STUDY OF SULFATE-REDUCING BACTERIA TOWARD MICROBIOAL CORROSION BEHAVIOR OF STAINLESS STEEL 304 IN SEAWATER USING IMERSION AND ELECTROCHEMICAL METHODS

• Main Author: Shofia Al Fitri , Devi
• Format: Final Project
• Language: Indonesia
• Subjects: Teknik (Rekayasa, enjinering dan kegiatan berkaitan)
• Online Access: https://digilib.itb.ac.id/gdl/view/21677
• Institution: Institut Teknologi Bandung

Stainless Steel is a kind of metal which engineered to reduce corrosion rate with addition of Cr element to form Cr2O3 as oxide passive layer. A kind of austenitic stainless steel AISI 304 is exposed to media with Chloride ion which can lead to local corrosion e.g. seawater environment. Seawater consists mainly of chloride and sulphate ions is a suitable media for growing microorganisms e.g. Sulphate Reducing Bacteria (SRB). Microorganisms in seawater can increase stainless steel corrosion rate which also widely known as microbiological corrosion (MIC). Research on Sulphate Reducing Bacteria effect on stainless steel need to be conducted so that corrosion engineer will be aware of the danger of this corrosion. In this final project, several experiments have been conducted in order to understand microbiological corrosion behaviour on stainless steel using seawater media for SRB. Experiments in this report included examination using immersion and electrochemical method, observation of morphological damage using optical microscope and SEM, specimen surface characterization using EDS and bacterial growth observation. From this research, it has been found that medium with SRB immersed for 4 weeks have not experience significant weight reduction and surface characterization using EIS have shown Nyquist curve with passive layer which protects the steel, however this passive layer have shown reduced protection over immersion time. During this immersion process, it has been observed from surface morphological damage experiment using optical microscope and SEM that steel in sterile seawater media have shown initial local corrosion and biofilm in SRB medium which shows microbiological corrosion mechanism at steel surface. EDS characterization also have shown bacterial metabolism with high C and O content and existence of sulphur element. Effect on SRB also supported by polarization experiment which have shown higher corrosion rate in SRB medium. <br />