Investigation of the influence of strength of charges of pyrotechnic nitrate-metal mixtures on fire safety of products on their basis

As a result of the conducted experimental researches it is established that the breaking of the strength of surface layers of pyrotechnic nitrate-metal mixtures leads to premature fire and explosive action of products on their basis in the conditions of external thermal influences. New data on the influence of technological parameters of mixture samples (the ratio and dispersion of components, the coefficient of their compaction, the nature of nitrate-containing oxidizer and organic additive, the pressure and compression direction, cure time, height and diameter of samples) on the limit of their strength are obtained. The tensile strength of the specimens is lower in the compression direction and their compressive strength is higher in this direction. The coefficient of compaction of the mixtures and their strength are independent characteristics: less dense pressed mixture may be more durable, and vice versa. As the content of the metal powder in the mixture increases, the strength of its samples increases monotonically, moving to the same limit value. With increasing the temperature of the mixture from 213 K to 333 K, regardless of the content of titanium, the nature of the oxidizer and the coefficient of compaction, the strength of its samples decreases; the degree of influence of the heating temperature decreases as the oxidant content decreases. The degree of the increase in the strength of samples of mixtures with a change in the dispersion of titanium powder practically does not depend on the nature of the oxidizer: for mixtures of Ti + NaNO₃ and Ti + Ba (NO₃)₂ with increasing the dispersion of titanium powder from 45 μm to 250 μm, the strength of their samples decreases in 1,4 … 1,6 times. Increasing the strength of the samples of these mixtures while reducing the dispersion of the oxidizer from 250 μm to 45 μm is also almost the same: for the mixture of Ti + NaNO3 – 1,3 times, and for the mixture of Ti + Ba (NO₃)₂ – 1,4 times