STP1188

    Use of Electrochemical Noise in the Study of Inhibitor Systems: Part I—The Effect of Silicate Polymerization on the Inhibition of Aluminum

    Published: Jan 1993


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    Abstract

    Electrochemical noise appearing in corrosion potential (Ecorr)-time plots and electrochemical impedance (EI) spectra were used to study the synergism between nitrate and different silicates in the inhibition of aluminum. Individually, nitrate and some of the silicates did not protect aluminum; however, by combining them, the protection was greatly enhanced as deduced from the reduction of noise and the elevation of both Ecorr and polarization resistance (Rp). The SiO2 to Na2O ratio (R) had a significant influence on the reaction of a silicate with aluminum. This was attributed to the amphoterism of aluminum as well as the polymerization of the silicate.

    Unstable protective films are probably the cause of electrochemical noise. It then follows that the elimination or reduction of noise would indicate improvement in the protectiveness of a film. Thus, noise reduction in Ecorr-time plots and EI spectra complements the elevation of Ecorr and Rp as tools in the improvement of inhibitor interaction with metal surfaces.

    Keywords:

    electrochemical impedance spectroscopy (EIS), corrosion potential, electrochemical noise, silicate, nitrate, inhibitors, aluminum, polymerization


    Author Information:

    Hirozawa, ST
    Senior research associate and research chemist, BASF Corporation, Wyandotte, MI

    Turcotte, DE
    Senior research associate and research chemist, BASF Corporation, Wyandotte, MI


    Paper ID: STP18071S

    Committee/Subcommittee: G01.11

    DOI: 10.1520/STP18071S


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