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Electrode Mounting for Potentiostatic Anodic Polarization Studies
[Technical Report, Technical Paper]
RENSSELAER POLYTECHNIC INST TROY NY
Pagination or Media Count:
Samples of an arc melted, 10Cr- 10Ni- Fe alloy were mounted with the Stern-Makrides compression gasket assembly. Some electrodes were mounted directly, others were partially encased or coated with various resins prior to mounting. Potentiostatic anodic polarization measurements were performed in hydrogensaturated, normal sulfuric acid at 25C, using an identical potential step technique for each specimen. Polarization behavior in the active region is unaffected by mounting material. However, all resins except heat-cured epoxy and alkyd types, markedly increase apparent passive current density. This is due to the presence of fine crevices at the electrode-resin interfaces. Although the area within crevices may be small, current density is high, and the effect on measured passive currents is pronounced. The results indicate that crevices in, or adjacent to, electrodes must be avoided during potentiostatic anodic polarization measurements. Specimens should be mounted with the Stern-Makrides compression gasket, in heat-cured epoxy resin, in alkyd varnish or other methods which ensure freedom from microscopic crevices. Extracted
[A, Approved For Public Release]