Accession Number : ADA260437
Title : A New Index for the Crevice Corrosion Resistance of Materials
Descriptive Note : Technical rept.
Corporate Author : PENNSYLVANIA STATE UNIV UNIVERSITY PARK DEPT OF MATERIALS SCIENCE AND ENGINEERING
Personal Author(s) : Xu, Yuan ; Pickering, Howard W
Report Date : Feb 1993
Pagination or Media Count : 21
Abstract : Recent studies have revealed the crucial role played by the macro corrosion cell (potential coupling between the inside and outside of a cavity) in crevice and pitting corrosion. It was found that acidification and the existence of chloride ions in the local cell are not the sole and necessary conditions for localized corrosion to occur, and that their accelerating effects on crevice corrosion and pit growth can be explained within the framework of the macro cell (the IR drop mechanism). Upon analysis of the results of the experiments, quantitative modeling, and the literature, a new characteristic parameter -- the critical distance into the crevice, d(sub c) -- has been suggested for indexing the crevice corrosion resistance of a material under specified conditions. The advantages of using d(sub c) as the index of the crevice corrosion resistance are as follows: (1) it may be obtained through experiment and may also be estimated through computational approaches; (2) it has a distinct and straightforward physical meaning; (3) it may be employed in engineering design; and (4) it is a single parameter that can reflect the integrated influence of several factors known to affect the crevice corrosion resistance of a material from past practical experience and research work. Preliminary work has shown good agreement between the measured and the computed values of d(sub c). The experimental technique and the principle of the mathematical approach to obtain d(sub c) are described.
Descriptors : *METALS , *MEASUREMENT , *CORROSION , *CORROSION RESISTANCE , *INDEXES , *DEPTH , MATHEMATICAL MODELS , PREDICTIONS , ACCELERATED TESTING , ANODIC POLARIZATION , CHLORIDES , ELECTRODES , CAVITIES , ELECTROCHEMISTRY , QUANTITATIVE ANALYSIS , COUPLING(INTERACTION) , IONS
Subject Categories : Physical Chemistry
Properties of Metals and Alloys
Electricity and Magnetism
Distribution Statement : APPROVED FOR PUBLIC RELEASE