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

Abstract

This study presents a comparison of commercially available titania nano‐particles produced using electric wire explosion with nano‐particles manufactured by the authors using a sol‐gel synthesis process. For the present study, 20‐nm titania was purchased off‐the‐shelf. It was determined to be rough spheres of 20 nm forming large, micron‐sized agglomerates, whereas particles synthesized using the sol‐gel process were found to be fundamentally 10 nm but with sub‐micron agglomerations thereof. The nano‐titania was added to 80% AP monomodal propellants at 0.3% and 1.0% by mass. Additional, 85% bimodal‐AP mixtures were made, comparing commercial titania to the laboratory‐synthesized particles at 1.0% by mass. Another set of samples compared a method of pre‐mixing the synthesized additives directly into the binder material at 0.3% by mass of laboratory titania; two additional pre‐mixed titania batches at 0.5% by mass were doped with either Fe or Cu into the nanocrystals. All propellants were tested up to 13.8 MPa at 3.8 MPa increments. Dry powder laboratory additives show a 60‐to‐100% increase in burning rate over the baseline samples with no catalyst and a 20‐to‐30% increase over the commercial nano‐particles. Pre‐mixed additives were found to produce similar burning rate increases but with lower concentrations required. This latest generation of particle synthesis techniques was further demonstrated in this study to have great potential for future propellant catalyst development.

Are All Solid Propellant Burning Rate Modifiers Catalysts?

“…the BRE will be most useful. Finally, the increase in burning rate from MO formed within the binder prepolymer [10] suggests that BRE may not only influence the oxidizer but the binder as well. Overall, classification of BRE will enable a more systematic approach to mechanistically understanding BRE in solid propellants.…”

Burning Rate Characterization of Ammonium Perchlorate Pellets Containing Micro- and Nano-Catalytic Additives

“…The inclusion of metal oxides, such as iron oxide (Fe2O3) and titanium oxide (TiO2), in composite AP/HTPB propellants has been observed to increase the global burning rates [2][3][4][5][6][7][8][9][10][11][12][13][14][15]. It is well documented in the literature that metal oxides enhance the thermal decomposition of AP [16].…”