Mechanical and corrosion behavior of thick and soft DLC coatings

The thickness of the DLC coating was about 37 μm, and its hardness was 12 GPa. The coatings presented a low friction coefficient, about 0.09. In the abrasive tests, the mass loss was negligible and in erosion experiments, the mass loss was reduced to 30%. Regarding the corrosion performance, the behavior in the Salt Spray Fog Test was good only in the duplex samples. In potentiostatic tests in 3.5% NaCl using steps, the current density increased at higher potentials for the duplex sample. Concerning the film adhesion, the critical load was also higher in theses samples than in the coated ones. The nitrided layer was a good interface for reducing the stresses and improving the adhesion, which is relevant for the decrease of the propagation rate of corrosion, when traversing defects are formed in the coating.