High Temperature Chemistry of Stored Chemical Energy Reactions for Propulsion.

Abstract : This report summarizes the results of a continuing study of the high temperature chemistry of stored chemical energy reaction systems. Thermogravimetric studies have been completed on the behavior of Aluminum oxide and Magnesium oxide in the presence of C103F. Based on these data a new ceramic containment systme comprised of alumina and magnesia parts has allowed extension of kinetic experiments from the 650 C limit previously encountered to a temperature in excess of 800 C. Using the new apparatus, we have observed the relative inertness of the Al component of the fuel to oxidation by ClO3F even at 800 C. We have also noted the extensive vapor phase transport of Lithium fluoride and Magnesium flouride not expected on the basis of known thermodynamic data. Thermogravimetric experiments have been completed on the oxidation of molten aluminum droplets by ClO3F. Rate data for this reaction indicate multiple mechanisms, possibly including the following steps: (1) nucleation and growth of AlF3 precipitation sites; (2) edge growth of AlF3 islands followed by coalescence of islands; (3) diffusion limited thickening of the AlF3 layer. Observations on the early stages of the Al/ClO3F reaction have also been made using high pressure sampling transpiration mass spectrometry.