ASTM G5-94

Standard Reference Test Method for Making Potentiostatic and Potentiodynamic Anodic Polarization Measurements

General Information

• Status: Historical
• Publication Date: 31-Dec-1993
• Technical Committee: G01 - Corrosion of Metals
• Drafting Committee: G01.11 - Electrochemical Measurements in Corrosion Testing

Standards Content (Sample)

AMERICAN SOCIETY FOR TESTING AND MATERIALS
SUPERSEDED
1916 Race SI. Philadelphia, Pa 19103
~ ~l~ Designation: G 5 - 94
Reprinted from the Annual Book of ASTM Standards. Copyright ASTM
If not listed in the current combined index, will appear in the next ed~ion.
Standard Reference Test Method for
Making Potentiostatic and Potentiodynamic Anodic
1
Polarization Measurements
Thi~ standard is issued under the fixed designation G 5: the number immediately following the designation indicates the year of
ongmal adoptIon or, m the case of revision. the year of last revision. A number in parentheses indicates the year of last reapproval. A
supe~npt epsilon (.) indicates an editorial change since the last revision or reapproval.
1. Scope 3.4 This test method may not be appropriate for polariza­
tion testing of all materials or in all environments.
1.1 This test method describes an experimental procedure
3.5 This test method is intended for use in evaluating the
for checking experimental technique and instrumentation.
accuracy of a given electrochemical test apparatus, not for
If followed, this test method will provide repeatable
use in evaluating materials performance. Therefore, the use
potentiostatic and potentiodynamic anodic polarization
of the plots in Figs. 4 and 5 or Appendix X2 is not
measurements that will reproduce data determined by others
recommended to evaluate alloys other than Type 430, or lots
at other times and in other laboratories provided all labora­
of Type 430 other than those available through ASTM. The
tories are testing reference samples from the same lot of Type
use of the data in this test method in this manner is beyond
430 stainless steel.
the scope and intended use of this test method. Users of this
1.2 Values stated in SI units are to be regarded as the
test method are advised to evaluate test results relative to the
standard. Inch-pound units given in parentheses are for
scatter bands corresponding to the particular lot of Type 430
information only.
stainless steel that was tested.
1.3 This standard does not purport to address all of the
safety concerns. if any, associated with its use. It is the
4. Apparatus
responsibility of the user of this standard to establish appro­
4.1 The test cell should be constructed to allow the
priate safety and health practices and determine the applica­
following items to be inserted into the solution chamber: the
bility of regulatory limitations prior to use.
test electrode, two auxiliary electrodes, a Luggin capillary
with salt-bridge connection to the reference electrode, inlet
2. Referenced Document
and outlet for an inert gas, and a thermometer. The test cell
2.1 ASTU Standard:
shall be constructed of materials that will not corrode
G 3 Practice for Conventions Applicable to Electrochem­
deteriorate, or otherwise contaminate the test solution. '
2
ical Measurements in Corrosion Testing
NOTE I-Borosilicate glass and TFE-fluorocarbon have been found
suitable.
3. Significance and Use
4.1.1 A suitable cell is shown in Fig. 1 (1).4 A 1-L, round­
3.1 The availability of a standard procedure, standard
bottom flask has been modified by the addition of various
material, and a standard plot should make it easy for an
necks to permit the introduction of electrodes, gas inlet and
investigator to check his techniques. This should lead to
o~tlet tubes, and a thermometer. The Luggin probe-salt
polarization curves in the literature which can be compared
bndge separates the bulk solution from the saturated calomel
with confidence.
refer~nce. e~ectrode, and. th~ probe tip can be easily adjusted
3.2 Samples of a standard ferritic Type 430 stainless steel
to bnng It In close proximity with the working electrode.
(UNS S43000) used in obtaining standard reference plot are
4.2 Potentiostat (Note 2):
available for those who wish to check their own test
. 4.2 . 1 ~ potentiostat that will maintain an electrode poten­
3
procedure and equipment.
tial ~lthIn 1 m V of a preset value over a wide range of
3.3 Standard potentiostatic and potentiodynamic polar­
apphed currents should be used. For the type and size of
ization plots are supplied with the purchase of the reference
standard specimen supplied, the potentiostat should have a
material. These reference data are based on the results from
potential range from -0.6 to 1.6 V and an anodic current
different laboratories that followed the standard procedure,
5
output range from 1.0 to 10 IlA.
using that material in 1.0 N H S0 , Maximum and min­
2 4
4.3 Potential-Measuring Instruments (Note 2):
imum current values are shown at each potential to indicate
. 4.3 . 1 The potential-measuring circuit should have a high
the acceptable range of values.
14
Input Impedance on the order ono" to 10 n to minimize
current drawn from the system during measurements. Such
circuits are provided with most potentiostats. Instruments
I This test method is under the
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