Materials Performance Supplements

CORTEC 2019

Materials Performance is the world's most widely circulated magazine dedicated to corrosion prevention and control. MP provides information about the latest corrosion control technologies and practical applications for every industry and environment.

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Application of Vapor Phase Corrosion Inhibitors for Contaminated Environments FIGURE 7 EIS Bode plot of UNS G10180 steel in 1.0% VCI-A at different aqueous solutions. FIGURE 8 EIS Bode plot of UNS G10180 steel in 1.0% VCI-B at different aqueous solutions. desiccator at room temperature. The three different USDA bio-based inhibitors labeled VCI-A, VCI-B, and VCI-C were remixed with different dosages (0.5% or 1.0%) in order to find out the optimum proportional relation for effective protection. The salt solutions were prepared based on 1.0% NaCl or 3.5% NaCl solutions. The corrosion behavior of the low CS was investigated when exposed to three different corrosion inhibitors in salt solutions using electrochemical tech- niques, total immersion tests, and vapor- inhibiting ability (VIA) (NACE TM0208- 201811). El e ctro ch emi cal p o l ari zation standards per ASTM G61 12 (cyclic polariza- tion), polarization resistance and corrosion rate measurements, and electrochemical impedance spectroscopic (EIS) techniques were used to evaluate the behavior of these inhibitors on the different alloys in different chloride solutions. The corrosion behavior of low CS was investigated using EIS in dif ferent salt concentrations. Th e exp erim ents were conducted using commercially available systems for EIS and direct current corro- sion tests. Bode plots were created from the data obtained using the potentiostatic technique. By comparing the Bode plots, changes in the slopes of the curves were monitored as a means of establishing a trend in the R p value over time. To verify this analysis, the R p values were also esti- mated by using a curve fitting algorithm on the Nyquist and Bode plots. In these plots, the R p and RΩ combined values are displayed in the low frequency range of the Bode plot and the RΩ value can be seen in the high frequency range of the Bode plot. The diameter of the Nyquist plot is a measure of the R p value. During this inves- tigation, changes in the polarization resis- tance (R p ) of these alloys were monitored to ascertain the degree of effectiveness for these inhibitors to lower the corrosion rate. The NACE TM0208-2018 Standard Test Method was also used to evaluate the VIA of various forms of VCI. 11 This laboratory test method evaluates the VIA of various forms of VCI materials for temporary corrosion pro- tection of ferrous metal surfaces. The VIA corrosion test method represents standard conditions in a test jar of water-saturated warm air without the presence of acceler- ating contaminants. The combination of (1) vapor transport across a gap containing FIGURE 6 Corrosion rate measurement (based on LPR) of UNS G10180 steel in 1.0% VCI-C at different aqueous solutions. 9 CORTEC SUPPLEMENT TO MP MATERIALS PERFORMANCE JUNE 2019

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