ASTM G106-89(2004)

Standard Practice for Verification of Algorithm and Equipment for Electrochemical Impedance Measurements

SIGNIFICANCE AND USE
The availability of a standard procedure, standard material, and standard plots should allow the investigator to check his laboratory technique. This practice should lead to electrochemical impedance curves in the literature which can be compared easily and with confidence.
Samples of a standard ferritic type 430 stainless steel (UNS 430000) used to obtain the reference plots are available for those who wish to check their equipment. Suitable resistors and capacitors can be obtained from electronics supply houses.
This test method may not be appropriate for electrochemical impedance measurements of all materials or in all environments.
SCOPE
1.1 This practice covers an experimental procedure which can be used to check one's instrumentation and technique for collecting and presenting electrochemical impedance data. If followed, this practice provides a standard material, electrolyte, and procedure for collecting electrochemical impedance data at the open circuit or corrosion potential that should reproduce data determined by others at different times and in different laboratories. This practice may not be appropriate for collecting impedance information for all materials or in all environments.
1.2 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

General Information

• Status: Historical
• Publication Date: 31-Oct-2004
• ICS: 71.040.40 - Chemical analysis
• Technical Committee: G01 - Corrosion of Metals
• Drafting Committee: G01.11 - Electrochemical Measurements in Corrosion Testing

Relations

• Replaces: ASTM G106-89(1999) - Standard Practice for Verification of Algorithm and Equipment for Electrochemical Impedance Measurements
• Effective Date: 01-Nov-2004
• Replaced By: ASTM G106-89(2010) - Standard Practice for Verification of Algorithm and Equipment for Electrochemical Impedance Measurements
• Effective Date: 01-May-2010
• Referred By: ASTM G208-12(2020) - Standard Practice for Evaluating and Qualifying Oilfield and Refinery Corrosion Inhibitors Using Jet Impingement Apparatus
• Effective Date: 01-Nov-2004
• Referred By: ASTM G199-09(2020)e1 - Standard Guide for Electrochemical Noise Measurement
• Effective Date: 01-Nov-2004
• Referred By: ASTM G135-95(2019) - Standard Guide for Computerized Exchange of Corrosion Data for Metals (Withdrawn 2023)
• Effective Date: 01-Nov-2004
• Referred By: ASTM D8370-22 - Standard Test Method for Field Measurement of Electrochemical Impedance on Coatings and Linings
• Effective Date: 01-Nov-2004
• Referred By: ASTM G170-06(2020)e1 - Standard Guide for Evaluating and Qualifying Oilfield and Refinery Corrosion Inhibitors in the Laboratory
• Effective Date: 01-Nov-2004
• Referred By: ASTM D6577-15(2019) - Standard Guide for Testing Industrial Protective Coatings
• Effective Date: 01-Nov-2004
• Referred By: ASTM G215-17 - Standard Guide for Electrode Potential Measurement
• Effective Date: 01-Nov-2004
• Referred By: ASTM G185-06(2020)e1 - Standard Practice for Evaluating and Qualifying Oil Field and Refinery Corrosion Inhibitors Using the Rotating Cylinder Electrode
• Effective Date: 01-Nov-2004
• Referred By: ASTM F3268-18a - Standard Guide for <emph type="bdit">in vitro</emph> Degradation Testing of Absorbable Metals
• Effective Date: 01-Nov-2004
• Referred By: ASTM G111-21a - Standard Guide for Corrosion Tests in High Temperature or High Pressure Environment, or Both
• Effective Date: 01-Nov-2004

