CORROSION BEHAVIOR TESTING OF SUPERHYDROPHOBIC COATING CU-ZN FABRICATED BY USING ELECTRODEPOSITION METHOD

• Main Author: Anggriani Simangunsong, Martha
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/69182
• Institution: Institut Teknologi Bandung

Currently, corrosion is widely recognized as one of the causes of damage to steel. There are various types of carbon steel, one of which is ASTM A36 steel. The high hardness, low price and ease of shaping are the reasons for the widespread use of ASTM A36 steel in industry and construction. However, the resistance of steel to corrosion is still a drawback of this metal. The greater the possibility of corrosion to occur when the steel surface is more easily wetted. Therefore, various studies have been carried out to produce steel surfaces that are not easily wetted. One of them is by applying a superhydrophobic layer which is characterized by a contact angle value of more than 150° on the steel surface derived from the Cu-Zn metal alloy electrodeposition process. However, the corrosion behavior of this superhydrophobic layer also remains to be tested. This study aims to examine the corrosion behavior of Cu-Zn superhydrophobic coating applied to ASTM A36 steel. This research uses electrochemical test methods which include Open Circuit Potential (OCP) test, Electrochemical Impedance Spectroscopy (EIS) test and Potentiodynamic Polarization (PDP) test. Prior to testing, the samples were fabricated with a superhydrophobic layer using the electrodeposition method which included three processes, namely solution immersion, and surface modification. The coating layer was observed using a Scanning Electron Microscope (SEM) to determine the surface morphology. Electrochemical testing was carried out with three variations, namely the type of coating including bare steel or without a coating layer, coated steel and modified coated steel, immersion time which included 1 hour, 12 hours and direct, and the type of solution included NaCl 3.5%, H2SO4 and aquadest. In addition, an immersion test in 3.5% NaCl solution was carried out for 7 days by measuring daily weight changes and observing the droplet shape on the sample surface on days 1, 3, and 7. OCP test results show that uncoated steel is easier to corrode than coated steel which is characterized by a more negative OCP value. The difference in the type of test solution did not give a significant change in the OCP value, meaning that the coating layer protects the steel well. The EIS test results in the form of Nyquist plots and equivalent circuits show that the resistance of the coating layer is higher than that of uncoated steel. Based on the PDP test, the immersion time did not have a significant effect on the Ecorr and icorr values, which means the steel is well protected even though it has been immersed in a corrosive solution such as 3.5% NaCl. SEM test results show that the morphology of the coating is dandelion or spherical