Microstructure and load bearing capacity of TiN/NbN superlattice coatings deposited on medical grade CoCrMo Alloy by HIPIMS

HOVSEPIAN, Papken, ARUNACHALAM SUGUMARAN, Arunprabhu, RAINFORTH, Mark, QI, Jiahui, KHAN, Imran and EHIASARIAN, Arutiun (2022). Microstructure and load bearing capacity of TiN/NbN superlattice coatings deposited on medical grade CoCrMo Alloy by HIPIMS. Journal of The Mechanical Behavior of Biomedical Materials, 132: 105267.

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Open Access URL: https://www.sciencedirect.com/science/article/pii/... (Published version)
Link to published version:: https://doi.org/10.1016/j.jmbbm.2022.105267


In recent years significant progress has been made in the application of various ceramic, namely MeN functional coatings to engineer the surfaces of medical implants utilising metal-on-metal (MoM) articulation. This article reports on the load bearing capacity and structural response of TiN/NbN superlattice coatings deposited on medical grade CoCrMo alloy substrate under the application of localised load and the subsequent crack formation mechanism. The coatings have been deposited by mixed High Power Impulse Magnetron Sputtering-Unbalanced Magnetron Sputtering (HIPIMS-UBM) process. In the case of TiN/NbN coating deposited on CoCrMo substrate where Ecoating/Esubstrate is as high as 1.81 indicating that the substrate does not provide the necessary load bearing support for the brittle thin film, the utilisation of the Berkovich indentation technique proved to be a potent approach to study coating material as well as structural response to applied concentrated load. FIB/SEM analyses of the indented coatings revealed that in the hard-on-soft material systems cracks will initiate due to sub-coating substrate deformation and then propagate towards the coating surface. The FIB/SEM and low magnification XTEM analysis showed that an exceptionally strong TiN/NbN coating substrate adhesion bonding was achieved due to the utilisation of the HIPIMS pre-treatment. High resolution XTEM analyses revealed for the first time that during the indentation a collective rotation and alignment of the individual layers of the superlattice stack takes place without compromising coatings integrity which is clear evidence for the exeptionally high coating fracture toughness. The high toughness of the superlattice structured TiN/NbN coatings combined with their exceptionally high adhesion on madical grade CoCrMo ranks them as a strong candidate for medical implant applications.

Item Type: Article
Uncontrolled Keywords: 0903 Biomedical Engineering; 0912 Materials Engineering; 0913 Mechanical Engineering; Biomedical Engineering
Identification Number: https://doi.org/10.1016/j.jmbbm.2022.105267
SWORD Depositor: Symplectic Elements
Depositing User: Symplectic Elements
Date Deposited: 06 May 2022 16:30
Last Modified: 12 Oct 2023 12:15
URI: https://shura.shu.ac.uk/id/eprint/30199

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