Investigation of Molten/Oxidized Aluminum Powder Deposition on Stainless Steel 304

Accidents involving solid propellants containing aluminum can be difficult to model due to the additional heat transfer from molten aluminum or aluminum combustion and impingement/deposition of oxide on target objects. A series of tests has been carried out using a commercially available oxy-acetylene torch and powder feeder to investigate the effects of molten/oxidized aluminum on stainless steel 304 substrates. SEM and EDS have been used to determine diffusion/interaction of aluminum with the stainless steel and characterize the constituents of the resulting interfacial layers. These techniques indicated that at the test conditions, aluminum was undetectably oxidized before it deposited on the substrate surface. However, temperature data from thermocouples attached to backside of each substrate detected an increased heat flux to the substrate when aluminum is introduced into the flame spray. Results also indicate that the boundary layers of the aluminum and stainless steel were well defined implying that little diffusion or solution of the aluminum with the stainless steel occurred.