STUDY OF BIOCORROSION BEHAVIOUR OF AA5083 ALLOY BY THE BACTERIA SERRATIA RUBIDAEA STRAIN SKC-11 IN THE MARINE ENVIRONMENT

• Main Author: Alhadi, Afif
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/69345
• Institution: Institut Teknologi Bandung

Indonesia, which is the largest archipelagic country in the world, has various advantages from its geographical location and resources. Because of that reason to facilitate inter-island connectivity and increase the utilization of maritime potential, it is necessary to develop the shipping industry. Ships that are a mode of sea transportation have a high risk to have a high risk of being corroded, especially in the hull section. Aluminum alloy 5083 (AA5083) is one of the aluminum alloys that can be used as a ship's hull because it has high corrosion resistance, lightweight, good workability, and can be recycled. However, in certain circumstances, aluminum can experience corrosion due to chloride ion attacks and microbiological Influenced Corrosion (MIC) phenomena. This research was conducted to determine the effect of the presence of sulfate-reducing bacteria (SRB) Serratia rubidaea strain SKC-11 on the biocorrosion process of aluminum alloy 5083 (AA5083) in seawater from Santolo Beach, West Java. A series of experiments were carried out beginning with specimen preparation. Specimens that have been cut into sizes of 50 mm x 20 mm and 10 mm x 10 mm are then sanded using 80-2000 grit carbide paper, then sterilized with alcohol. Especially for electrochemical testing before being sanded and given alcohol, specimens that have been cut and then connected with cables using copper tape and then mounted. Preparation of seawater as a medium, started with the filtration of seawater and followed by sterilization using an autoclave. Then, inoculation of Serratia rubidaea strain SKC-11 was carried out on a modified Luria Bertani (LB) medium with an incubation time of 20 hours, according to the results of the growth curve experiment. The immersion of the specimens was carried out in sterile seawater media and sterile seawater media with added bacteria for a period of 7, 14, 30, and 40 days. Carried out to determine its effect on corrosion rate, corrosion potential, corrosion current density, polarization resistance, and corroded specimen surface. With the immersion test method, it was found that the average corrosion rate based on the results of the immersion test results that on the 7th and 14th days, almost the same results were obtained between sterile seawater medium and medium containing the bacteria Serratia rubidaea strain SKC-11, meanwhile on On the 30th day there was a significant increase in immersion in seawater medium containing bacteria, which was 0.1832 mm/year, this result was higher than AA5083 in sterile seawater medium of 0.1508 mm/year. Based on the results of the EIS test, it was found that the polarization resistance of the AA5083 alloy in seawater medium containing the bacteria Serratia rubidaea strain SKC-11 until the 3rd day had a higher value of Rp. Different results were obtained on the 7th and 14th days of immersion, where the results are 18683 ?.cm2 and 13640 ?.cm2 for immersion in sterile seawater medium, these results were higher than AA5083 in seawater medium containing bacteria, namely 13800 ?.cm2 and 7290 ?.cm2. Based on the results of the polarization test, in seawater medium containing the bacteria Serratia rubidaea strain SKC-11 on the 14th day it increased significantly by 0.4960 mm/year and this result was greater when compared to sterile seawater medium of 0.2425 mm/year. Scanning Electron Microscope-Energy Dispersive Spectroscopy Mapping (SEM-EDS mapping) and Fourier Transform Infra Red (FTIR) analysis showed the presence of a biofilm layer and bacterial metabolic activity on the surface of AA5083 immersed in seawater medium containing the bacterium Serratia rubidaea strain SKC-11 containing evidence of a biocorrosion process.