Scratch Resistance of Sputter Deposited Ruthenium-Samarium Doped Ceria (Ru-SDC) Nanoscale Films with Various SDC Compositions

Interest in the use of thin film of Ruthenium-Samaria doped ceria cermet (Ru-SDC) as anode in solid oxide fuel cells is increasing due to its high oxygen storage capacity and high chemical and thermal stability. To have enough structural integrity between sputtered Ru-SDC films and underlying substrates, good adhesion property is required. In this work, scratch resistance and failure mode for Ru-SDC films with various SDC composition were investigated using a scratch test method employing linearly increasing load from 1 to 50 N using a 200 μm radius Rockwell C indenter. Scratched surfaces were examined with a field emission scanning electron microscope. Chemical compositions in scratch tracks were analyzed by energy dispersive X-Ray spectroscopy. Critical loads for films with different SDC ratios were assessed and associated failure modes were identified. The highest scratch resistance among tested film compositions was the one that contained 50% of SDC. Failure modes of tested films regardless of the ratio of SDC were identified to be the initiation of tensile cracks with rapid increase of friction coefficient followed by chipping, and eventually the generation of a severe crack network.