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Biocompatibile TiN-based novel nanocrystalline films |
R.
EBNER, J.M. LACKNER, W. WALDHAUSER, R. MAJOR, E. CZARNOWSKA, R. KUSTOSZ, P.
LACKI, and B. MAJOR |
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Titanium nitride (TiN) is regarded as a potential biomaterial for blood-contact applications. TiN thin films were fabricated by pulsed
laser deposition with the Nd:YAG laser on biologically applied polyurethane. Transmission electron microscopy (TEM) study of 250 nm
thick films revealed columnar structure. Such films were observed to be brittle, which led to crack formation and secondary nucleation of
microcolumn. TEM studies showed a kinetic mechanism of growth (columnar) in films of 250 nm thickness. It was stated that thinner films
were much smoother and uniform than the thicker ones, which could be associated with the surface diffusion mechanism to appear. In order to
improve the coatings elasticity, the thickness was reduced to 50 nm, which limited the deposition mechanism operation to the early stage. TEM
cross-section observation revealed elastic properties of thin films. A biological test showed that TiN surface film produced on polyurethane is
characterized by good biocompatibility and decreased surface affinity for cell adhesion. Films of 0.25 and 0.5 1m thick of TiN were selected
for theoretical finite element modelling (FEM) using ADINA program. The micro cracks formation predicted in simulation was verified by
phenomena observed in microstructure examinations. |
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Keywords: |
titanium nitride, thin films, polyurethane, biocompatibility, finite element modelling |