Standards Content (Sample)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information.
Designation: G106 – 89 (Reapproved 2004)
Standard Practice for
Verification of Algorithm and Equipment for Electrochemical
Impedance Measurements
This standard is issued under the fixed designation G106; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope
−2
C = capacitance (farad-cm )
1.1 This practice covers an experimental procedure which
E8 = real component of voltage (volts)
can be used to check one’s instrumentation and technique for
E9 = imaginary component of voltage (volts)
collecting and presenting electrochemical impedance data. If
E = complex voltage (volts)
followed, this practice provides a standard material, electro-
−1
f = frequency (s )
lyte, and procedure for collecting electrochemical impedance
−2
I8 = real component of current (amp-cm )
data at the open circuit or corrosion potential that should
−2
I9 = imaginary component of current (amp-cm )
reproduce data determined by others at different times and in
−2
I = complex current (amp-cm )
different laboratories. This practice may not be appropriate for
j = 21
=
collecting impedance information for all materials or in all
L = inductance (henry−cm )
environments.
R = solution resistance (ohm-cm )
s
1.2 This standard does not purport to address all of the
R = polarization resistance (ohm-cm )
p
safety concerns, if any, associated with its use. It is the R = charge transfer resistance (ohm-cm )
t
responsibility of the user of this standard to establish appro- Z8 = real component of impedance (ohm-cm )
Z9 = imaginary component of impedance (ohm-cm )
priate safety and health practices and determine the applica-
Z = complex impedance (ohm-cm )
bility of regulatory limitations prior to use.
a = phenomenological coefficients caused by depression
2. Referenced Documents
of the Nyquist plot below the real axis, a is the
exponent and t is the time constant(s).
2.1 ASTM Standards:
u = phase angle (deg)
D1193 Specification for Reagent Water
−1
v = frequency (radians-s )
G3 Practice for ConventionsApplicable to Electrochemical
Measurements in Corrosion Testing
Subscripts:
G5 Reference Test Method for Making Potentiostatic and
x = in-phase component
Potentiodynamic Anodic Polarization Measurements
y = out-of-phase component
G15 Terminology Relating to Corrosion and Corrosion
Testing
4. Summary of Practice
G59 Test Method for Conducting Potentiodynamic Polar-
4.1 Reference impedance plots in both Nyquist and Bode
ization Resistance Measurements
formatareincluded.Thesereferenceplotsarederivedfromthe
results from nine different laboratories that used a standard
3. Terminology
dummy cell and followed the standard procedure using a
3.1 Definitions—For definitions of corrosion related terms, 3
specific ferritic type alloy UNS-S43000 in 0.005 M H SO
2 4
see Terminology G15.
and 0.495 M Na SO . The plots for the reference material are
2 4
3.2 Symbols:
presentedasanenvelopethatsurroundsallofthedatawithand
without inclusion of the uncompensated resistance. Plots for
one data set from one laboratory are presented as well. Since
the results from the dummy cell are independent of laboratory,
This practice is under the jurisdiction ofASTM Committee G01 on Corrosion
ofMetalsandisthedirectresponsibilityofSubcommitteeG01.11onElectrochemi-
only one set of results is presented.
cal Measurements in Corrosion Testing.
4.2 A discussion of the electrochemical impedance tech-
Current edition approved Nov 1, 2004. Published November 2004. Originally
nique, the physics that underlies it, and some methods of
approved in 1989. Last previous edition approved in 1999 as G106–89 (1999).
DOI: 10.1520/G0106-89R04.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM ThesestandardsamplesareavailablefromASTMHeadquarters.Generally,one
Standards volume information, refer to the standard’s Document Summary page on sample can be repolished and reused for many runs. This procedure is suggested to
the ASTM website. conserve the available material.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
G106 – 89 (2004)
interpreting the data are given in the Appendix X1-Appendix adjusted to bring it into close proximity to the working
X6. These sections are included to aid the individual in electrode. The minimum distance should be no less than two
understanding the electrochemical impedance technique and capillary diameters from the working electrode.
some of its capabilities. The information is not intended to be 6.3 Electrode Holder—The auxillary and working elec-
all inclusive. trodes can be mounted in the manner shown in Reference Test
Method G5. Precautions described in Reference Test Method
5. Significance and Use
G5 about assembly should be followed.
