Thermal activation of Ti(1-x)Au(x) thin films with enhanced hardness and biocompatibility

Cherian Lukose, Cecil, Anestopoulos, Ioannis, Mantso, Theodora, Bowen, Leon, Panayiotidis, Mihalis I. and Birkett, Martin (2022) Thermal activation of Ti(1-x)Au(x) thin films with enhanced hardness and biocompatibility. Bioactive Materials, 15. pp. 426-445. ISSN 2452-199X

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Official URL: https://doi.org/10.1016/j.bioactmat.2022.02.027

Abstract

The lifetime of orthopaedic implants can be extended by coating the softer Ti6Al4V alloy with harder biocompatible thin films. In this work, thin films of Ti(1-x)Au(x) are grown on Ti6Al4V and glass substrates by magnetron sputtering in the entire x=0-1 range, before their key biomechanical properties are performance tuned by thermal activation. For the first time, we explore the effect of in-situ substrate heating versus ex-situ post-deposition heat-treatment, on development of mechanical and biocompatibility performance in Ti-Au films. A ~250 increase in hardness is achieved for Ti-Au films compared to bulk Ti6Al4V and a ~40 improvement from 8.8 GPa as-grown to 11.9 and 12.3 GPa with in-situ and ex-situ heat-treatment respectively, is corelated to changes in structural, morphological and chemical properties, providing insights into the origins of super-hardness in the Ti rich regions of these materials. X-ray diffraction reveals that as-grown films are in nanocrystalline states of Ti-Au intermetallic phases and thermal activation leads to emergence of mechanically hard Ti-Au intermetallics, with films prepared by in-situ substrate heating having enhanced crystalline quality. Surface morphology images show clear changes in grain size, shape and surface roughness following thermal activation, while elemental analysis reveals that in-situ substrate heating is better for development of oxide free Ti3Au β-phases. All tested Ti-Au films are non-cytotoxic against L929 mouse fibroblast cells, while extremely low leached ion concentrations confirm their biocompatibility. With peak hardness performance tuned to >12 GPa and excellent biocompatibility, Ti-Au films have potential as a future coating technology for load bearing medical implants.

Item Type: Article
Additional Information: Funding information: This work was funded and supported by the Leverhulme Trust Research Project Grant (RPG-2018-344) to develop super hard biocompatible coatings of a Ti based thin film material system.
Uncontrolled Keywords: Ti-Au thin film coating, Hardness, Biocompatible, L929 mouse fibroblast, Implants
Subjects: F200 Materials Science
H300 Mechanical Engineering
Department: Faculties > Engineering and Environment > Mechanical and Construction Engineering
Faculties > Health and Life Sciences > Applied Sciences
Depositing User: John Coen
Date Deposited: 23 Feb 2022 08:26
Last Modified: 30 Mar 2022 11:45
URI: http://nrl.northumbria.ac.uk/id/eprint/48522

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