Modified diamond-like carbon coatings (a-C:H:X) for anti-fouling applications

Amorphous hydrogenated diamond-like carbon films (a-C:H) are well known for their high hardness, high wear resistance and low friction coefficients. The incorporation of additional elements leads to considerable modifications of the coating properties. E.g. silicon containing a-C:H:Si coatings provide low friction coefficients and lower surface energies. Incorporation of Si and O (a-C:H:Si:O) leads to highly hydrophobic coatings with still lower surface energies (< 25 mN/m). Both types of modified coatings had anti-adhesive properties. Modified DLC coatings were prepared by Plasma Enhanced Chemical Vapor Deposition (PECVD) processes, powered with radio frequency, bipolar pulsed DC voltage or by a linear micro wave plasma source in industrial scale coating machines. The different DLC modifications can be combined in a multilayer coating for optimization of properties. The developed modified DLC films with low surface energies and high wear resistance are promising for several technical applications, e.g. for forming or pressing tools or for reduction of fouling effects in heat exchangers. These coatings were used to realize an alternative approach for inside coating of pipes. After coating deposition on flat metal sheets followed a cold forming process to fabricate a pipe and a welding along the joint line to close the pipe.