Non-Invasive Techniques to Study Local Passivity Breakdown of Metal Alloys in Aqueous Media

65519 The corrosion of metal alloys used in energy production and conservation limits the lifetime of components made from these materials. The metal surfaces are protected by passive oxide layers, yet basic questions about how these layers break down and initiate corrosion are not answered. This project will develop a non-invasive, video microscopy technique to assay the initiation and subsequent dynamics of localized corrosion on metal surfaces. Phase I developed a system to control a video microscope, image capture board, and a proprietary in-house video analysis software program to create a visual assay of a corroding metal surface in an aqueous solution. Areas of change less than 8 microns in diameter were clearly seen on an aluminum sample surface within 6 seconds of immersion in a corrosive solution (with 10x magnification). Phase II will improve the video assay and merge it with scanning probe techniques and standard electrochemical techniques within a single platform. This system will provide four simultaneous non-invasive methods to monitor localized corrosion on metal surfaces in corrosive solutions. All techniques will have three-dimensional capability. Commercial Applications and Other Benefits as described by the awardee: This non-invasive assay combining different techniques should be used in corrosion laboratories to study basic mechanisms of passivity breakdown and thereby improve metal alloys and corrosion protection. The video assay also should have application to the analysis of other phenomena for studying the kinetics of localized changes (e.g. growth of bio-films).