Accidental damaged diamond-like carbon coating by prefabricated scratches: Experimental exploration on anticorrosion and tribological performances

Abstract Accidental damage on the diamond-like carbon (DLC) coating can have a great influence on the anticorrosion and tribological performances. In this study, DLC coating was deposited by a DC unbalanced magnetron sputtering technique. The scratch tests with different damage loads of 2, 10, 20, 30, 40 and 50 N were used to imitate the different types of accidental damage. The influence of different types of surface damage states on anticorrosion performance and scratch damage structures on tribological performance were studied and compared with those of the coating without damage. Cracking or spalling of the coating promotes the corrosion failure of the coating system and pitting corrosion of the stainless steel substrate, resulting in the deterioration of the corrosion protection effectiveness. With the damage increases from fine crack to complete failure, the corrosion resistance decrease obviously and the corrosion rate increases from 1.796 × 10−9 to 2.880 × 10−8 (A/cm2). The coating with an appropriate scratch structure as the sample S2 (scratch width of 0.012 mm and the ratio of the scratch width to the contact width is 0.033) can effectively avoid the softening of the coating surface caused by graphitization and collect the wear debris particles, resulting in the excellent tribological behaviors with the lowest wear rate of 1.848 × 10−16 m3/(N·m).