Abstract
In order to clarify wire diameter dependency of corrosion rate of steel wires, which have been widely used in various fields, immersion tests and polarization tests in pH 5.9 and pH 2.5 NaCl solutions were conducted to high carbon steel wires with 0.1 to 1.0mm in diameter. It was found that the corrosion rate was largely dependent upon the diameter in both solutions, that is, it increased with the decrease of the diameter. Diffusion limiting current was observed in both solution, and it also had the same diameter dependency. Corrosion rate and diffusion limiting current in pH 2.5 solution were about one order larger than those in pH 5.9 solution. The analysis of diffusion limiting current and diffusion model for cylinder-shaped wire electrode based on Fick's law indicated that corrosion rate was controlled by diffusion of dissolved oxygen in pH 5.9 solution and that by diffusion of hydrogen ion in pH 2.5 solution, and that the increase of corrosion rate with the decrease of wire diameter was attributable to promotion of cathodic reduction reaction of dissolved oxygen in the neutral solution, and that of hydrogen ion in the weak acid solution, respectively.