5.1 The availability of a standard procedure, standard ma- 6.4 Potentiostat—The potentiostat must be of the kind that
allows for the application of a potential sweep as described in
terial,andstandardplotsshouldallowtheinvestigatortocheck
his laboratory technique. This practice should lead to electro- Reference Test Method G5 and Reference Practice G59. The
potentiostat must have outputs in the form of voltage versus
chemical impedance curves in the literature which can be
compared easily and with confidence. ground for both potential and current. The potentiostat must
havesufficientbandwidthforminimalphaseshiftuptoatleast
5.2 Samples of a standard ferritic type 430 stainless steel
(UNS 430000) used to obtain the reference plots are available 1000Hzandpreferablyto10000Hz.Thepotentiostatmustbe
capable of accepting an external excitation signal. Many
forthosewhowishtochecktheirequipment.Suitableresistors
commercial potentiostats meet the specification requirements
andcapacitorscanbeobtainedfromelectronicssupplyhouses.
for these types of measurements.
5.3 This test method may not be appropriate for electro-
6.5 Collection and Analysis of Current-Voltage Response—
chemical impedance measurements of all materials or in all
environments. The potential and current measuring circuits must have the
characteristics described in Reference Test Method G5 along
6. Apparatus
with sufficient band-width as described above. The impedance
can be calculated in several ways, for example, by means of a
6.1 Dummy Cell—The dummy cell used to check the
transferfunctionanalyzer,Lissajousfiguresonanoscilloscope,
equipment and method for generating electrochemical imped-
ortransientanalysisofawhitenoiseinputusingaFastFourier
ance data is composed of a 10 V precision resistor placed in
Transform algorithm. Other methods of analysis exist.
series with a circuit element composed of a 100 V precision
6.6 Electrodes:
resistorinparallelwitha100µFcapacitor.Theresistorsshould
6.6.1 Working electrode preparation should follow Refer-
have a stated precision of 60.1%. The capacitor can have a
ence Test Method G5, which involves drilling and tapping the
precision of 620%. The cell can be constructed from readily
specimen and mounting it on the electrode holder.
available circuit elements by following the circuit diagram
6.6.2 Auxillary electrode preparation should follow Refer-
shown in Fig. 1.
ence Test Method G5. The auxillary electrode arrangement
6.2 Test Cell—The test cell should be constructed to allow
should be symmetrical around the working electrode.
the following items to be inserted into the solution chamber:
6.6.3 Reference electrode type and usage should follow
the test electrode, two counter electrodes or a symmetrically
Reference Test Method G5. The reference electrode is to be a
arranged counter electrode around the working electrode, a
saturated calomel electrode.
Luggin-Haber capillary with salt bridge connection to the
reference electrode, an inlet and an outlet for an inert gas, and
7. Experimental Procedure
a thermometer or thermocouple holder. The test cell must be
constructed of materials that will not corrode, deteriorate, or 7.1 Test of Algorithm and Electronic Equipment (Dummy
otherwise contaminate the solution. Cell):
6.2.1 OnetypeofsuitablecellisdescribedinReferenceTest 7.1.1 Measuretheimpedanceofadummycellconsistingof
Method G5. Cells are not limited to that design. For example, a10 V resistor in series with a parallel combination of a 100
a 1-L round-bottom flask can be modified for the addition of Vresistoranda100µFcapacitor.Thecircuitdiagramisshown
variousneckstopermittheintroductionofelectrodes,gasinlet in Fig. 1.
and outlet tubes, and the thermometer holder.ALuggin-Haber 7.1.2 Typicalconnectionsfromthepotentiostatareshownin
capillaryprobecouldbeusedtoseparatethebulksolutionfrom Fig. 1. Connect the auxillary electrode and reference electrode
the saturated calomel electrode. The capillary tip can be easily leads to the series resistor side of the circuit. Connect the
FIG. 1 Circuit Diagram for Dummy Cell Showing Positions for Hook-Up to Potentiostat
G106 – 89 (2004)
working electrode lead to the opposite side of the circuit
beyond the resistor-capacitor parallel combination.
7.1.3 Set the potential at 0.0V. Collect the electrochemical
impedance data between 10 000 Hz (10 kHz) and 0.1 Hz (100
mHz) at 8 to 10 steps per frequency decade. The amplitude
mustbethesameasthatusedtochecktheelectrochemicalcell,
10 mv. The resulting frequency response when plotted in
Nyquist format (the negative of the imaginary impedance
versustherealimpedance)mustagreewiththatshowninFigs.
2-4. Testing with the electrochemical cell should not be
attempteduntilthatagreementisestablished.Resultsusingthe
dummy circuit were found to be independent of laboratory.
7.2 Test of Electrochemical Cell:
