Fig 1.
XRD patterns (a) and XPS survey scan spectra (b) of the pristine Ti, TiN-coated and TaN-coated Ti: (bi) XPS wide spectra; the high-resolution Ti 2p spectra for the pristine Ti (bii), TiN-coated Ti (biii), and Ta 4f spectrum for TaN-coated Ti (biv).
Fig 2.
Surface characteristics of the pristine Ti, TiN-coated Ti and TaN-coated Ti samples: (a) SEM images, the insets show the water contact angle of the corresponding materials; (b) in situ SPM images; and (c) surface roughness, root-mean-square roughness (RMS) and average roughness (Ra) are used to present the surface roughness.
Fig 3.
Hardness (a) and elastic modulus (b) vs. depth curves for the uncoated Ti, TiN-coated Ti, and TaN-coated Ti samples.
Fig 4.
Open circuit potentials (a) and potentiodynamic polarization curves (b) of the uncoated Ti, TiN-coated Ti, and TaN-coated Ti in AS, AS-S.mu, and AS-A.vi solutions, respectively.
The inset table in (b) shows the corrosion current density (Icorr) of the samples.
Fig 5.
Representative EIS spectrum plots of the pristine Ti, TiN-coated Ti, and TaN-coated Ti in AS, AS-S.mu, and AS-A.vi solutions: Nyquist plots (a), Bode plots (b), and the equivalent electrical circuit model (c).
Fig 6.
Biofilm formation observation of the pristine Ti, TiN-coated Ti, and TaN-coated Ti after 14 days of incubation with mixed bacteria: SEM images of bacteria and EPS (a), WLI images (b), and Live/dead cell staining of CLSM.
In WLI images, the brown represents bacterial cells, and the orange represents substrates. Red arrows in (a) point to the secreted EPS of bacteria. * represents p < 0.05 compared with other groups.
Fig 7.
The SEM micrographs (a) and in situ SPM (b) of the pure Ti, TiN-coated and TaN-coated surfaces exposed to medium with and without the mixed bacteria for 7 and 28 days after the removal of biofilm and corrosion products.
Fig 8.
The XPS high-resolution spectra of Ti 2p and O 1s for bare Ti (a), Ti 2p and N 1s for TiN-coated Ti (b), and Ta 4f and N 1s for TaN-coated Ti samples (c) in medium with and without the mixed bacteria for 28 days after the removal of biofilm and corrosion products.