Νανομηχανικός χαρακτηρισμός λεπτών υμενίων με τη χρήση συσκευής νανοδιείσδυσης (nanoindentation)

Abstract

Recent technological advancements in manufacturing techniques have shifted the bulk of technologically important devices into the submicron regime.Examples include the micro-and nano-electromechanical devices (MEMS and NEMS), micro-fibers, microchips, protective coatings for biomedical materials or engineering tools/equipment.These technologies find application in various areas such as cutting tools, coatings in automotive and industrial electronics, in sensors, in implants, etc.The study of the mechanical response of the systems as well as the mechanical properties of the materials that they are composed of are essential for their design, optimization and quality control purposes on an industrial scale.This thesis elaborates on the available procedures for the mechanical characterization of materials and products at these small scales.After a general examination of the thin films deposition techniques, we used the Instrumented Nanoindenter located in the Laboratory of Mechanics and Testing of Materials to characterize a series of titanium alloys and two samples of amorphous carbon.In this thesis the operating principles as well as the theoretical background required for data collection and analysis are presented.Binary and ternary Titanium alloys consisting of various percentages of niobium and hafnium were prepared by magnetron sputtering.The alloys exhibited superior mechanical response in comparison to pure titanium: the hardness of the alloys increased and their creep behavior significantly improved.TiNb and TiNbHf alloys tend to reduce the elastic modulus compared to pure titanium, which is favorable for implant applications, while TiHf alloys increase the material stiffness. The presented procedure is general and could be equally applied to other materials and systems.For the purposes of illustration we present preliminary results on an amorphous carbon-silver (a- C:Ag) nanocomposite thin film and a carbon nanofoam thin film.