Sungkyu Lee, Min Jung Kim, Jieun Lee, Suk-Hwan Kang, Seung-Jong Lee, Yongseung Yun
April 21, 2015
A corrosion exposure test was performed on a commercially available Haynes® 556® Fe-Ni-Cr-Co alloy sample to investigate its solid/gas reaction behavior in integrated coal gasification combined cycle pilot plant facilities affiliated with the Institute for Advanced Engineering (2.005 MPa and 160–300 °C). Thermodynamic Ellingham-Pourbaix stability diagrams were constructed and the post-exposure samples were examined ex-situ by morphological and microstructural SEM and EDS analyses on the external surfaces to obtain information on the corrosion scale and provide insight into the mechanism of the observed corrosion behavior in the piping materials connecting the particulate removal unit and water scrubber of the integrated coal gasification combined cycle pilot plant. Uniform material thinning was observed after 46 hours of operation, and a preliminary corrosion mechanism was suggested. The observed material wastage and corrosion behavior of the Haynes® 556® Fe-Ni-Cr-Co alloy sample cut off from the coal syngas IGCC plant were explained by the formation of discontinuous (complex) oxide phases and subsequent chlorine-induced active oxidation under the predominantly reducing environment encountered.