Electrolytic deposition of titania films as interference coatings on biomedical implants: Microstructure, chemistry and nano-mechanical properties

Kern, P.; Schwaller, Patrick; Michler, J. (2006). Electrolytic deposition of titania films as interference coatings on biomedical implants: Microstructure, chemistry and nano-mechanical properties Thin Solid Films, 494(1-2), pp. 279-286. Elsevier Science 10.1016/j.tsf.2005.09.068

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TiO2 films with uniform thickness were electrolytically deposited on AISI 316L stainless steel and Ti6Al4V substrates for potential use as color coded biocompatible coatings on biomedical implants. Deposition occurred via a peroxoprecursor method from solutions containing TiCl4 and H2O2. By optimizing electrolyte formulation and deposition parameters, thin stoichiometric titania films with almost uniform thicknessdependent interference colors, similar as known from the color anodization processes of Ti-alloys, were obtained. Crack-free films were found up to 140 nm on AISI 316L and up to 190 nm on Ti6Al4V substrates. After thermal annealing at 450 -C of as-deposited amorphous peroxotitanium hydrate films, Raman and transmission electron microscopy showed highly stoichiometric, nanocrystalline anatase films. Chemical depth profiling was performed by glow-discharge optical emission spectrometry (GD-OES), showing clearly a densification and loss of water during annealing. On AISI 316L, GD-OES revealed stoichiometric TiO2 films containing a small Fe (3–4 at.%) and Cr (1 at.%) contamination due to thermal diffusion from the substrate. On Ti6Al4V, the comparison between electrolytic TiO2 films and color-anodization in different sulfuric and phosphoric acid containing electrolytes showed significant higher purity of electrolytic films, absent of V, Al, S, P contaminations as they were found in anodic oxides (4–6 at.% Al, 1–2 at.% V), especially Vand S being problematic in biomedical applications. Annealing greatly increased the mechanical properties of the green films. A nano-hardness of 5.5–6.6 GPa, elastic modules close to substrate modules, excellent adhesion and very ductile behavior were found from nanoindentation and scratch tests. Based on thickness uniformity, high purity and good mechanical properties, electrolytic TiO2 films are not only attractive as biocompatible colored coatings on non-anodizable biomedical alloys such as AISI 316L and CoCrMo, but also for Ti-alloys that are anodized for protective as well as coding reasons prior to implantation

Item Type:	Journal Article (Original Article)
Division/Institute:	School of Engineering and Computer Science > Institute for Surface Applied Laser, Phototonics and Surface Technologies ALPS School of Engineering and Computer Science
Name:	Kern, P.; Schwaller, Patrick and Michler, J.
ISSN:	0040-6090
Publisher:	Elsevier Science
Language:	English
Submitter:	Patrick Schwaller
Date Deposited:	10 Dec 2019 09:16
Last Modified:	10 Dec 2019 09:16
Publisher DOI:	10.1016/j.tsf.2005.09.068
ARBOR DOI:	10.24451/arbor.9288
URI:	https://arbor.bfh.ch/id/eprint/9288