Effect of some catalysts on combustion of double-base propellants

The effect of PbO$_2$, SnO$_2$, TiO$_2$, and Bi on the combustion of propellants of various compositions is investigated. It is established that SnO$_2$, TiO$_2$, and Bi have a significant effect on the burning rate of propellants without carbon black and additional plastifiers. A marked catalytic effect of PbO$_2$ is manifested only when its content is higher than 5%. It is shown that the addition of SnO$_2$ and PbO$_2$ to propellants leads to formation of a carbon black matrix on the burning surface, on which catalyst particles build up. With the addition of carbon black to propellants, the catalytic action of TiO$_2$ and Bi is enhanced only slightly, and the effect of SnO$_2$ at moderate pressures is markedly reduced due to a considerable increase in the degree of reduction of the active form of (SnO$_2$) catalyst up to its inactive forms (SnO and $\beta$-Sn).