title: Nitinol: Tubing versus sputtered film - microcleanliness and corrosion behavior.
abstract: Corrosion behavior and microcleanliness of medical-device grade Nitinol tubing (Nix Ti1- x , x = 0.51; outer diameter 7 mm, wall thickness 0.5 mm), drawn from various ingot qualities, are compared to the characteristics of sputtered Nitinol film material (Nix Ti1- x , x = 0.51; thickness 50 µm). Electropolished tubing half-shell samples are tested versus as-received sputtered film samples. Inclusion size distributions are assessed using quantitative metallography and corrosion behavior is investigated by potentiodynamic polarization testing in phosphate-buffered saline at body temperature. For the sputtered film samples, the surface chemistry is additionally analyzed employing Auger Electron Spectroscopy (AES) composition-depth profiling. Results show that the fraction of breakdowns in the potentiodynamic polarization test correlates with number and size of the inclusions in the material. For the sputtered Nitinol film material no inclusions were detectable by light microscopy on the one hand and no breakdowns were found in the potentiodynamic polarization test on the other hand. As for electropolished Nitinol, the sputtered Nitinol film material reveals Nickel depletion and an Oxygen-to-Titanium intensity ratio of ∼2:1 in the surface oxide layer, as measured by AES. © 2015 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 104B: 1176-1181, 2016.
authors.affiliation: ADMEDES Schuessler GmbH, Pforzheim, Baden-Württemberg, 75179, Germany.
authors.forename: Markus
authors.initials: M
authors.lastname: Wohlschlögel
authors.affiliation: ACQUANDAS GmbH, Kiel, Schleswig-Holstein, 24143, Germany.|Chair for Inorganic Functional Materials, Institute of Materials Science, University of Kiel, Schleswig-Holstein, 24143, Germany.
authors.forename: Rodrigo
authors.initials: R
authors.lastname: Lima de Miranda
authors.affiliation: ADMEDES Schuessler GmbH, Pforzheim, Baden-Württemberg, 75179, Germany.
authors.forename: Andreas
authors.initials: A
authors.lastname: Schüßler
authors.affiliation: Chair for Inorganic Functional Materials, Institute of Materials Science, University of Kiel, Schleswig-Holstein, 24143, Germany.
authors.forename: Eckhard
authors.initials: E
authors.lastname: Quandt
mesh_terms: D003343:Corrosion; D008567:Membranes, Artificial; D013499:Surface Properties; D013729:Terpenes / Q000737:chemistry*
chemical_list: D008567:Membranes, Artificial; D013729:Terpenes; C401231:nitiol
keywords: corrosion; metallurgy; microscopy; surface analysis