Hot corrosion of materials: a fluxing mechanism?

• Published in: Corrosion science Vol. 44; no. 2; pp. 209 - 221
• Main Author: Rapp, Robert A
• Format: Journal Article Conference Proceeding
• Language: English
• Published: Oxford Elsevier Ltd 01.02.2002; Elsevier Science
• Subjects: Applied sciences; Corrosion; Corrosion environments; Exact sciences and technology; Fluxing mechanism sulfidation; Hot corrosion; Metals. Metallurgy; Negative solubility gradient; Oxide solubilities; Synergistic dissolution; Oxide solubilities; Fluxing mechanism sulfidation; Negative solubility gradient; Hot corrosion; Synergistic dissolution; Corrosion mechanism; Sodium sulfate; Solubility; Oxides; Oxidation; Molten salt
• ISSN: 0010-938X; 1879-0496
• DOI: 10.1016/S0010-938X(01)00057-9

Hot corrosion is the accelerated oxidation of a material at elevated temperature induced by a thin film of fused salt deposit. Fused Na 2SO 4, which is the dominant salt involved in hot corrosion, is an ionic conductor, so that the corrosion mechanism is certainly electrochemical in nature. Further, the acid/base nature of this oxyanion salt offers the possibility for the dissolution (fluxing) of the normally protective oxide scale. Non-protective precipitated oxide particles are often observed in the corrosion products. In this paper, the status of knowledge for the solubilities of oxides in fused Na 2SO 4 is reviewed, and the effects of various influences on a fluxing mechanism are discussed. An evaluation of a “negative solubility gradient” as a criterion for continuing hot corrosion is made.