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2001
Journal Article
Titel
Mechanical properties and characterisation of very thin CNx films synthesised by IBAD
Abstract
Nanoindentation has been used to investigate the mechanical properties of very thin (<1 m) CNx films deposited by IBAD in order to understand the variation of properties with process parameters. The structural features of the films were characterised by EELS, XPS and ERDA. Examining the loaddisplacement (P) curves in detail revealed a number of film responses such as pure elastic behaviour, dens ification and elastic-plastic deformation. The film-only hardness was calculated using a recently developed energy based model while the Hertzian contact analysis and laser-acoustic measurements were used to determine the Young's modulus. Generally, the film hardness and modulus exhibit two different regimes depending on the deposition parameters. Films deposited at high temperature contain less nitrogen and have lower hardness and Young's modulus than those deposited at room temperature. All films examined displayed P curves exhibiting unusually large elastic recovery (~80% or more) during unloading. Because of this, resultant ind entation sizes always appear to be very small thus apparently producing very hig h hardnesses. However, our results clearly establish that the film behaviour is better viewed as that of a 'super-hard rubber' in which a large proportion of the contact load is supported elastically.