Influence of hydrogenated amorphous carbon coatings on the formation of paraffin deposits

In this work, the formation of paraffin deposits onto uncoated and amorphous carbon-coated substrates was studied. Carbon-based films were deposited onto silicon (Si) and stainless steel (SS) substrates from methane (CH4) gas using radio-frequency plasma-enhanced chemical vapor deposition (rf-PECVD). The surface free energy of substrates was evaluated by contact angle measurements by the sessile-drop technique. Paraffin was deposited onto the substrates by both casting and cold-finger methods and characterized by optical and AFM microscopies. The results indicate a correlation between the morphology of paraffin deposits with the substrate free energy. Also, the total mass of paraffin deposited on DLC-coated substrates is much lower than in the case of uncoated SS substrates. This suggests that carbon-based films can be used as coatings to prevent or reduce the formation of paraffin deposits in the petroleum industry.