Several advanced air separation unit (ASU) designs being considered for use in coal gasification rely on the use of solid state mixed ionic and electronic conductors. Nicrofer-6025HT, a nickel-based alloy, has been identified as a potential manifold material to transport the hot gases into the ASUs. In the current study, isothermal oxidation tests were conducted on Nicrofer-6025HT in the temperature range of 700–900 °C for up to 24 h. The evolution of oxide scale was evaluated using SEM, XRD, and XPS. The composite surface oxide layer that formed consisted of an outer chromia-rich scale and an inner alumina scale. For the longer times at the higher temperatures evaluated, a NiCr2O4 spinel phase was located at the interface between the alumina and chromia. Based on the experimental results a four-step oxidation model was proposed.
Revised: June 22, 2013 |
Published: April 1, 2013
Citation
Joshi V.V., A. Meier, J.T. Darsell, P. Nachimuthu, M.E. Bowden, and K.S. Weil. 2013.Short-Term Oxidation Studies on Nicrofer- 6025HT in Air at Elevated Temperatures for Advanced Coal Based Power Plants.Oxidation of Metals 79, no. 3-4:383-404.PNNL-SA-94018.doi:10.1007/s11085-013-9362-6