Influence of silver content on the tribomechanical behavior on Ag-TiCN bioactive coatings

Surface modification of bulk materials used in biomedical applications has become an important prerequisite for better biocompatibility. In particular, to overcome the particle generation, low-wear coatings based on carbon (nitrogen) and containing antimicrobial elements such as silver are promising...

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Bibliographic Details
Published in:Surface & coatings technology 2012-01, Vol.206 (8), p.2192-2198
Main Authors: Sánchez-López, J.C., Abad, M.D., Carvalho, I., Escobar Galindo, R., Benito, N., Ribeiro, S., Henriques, M., Cavaleiro, A., Carvalho, S.
Format: Article
Language:English
Subjects:
Amorphous carbon phases
Applied sciences
Biocompatibility
Coatings
Contact of materials. Friction. Wear
Cross-disciplinary physics: materials science
rheology
Cytotoxicity
Exact sciences and technology
Fetal bovine serum
Friction
Magnetron sputtering
Materials science
Mechanical properties and methods of testing. Rheology. Fracture mechanics. Tribology
Metals. Metallurgy
Nanocomposite
Physics
Production techniques
Scanning electron microscopy
Silver
Surface treatment
Surface treatments
Titanium
Tribology
Wear mechanism
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Summary:Surface modification of bulk materials used in biomedical applications has become an important prerequisite for better biocompatibility. In particular, to overcome the particle generation, low-wear coatings based on carbon (nitrogen) and containing antimicrobial elements such as silver are promising candidates. Thus, the present work explores the potentialities of silver-containing carbonitride-based (Ag-TiCN) thin films prepared by direct current unbalanced reactive magnetron sputtering. The silver content in the coatings was varied from 0 to 26.7 at.% by changing the targets and the fraction of C 2H 2 and N 2 in the gas mixture with Ar. The obtained Ag-TiCN based coatings were characterized in terms of composition and microstructure. Mechanical and tribological properties of the films were studied by nanoindentation and reciprocating pin-on disk testing in a fetal bovine serum solution, respectively. Raman, scanning electron microscope and energy dispersive X-ray analysis was carried out in the contact region after tribological tests to obtain information about the friction mechanism. The cytotoxicity of the coatings was assessed by in vitro tests using fibroblast cells. The coatings comprised a mixture of TiC xN 1 − x , Ag and a-C(N) x phases whose relative proportion varied depending on the Ag/Ti ratio. The mechanical, tribological and cytotoxicity properties were correlated with the chemical and phase composition. When the Ag/Ti ratios were below 0.20 (Ag contents < 6.3 at.%) the films resulted harder (~ 18 GPa) with higher wear resistance (~ 10 −6 mm 3/Nm), showing similar friction coefficient (~ 0.3) and good biocompatibility. ► Correlations between phase composition, microstructure and tribomechanical properties. ► Optimized tribological behavior of Ag-TiCN is found to be for [Ag] up to 6.3 at.%. ► Increasing Ag/Ti above 0.4 the films soften and reduce the wear resistance. ► The cytotoxicity of the coatings is inferior to 10% for Ag contents up to 20 at.%.
ISSN:0257-8972
1879-3347
DOI:10.1016/j.surfcoat.2011.09.059