Indentation of silicate-glass films on Al2O3 substrates

The deformation of thin layers of glass on crystalline materials has been e xamined using newly developed experimental methods for nanomechanical testi ng. Continuous films of anorthite (CaAl2Si2O8) were deposited onto Al2O3 su rfaces by pulsed-laser deposition. Mechanical properties such as Young's mo dulus and hardness were probed with a high-resolution depth-sensing indenta tion instrument. Nanomechanical testing, combined with AFM in situ imaging of the deformed regions, allowed force-displacement measurements and imagin g of the same regions of the specimen before and immediately after indentat ion. This new technique eliminates any uncertainty in locating the indentat ion after unloading. Emphasis has been placed on examining how the Al2O3 su bstrate crystallographic orientation will affect mechanical composite respo nse of silicate-glass film/Al2O3 system.