Oxidation Behavior and Electrical Property of a Ni-Based Alloy in SOFC Anode Environment

The oxidation behavior and electrical property of a Ni-Mo-Cr alloy at 750 degrees C in a simulated solid oxide fuel cell (SOFC) anode environment (humidified and diluted H-2) have been Studied. The thermally grown oxide scale presents a multilayered structure, which is similar to that formed in air, with densely grown Cr2O3 in between an underneath layer of the intermetallic compound MoNi3 and a less compact top layer consisting of MnCr2O4 with Cr2O3 flakes embedded. The oxidation kinetics obey a two-stage parabolic law with an initially fast oxidation (0-170 h at a rate of 4.94 x 10(-14) g(2) cm(-4) s(-1)) followed by a slower steady oxidation (170-1000 h at a rate of 2.84 x 10(-14) g(2) cm(-4) s(-1)). The H-2/H2O reducing atmosphere, even with a significantly lower oxygen partial pressure, has a negative effect on the high temperature oxidation resistance: however, it enhances the adherence of the scale to the substrate. The Outward diffusion of Ti ions changes the composition, lattice parameters, and diffraction peak positions of the formed oxides, leading to Ti-doped Cr2O3 and the MnCr2O4 spinel. The area specific resistance of the oxide scale preformed at 750 degrees C for 1000 h is 8.34 m Omega cm(2) at 750 degrees C, which is higher than that formed in air and lower than that of other studied Ni-based alloys. (C) 2009 The Electrochemical Society. [DOI: 10.1149/1.3194788] All rights reserved.