Local Adhesion of Diamond-Like Carbon Films Coated on Substrates in a Trench-shaped Cathode

A negative potential is applied to an object in plasma consisting of methane or acetylene in order to coat a solid thin film such as DLC (diamond-like-carbon) on a material surface. The method is called plasma-based ion implantation (PBII). Since mechanical objects commonly possess complex shapes, it may be difficult to coat DLC on them in a uniform manner. This non-uniformity in thickness has been studied in many papers, and it has been reported that it is improved by applying a pulse potential repeatedly to the coated material. Using a scratch test, we studied the local adhesion of DLC coated by PBII to SUS304 thin plates attached at several places in a trench-shaped cathode. We found that the adhesion gets greater, in order, for the plates at the side, the bottom of the groove in a trench, and the top of a trench. In order to explain the results, further studies are required