Preparation of NCh-B and NCh-B-Ti nanocomposites and their ignition and combustion performances

To overcome the agglomeration and insufficient combustion of nano-boron (n-B) powders, this study successfully prepared two novel types of boron-based nanocomposites using the acoustic resonance technology, namely high-substitute nitrochitosan/nano-boron (NCh-B) with ratios of 1:3, 1:5, 1:7, and 1:9 and nitrochitosan/nano-boron powder/nano-titanium (NCh-B-Ti) with Ti contents of 5 wt%, 10 wt%, 15 wt%, and 20 wt%. The structural morphologies, laser ignition, and combustion properties of the composites were systematically investigated. The results suggest that the addition of NCh can significantly improve the dispersion of n-B. NCh-B exhibited a higher combustion performance than n-B, as evidenced by their ignition delay and flame areas. When the laser power density was 81 W, NCh-B5-Ti15% exhibited a combustion time and an ignition delay of 240 ms and 5.5 ms respectively, which were higher and lower than those of NCh-B5 (199 ms and 17 ms, respectively). Furthermore, NCh-B5-Ti15% displayed a lower ignition delay than both n-B powders (12 ms) and NCh-B (11 ms), as well as brighter flames and a larger combustion area. Therefore, the addition of n-Ti can promote the combustion of the n-B powders, with the combustion products of NCh-B-Ti including H3BO3, B2O3, TiB2, and TiO. This study provides a new method for improving the ignition performance and combustion efficiency of n-B powders.