9 December 1999 Advances in chemical sensing for occluded environments
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High concentrations of H+ and other chemical species can enhance the growth rate of sub-critical cracks in metals subjected to corrosive environments. High concentrations of H+ are thought to be the result of both metallic dissolution and bulk transport. The rate of mass transport of chemical constituents into the crack tip is proposed to be largely a function of the surface geometry of the crack. For this study, a fiber optic chemical sensor (FOCS) is developed to investigate the influence of crack size and crack surface roughness on the transport rate of hydrogen in an occluded environment. The FOCS combines pH sensitive fluoresceinamine attached by photopolymerization to the distal tip of a single optical fiber to non-invasively monitor pH in the occluded cell. This sensor geometry provides the benefit of real-time pH measurement at specific points in the crack tip environment. Chemically inert crack specimens have been used in order to investigate crack surface geometry affects without the added complexities of metallic dissolution. Varying crack sizes and roughnesses are considered and preliminary results for model geometries are presented.
© (1999) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Paul D. Peterson, Paul D. Peterson, Anthony P. Reynolds, Anthony P. Reynolds, Michael A. Sutton, Michael A. Sutton, } "Advances in chemical sensing for occluded environments", Proc. SPIE 3860, Fiber Optic Sensor Technology and Applications, (9 December 1999); doi: 10.1117/12.372988; https://doi.org/10.1117/12.372988


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