Preparation of Biomimetic Multi-Scale Oleophobic Surface on X70 Pipeline Steel

Abstract

Oleophobic surface has broad application prospects in petroleum, petrochemical, and food industries because of its non-stick oil and self-cleaning characteristics. Oleophobic surface has mainly two features: one is fine structure with micro-nano combined scale, and another is low surface energy. An oleophobic surface was successfully prepared on X70 pipeline steel surface using shot peening, chemical etching and low surface energy modifying composite methods in this study. The surface of X70 pipeline steel sample was first treated by shot peening, forming a rough structure on the sample surface. And then the sample surface was chemically etched with hydrochloric acid (HCl) solution to further refine the surface structure, forming micro-nano combined structure. Finally the surface of the specimen was low energy modified using perfluorooctanoic acid ethanol solution (PAES). The influences of HCl concentration, chemical etching time, perfluorooctanoic acid concentration, and modification time on the contact angle were analyzed. The best process parameters were optimized. The surface morphology of X70 pipeline steel sample was observed using scanning electron microscope (SEM). It was observed that there were micron structures composed of the convexes and concaves on the specimen surface treated by shot peening and chemical etching. There were nanoscale acicular structures on the micrometer grade structure. After the micro-nano composite structure was modified with PAES, the contact angle between the sample surface and oil droplet was significantly improved. The maximum contact angle of the sample surface with oil droplet was 141°.