Although porosity of metallic coatings presents a serious problem, few quantitative test methods have been developed. (For a summary, see Tödt1 ). Recently, Ciambrone2 described a comparative test to determine porosity of gold plates, where an anodic potential is applied to the test specimen and the charge (in μamp-hr) is measured corresponding to dissolution of the substrate through pores penetrating the coating. This allows comparison of porosity of different samples.
Permalloy plated memory wire consists of 1.27 × 10−2 cm diameter Cu-Be wire with 1 × 10−4 cm of Cu plate and a permalloy plating of 1 × 10−4 cm thickness. Because of its small dimensions, usual methods1 of porosity measurement are not applicable. Thus, such techniques as electrolyzing substrate ions onto a filter paper and developing “spots” with a suitable reagent cannot be considered. A quantitative electrochemical test for measuring porosity of...
