Coalescence of metal particles during the combustion of metallized ballistite compositions and fuel-oxidizer mixtures

Conclusions

• 1. When ballistite compositions containing aluminum burn, metal particles and the heat-resistant products of nitrocellulose decomposition agglomerate on the surface of the charge and subsequently coalesce near the surface.

• 2. When fuel-oxidizer-metal compositions burn, the metal particles coalesce on the surface of the charge, since the charge temperature is sufficient to melt aluminum and magnesium.

• 3. As the percentage of metal in the composition increases, the mean volume size of the aluminum and magnesium particles formed as a result of coalescence on the surface of the charge also increases.

• 4. The degree of coalescence of the metal particles on the charge surface increases with decrease in the size of the starting metal particles in the model composition.

• 5. The mean volume size of the aluminum and magnesium particles formed as a result of coalescence on the charge surface decreases with increase in the burning rate of the model mixture, i.e., the greater the burning rate of the charge, the less the degree of particle coalescence.

• 6. The burning rate of the aluminum and magnesium particles formed as a result of coalescence at the burning surface of a model mixture is equal to 2–3 mm/sec for aluminum and 4–5 mm/sec for magnesium.