Composition of Copper Tarnish Products Formed in Moist Air with Trace Levels of Pollutant Gas: Hydrogen Sulfide and Sulfur Dioxide/Hydrogen Sulfide

    1. J. H. Payer1
    1. 1 Department of Materials Science and Engineering, The Case School of Engineering, Case Western Reserve University, Cleveland, Ohio 44106, USA

    Abstract

    The objective of the work reported here was to characterize the tarnish products formed on copper during the early stages of exposure to moist air with trace levels of pollutant gas, in particular hydrogen sulfide and sulfur dioxide/hydrogen sulfide. As determined by x‐ray photoelectron spectroscopy and coulometric reduction (chronopotentiometry), the exposure of copper to 50 ppb hydrogen sulfide at 23°C and 70% relative humidity was found to produce a tarnish layer consisting of Formula and Formula . Addition of 75 ppb sulfur dioxide to a 50 ppb hydrogen sulfide, moist air environment at 23°C and 70% relative humidity encouraged the growth of a thicker tarnish product layer, with proportionally more Formula in the Formula structure.

    Key Words
    • Manuscript received October 28, 1994.
    • Revised manuscript received May 31, 1995.
    • Available electronically November 1, 1995.
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