Date of Award
Master of Science in Mechanical Engineering (MSME)
Mechanical, Industrial and Systems Engineering
In this study, Impedance Spectroscopy (EIS), was performed. The corrosion resistance versus time of exposure of both carbon fiber and metal alloys were thoroughly examined and compared for just over a 200-day period. Collecting this data revealed drastic changes in impedance values for several of the 11-examined fastener/carbon fiber interconnections immersed in 3.5% sodium chloride (NaCl) solution, from day one of exposure to day sixty specifically. The range of impedance values directed the preselection of one stainless-steel and titanium fastener for further assessment, with the goal of recognizing that EIS could detect trends of corrosion and degradation of material.
Equivalent R/C Circuit modeling was created and conducted from the impedance data obtained via potentiostat for selected stainless steel and titanium fasteners. This was done to determine how many interfaces the interconnected model contained. After trials of 1RC, 2RC, 3RC and 4RC imbedded circuit analysis, the identification of three overall interfaces was suggested. This meant the interconnected system contained three interfaces that were reacting with seawater within the replicated galvanic system. After EIS and equivalent R/C circuit analysis was complete, the identification of interactions between the interfaces and what type of surface changes had taken place was completed by a well-known electron microscopy process.
Scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS) was conducted on both selected fasteners and carbon fiber coupons. The primary focus was on the metal fasteners, the carbon fiber was to be studied in the future. The enhanced photos revealed corrosion of the stainless-steel fastener. Specifically, there was signs of crevice corrosion on the outer threads in between two interfaces. There was also the identification of chlorine atoms on the surface of stainless steel fasteners, recognizing the cause of corrosion was by chemical reaction and not mechanical failure.
Ortiz, Jordan Angel, "Corrosion of Different Materials Connected to Carbon Fiber" (2018). Open Access Master's Theses. Paper 1212.