Boron particles agglomeration and slag formation during combustion of energetic condensed systems

Boron is a promising component of energetic condensed systems due to its high gravimetric heat value, which is significantly higher than that one of aluminum. In the present work, two non-equilibrium processes, i.e., boron particles agglomeration and framework (slag) formation during combustion of high-energy compositions were investigated experimentally. The quench particle collection bomb technique was used to collect the condensed combustion products formed under nitrogen pressures of 0.1-4 MPa. The formation of a framework was visualized using high-speed video registration (1200 fps). Particle size, morphology, and surface structure of collected condensed products were evaluated using laser diffractometry and scanning electron microscopy. In the experiments, the weight of the collected condensed combustion products was about 30% of the initial sample weight, where 26% belonged to the products collected from the gas phase and 4% were remained in a highly-porous framework. The initial amorphous boron powder consisted of 1-micron particles, whereas agglomerated particles, which were collected from the gas phase, were 10 |um in diameter. The burning rate of compositions without binder was 4 times higher and the diameter of collected agglomerates was 10 times larger than those for compositions with binder.