TiH2 content-tuning strategy for synergistic enhancement of safety and combustion performance in HMX/TiH2/F composite microspheres

To achieve high-energy composites with both high energy density and enhanced safety, TiH 2 /HMX/F energetic microspheres were fabricated using a coaxial flow-focusing microdroplet technique. The effects of varying TiH 2 contents on the chemical structure, thermal decomposition, mechanical sensitivity, combustion characteristics, and combustion products were systematically examined. The results show that the microspheres exhibit a dense structure, narrow particle-size distribution, and uniform component dispersion, while retaining the crystalline form and chemical structure of the raw HMX and TiH 2 . With increasing TiH 2 content (5, 10, 15, and 20 wt%), the apparent activation energy rises by 21.58, 66.35, 98.33, and 146.09 kJ mol −1 , respectively, compared with the H/F sample, indicating reduced reactivity but significantly improved thermal stability. At 10 wt% TiH 2 , the critical impact energy and friction force increase by 4.0 J and 164.0 N, respectively, demonstrating enhanced mechanical safety. Combustion tests reveal that TiH 2 not only strengthens combustion intensity but also prolongs the reaction duration. When the TiH 2 content exceeds 5 wt%, oxidation becomes more complete, with TiO 2 and TiN identified as the main products. In addition, the combustion mechanism was clarified, highlighting the role of TiH 2 in promoting high-temperature oxidation and improving combustion completeness. These findings provide both theoretical insights and process guidance for optimizing the performance and safety of high-energy composite materials.