ASTM_F_2129_-_15.pdf

Designation:F212915Standard Test Method forConducting Cyclic Potentiodynamic PolarizationMeasurements to Determine the Corrosion Susceptibility ofSmall Implant Devices1This standard is issued under the fixed designation F2129;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the year of last revision.A number in parentheses indicates the year of last reapproval.Asuperscript epsilon()indicates an editorial change since the last revision or reapproval.1.Scope1.1 This test method assesses the corrosion susceptibility ofsmall,metallic,implant medical devices,or componentsthereof,using cyclic(forward and reverse)potentiodynamicpolarization.Examples of device types that may be evaluatedby this test method include,but are not limited to,vascularstents,ureteral stents(Specification F1828),filters,supportsegments of endovascular grafts,cardiac occluders,aneurysmor ligation clips,staples,and so forth.1.2 This test method is used to assess a device in its finalform and finish,as it would be implanted.These small devicesshould be tested in their entirety.The upper limit on device sizeis dictated by the electrical current delivery capability of thetest apparatus(see Section 6).It is assumed that test methods,such as Reference Test Method G5 and Test Method G61 havebeen used for material screening.1.3 Because of the variety of configurations and sizes ofimplants,this test method provides a variety of specimenholder configurations.1.4 This test method is intended for use on implantabledevices made from metals with a relatively high resistance tocorrosion.1.5 The values stated in SI units are to be regarded asstandard.No other units of measurement are included in thisstandard.1.6 This standard does not purport to address all of thesafety concerns,if any,associated with its use.It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2.Referenced Documents2.1 ASTM Standards:2D1193 Specification for Reagent WaterE177 Practice for Use of the Terms Precision and Bias inASTM Test MethodsE691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test MethodF1828 Specification for Ureteral StentsG3 Practice for Conventions Applicable to ElectrochemicalMeasurements in Corrosion TestingG5 Reference Test Method for Making PotentiodynamicAnodic Polarization MeasurementsG15 Terminology Relating to Corrosion and Corrosion Test-ing(Withdrawn 2010)3G61 Test Method for Conducting Cyclic PotentiodynamicPolarization Measurements for Localized Corrosion Sus-ceptibility of Iron-,Nickel-,or Cobalt-Based Alloys3.Terminology3.1 Definitions:3.1.1 potentiostat,nan instrument for automatically main-taining an electrode in an electrolyte at a constant potential orcontrolled potentials with respect to a suitable referenceelectrode(see Terminology G15).3.1.2 potentiodynamic cyclic polarization(forward and re-verse polarization),na technique in which the potential ofthe test specimen is controlled and the corrosion currentmeasured by a potentiostat.The potential is scanned in thepositive or noble(forward)direction as defined in Practice G3.The potential scan is continued until a predetermined potentialor current density is reached.Typically,the scan is run until thetranspassive region is reached,and the specimen no longerdemonstrates passivity,as defined in Practice G3.The potentialscan direction is then reversed until the specimen repassivatesor the potential reaches a preset value.1This test method is under the jurisdiction ofASTM Committee F04 on Medicaland Surgical Materials and Devices and is the direct responsibility of SubcommitteeF04.15 on Material Test Methods.Current edition approved March 1,2015.Published May 2015.Originallyapproved in 2001.Last previous edition approved in 2008 as F2129 08.DOI:10.1520/F2129-15.2For referenced ASTM standards,visit the ASTM website,www.astm.org,orcontact ASTM Customer Service at serviceastm.org.For Annual Book of ASTMStandards volume information,refer to the standards Document Summary page onthe ASTM website.3The last approved version of this historical standard is referenced onwww.astm.org.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 3.1.3 scan rate,nthe rate at which the controlling voltageis changed.3.2 Symbols:3.2.1 Eb=Breakdown or Critical Pitting Potentialtheleast noble potential at which pitting or crevice corrosion orboth will initiate and propagate as defined in Terminology G15.An increase in the resistance to pitting corrosion is associatedwith an increase in Eb.3.2.2 Er=Rest Potentialthe potential of the workingelectrode relative to the reference electrode measured undervirtual open-circuit conditions(working electrode is not polar-ized).3.2.3 Ezc=Zero Current Potentialthe potential at whichthe current reaches a minimum durin