Speaker
Description
The nature of interface in contact with living species is the prime interest for biomaterials, prostheses, biosensors… This interface is easily modified by PVD processes in terms of chemistry, structure, microstructure… In the past decade, intense research activity was devoted to Ti-Ag coatings for biosensors; titanium being strongly biocompatible, while silver brought its good electrical response and ductility(1). Even though some papers are focused on optimizing films’ chemical composition and phases, no data are available on their wear resistance.
To better understand tribological behaviour of this metallic ductile thin systems, an original approach is required. It consists of using a laboratory-made reciprocating ball-on-disc mini tribometer, specifically-designed to be introduced into an SEM chamber(2) or under Raman spectrometer, allowing a small-scale in situ characterisation of the damaging surface. An environmental SEM was used, which is able to expose contact area to different environments (vacuum, water, nitrogen..). The study’s objective is to link the tribological behaviour of films both with their characteristics and with the role of atmosphere.
Titanium-based films were deposited by magnetron sputtering, silver content was being controlled by the relative Ag/Ti areas ratio of targets. Considering a previous study on both flexibility and electrical conductivity of films1, 4 compositions were identified (Ag-free, low-, moderate and high-Ag contents). Films characteristics were determined by RBS spectroscopy, TEM, XRD and high-temperature XRD.
Even if mechanical properties are not really influenced by the silver content of films, their microstructure is drastically changed with presence of Ag-rich submicrometric particles for moderate and high silver enrichments. The presence of this further phase appears to change the rubbing dynamics strongly.
(1)Etiemble, A. et al., Surf. Coat. Technology.,358,(2019),646.
(2)Krid, A.,(2018), Jin, L.,(2019),Master internship reports
| Speaker Country | France |
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