Microstructural and chemical changes at the Ni/YSZ interface

A bent nickel wire was pressed against a yttria-stabilised zirconia (YSZ) surface, creating a small contact area. The Ni/YSZ interface was investigated and characteristic microstructures were found to develop during 200–300 h heat treatment at 1000°C in 97% H2/3% H2O with and without polarisation. A ridge of impurities up to 1.6 μm high was seen to develop along the Ni/YSZ/H2 boundary. The impurity phase can be characterised as an alkali silicate phase containing Mn, Na, Ti, Mg, K, Al and Si. Most of these elements seem to be coming from impurities in the nickel. The initially flat contact area on the YSZ developed a hill and valley structure with an amplitude of 100 nm. The nickel wires showed negative imprints of the YSZ structures.