Study on Surface Structure Characterization and Stability of α-AlH3 coated with PW

Abstract Alpha-aluminum hydride (a-AlH3) is usually metastable due to the small enthalpy of formation, poor stability, high chemical activity, sensitive to moisture, easy to combine with water in the air. In order to inhibit the hygroscopicity of α-AlH3 and improve its storage and stability, PW (paraffin wax) is selected as the coating material, and the solvent-non-solvent method is used to coat the surface of α-AlH3. The structure and topography of α-AlH3 before and after coating are characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray diffractometer (XRD), X-ray electron spectroscopy (XPS), elemental analysis, and scanning electron microscopy (SEM). The results show that PW forms a uniform and complete coating layer on the surface of α-AlH3, and the crystal structure and morphology of the α-AlH3 samples after the coating are not changed, and the moisture absorption weight gain rate is reduced from 12% before the coating to 0.05%, and the hygroscopicity is greatly reduced. Furthermore, the a-AlH3 coated by PW also shows excellent performance in resisting water erosion, and the hydrophobic angle increases from 27° to 98° after the PW is coated on the a-AlH3 surface. This research provides a easy method for the safe application of a-AlH3 in the field of solid propellants.