Improved reactivity and energy release performance of core-shell structured fuel-rich Si/PTFE energetic composites

Si is an attractive fuel in pyrotechnic applications due to its high gravimetric and volumetric energy density. In this article, core-shell structured fuel-rich Si/PTFE (CS-PSi) energetic composites were prepared through high-power ultrasonic mixing. The energy release performance of the CS-PSi composites with different equivalence ratios (ϕ=1.5, 2.5, and 3.5) is characterized, and the magnetic stirring mixed Si/PTFE (MS-PSi, ϕ=3.5) composite is also studied for comparison. For the CS-PSi composites, with the increase in equivalence ratio, the relative intensity and burning rate both increase. Evaluated in a closed vessel, the CS-PSi (ϕ=2.5) exhibits the optimum pressure performance in terms of peak pressure and pressurization rate. By modifying the equivalence ratio, the reactivity, as indicated by the pressurization rate, of the CS-PSi energetic composites can be tuned accordingly. Having the same equivalence ratio (ϕ=3.5), the relative intensity, burning rate, peak pressure, and pressurization rate of the CS-PSi composite are 6.1, 4.3, 1.3, and 4.1 times larger than those of MS-PSi counterpart, respectively, while the apparent activation energy of the CS-PSi composites is reduced by 23.6%. The improved reactivity and superior energy release performance of the CS-PSi composites can be attributed to the higher degree of intimacy between the reactants as a result of core-shell configuration. Our approach provides a facile and efficient way to elevate the performance of the Si/PTFE energetic composites.