Handling,Characterization,and Monitoring of Condensates Produced by Atomization from the Molten State

In any process of atomization from the molten state it is inevitable that vapour species are produced. It has been found that these vapours condense to extremely small particles of the order of 0·04 μm dia. and larger. When such particles are produced under high-purity inert atmospheres, they are extremely pure, remain in suspension, and are therefore intensely pyrophoric when introduced to oxidizing atmospheres. In addition such particles are often toxic. The dusts resulting from the processing of ferrous, nickel, and titanium alloys have been characterized by electron microscopy in order to assess the problem of safe removal. The procedures developed to minimize the handling risks of such condensates are described in the context of operation of an arc-melting centrifugal atomizer. Sensitive monitoring techniques are available for specialized materials such as beryllium and uranium as well as the more common metals, and these can be utilized to assess the levels of both airborne and surface contamination that are likely to arise in the laboratory or plant environment from powder atomization.