Size Effects in Corrosion Behavior of Electropolished Nitinol – Neurovascular Implants versus Heart Valve Frames
Friday, May 19, 2017: 9:15 AM
Sunset Ballroom 4 - 5 (Paradise Point Resort )
Dr. Markus Wohlschlögel
,
Admedes Schuessler GmbH, Pforzheim, Germany
Mrs. Kerstin Stöffler
,
Admedes Schuessler GmbH, Pforzheim, Germany
Mr. Chris Bräuner
,
Admedes Schuessler GmbH, Pforzheim, Germany
Dr. Nils-Agne Feth
,
Admedes Schuessler GmbH, Pforzheim, Germany
It has been shown previously that the corrosion behavior of electropolished Nitinol implants laser-cut from tubing depends on the respective tubing size (outer diameter, wall thickness): the larger the tubing size, the lower the stability against breakdown in a potentiodynamic polarization test. This relationship could be explained with the size of nonmetallic inclusions and associated voids, which again depend on the tubing size
[1].
While previous work involved testing of peripheral stents versus heart valve frames, the present study focuses on the cyclic potentiodynamic polarization behavior of neurovascular implants, laser-cut from small size Nitinol tubing (outer diameters ranging from approx. 0.25 mm to 1.5 mm). As a comparison group current potentiodynamic polarization data of heart valve frames, laser-cut from large Nitinol tubing (outer diameters ranging from approx. 6 mm to 10 mm), is analyzed. All samples are tested per ASTM F2129 [2] in electropolished surface condition.
Results of cyclic potentiodynamic polarization testing are compared with tubing inclusion size data from metallographic analyses in order to rank the corrosion behavior of neurovascular implants against that of heart valve frames.
[1] Wohlschlögel M., Steegmüller R., Schüßler A. (2012) J. Biomed. Mater. Res. B, 100B, 2231-2238.
[2] ASTM F2129-15, ASTM International, West Conshohocken PA, USA, 2015.
