Passivated Pyrophoric Metal Powders

Metal powders with good combustion, high heat of fusion and safe toxicology such as zirconium and hafnium offer performance advantages when compounding into munitions, propoellants, flares, primers and incendiaries. However, fire and explosion hazards especially associated with electro static discharge (ESD) sensitivity, limit the use of these metals. This problem increases as the particle size decreases. Four surface passivation techniques will be evaluated in an attempt to desensitize hafnium powder: - Surface Nitradation by chemical vapor deposition to form Hf3N4 - Surface Nitridation by direct reaction to form HfN - Controlled Surface Oxidation to form Hf)2 - Metal encapsulation of hafnium particles with a sub-micron layer of magnesium by physical vapoer deposition Passivation of the metal powder by a thin layer of metal compound such as its nitride of oxide may reduce the explosive and fire hazards during mixing and compounding of energetics using these metals. Passivation by use of a thin layer of another metal as a top coat may also desensitize the metal without altering its combustion and ignition properties.