Investigation of High-Temperature Corrosion in an Incinerator Offgas System.

摘要

Corrosion studies have been carried out in the offgas system of a radioactive-waste incinerator at the Department of Energy's Savannah River Plant. Many advanced alloys exhibited severe corrosion and poor performance in the high-temperature region (>100/degree/C). The environment includes O2, SO3, P2 O5 and HCl. Extensive corrosion for most alloys containing less than /approximately/25% Cr, and most iron-base materials were destroyed. An Fe-20Cr-5Al alloy had good appearance after exposure. Duplex chromium/aluminium diffusion coatings improve performance of substrate alloys having high Cr content. However, neither aluminizing nor chromizing alone provided sufficient benefit to warrant their use on the alloys examined. Carbon steel received no real long-term protection from either coating. Metallographic investigation indicates that reactions penetrate to substantial depths beneath the surface of most alloys. Where metal parts were cooled by air or water flow, corrosion was essentially eliminated. Thus, use of alloys with high chromium content (>30%), use of an iron-base alloy with aluminium plus chromium, application of duplex Cr/Al diffusion coatings on high-Cr materials, and application of water cooling to these high alloys each benefits reduction of high-temperature metallic corrosion in the incinerator offgas systems. 11 refs., 9 figs., 4 tabs. (ERA citation 14:021774)