Corrosion performance of DLC coatings with laser-induced graphitized periodic surface structure

Two types of diamond-like carbon (DLC) thin films, hydrogenated amorphous carbon (a-C:H) and super-hard tetrahedral amorphous carbon (ta-C), were irradiated with femtosecond laser pulses, and the corrosion resistance of the DLC films with laser-induced periodic surface structure (LIPSS) and modified to nanocrystalline graphite (nc-G) was electrochemically evaluated from anodic polarization measurements. The polarization curve for a glassy carbon (GC) plate, which is a type of nc-G, was measured for comparison. The polarization curve for stainless steel with LIPSS was also measured, and it was confirmed that LIPSS increased the surface area of the irradiated part, which resulted in an increased apparent corrosion current density. Polarization curve measurements for irradiated DLC indicated that the corrosion current density was reduced, despite the effect of an increased surface area by the formation of LIPSS, and the polarization curves tended to approach those for GC plates. Therefore, the irradiated surface layer of DLC is modified to nc-G, which results in excellent corrosion resistance similar to that of GC. [Display omitted] •Femtosecond laser-induced graphitized periodic surface structure (LIPSS) on DLC•Corrosion resistance of Graphitized LIPSS was evaluated by polarization curve.•LIPSS increased the corrosion current due to the increase of the surface area.•Graphitized LIPSS decreased the corrosion current.•Graphitized LIPSS on DLC improves the substrate protection effect of DLC.