1、Designation:F74604(Reapproved 2014)Standard Test Method forPitting or Crevice Corrosion of Metallic Surgical ImplantMaterials1This standard is issued under the fixed designation F746;the number immediately following the designation indicates the year of originaladoption or,in the case of revision,th
2、e year of last revision.Anumber in parentheses indicates the year of last reapproval.Asuperscriptepsilon()indicates an editorial change since the last revision or reapproval.1.Scope1.1 This test method covers the determination of resistanceto either pitting or crevice corrosion of metals and alloys
3、fromwhich surgical implants will be produced.It is a modifiedversion of an established test2and is used as a screening test torank surgical implant alloys in order of their resistance tolocalized corrosion.1.2 This test method applies only to passive metals andalloys.Nonpassive alloys(other than nob
4、le alloys)are suscep-tible to general corrosion and are not normally suitable forimplant use.1.3 This test method is intended for use as a laboratoryscreening test for metals and alloys which undergo pitting orcrevice corrosion,or both.1.4 The values stated in either SI units or inch-pound unitsare
5、to be regarded separately as standard.The values stated ineach system may not be exact equivalents;therefore,eachsystem shall be used independently of the other.Combiningvalues from the two systems may result in non-conformancewith the standard.1.5 This standard does not purport to address all of th
6、esafety 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:3D1193 Specification for Reagent
7、 WaterF86 Practice for Surface Preparation and Marking of Metal-lic Surgical ImplantsF2129 Test Method for Conducting Cyclic PotentiodynamicPolarization Measurements to Determine the CorrosionSusceptibility of Small Implant DevicesG3 Practice for Conventions Applicable to ElectrochemicalMeasurements
8、 in Corrosion TestingG5 Reference Test Method for Making PotentiodynamicAnodic Polarization MeasurementsG15 Terminology Relating to Corrosion and Corrosion Test-ing(Withdrawn 2010)43.Summary of Test Method3.1 Acylindrical specimen fitted with an inert tapered collaris immersed in a phosphate buffere
9、d saline electrolyte at 37Cfor 1 h to establish a corrosion potential.Pitting(or crevicecorrosion)is then stimulated by potentiostatically polarizingthe specimen to a potential much more noble than the corrosionpotential.Stimulation of pitting(or crevice corrosion)will bemarked by a large and genera
10、lly increasing polarizing current.3.2 Immediately after the stimulation step,the potential isdecreased as rapidly as possible to one of several preselectedpotentials at,or more noble than,the corrosion potential.If thealloy is susceptible to pitting(or crevice corrosion)at thepreselected potential,t
11、he polarizing current will remain atrelatively high values and will fluctuate or increase with time.A post-test examination of the metal specimen establisheswhether localized corrosion has occurred by pitting of theexposed surface or by preferential attack at the crevice formedby the tapered collar,
12、or both.3.3 If the pit(or crevice)surface repassivates at the pre-selected potential and localized corrosion is halted,the polar-izing current will drop to values typical for passive surfacesand the current will decrease continuously.The parameter ofinterest,the critical potential for pitting(or cre
13、vice corrosion),is defined as the highest(most noble)pre-selected potential atwhich pit(or crevice)surfaces repassivate after the stimulationstep.4.Significance and Use4.1 This test method is designed solely for determiningcomparative laboratory indices of performance.The results1This test method is
14、 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 Oct.1,2014.Published November 2014.Originallyapproved in 1981.Last previous edition approved in 2009 as F
15、746 04(2009)1.DOI:10.1520/F0746-04R14.2Syrett,B.C.,Corrosion,Vol 33,1977,p.221.3For 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
16、ASTM website.4The 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 may be used for ranking alloys in order of increasing resistanceto pitting and crevice corrosion under the specific conditions ofthis method.It should be noted that the method is intentionallydesigned to reach conditions that are sufficiently severe tocause breakdown of at least one alloy(Typ
