Deposition and characterization of TiB2/TiN nanolaminate coatings via pulsed laser ablation technique

This paper describes the development of a state-of-the-art pulsed laser ablation deposition (PLAD) experimental capability for the investigation of advanced nanolaminate hard face coatings. Both TiB2 and TiN are known for their hardness, adhesion, erosion resistance, toughness and high melting points and were subsequently selected for the target materials in this study. The titanium alloy Ti-6Al-4V was selected as the initial substrate material due to its excellent match of the coefficient of thermal expansion with the target materials and its extensive use in many aerospace and commercial applications. Results indicate the feasibility of depositing high quality, thin, alternating layered coatings (10 - 100 nm range) on room temperature substrates (minimize thermal/residual stresses). Nanoindenter hardness levels approaching 40 GPa were reproducibly measured. It is postulated that a connection exists between the indentation size effect (ISE) seen at nanoscale depth indents and the Vickers hardness of multilayer films with alternating layer-thicknesses in the nanometer range.