Strong bonding between sputtered bioglass-ceramic films and Ti-substrate implants induced by atomic inter-diffusion post-deposition heat-treatments

abstract

Bioglasses (BG) are the inorganic materials exhibiting the highest indices of bioactivity. Their appliance as films for bio-functionalization of metallic implant surfaces has been regarded as an optimal solution for surpassing their limited bulk mechanical properties. This study reports on magnetron sputtering of alkali-free BG thin films by varying the target-to-substrate working distance, which proved to play an important role in determining the films' properties. Post deposition heat-treatments at temperatures slightly above the glass transformation temperature were then applied to induce inter-diffusion processes at the BG/titanium substrate interface and strengthening the bonding as determined by pull-out adherence measurements. The morphological and structural features assessed by SEM-EDS, XRD, and FTIR revealed a good correlation between the formations of inter-metallic titanium silicide phases and the films' bonding strength. The highest mean value of pull-out adherence (60.3 +/- 4.6 MPa), which is adequate even for load-bearing biomedical applications, was recorded for films deposited at a working distance of 35 mm followed by a heat-treatment at 750 degrees C for 2 h in air. The experimental findings are explained on the basis of structural, compositional and thermodynamic considerations. (C) 2013 Elsevier B.V. All rights reserved.

keywords

BIOACTIVE GLASS COATINGS; IN-VITRO BEHAVIOR; THIN-FILMS; MECHANICAL-PROPERTIES; THERMAL-EXPANSION; GRADED COATINGS; SILICATE GLASS; TITANIUM; MICROSTRUCTURE; DEPOSITION

subject category

Chemistry; Materials Science; Physics

authors

Stan, GE; Popa, AC; Galca, AC; Aldica, G; Ferreira, JMF

our authors

acknowledgements

G.E.S. and A.C.P. are thankful for the financial support from the Romanian National Authority for Scientific Research through the UEFISCDI TE 49/05.10.2011 (TE-0164). The support from CICECO is also acknowledged.

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