7.2.1 Test specimens of the reference material should be
prepared following the procedure described in Reference Test
Method G5. This procedure involves polishing the specimen
with wet SiC paper with a final wet polish using 600 grit SiC
paper prior to the experiment. There should be a maximum
delay of 1 h between final polishing and immersion in the test
solution.
7.2.2 Prepare a 0.495 M Na SO solution containing 0.005
2 4
FIG. 3 Bode Plot, Impedance Magnitude Versus Frequency, of
MH SO from reagent grade sulfuric acid and sodium sulfate
2 4
Electrochemical Impedance Response for Dummy Cell
and Type IV reagent water described in Specification D1193.
The test is to be carried out at 30 6 1°C.
7.2.3 At least 1 h before specimen immersion, start purging
the solution with oxygen-free argon, hydrogen, or nitrogen gas
ataflowrateofabout100to150cm /min.Continuethepurge
throughout the test.
7.2.4 Transfer the specimen to the test cell. Adjust the
Luggin-Haber probe tip so that it is no less than two capillary
diameters from the sample. However, since this distance will
affect the uncompensated solution resistance, the greater the
distance, the larger the resistance. Therefore, close placement
is important.
FIG. 4 Bode Plot, Phase Angle Versus Frequency, of
Electrochemical Impedance Response for Dummy Cell
7.2.5 Connect the potentiostat leads to the appropriate
electrodes, for example, working electrode lead to working
electrode, counter electrode lead to counter electrode, and
reference electrode lead to reference electrode. Hook-up in-
structions provided with the potentiostat must be followed.
7.2.6 Recordtheopencircuitpotential,thatis,thecorrosion
potential, for 1 h.The potential should be about−645 mv 610
mv relative to the saturated calomel electrode. If the potential
is more positive than−600 mv (SCE) then the specimen may
have passivated. If so, remove the specimen and repolish with
FIG. 2 Nyquist Plot of Electrochemical Impedance Response for
Dummy Cell 600 grit wet silicon carbide paper. Then reimmerse the sample
G106 – 89 (2004)
and monitor the corrosion potential for 1 h. If the potential
again becomes more positive than−600 mv (SCE) check for
oxygen contamination of the solution.
7.2.7 Recordthefrequencyresponsebetween10000Hz(10
kHz)and0.1Hz(100mHz)atthecorrosionpotentialrecorded
after1hof exposure using 8 to 10 steps per frequency decade.
The amplitude must be the same as that used in 6.1.3, 10 mv.
7.2.8 Plot the frequency response in both Nyquist format
(real response versus the negative of the imaginary response)
and Bode format (impedance modulus and phase angle versus
frequency). Frequency can be reported in units of radians/
second or hertz (cycles/s).
7.2.9 Therewasnoattempttoestimatecircuitanaloguesfor
the electrochemical impedance curves since there is no univer-
sally recognized, standard method for making such estimates.
8. Standard Reference Results and Plots
8.1 Dummy Cell:
8.1.1 The results from nine different laboratories were
FIG. 6 Bode Plot, Impedance Magnitude Versus Frequency, for
virtually identical and overlayed each other almost perfectly.
UNS-S43000 From One Laboratory
TypicalplotsoftherawdataareshowninFigs.2-4.Noattempt
has been made to estimate the variance and standard deviation
of the results from the nine laboratories. The measured values
of R,R , and the frequency at which the phase angle is a
s p
maximum must agree with these curves within the specifica-
tions of the instrumentation, resistors, and capacitors before
testing of the electrochemical cell commences. See 9.1.1.
8.2 Electrochemical Cell:
8.2.1 Standard electrochemical impedance plots in both
NyquistformatandBodeformatareshowninFigs.5-7.These
are actual results from one laboratory. Figs. 8-10 show plots in
bothNyquistandBodeformatswhichenvelopalloftheresults
from the nine laboratories. The solution resistance from each
laboratory was not subtracted out prior to making this plot.
8.2.2 The average solution resistance from the nine labora-
2 2
tories in 3.3 V-cm 6 1.8 V-cm (one standard deviation).The
solution resistance of the user’s test cell as measured by the
high frequency intercept on the Nyquist plot must lie in this
FIG. 7 Bode Plot, Phase Angle Versus Frequency, for UNS-
S43000 From One Laboratory
range to use agreement with Figs. 8-10 for verification of the
electrochemical test cell. If the uncompensated resistance lies
outside of this range, it should be subtracted from the results
(see 7.2.4).Then, results from the electrochemical test cell can
be compared with the results in Figs. 11-13 to verify the test
cell. Figs. 11-13 envelop all of the results from the nine
laboratories with the uncompensated resistance subtracted out.
9. Precisio
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