ASTM F746-2004(2009)e1 Standard Test Method for Pitting or Crevice Corrosion of Metallic Surgical Implant Materials《金属外科植入材料的凹痕或裂隙腐蚀的试验方法》.pdf
《ASTM F746-2004(2009)e1 Standard Test Method for Pitting or Crevice Corrosion of Metallic Surgical Implant Materials《金属外科植入材料的凹痕或裂隙腐蚀的试验方法》.pdf》由会员分享,可在线阅读,更多相关《ASTM F746-2004(2009)e1 Standard Test Method for Pitting or Crevice Corrosion of Metallic Surgical Implant Materials《金属外科植入材料的凹痕或裂隙腐蚀的试验方法》.pdf(6页珍藏版)》请在麦多课文档分享上搜索。
1、Designation: F746 04 (Reapproved 2009)1Standard 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 revis
2、ion, the year of last revision.Anumber in parentheses indicates the year of last reapproval.Asuperscriptepsilon () indicates an editorial change since the last revision or reapproval.1NOTEUnits information was editorially corrected in January 2010.1. Scope1.1 This test method covers the determinatio
3、n of resistanceto either pitting or crevice corrosion of metals and alloys 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 meth
4、od applies only to passive metals andalloys. Nonpassive alloys (other than noble 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 cor
5、rosion, or both.1.4 The values stated in either SI units or inch-pound unitsare 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-
6、conformancewith the standard.1.5 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
7、 prior to use.2. Referenced Documents2.1 ASTM Standards:3D1193 Specification for Reagent WaterF86 Practice for Surface Preparation and Marking of Me-tallic Surgical ImplantsF2129 Test Method for Conducting Cyclic PotentiodynamicPolarization Measurements to Determine the CorrosionSusceptibility of Sm
8、all Implant DevicesG3 Practice for Conventions Applicable to ElectrochemicalMeasurements in Corrosion TestingG5 Reference Test Method for Making Potentiostatic andPotentiodynamic Anodic Polarization MeasurementsG15 Terminology Relating to Corrosion and CorrosionTesting3. Summary of Test Method3.1 Ac
9、ylindrical specimen fitted with an inert tapered collaris immersed in a phosphate buffered saline electrolyte at 37Cfor1htoestablish a corrosion potential. Pitting (or crevicecorrosion) is then stimulated by potentiostatically polarizingthe specimen to a potential much more noble than the corrosionp
10、otential. Stimulation of pitting (or crevice corrosion) will bemarked by a large and generally 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 pote
11、ntial. If thealloy is susceptible to pitting (or crevice corrosion) at thepreselected potential, the 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 p
12、itting of theexposed surface or by preferential attack at the crevice formedby the tapered collar, 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
13、 current will decrease continuously. The parameter ofinterest, the critical potential for pitting (or crevice corrosion),is defined as the highest (most noble) pre-selected potential atwhich pit (or crevice) surfaces repassivate after the stimulationstep.1This test method is under the jurisdiction o
14、fASTM Committee F04 on Medicaland Surgical Materials and Devices and is the direct responsibility of SubcommitteeF04.15 on Material Test Methods.Current edition approved Dec. 1, 2009. Published January 2010. Originallyapproved in 1981. Last previous edition approved in 2004 as F746 04. DOI:10.1520/F
15、0746-04R09E01.2Syrett, 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 ASTM website
16、.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.4. Significance and Use4.1 This test method is designed solely for determiningcomparative laboratory indices of performance. The resultsmay be used for ranking alloys in order of incre
17、asing 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 (Type 316 L stainlesssteel) currently considered acceptab
18、le for surgical implant use,and that those alloys which suffer pitting or crevice corrosionduring the more severe portions of the test do not necessarilysuffer localized corrosion when placed within the human bodyas a surgical implant.5. Apparatus5.1 The following required equipment is described in
19、Ref-erence Test Method G5:5.1.1 Standard Polarization Cell, of 1000 cm3.5.1.2 Electrode Holders, for auxiliary and working elec-trodes.5.1.3 Potentiostat, calibrated in accordance with ReferenceTest Method G5.5.1.4 Potential-Measuring Instrument.5.1.5 Current-Measuring Instrument.5.1.6 Anodic Polari
20、zation Circuit.5.1.7 Platinum Auxiliary Electrodes.5.1.8 Saturated Calomel Electrode (SCE).5.1.9 Salt Bridge Probe.5.2 A cylindrical working electrode is fabricated from thetest material by machining, grinding, and suggested finalpolishing with 600-grit metallographic paper. It is suggestedthat the
21、part of the cylindrical specimen that is exposed to thetest solution have a length of 20.00 6 1.00 mm 0.787 6 0.039in. and a diameter of 6.35 6 0.03 mm 0.250 6 0.001 in. (seeFig. 1).5.3 A crevice is created by fitting the cylindrical specimenwith a tapered collar, machined from commercial puritypoly
22、tetrafluoroethylene (PTFE). The collar should have anouter diameter of 12.70 6 0.05 mm 0.500 6 0.002 in. and athickness of 3.18 6 0.20 mm 0.125 6 0.008 in. The insidediameter of the tapered collar should range from 0.38 mm0.015 in. smaller than the diameter of the specimen to 0.38mm 0.015 in. larger
23、. To be consistent with the dimensionssuggested in 5.2, the inside diameter should taper from 5.97 60.05 mm 0.235 6 0.002 in. to 6.73 6 0.05 mm 0.265 60.002 in. See Fig. 1 for drawing of the tapered collar. Therelatively fine tolerances are needed to ensure a reproducible fitand crevice.5.4 In Refer
24、ence Test Method G5, the method of specimenattachment is to drill and tap the specimen to receive a threadedstainless steel connection rod. A4-40 thread is used, typically.However, because many surgical implant alloys are not easilydrilled, external threads may also be machined, ground, or cast,as i
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