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ASTM Selected Technical Papers
The Measurement and Correction of Electrolyte Resistance in Electrochemical Tests
By
R Taylor
R Taylor
1
University of Virginia
, Department of Materials Science, Thornton Hall,
Charlottesville, VA 22903
;
symposium chairman and editor
.
Search for other works by this author on:
L Scribner
L Scribner
2
University of Virginia
, Department of Materials Science, Thornton Hall,
Charlottesville, VA 22903
;
symposium chairman and editor
.
Search for other works by this author on:
ISBN-10:
0-8031-1283-1
ISBN:
978-0-8031-1283-4
No. of Pages:
231
Publisher:
ASTM International
Publication date:
1990

A numerical method is presented for adjusting experimental current-potential curves for the ohmic resistance corresponding to a secondary current distribution on a (rotating) disk electrode. The nonuniform current and potential distributions on the disk electrode cause the electrolyte resistance itself to be a function of measured current. The method described here is employed after the experiments are conducted and yields the Tafel slope as well as adjusted values for current density and surface overpotential that apply to the center of the disk. This facilitates the comparison of the experimental data to those obtained using mathematical models of the rotating disk electrode that, in the secondary current regime, apply strictly only to the center of the electrode. The Tafel slopes obtained agree to within 3 mV/decade with standard techniques for ohmic correction such as current interruption because, at the high current densities where the ohmic correction is most significant, the resistance correction approaches the primary resistance obtained by current interruption. The Tafel slope values for the two methods differ most for solutions of low conductivity. The major advantages of the ohmic correction method described here are that the experimental condition is never perturbed and that the method indicates the extent to which the current distribution is nonuniform.

1.
Lowry
,
M. M.
, “
Corrosion of Iron in Acidic Chloride Solutions
,” M.S. Thesis,
University of Virginia
,
1988
.
2.
Lowry
,
M. M.
,
Joyce
,
L. A.
,
Moghissi
,
O. C.
,
Diem
,
C. B.
, and
Orazem
,
M. E.
, “
Corrosion of Iron in Acidic Chloride Solutions
,” in preparation,
1988
.
3.
Newman
,
J.
, “
Resistance for Flow of Current to a Disk
,”
Journal of the Electrochemical Society
 0013-4651, Vol.
113
, pp. 501–502.
4.
Newman
,
J.
, “
Current Distribution on a Rotating Disk Below the Limiting Current
,”
Journal of the Electrochemical Society
 0013-4651, Vol.
113
, pp. 1235–1241.
5.
Newman
,
J.
,
Electrochemical Systems
,
Prentice-Hall, Inc.
,
NJ
,
1973
.
6.
Wagner
,
C.
and
Traud
,
W.
,
Z. Electrochem.
, Vol.
44
, p. 391.
7.
Stern
,
M.
and
Geary
,
A. L.
, “
Electrochemical Polarization: I. A Theoretical Analysis of the Shape of Polarization Curves
,”
Journal of the Electrochemical Society
 0013-4651, Vol.
104
, pp. 56–63.
8.
Mansfeld
,
F.
and
Oldham
,
K. B.
, “
A Modification of the Stern-Geary Linear Polarization Equation
,”
Corrosion Science
 0010-938X, Vol.
11
, pp. 787–796.
9.
Mansfeld
,
F.
, “
Simultaneous Determination of Instantaneous Corrosion Rates and Tafel Slopes from Polarization Resistance Measurements
,”
Journal of the Electrochemical Society
 0013-4651, Vol.
120
, pp. 515–518.
10.
Mansfeld
,
F.
, “
Tafel Slopes and Corrosion Rates from Polarization Resistance Measurements
,”
Corrosion
, Vol.
29
, pp. 397–402.
11.
Mansfeld
,
F.
, “
Some Errors in Linear Polarization Measurements and Their Correction
,”
Corrosion
, Vol.
30
, pp. 92–96.
12.
Gershakove
,
S. M.
,
Udey
,
L. R.
, and
Mansfeld
,
F.
, “
An Improved Method for Analysis of Polarization Resistance Data
,”
Corrosion
, Vol.
37
, pp. 696–700.
13.
Barnartt
,
S.
, “
Two-point and Three-point Methods for the Investigation of Electrode Reaction Mechanisms
,”
Electrochimica Acta
 0013-4686, Vol.
15
, pp. 1313–1324.
14.
Barnartt
,
S.
, “
Tafel Slopes for Iron Corrosion in Acidic Solutions
,”
Corrosion
, Vol.
27
, pp. 467–470.
15.
McLaughlin
,
B. D.
, “
A New Approach for Determining Corrosion Currents and Tafel Slopes
,”
Corrosion
, Vol.
37
, pp. 723–726.
16.
Newman
,
J.
, “
Ohmic Potential Measured by Interrupter Techniques
,”
Journal of the Electrochemical Society
 0013-4651, Vol.
117
, pp. 507–508.
17.
Nisancioglu
,
K.
, “
The Error in Polarization Resistance and Capacitance Measurements Resulting from Nonuniform Ohmic Potential Drop to Flush-Mounted Probes
,”
Corrosion
, Vol.
43
, pp. 258–265.
18.
Asakura
,
S.
and
Nobe
,
K.
, “
Electrodissolution Kinetics of Iron in Chloride Solutions. Part I. Neutral Solutions
,”
Journal of the Electrochemical Society
 0013-4651, Vol.
118
, pp. 13–18.
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