ASTM F2129-04

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Designation:F2129–04
Standard Test Method for
Conducting Cyclic Potentiodynamic Polarization
Measurements to Determine the Corrosion Susceptibility of
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Small Implant Devices
This standard is issued under the fixed designation F 2129; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
1. Scope G 3 PracticeforConventionsApplicabletoElectrochemical
Measurements in Corrosion Testing
1.1 This test method assesses the corrosion susceptibility of
G 5 Reference Test Method for Making Potentiostatic and
small, metallic, implant medical devices, or components
Potentiodynamic Anodic Polarization Measurements
thereof, using cyclic (forward and reverse) potentiodynamic
G 15 Terminology Relating to Corrosion and Corrosion
polarization. Examples of device types that may be evaluated
Testing
by this test method include, but are not limited to, vascular
G 61 Test Method for Conducting Cyclic Potentiodynamic
stents, filters, support segments of endovascular grafts, cardiac
Polarization Measurements for Localized Corrosion Sus-
occluders, aneurysm or ligation clips, staples, and so forth.
ceptibility of Iron-, Nickel-, or Cobalt-Based Alloys
1.2 This test method is used to assess a device in its final
G 102 Practice for Calculation of Corrosion Rates and
form and finish, as it would be implanted. These small devices
Related Information from Electrochemical Measurements
shouldbetestedintheirentirety.Theupperlimitondevicesize
is dictated by the electrical current delivery capability of the
3. Terminology
test apparatus (see Section 6). It is assumed that test methods,
3.1 Definitions:
suchasReferenceTestMethodG 5andTestMethodG 61have
3.1.1 potentiostat,n—aninstrumentforautomaticallymain-
been used for material screening.
taining an electrode in an electrolyte at a constant potential or
1.3 Because of the variety of configurations and sizes of
controlled potentials with respect to a suitable reference
implants, this test method provides a variety of specimen
electrode (see Terminology G 15).
holder configurations.
3.1.2 potentiodynamic cyclic polarization (forward and re-
1.4 This test method is intended for use on implantable
verse polarization), n—a technique in which the potential of
devices made from metals with a relatively high resistance to
the test specimen is controlled and the corrosion current
corrosion.
measured by a potentiostat. The potential is scanned in the
1.5 This standard does not purport to address all of the
positiveornoble(forward)directionasdefinedinPracticeG 3.
safety concerns, if any, associated with its use. It is the
The potential scan is continued until a predetermined potential
responsibility of the user of this standard to establish appro-
or current density is reached.Typically, the scan is run until the
priate safety and health practices and determine the applica-
transpassive region is reached, and the specimen no longer
bility of regulatory limitations prior to use.
demonstrates passivity, as defined in Practice G 3. The poten-
2. Referenced Documents tial scan direction then is reversed until the specimen repassi-
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vates or the potential reaches a preset value.
2.1 ASTM Standards:
3.1.3 scan rate, n—the rate at which the controlling voltage
D 1193 Specification for Reagent Water
is changed.
F 1828 Specification for Ureteral Stents
3.2 Symbols:
3.2.1 E = Breakdown or Critical Pitting Potential—the
b
least noble potential at which pitting or crevice corrosion or
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This test method is under the jurisdiction ofASTM Committee F04 on Medical
both will initiate and propagate as defined in Terminology
and Surgical Materials and Devices and is the direct responsibility of Subcommittee
G 15. An increase in the resistance to pitting corrosion is
F04.15 on Material Test Methods.
associated with an increase in E .
Current edition approved May 1, 2004. Published May 2004. Originally
b
approved in 2001. Last previous edition approved in 2003 as F 2129 – 03.
3.2.2 E = Rest Potential—the potential of the working
r
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
electrode relative to the reference electrode measured under
contactASTM Customer Service at service@astm.org. ForAnnual Book ofASTM
virtual open-circuit conditions (working electrode is not polar-
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. ized).
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F2129–04
3.2.3 E = Zero Current Potential—the potential a
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