The effect of surface abrasion on the polarization behavior of CoCr, Ti-6Al-4V and 316L SS in PBS at pH 7 and 2

Jeremy L. Gilbert, Brian Lam

Research output: Chapter in Book/Report/Conference proceedingConference contribution

1 Scopus citations

Abstract

In the past, our laboratory and others have documented significant and severe corrosion of medical alloys in vivo that has resulted from the process of mechanically assisted corrosion where the oxide films on these surfaces are abraded (e.g., fretting), and the corrosion rate is significantly increased as a result. In this study, we have performed a simple set of voltage-controlled tests of the current response of alloy surfaces while abrading the surface with 600 grit emory paper in either pH 7.4 or pH 2 phosphate buffered saline solutions. Samples of Ti-6Al-4V (ASTM F-136) , Co-Cr-Mo (ASTMF-1537), and 316L SS (ASTM F138) were potentiostatically held at fixed voltages ranging from -1200 mV to +700 mV (100 mV increment) for 60 s. During this time, the sample currents equilibrated without abrasion for 15 s, then from 15 s to 30 s the samples were vigorously abraded with 600 grit sand paper, and from 30 to 60 s the sample was allowed to recover to its resting current. Data was acquired at 1000 pts per minute and the tests were repeated on three separate samples at each voltage, pH condition. The resting current density, average current density during abrasion, and the recovery time constant were all measured as a function of pH and voltage. The results of this study show significant effects of abrasion on current densities resulting in abrasion-polarization plots that are about 1 to 2 orders of magnitude higher current densities than the at-rest response, that each material exhibited unique ranges of behavior, and that the different pH's mostly affected the cathodic response region. The differences between abraded and resting current densities were voltage and pH dependent. The time constants for recovery were also a function of pH, voltage and material. These results show the underlying effects of the oxide film on these surfaces and its role in modulating the electrochemical response during mechanical abrasion.

Original languageEnglish (US)
Title of host publicationMedical Device Materials V - Proceedings of the Materials and Processes for Medical Devices Conference
Pages30-34
Number of pages5
StatePublished - Aug 26 2010
Event5th Materials and Processes for Medical Devices Conference, MPMD - Minneapolis, MN, United States
Duration: Aug 10 2009Aug 12 2009

Publication series

NameMedical Device Materials V - Proceedings of the Materials and Processes for Medical Devices Conference

Other

Other5th Materials and Processes for Medical Devices Conference, MPMD
CountryUnited States
CityMinneapolis, MN
Period8/10/098/12/09

ASJC Scopus subject areas

  • Biomedical Engineering
  • Materials Chemistry

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