Effects of electroless nickel plating on 441 stainless steel as SOFC interconnect

Metal nickel was electrolessly deposited in thickness of approximately 6, 8, and 10 mu m on ferritic stainless steel 441. Oxidation behaviour of plated samples was investigated after isothermal ageing at 750 degrees C for 400 h in an air atmosphere. Microstructure examination showed that nickel oxide formed on the surface, (Fe, Ni)(3)O-4 spinel layer at the subsurface, and chromite at the oxide scale/steel interface. No chromium species was readily detected on the outer surface. Area specific resistance measurement indicated 2.0, 3.3, and 6.3 m Omega cm(2) for 6, 8, and 10 mu m plating layers, respectively, all lower than that of the uncoated case, 28 m Omega cm(2). Results suggested nickel plating of thickness 8 pm would be sufficient for effectively preventing Cr out-diffusion while maintaining a low electric resistivity. (C) 2012 Elsevier B.V. All rights reserved.