Comparing depth profiling of oxide scale on SOFC interconnect-materials using ToF-SIMS with ⁶⁹Ga⁺, Bi₃⁺/Cs⁺ and C₆₀⁺/C₆₀²⁺ as primary and sputter ions

Abstract

Oxide scale cross-sections of CeO₂ coated FeCr based solid oxide fuel cell interconnect materials were examined using secondary ion mass spectrometry (SIMS) depth profiling. A duplex spinel∶chromia scale was formed after 1 h at 850°C. Ti and ceria were observed between these layers. Additionally, minor concentrations of Mn, Si and Nb were observed at the oxide/metal interface. Furthermore, Al and Ti were concentrated primarily in the metal surface close to the oxide/metal interface. Secondary ion mass spectrometry sputter depth profiles using different ion sources; ⁶⁹Ga⁺, Bi₃⁺/Cs⁺ and C₆₀⁺/C₆₀²⁺ were compared with TEM oxide scale cross-section and field emission gun–Auger electron spectroscopy depth profiling. Secondary ion mass spectrometry depth profiling with ⁶⁹Ga⁺, Bi₃⁺/Cs⁺ showed decreased secondary ion yields in the metallic matrix. This decrease could be avoided using oxygen flooding. The C₆₀ cluster ion depth profiles were less sensitive to type of matrix and gave the best correspondence to the TEM cross-section. However, the impact energy has to be high enough to avoid carbon deposition.

Keywords:

• Secondary ion mass spectrometry
• Oxide scale
• Depth profiling
• Solid oxide fuel cell

Acknowledgements

The authors wish to acknowledge Robert Berger at Sandvik Materials Technology for providing sample material and help with the CeO₂ coating procedure. The authors also wish to express thanks to Rakshith Nugehalli Sachitanand for providing the sample Sanergy HT exposed during 1 h at 850°C.