Sustainable and Eco-Friendly DLC Fabrication for Replacing Chrome on a Gravure Cylinder Surface

This paper evaluates the potential of diamond-like carbon (DLC) as a durable surface protection to replace the chromium (Cr) layer, which is traditionally applied to gravure print cylinders and other components through a galvanic electroplating process. The fabrication of DLC is more eco-friendly and could reduce the environmental hazard posed by hexavalent chromium in liquid form that is used in Cr application and better adhere to environmental regulations. This could encourage businesses to bring the DLC fabrication process in-house, sharing resources such as materials, labor, and equipment, to help reduce costs. Four DLC variants (standard DLC, A-DLC, S-DLC, and organic silica) and chrome were analyzed and tested for their surface properties and durability. Data suggest that both standard DLC and S-DLC had higher surface free energy, allowing for good ink wetting on the surface when compared to chrome. In addition, the standard DLC and S-DLC surfaces are generally smoother than the chrome, resulting in lower relative hydrophilicity and allowing for easier removal of ink in the nonimage regions with the doctor blade. The elcometer adhesion test demonstrated that the bond strength of the DLC variants to their base layer was comparable to the bond strength of chrome, indicating that the adhesion strength of the two materials was similar. Furthermore, in the abrasion test, the wear on the standard DLC surface and the corresponding wear on the lamella tip of the metal doctor blades were notably lower than that observed on chrome. This distinction is particularly evident in each of the test trials, specifically run 1, which involved 2,000,000 wiping actions of a metal doctor blade in the presence of abrasive TiO₂ ink pigments. Statistical analysis on standard DLC versus chrome suggests that DLC fabrication is effective and durable on plain and patterned surfaces. Therefore, from a sustainable and eco-friendly perspective, standard DLC and S-DLC would be good alternative durable surfaces for print cylinders and other components used in various industries due to superior wear resistance properties.