Convenient design of anti-wetting nano-Al/WO3 metastable intermolecular composites (MICs) with an enhanced exothermic life-span

For solving the dilemma of the short exothermic life-span of WO3 based metastable interstitial composites (MICs) with extensive application prospect, this paper has firstly designed the promising anti-wetting Al/WO3 MICs via electrophoresis assembly of nano-Al and WO3 particles fabricated by hydrothermal synthesis method, followed by the subsequent fluorination treatment. A combination of X ray diffraction (XRD), field emission scanning electron microscope (FESEM), energy dispersive X-ray spectroscopy (EDX), and Fourier transform infrared spectroscopy (FT-IR) techniques were utilized in order to characterize the crystal structure, microstructure, and elemental composition distribution of target films after different natural exposure tests. The product with uniform distribution and high purity possesses a high contact angle of ∼170° and a minute sliding angle of ∼1°, and displays the outstanding anti-wetting property using droplets with different surface tensions. It also shows great moisture stability in high relative-humidity circumstances after one year of the natural exposure experiment. Notably, the heat output of a fresh sample can reach up to 2.3 kJ/g and retain 96% after the whole exposure test, showing outstanding thermo-stability for at least one year. This work further proposed the mechanism of anti-wetting Al/WO3 MICs considering the variation tendency of their DSC curve, providing a valuable theoretical reference for designing other self-protected MICs with a long exothermic life-span applied in wide fields of national defense, military industry, etc.