In the present investigation, an optical corrosion-meter has been developed for materials testing and evaluation of different corrosion phenomena. The idea of the optical corrosion-meter was established based on principles of 3D- holographic interferometry for measuring microsurface dissolution, i.e. mass loss, and on those of electrochemistry for measuring the bulk electronic current, i.e. corrosion current of metallic samples in aqueous solutions. In the present work, an early stage of pitting corrosion of a pure copper and an aluminium-brass alloy in tap water was monitored in situ by the optical corrosion- meter during the cyclic polarization test. The observations of pitting were basically interferometric perturbations detected only on the surface of the pure copper in tap water. The interferometric perturbations interpreted as a localized corrosion in a form of an early pittings, of a depth ranged between 0.3 mm to several micrometers. Consequently, results of the present work indicate that holographic interferometry is very useful technique as a 3D- interferometric microscope for monitoring pittings at the initiation stage of the phenomenon for different metallic samples in aqueous solutions.

Date Published: 21 November 1997
PDF: 8 pages
Proc. SPIE 3172, Optical Technology in Fluid, Thermal, and Combustion Flow III, (21 November 1997); doi: 10.1117/12.279738

Published in SPIE Proceedings Vol. 3172:
Optical Technology in Fluid, Thermal, and Combustion Flow III
Soyoung Stephen Cha; James D. Trolinger; Masaaki Kawahashi, Editor(s)