Effect of Humidity on the Thermal Properties of Aluminum Nanopowders with Different Surface Coatings

To investigate the effect of surface coating materials on the humidity stability of aluminum (Al) nanopowders, three kinds of core–shell structure Al nanopowders with an Al2O3 passivation coating, carbon coating, and plasticizer dioctyl sebacate (DOS) coating were prepared through laser-induction complex heating method. After one year’s storage at 95% relative humidity, their thermal properties were tested through differential scanning calorimeter (DSC) and thermal gravimeter (TG) analysis. The results show that the thermal properties of Al2O3-passivated Al nanopowders are entirely lost under high humidity because the Al2O3 passivation coating is very sensitive to moisture. The thermal properties of carbon-coated Al nanopowders are not well-protected under a high humidity due to the uneven thickness and structural defects of carbon coatings. However, the thermal enthalpy of DOS-coated Al nanopowders remains at 3.56 KJ/g under high humidity, which indicates that an organic DOS coating with a hydrophobic nature has an excellent protective effect on the thermal properties of the Al nanopowders. Given the good forming performance of organic DOS coatings and other components of propellants, DOS-coated Al nanopowders are a kind of energetic material with potential application value.