A comparative study of titanium nitride (TiN), titanium oxy nitride (TiON) and titanium aluminum nitride (TiAlN), as surface coatings for bio implants

In the present study, the performance of three titanium nitride coatings: TiN, TiON, and TiAlN for biomedical applications were assessed in terms of their surface properties electrochemical corrosion in simulated body fluid and cytotoxicity. Layers of TiN, TiON and TiAlN were deposited onto CP–Ti substrates by DC reactive magnetron sputtering method using a combination of a Ti, Ti–Al targets and an Ar–N2 mixture discharge gas. The presence of different phases was identified by XRD analysis. The morphology was determined through atomic force microscopy (AFM) imaging. The XPS survey spectra on the etched surfaces of TiN film exhibited the characteristic Ti2p, N1s, O1s peaks at the corresponding binding energies 454.5, 397.0, and 530.6 eV respectively. The characteristic Raman peaks were observed from the Laser Raman spectrometer. Platelet adhesion experiments were done to examine the interaction between blood and the materials in vitro. On Control samples (CP Ti), platelets were seen as aggregates, whereas on coated samples, platelets were seen as singles, without any significant spreading. Cytocompatibility studies of coated samples were carried out with bare titanium (CP Ti — ASTM B 348) as controls. L-929 mouse fibroblast cells were used for samples. All materials showed good cytocompatbility with cell lines used.

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► TiN, TiON and TiAlN coatings were deposited by reactive DC magnetron sputtering.
► XPS analyses exhibited a mixture of Ti–N, Ti–O–N and Ti–Al–N chemical binding states.
► TiAlN coatings exhibited superior corrosion resistance than bare CP–Ti substrates.
► Cytotoxicity studies revealed that all these coatings could be classified as non-cytotoxic.