FABRICATION OF CU-ZN SUPERHYDROPHOBIC COATING ON STEEL WITH PULSED CURRET ELECTRODEPOSITION TECHNIQUE: CURRENT DENSITY AND DUTY CYCLE VARIATION

• Main Author: Wicak Yusri A., Pandhega
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/75916
• Institution: Institut Teknologi Bandung

???? Steel is prone to corrosion due to its main component is iron, which has a relatively low reduction potential. One of the primary factors causing corrosion in steel is the presence of a thin layer of water from the surrounding environment on the steel surface. To prevent this, a protective coating with superhydrophobic properties with a water contact angle > 150° to minimize water contact, is needed. One of many techniques used to fabricate a superhydrophobic coating is electrodeposition. By employing pulsed current with specific on-off cycles during electrodeposition, a more compact coating can be obtained. This research aims to study the influence of current density and duty cycle on the water contact angle values of the fabricated superhydrophobic coating using pulsed current electrodeposition on API 5L X52m steel with a Cu-Zn anode. Before the fabrication of superhydrophobic coatings, all samples were prepared. The fabrication process was conducted in two stages using the pulsed current electrodeposition technique with variations of 1,6;2;3 A/dm2 in current density and variation of 30%, 50%, and 70% in duty cycle, and carried out for 60 minutes with a frequency of 250 Hz. The process was then followed by solution immersion for 30 minutes to obtain a micro-nano hierarchical structure. Then, the samples were immersed in myristic acid solution for 36 hours to reduce the surface tension. Then, water contact angle measurement was performed. The surface characteristics of the superhydrophobic coatings were observed using scanning electron microscope and X-ray diffraction. Then, electrochemical tests, immersion tests, self-cleaning tests, and mechanical durability tests were performed. The fabrication results showed the highest water contact angle of 160.609°, which was achieved using a current density of 3 A/dm2 and a duty cycle of 30%. However, the water contact angle tended to decrease after being exposed to atmospheric air for 21 days. The surface morphology of coating film exhibited a micro-nano hierarchical structure with micro and nano structure sizes approximately ±5.54 ?m and ±750-860 nm. The formed phases on the coating surface were identified as ZnO, CuO, and Cu-Zn. The corrosion potential and corrosion current density values were -0.395 V vs Ag/AgCl and 46.519 ?A/dm2, respectively. The appropriate equivalent circuit model indicated the presence of a protective layer at the metalenvironment interface. The superhydrophobic layer was resistant to a corrosive environment containing 3.5% NaCl, but the hydrophobic properties decreased. The fabricated superhydrophobic layer also exhibited self-cleaning properties and reasonably good mechanical resistance.