Fig. 1. Cross-sectional SEM images of the films deposited at different pulse durations: (a) 30 μs; (b) 60 μs; (c) 90 μs.

Fig. 2. AFM surface micrographs of the N-DLC films deposited at different pulse durations: (a) 30 μs; (b) 60 μs; (c) 90 μs.

Fig. 3. XPS C1s and N1s spectra of the N-DLC films deposited at different pulse durations: (a), (b) 30 μs; (c), (d) 60 μs; (e), (f) 90 μs

Fig. 4. The fitting result of the C1s spectra of the N-DLC films deposited at different pulse durations.

Fig. 5. Mechanical properties of the N-DLC films deposited at different pulse durations: (a) Hardness and elasticity modulus; (b) H/E^* and H³/E^*2.

Fig. 6. Potentiodynamic polarization curves of the N-DLC films and substrate immersed in Hank’s solution.

Fig. 7. (a) The structure diagram of electrolytic cells used for tribocorrosion tests; (b) sequence of operations during the tribocorrosion test illustrated by the OCP evolution.

Fig. 8. (a)–(c) The changes of OCP and coefficient of friction as a function of sliding times and the inserted optical micrographs of tribocorrosion tracks for coatings; (d) the normal coefficient of friction and micrographs of wear tracks.

Fig. 9. The contact angle of films: the morphologies of deionized water (a)–(c) and Hank’s solution (d)–(f) droplets on the surfaces: (a), (d) 30 μs: (b), (e) 60 μs: (c), (f) 90 μs.