Ignition Delay Times of Composite Solid Propellants Using Novel Nano-Additive Catalysts

Abstract

Ignition delay time measurements on solid energetic materials lead to better fundamental understanding of the ignition process and provide benchmark data for improving models of the ignition process. Validation for such models is typically done by collecting ignition data over a wide range of propellant formulations. This study focused on the development of a setup to obtain ignition delay times of AP/HTPB-based composite solid propellants with and without aluminum and with and without various metal-oxide nanoparticle catalysts. A CO 2 laser with a wavelength of 10.6 μm was utilized to achieve a quantifiable and reliable ignition event over a power range of 30 to 100 W. AP and HTPB propellants have been shown to have high absorption and low reflection at this 10.6-μm wavelength. Resulting from this study was the development of a method to measure the ignition delay time for ammonium perchlorate composite propellants (APCP) at elevated pressures between 3.5 and 15.5 MPa. A comparison of the laser power flux as it relates to the change in ignition delay time was found to match available literature values at similar conditions. Additional studies to examine the effects of in-situ titania nanoparticles on the ignition delay times demonstrated that the nano-additives only appeared to alter the ignition behavior of the aluminized APCP.When iron-oxide was added, the ignition delay time was reduced at lower pressures. Additives which aid in the low-temperature decomposition of AP are believed to impact the ignition delay times the most. Nomenclature a = burning rate constant (also called temperature coefficient) n = pressure coefficient in burning rate relation P = pressure r = burning rate T = temperature σ p = propellant temperature sensitivity

Comparison of Commercially Available and Synthesized Titania Nano‐Additives in Composite HTPB/AP Propellant

“…Doping the titania increased its effectiveness in accelerating the burning rate. Ignition delay times for titania were evaluated in a separate study and demonstrated no change [29]. However, iron oxide was observed to lower the ignition delay time at lower pressures.…”