Augmented Ignition Efficiency for Aluminum

Abstract

High ignition temperatures for Al and Be are responsible in part for inability of additives of these metals to attain theoretical performance in propulsion systems. A model of metal ignition has been developed which suggests that more efficient ignition of these metals will be observed if they are coated with films of Mg or Ca [Mellor and Glassman (1965), (1969), and Mellor (1967)], In the present paper experimental verification of the improvement in ignition for Al wires coated with thin films of Mg or Ca is discussed. Several pretreatments of the Al wires were used; in some, the room-temperature film of Al₂0₃ was removed. The best results were obtained if the natural A1₂0₃ film was removed by an amalgamation pretreatment and the clean Al surface which resulted was coated with Mg. It is thought that similar techniques will improve the ignition efficiency for Be.