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Title: Comparative corrosion performance of black oxide, sandblasted, and fine-drawn nitinol wires in potentiodynamic and potentiostatic tests: Effects of chemical etching and electropolishing
Authors: Shabalovskaya, Svetlana ×
Rondelli, G
Anderegg, J
Xiong, JP
Wu, Ming #
Issue Date: May-2004
Publisher: Wiley-liss
Series Title: Journal of biomedical materials research part b-applied biomaterials vol:69B issue:2 pages:223-231
Abstract: The corrosion performance of sandblasted (SB) and smooth fine-drawn (FD) medical-use nitinol wires was compared with the performance of wires with black oxide (BO) formed in air during their manufacture. Potentiodynamic and ASTM F746 potentiostatic tests in a 0.9 % NaCl solution were conducted on wires in their as-received, chemically etched, aged in boiling water, and electropolished states. As-received wires with various surface finishes revealed breakdown potentials in the range from -100 mV to +500 mV; similar passive current density, 10(-6) A/cm(2); and a wide hysteresis on the reverse scan, demonstrating strong susceptibility to localized corrosion. Chemically etched wires with original black oxide displayed consistent corrosion performance and surpassed, in corrosion resistance, electropolished wires that showed significantly lower breakdown (400-700 mV) and localized corrosion potentials (similar to -50 to +113 mV). Sandblasted and fine-drawn wires exhibited rather inconsistent corrosion behavior. In potentiodynamic tests these wires could perform with equal probability either on the level of pretreated BO wires or rather similar to as-received wires. Both SB and FD wires revealed low breakdown potentials in the PS regime. SEM analysis performed before tests indicated that sandblasting was not efficient for the complete removal of the original scaling, and fine drawing aggravated the situation, resulting in a persistent scaling that contributed to the inferior corrosion performance. Inclusions (oxides, carbides, and oxidized carbides) inherited from the bulk and retained on electropolished surfaces are the cause of their inferior performance compared to chemically etched surfaces. In electropolished wires corrosion was initiated around inclusions. (C) 2004 Wiley Periodicals, Inc.
URI: 
ISSN: 0021-9304
Publication status: published
KU Leuven publication type: IT
Appears in Collections:Physical Metallurgy and Materials Engineering Section (-)
Cardiovascular Imaging and Dynamics
× corresponding author
# (joint) last author

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