AVS 45th International Symposium
    Thin Films Division Monday Sessions
       Session TF-MoA

Paper TF-MoA6
Meso-Scale Contact Hardness, Friction, and Wear of Aluminum Oxynitride Films

Monday, November 2, 1998, 3:40 pm, Room 310

Session: Mechanical Properties of Thin Films
Presenter: S.D. Dvorak, University of Maine
Authors: S.D. Dvorak, University of Maine
G.P. Bernhardt, University of Maine
O.D. Greenwood, University of Maine
R.J. Lad, University of Maine
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Aluminum oxynitride (AlO@sub x@N@sub y@) thin films attract interest as hard, wear resistant coatings for high temperature, oxidizing environments. We have used electron-cyclotron-resonance (ECR) plasma assisted electron beam evaporation of aluminum to grow aligned crystalline films on r-sapphire at 800 - 1100 K to nominal thicknesses of 100 nm at about 0.5 Å/s deposition rates. These AlO@sub x@N@sub y@ films were fabricated with compositions ranging from aluminum oxide to aluminum nitride, depending on the N@sub 2@/O@sub 2@ gas flow ratio in the ECR source. Film hardness as a function of depth was measured by nanoindentation, while friction and wear properties were determined during reciprocal sliding experiments using well characterized sapphire and diamond probe tips with applied loads in the micro-newton to milli-newton force range. Film topography examined with atomic force microscopy indicated rms roughness values ranging from 20 Å to 140 nm. Wear tracks examined by AFM consist of wear debris as well as microstructural features. We observe that friction is affected by the roughness of the surfaces in contact, and that these roughness effects are dependent on the hardness of the contacting asperities, as measured by a Hysitron Pico-Indentor. Inhanced surface diffusivity of oxygen and nitrogen species provided by the ECR source during film growth yields highly-oriented films with very high wear resistance.