Korean J Med Phys.  2009 Jun;20(2):80-87.

Application of Ultrasonic Nano Crystal Surface Modification into Nitinol Stent Wire to Improve Mechanical Characteristics

Affiliations
  • 1Department of Biomedical Engineering, College of Medicine, The Catholic University of Korea, Seoul, Korea. shkim@mitech.co.kr
  • 2Department of Hybrid Engineering, Sunmoon University, Asan, Korea.
  • 3Department of Mechanical Engineering, Sunmoon University, Asan, Korea.
  • 4Institute of Interventional Medicine, M. I. Tech Co., Lnc, Pyeongtaek, Korea.

Abstract

Phase transformation, superelastic characteristics and variation of surface residual stress were studied for Nitinol shape memory alloy through application of UNSM technology, and life extension methods of stent were also studied by using elastic resilience and corrosion resistance. Nitinol wire of Oslash1.778 mm showed similar surface roughness before and after UNSM treatment, but drawing traces and micro defects were all removed by UNSM treatment. It also changed the surface residual stress from tensile to compressive values, and XRD result showed less intensive austenite peak and clear martensite and additional R-phase peaks after UNSM treatment. Fatigue resistance could be greatly improved through removal of surface defects and rearrangement of surface residual stress from tensile to compressive state, and development of surface modification system to improve not only bio-compatability but also resistance to corrosion and wear will make it possible to develop vascular stent which can be used for circulating system diseases which run first cause of death of recent Koreans.

Keyword

Stent; Nitinol wire; Ultrasonic nano crystalline surface modification

MeSH Terms

Alloys
Cause of Death
Corrosion
Dental Alloys
Fatigue
Life Expectancy
Memory
Stents
Ultrasonics
Alloys
Dental Alloys
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