Preparation And Properties Of Aluminum-based Infrared Stealth Functional Fillers

Infrared stealth coatings are composed of fillers,adhesives and additives.They have an important position in the research of infrared stealth technology because of their advantages such as convenient manufacturing and low cost.The selection and preparation of infrared stealth fillers is an important topic to achieve infrared stealth coatings.In recent years,single infrared stealth material has been no longer to adapt to the rapid development of infrared detection and multiple guidance technology and improve the survival on the battlefield.Infrared stealth materials must have the effect of significantly reducing the target infrared emissivity and decreasing the difference between the target and the environment in the infrared band.Furthermore,they can stealth on other bands.Therefore,the fillers with excellent infrared and other wavelength stealth performance have become increasingly important in modern military.In this paper,Al/ATO composites and Al/Bi₂O₃composites were prepared by a co-precipitation method.The phase structure,micro-morphology,reflectivity at1064nm laser wavelength,and infrared emissivity of the composites were tested and analyzed by XRD,SEM,UV spectrophotometer,IR-2 infrared emissivity meter,respectively.The study shows that the content of aluminum,the molar ratio of Sn/Sb,the reaction temperature,the reaction time,and the calcination temperature have significantly effects on the composition and structure of the composites.The results show that,the thickness of the coating layer on the surface of the aluminum powders was controlled by adjusting the content of aluminum powder.It affected the reflectance of the composites at the 1064 nm laser wavelength and the emissivity in the 8～14μm infrared wavelength range;The Sn/Sb molar ratio was reduced,the Sb doping concentration in ATO was increased,the donor energy level was easier to transition,and the absorption of the Al/ATO composites at the 1064nm laser was enhanced;With the reaction temperature increases,the degree of hydrolysis of ammonia water was increased,the surface coating layer of the flake aluminum powder became thicker,and the infrared emissivity of the composite particles was increased;With the reaction time increased,the co-precipitation reaction rate was decreased,the metal salt ions fully reactd with OH^-,the precursor nucleated on the surface of the flake aluminum;When the calcination temperature was increased,the crystallinity of Bi₂O₃particles on the surface of the flake Al powder was enhanced,the grain size was reduced,and the thickness of the coating was increased,the coatings effectively suppressed the gloss of the flaky aluminum.When the flaky aluminum powder content is 20wt%,the molar ratio of Sn/Sb is10:1,the reaction temperature is 50℃,the reaction time is 2h,and the calcination temperature is 800℃,Al/ATO composites with an optimal core-shell structure can be prepared;Al/Bi₂O₃composites with optimal core-shell structure were prepared when the content of aluminum powder was 20wt%,the reaction temperature was 50℃,the reaction time was 2h,and the calcination temperature was 450℃.In addition,the reflectivity at 1064nm laser wavelength and the emissivity in the8～14μm band of Al/ATO composites are 43%and 0.708,respectively.The composites shows excellent infrared/laser compatibility.Furthermore,the Al/Bi₂O₃composites are yellow-green,the infrared emissivity of 8～14μm is 0.462,and the reflectivity at1064nm laser is 44.8%,which has excellent infrared/visible/laser compatible stealth performance.In this paper,the infrared stealth fillers with excellent performance was obtained by surface modification of the flaky aluminum.They are helpful to achieve multi-spectrum compatible stealth,improve the survival rate of military targets on the battlefield and counter reconnaissance ability.