TECHNIQUE FOR MEASURING STRESS-CORROSION CRACKING OF METALLIC ELECTRODES IN AQUEOUS-SOLUTIONS

A mathematical model relating deformation to electrochemical behaviors of metals in aqueous solution has been developed. The model was established based upon principles of holographic interferometry for measuring microscopic deformation and of electrochemistry for measuring the corrosion of metals, i.e., anodic dissolution current. The model can be used to calculate the stress corrosion of metals under a constant load or displacement in a polarized or unpolarized condition. The current density of metals can be calculated as a function of imposed deformations. The model was used to calculate the stress corrosion behavior of a nickel electrode under a constant load in 1 N H2SO4 solution. The calculation was based on a hypothetical optical arrangement of the holographic interferometry as well as on empirical parameters of Ni electrochemistry in the solution. The study was successful in developing an experimental technique for investigating the influence of deformation on corrosion. The development of the technique was based on a new optical transducer. The new transducer incorporated electrochemical methods with those of holographic interferometry. The transducer was capable of measuring microscopic deformation and the corresponding anodic dissolution current of the surface of metal simultaneously. As a result, data on stress corrosion tests of a molybdenum electrode in 0.75 N KCI and a nickel electrode in 1 N H2SO4 were obtained.