XPS Analysis of Copper Tubes and Effects of Carbon Film on Corrosion Behavior

Abstract

This study was performed to examine type I pitting corrosion in copper tubes due to the synergistic effects of water quality and carbon film produced by the influence of oil and heat treatment. Although carbon film was considered to be one factor responsible for pitting corrosion, the relationship between the amount of carbon film and corrosion was not well understood. Therefore, a simple method for quantifying carbon film is required. In this study, we first examined copper tubes with unknown residual carbon amounts by X–ray photoelectron spectroscopy (XPS) and the conventional procedure. The results were the same by both procedures, confirming that the residual carbon amount can be determined by XPS. Next, we investigated the effects of carbon films on the corrosion behavior of copper tubes utilizing galvanic current measurements and polarization curve measurements. The carbon area ratio was dependent on galvanic current. Polarization curve measurements were closely correlated with galvanic current measurements, indicating that polarization curve measurements could be used to determine the relationship between the area ratio of the carbon film and galvanic current density.