Effect of Surface Texture on Wettability and Tribological Properties of Carbon-Based Coatings on the Inner Surface of Pipes

Diamond-like carbon (DLC) coating was deposited on the inner surface of the pipe by plasma enhanced chemical vapor deposition technology, and the inner surface of the pipe was textured by laser surface texture and sand blasting before and after depositing coatings. The morphology and structures of the DLC coatings were characterized by Raman spectrum and field-emission scanning electron microscope (FE-SEM). The lubricant retention property and tribological properties of the coating were analyzed by a tribometer. The results showed that the surface texture improved the wettability and tribological properties of the DLC coatings by changing the laser texture patterns and blasting pressure. In addition, we found that the DLC coating can be transformed into graphite with stratified structure by laser ablation. Specifically, the textured coatings with a blasting pressure of 2.06×10⁵ Pa(30 psi) or a lattice of 0.01 mm × 0.01 mm had the best lubricant retention property, while the surface texture with a lattice of 0.01 mm × 0.01 mm had the best tribology performance. Therefore, only suitable surface textures with optimum diameter and depth can properly promote the properties of DLC coatings.