the best resilience and compression resistance at an actual solid content of 15%WPU with a powder content of 4 wt%and SiO₂ to SiO₂@ZnO with 1:2 ratio of in the powder.A universal material tester test showed that the composite could be maintained at 50%compression deformation for more than 20 cycles without any change in appearance,and SEM and dispersive spectroscopy（EDS）showed that there was a clear delamination between the surface layer and the insulation layer.A thermogravimetric analysis（TGA）showed that the composites were safe and stable at a temperature of 300°C.The thermal conductivity of the aerogel material was measured by a thermal conductivity meter to be only 0.056 W/m K,which provides excellent thermal insulation properties.The surface emissivity was tested as low as 0.67（3-5μm）and 0.71（8-14μm）by infrared emissivity.The thermal imager shows that in practice,the infrared radiation intensity of the composite at a surface temperature of 60°C is equivalent to that of a normal material at 40°C,which effectively circumvents the detection of the target object by infrared detection devices.Taken all these studies together,the results demonstrate that combining low emissivity with thermal insulation is a successful and effective approach in the field of infrared stealth,and this project provides a viable solution for achieving stable and efficient infrared stealth.