Protection and Biocompatibility of DLC coating on pure titanium

Abstract

Objectives: The aim of this study was to evaluate the wear protection and biocompatibility of diamond-like carbon (DLC) coating on pure titanium and Ti-N was selected as transition layer.

Methods: DLC coatings were prepared on pure titanium using the pulse multi-arc ion source and deposited with Ti-N as transition layer. Using toothbrushes machine and scratch test to evaluate the wear protection and the adhesion strength between DLC coatings and pure titanium compared with Ti-N coatings, anodizing coatings, DLC coatings without transition layer and uncoated pure titanium. Scanning electron microscopy (SEM), X-ray photoelectron (XPS) were employed to analysis the microstructure properties of DLC coatings after test. Biocompatibility was measured by MTT assay.

Results: The evaluation of wear protection reveals that the frictional resistance of DLC coatings is much higher than other samples(P<0.01). The scratch test reveals that the DLC coatings with transition layer has good adhesion strength between the coating and substrate(P<0.01), SEM and XPS manifest that C,N,Ti was infiltrated to each side between coatings and substrate. In cytotoxic test OD-values of each test groups were similar to that of negative control and significantly lower than that of positive control, which indicate that the DLC coatings was safe to L-929 cells.

Conclusion: The bonding strength between DLC and pure titanium can be increased with Ti-N as transition layers. DLC coatings can endure daily brushing. Cytotoxic test manifest DLC coatings were safe to use in human body.

Key word: pure titanium; diamond-like carbon coatings; compound multi-layer; wear protection; biocompatibility