Energy output characteristics and safety design of Al-AlH3 composite dust for energetic material additive

Aluminum (Al) is the most widely used metal additive in energetic materials, but its application is limited due to its oxidizable nature. However, aluminum hydride (AlH3) could disrupt the oxide film structure and improve applications of the Al additive in energetic materials by releasing hydrogen. Therefore, this paper explored the explosion characteristics of the Al-AlH3 composite dust by conducting composite dust explosion venting experiments. The influences of composite dust concentrations and mass ratios on the explosion pressure and flame were evaluated. The consequences indicated that when the composite dust concentration was constant, the explosion pressure and the reduction rate of explosion pressure gradually decreased as increasing the mass ratio, which confirmed that the explosion intensity of AlH3 was greater than that of Al. When the composite dust mass ratio was the same, the increase in dust concentration caused the explosion pressure, the pressure rise rate, the flame front propagation distance, and velocity to increase first and then attenuate. 750 g/m3 was the best dust explosion concentration. On this basis, the safety design applicability of composite dust was conducted based on the NFPA 68 explosion venting design standard, which was verified to be suitable for Al dust. Notably, the safety margin should be taken into account when carrying out a safety design for composite dust using NFPA 68. In the paper, the composite dust explosion characteristics were obtained through experiments and mechanism analysis, which provided data support for the research of Al-AlH3 composite dust for energetic material additives.