ASTM F2129-01

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Designation: F 2129 – 01
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 61 Test Method for Conducting Cyclic Potentiodynamic
Polarization Measurements for Localized Corrosion Sus-
1.1 This test method assesses the corrosion susceptibility of
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ceptibility of Iron-, Nickel-, or Cobalt-Based Alloys
small, metallic, implant medical devices, or components
G 102 Practice for Calculation of Corrosion Rates and
thereof, using cyclic (forward and reverse) potentiodynamic
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Related Information from Electrochemical Measurements
polarization. Examples of device types, which may be evalu-
ated by this test method include, but are not limited to, vascular
3. Terminology
stents, filters, support segments of endovascular grafts, cardiac
3.1 Definitions:
occluders, aneurysm or ligation clips, staples, and so forth.
3.1.1 potentiostat, n—an instrument for automatically main-
1.2 This test method is used to assess a device in its final
taining an electrode in an electrolyte at a constant potential or
form and finish, as it would be implanted. These small devices
controlled potentials with respect to a suitable reference
should be tested in their entirety. The upper limit on device size
electrode (see Terminology G 15).
is dictated by the electrical current delivery capability of the
3.1.2 potentiodynamic cyclic polarization (forward and re-
test apparatus (see Section 6). It is assumed that test methods,
verse polarization), n—a technique in which the potential of
such as Test Methods G 5 and G 61 have been used for material
the test specimen is controlled and the corrosion current
screening.
measured by a potentiostat. The potential is scanned in the
1.3 Because of the variety of configurations and sizes of
positive or noble (forward) direction as defined in Practice G 3.
implants, this test method provides a variety of specimen
The potential scan is continued until a predetermined potential
holder configurations.
or current density is reached. Typically, the scan is run until the
1.4 This test method is intended for use on implantable
transpassive region is reached, and the specimen no longer
devices made from metals with a relatively high resistance to
demonstrates passivity, as defined in Practice G 3. The poten-
corrosion.
tial scan direction then is reversed until the specimen repassi-
1.5 This standard does not purport to address all of the
vates or the potential reaches a preset value.
safety concerns, if any, associated with its use. It is the
3.1.3 scan rate, n—the rate at which the controlling voltage
responsibility of the user of this standard to establish appro-
is changed.
priate safety and health practices and determine the applica-
3.2 Symbols:
bility of regulatory limitations prior to use.
3.2.1 E = Breakdown or Critical Pitting Potential—the
b
2. Referenced Documents least noble potential at which pitting or crevice corrosion or
both will initiate and propagate as defined in Terminology
2.1 ASTM Standards:
2
G 15. An increase in the resistance to pitting corrosion is
D 1193 Specification for Reagent Water
associated with an increase in E .
G 3 Practice for Conventions Applicable to Electrochemical b
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3.2.2 E or OCP—the potential of a corroding surface in
corr
Measurements in Corrosion Testing
an electrolyte relative to a reference electrode measured under
G 5 Reference Test Method for Making Potentiostatic and
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open-circuit conditions, as defined in Terminology G 15.
Potentiodynamic Anodic Polarization Measurements
3.2.3 E = Final Potential—a preset potential at which the
f
G 15 Terminology Relating to Corrosion and Corrosion
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scan is stopped.
Testing
3.2.4 E = Initial Potential—the potential at which the
i
potentiostat begins the controlled potentiodynamic scan.
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This test method is under the jurisdiction of ASTM Committee F04 on Medical
3.2.5 E = Protection Potential—the potential at which the
p
and Surgical Materials and Devices and is the direct responsibility of Subcommittee
reverse scan intersects the forward scan at a value that is less
F04.15 on Material Test Methods.
noble than E . E cannot be determined if there is no
Current edition approved July 10, 2001. Published September 2001. b p
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Annual Book of ASTM Standards, Vol 11.01.
breakdown. Whereas, pitting will occur on a pit-free surface
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Annual Book of ASTM Standards, Vol 03.02.
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