| Pacific Rim Symposium on Surfaces, Coatings and Interfaces (PacSurf 2014) | |
| Thin Films | Wednesday Sessions |
| Session TF-WeE |
| Session: | Thin Film Synthesis and Characterization III |
| Presenter: | Tomas Polcar, University of Southampton, UK |
| Authors: | M. Callisti, University of Southampton T. Polcar, University of Southampton, UK |
| Correspondent: | Click to Email |
Shape memory alloys could be effectively used as thin films acting either as active/passive actuators or superelastic interlayers. In this study s series of NiTiCu coatings with increasing was fabricated by magnetron sputtering with a thickness of 2 µm. In order to obtain superelastic properties, the films were isothermally annealed for 1 hour at 500°C in a high vacuum environment. Subsequently the superelastic layers were coated by magnetron sputtering with a functional tribological coating (DLC-W and self-lubricant WSC film).
The chemical composition of every single layer was measured by Energy-dispersive X-ray spectroscopy (EDS), while the structure was evaluated by grazing-incidence X-ray diffraction (GIXRD) and transmission electron microscopy (TEM). The mechanical properties of the single layers as well as those of the bilayers were measured by nanoindentation. Finally, the tribological behaviour of the bilayers and of the single layers were characterised by pin-on-disc.
We will demonstrate that superelestic interlayer could significantly increase coating adhesion. Pure NiTi interlayers underwent progressive irreversible martensitic transformation during the sliding and lost superelasticity; on the other hand, transformation of NiTiCu film was fully reversible. We will show that we can control compressive and shear stress in functional coating during sliding by selection of an optimum superelastic interlayer.