The effect of Cl, Br, and F on high-temperature corrosion of heat-transfer alloys
Jan-Erik Eriksson, Juho Lehmusto, Meheretu Jaleta Dirbeba, L. Silvander, Daniel Lindberg, Leena Hupa
Abstract
The impact of small alkali halide additions on the melting behavior and corrosivity of a synthetic sulfate deposit at 500, 550, and 600 °C was investigated. Three differently alloyed commercial heat-transfer materials; low-alloyed 10CrMo9-10, stainless AISI 347, and high-alloyed Sanicro 28, were studied. The samples were exposed for 168 h in a tube furnace to a K2SO4 + Na2SO4 mixture containing 0.85 mol% KCl, KBr, or KF. The extent of material degradation was determined by weight loss measurements, while the morphology, thickness, and composition of the formed oxide scale were characterized with SEM-EDS. Additionally, the melting behavior of the mixtures was studied with TG-DTA. It could be concluded that already small amounts of reactive alkali halides in an otherwise inert K2SO4 + Na2SO4 mixture change significantly the corrosion and melting behavior of the mixture.