%0 Journal Article %A Houim, Ryan W. %A Boyd, Eric %D 2008 %I Begell House %N 1 %P 55-71 %R 10.1615/IntJEnergeticMaterialsChemProp.v7.i1.40 %T COMBUSTION OF ALUMINUM FLAKES IN THE POST-FLAME ZONE OF A HENCKEN BURNER %U https://www.dl.begellhouse.com/journals/17bbb47e377ce023,347510e813dc34a0,51f557ee1de90d45.html %V 7 %X Aluminum flakes have been used in propellants and explosives. The objective of this paper is to experimentally study the ignition and combustion behavior of aluminium flakes that have a thickness of 200 nm and a nominal diameter of 16 μm. Flakes with and without a thin coating of Teflon were studied. Teflon-coated Al flakes have a very strong tendency to agglomerate, up to four times their original size, resulting in a drastically increased particle burning time when compared to single aluminum flakes. Ignition of single flakes and agglomerates of Al flakes was observed at 1,800 K, which is about 300 to 500 K below the normal ignition temperature of aluminum. This observation also indicates that the ignition of agglomerates of Al flakes is governed by the heating process of a single flake. Under the same test conditions, single uncoated aluminum flakes exhibited two different burning modes; one mode produced a long, dim burning streak with combustion times on the order of 6 ms, the particles burning in the other mode showed vigorous reaction, producing a very short, bright burning streak with combustion times less than 1 ms. This phenomenon is believed to be governed by whether or not the Al flakes fragment during ignition process. The recovered samples from dimly burning particles are about the same diameter as the original flakes, but those recovered from the vigorously burning Al flakes showed much smaller sizes, indicating particle fragmentation. Measurements of combustion times of the intensely burning Al flakes are very close to measurements performed on nano-aluminum with a diameter of 192 nm performed by Parr et al. This agreement indicates the combustion times of intensely burning aluminum flakes are determined by the thickness rather than the diameter of the flake. %8 2008-02-01