Surface properties of a nano-quasicrystalline forming Ti based system

Two decades of intense research on quasicrystalline materials have suggested their potential use as surface coatings, considering their low coefficient of friction, high hardness, good corrosion and wear resistances and low surface energy. In that sense, quasicrystals could be introduced into the field of biomolecules are well known to be sensitive to solid surface properties. In this paper we report on investigations of the early stage of oxidation of the quasicrystals forming Ti45Zr38Ni17 alloy and its surface reactivity with respect to an amino-acid. After analysing the microstructure of as-quenched ribbons both by transmission electron microscopy and X-ray diffraction, surface oxide layers were characterized by X-ray Photoelectron Spectroscopy (XPS). Oxidation of Ti45Zr38Ni17 results in the formation of a ZrO2/TiO2 barrier oxide layer, avoiding toxic Ni release. This latter is mainly present at the oxide/alloy interface. Thereafter, adsorption of L-glutamic acid has been investigated by infrared spectroscopy. Even if this biomolecule is found to absorb to each substrate, it seems to display different adsorption mechanisms on quasicrystalline ribbons compared to that on pure titanium (CpTi) or on pure zirconium (Zr), leading to a weaker signal on Ti45Zr38Ni17. We discuss these results along with the affinities of each alloying metal to oxygen and with the peculiar electronic properties of quasicrystals which could affect the surface properties of Ti45Zr38Ni17. (author)