Nanostructured TiO2-Al2O3 Multilayer Thin Films: Structural and Mechanical Properties

The proposed project aims to investigate the nanostructure and mechanical properties of ceramic TiO2-Al2O3 multilayer thin films by using x-ray photoelectron spectroscopy (XPS), small-angle x-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), atomic force microscopy (AFM), nanoindentation measurements and optical interference method. Multilayer thin films of TiO2-Al2O3 with microstructures consisting of amorphous Al2O3 and nanocrystalline TiO2 will be deposited by reactive pulsed dc-magnetron sputtering in an Ar-O2 atmosphere. The main objectives are to establish the inter-relationships among hardness, hardness-to-modulus ratio (H/E), layer period, microstructure and mechanical stress of these TiO2-Al2O3 multilayers by systematically varying process parameters; to investigate increased hardness with desirable properties of TiO2- Al2O3, including nanolayer structure, excellent wear resistance, stability in oxidizing atmosphere, and high temperature stability (up to 1300 oC), and to understand the origin of hardness enhancement mechanisms and large H/E ratios. The results extracted from the proposed investigation will be used to guide the structural design of fabricating nanostructured oxide/oxide multilayers if the preparation conditions are strictly controlled.