Combustion of spherical agglomerates of titanium in air. II. Results of experiments

Combustion of titanium particles in free fall in air were investigated. Burning monodisperse particles with a diameter of 300, 390, and 480 $\mu$m were obtained by merging of many small particles during ignition of miniature pieces of a pyrotechnic composition comprising 69% powdered titanium. Motion parameters and the drag of the burning particles were determined. The fragmentation phenomenon (the onset time and duration of the phenomenon, dispersion dynamics of fragments, fragment size distribution functions) were described qualitatively. For the investigated particles, the dispersion of fragments has the form of a spruce branch: the mother particle is retained and ejects small fragments. The distance and velocity of a particle at the moment of fragmentation and at the end of combustion were determined. Data are given on the structure and morphology of the combustion product particles represented by the reside of the mother particle and the set of small fragmented particles and data on changes in the size and glow intensity of the burning particle. At the end of combustion, the mother particle is transformed to a sphere consisting of a mixture of oxides of the averaged composition TiO$_{2.76}$.