Combustion of Ti–Si–C Mixtures: Impact of Medium Structure and Impurity Gas Release

A study was made of the combustion of powder and granular mixtures (1 – X)(Ti + C) + X(5Ti + 3Si), where 0 ≤ X ≤ 1, on the base of titanium powder with the characteristic size of Ti particles d(Ti) = 120 μm. The values of the burning velocity of powder mixtures were shown to depend on the free volume above the charge in the reactor. The velocity dependences on X had a maximum at about X = 0.4 in contrast to minimum in the earlier study of the same mixtures with d(Ti) = 20 μm. The results were explained using the convective–conductive model of combustion. It was shown that the velocity of the combustion front of the powder mixture depends on the location of the predominant release of impurity gas in the charge: in front of or behind the melt layer. The maximum content of the liquid phase in the reaction mixture at 0.4 < X < 0.6 ensured the high filtration resistance of the melt layer and its maximum (at d(Ti) = 120 μm) or minimum (at d(Ti) = 20 μm) propagation velocity. Changing the structure of mixtures by granulation ensured the leveling of the effect of impurity gases and a decrease in the burning velocity corresponding to the decrease in the content of desorbing components, titanium and soot.