AVS 52nd International Symposium
    Advanced Surface Engineering Monday Sessions
       Session SE-MoM

Paper SE-MoM11
Multifunctional SiAlON Ceramic Coatings for High Temperature Applications

Monday, October 31, 2005, 11:40 am, Room 201

Session: Nanocomposites and Coatings with Enhanced Thermal Stability
Presenter: R.J. Lad, University of Maine
Authors: J.I. Krassikoff, University of Maine
D.J. Frankel, University of Maine
T.A. Dunn, University of Maine
D.R. Southworth, University of Maine
R.J. Lad, University of Maine
Correspondent: Click to Email
SiAlON ceramics possess oxidation resistance, high strength, and thermal shock resistance, which make them extremely attractive for applications in 1000-1500°C oxidation environments. We have investigated well-defined SiAlON thin films deposited by rf magnetron co-sputtering of Al and Si targets in Ar/O@sub 2@/N@sub 2@ mixtures. By precisely controlling film architecture at the nanometer level, coating structures having homogenous, gradient, or multilayer compositions that span the full range of O/N and Al/Si ratios have been synthesized, and their chemical, thermal, and mechanical properties have been characterized. Nitride-rich SiAlON film compositions are extremely wear resistant, yet they become oxidized during thermal treatments in air between 1000-1500°C. Compositionally graded coatings with oxide-rich terminations show improved oxidation resistance. Similarly, Al@sub 2@O@sub 3@/Si@sub 3@N@sub 4@ laminate structures exhibit low wear and chemical stability at high temperature. Photolithographically patterned thin film metal resistors embedded at the SiAlON/substrate interface have been used to quantify the oxygen penetration rates through the SiAlON film structures during isothermal annealing and thermal cycling experiments. Accelerated testing consisting of rapid thermal cycling in various reactive environments was accomplished using a microfabricated heater platform. The role of film stress on resulting mechanical properties was investigated using microfabricated cantilever structures.