Growth and characterization of nanocomposite yttria-stabilized zirconia with Ag and Mo

The effect of metal additions on the structure and properties of nanocrystalline yttria-stabilized zirconia (YSZ) thin films deposited by a hybrid magnetron sputtering/pulsed laser deposition technique was studied. The materials are candidates for use as adaptive, “chameleon” nanocomposites for tribological applications subjected to thermal cycling up to high (700 °C) temperatures. The composition, structure and mechanical properties of the films were characterized with X-ray photoelectron spectroscopy, electron dispersive spectroscopy scanning electron microscopy, high-resolution transmission electron microscopy, X-ray diffraction and nanoindentation. Increasing the metal content of the films by increasing the magnetron power resulted in decreased zirconia grain sizes for films with silver and/or molybdenum additions. The reduced zirconia grain size was attributed to a decrease in the ion-to-atom ratio during deposition. Unlike the YSZ–Ag films that exhibited reduced hardness with increasing metal content, YSZ–Mo film hardness increased from 12 to 17.5 GPa at 15 and 24 at.% molybdenum, respectively. Adding molybdenum to the films resulted in cracks and holes in the film surface indicative of molybdenum oxidation during processing. Adding both silver and molybdenum eliminated the undesirable surface features found in the YSZ–Mo films.