Structure and biocompatibility of Titanium Nitride Coatings on Polyurethane produced by laser ablation

Titanium nitride (TiN) coatings on polyurethane (PU) were produced by pulsed laser deposition, by means of a system working with a Nd:YAG laser for ablation of titanium target. Nitrogen environment was applied in the reactive chamber. Structure examinations – X-ray diffraction (XRD), atomic force micro-scopy (AFM) and transmission electron microscopy (TEM) – were performed to study surface morphology (AFM) and microstructure of the cross-section (TEM) as well as crystallographic texture and residual stresses (XRD). AFM results revealed diminishing roughness of the surface when the coating thickness increased in the range from 0.25 via 0.5 and 1 up to 3 μm. The appearance of characteristic features on the surface leads to the conclusion that the contribution of kinetic pro-cesses in the formed morphology was dominant. XRD measurements showed an increase of the lattice parameter, accompanied by an increasing coating thickness, which could be explained by the change of the deposition mechanism. Crystallo-graphic texture measured in TiN layers presented close to random crystallographic orientation, while pole figures of the residual stress distribution suggested isotropic character. Thin foils prepared from the cross-section by the microtome method showed a form of anchoring of the deposited TiN layer to the PU substrate with possible local remelting of substrate by the first deposited particles. Residual stress measured in the TiN layer was in the range of about 2 GPa and its value dimin-ished together with the rise of coating thickness. Biological tight examinations of the coating were carried out with respect to cell proliferation, death and adhesion