THE IMPACT OF EXTERNAL AND SELF-INDUCED MAGNETIC FIELDS ON THE DEVELOPMENT OF CORROSION ON FEROUS AND NON-FERROUS MATERIALS
Gnegy-Davidson, Clint G
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As the US Navy continues to field ships with an increasing number of electrical generators and loads, it is unclear how the high magnetic fields being generated throughout the ship will affect the corrosion rate of the ships structural and high current conducting alloys. Given the high- pulsed current carried by pulsed power systems, it is of increased interest to understand what impact their deployment will have on metallic corrosion. In this work, a number of experiments have been designed and performed to study these phenomena. In the first set of experiments several alloys have been subjected to a continuous, externally applied magnetic field while submersed in a 3.5% NaCl solution with and without iv the presence of dissolved oxygen. In those without dissolved oxygen, argon is used to displace oxygen from the solution in order to determine the effect that oxygen has on corrosion. Within the subset of alloys being studied are ones with and without magnetic properties of their own that affect the distribution of magnetic flux around the sample when magnetic fields are present. A novel test stand was designed for the second set of experiments in which high pulsed currents, with amplitudes as high as a few kA, were conducted through 6.1 mm diameter rod samples. These experiments are aimed at studying how self-induced magnetic fields affect the rate of metallic corrosion of the same four materials evaluated in the first test series. Finally, a third test series has been performed in which samples have been subjected to repetitive pulsed current carry over a ten- minute period. In all experiments, diagnostic techniques including open circuit potential (OCP) measurements, anodic polarization measurements, linear polarization measurements, energy dispersive x-ray spectroscopy (EDS), and scanning electron microscope (SEM) imaging have been used to characterize each sample’s corrosion properties with and without the presence of a magnetic field.