Modification of diamond-like carbon coatings with fluorine to reduce biofouling adhesion

Diamond-like carbon (DLC) and fluorinated DLC (F-DLC) coatings were deposited onto 10 mm stainless steel 316 L discs by radio frequency plasma-enhanced chemical vapour deposition (rf PECVD). Surface energy analysis of the F-DLC coatings revealed that with increasing F content the total surface energy decreased significantly, which was attributed to the change of the bonding nature in the coatings, in particularly increasing CF and CF2 bonds. The anti-biofouling property of F-DLC coatings was evaluated with Pseudomonas fluorescens, which is one of the most common bacteria forming biofilms on the surface of heat exchangers in cooling water systems. The experimental results showed that the incorporation of fluorine into the DLC coatings reduced bacterial attachment and increased bacterial removal. The F-DLC coatings with higher F content (39.2 at.%) reduced bacterial attachment by 48.8% and increased removal by 90.2%, compared with a standard DLC coating.