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| Journal:
IRANIAN JOURNAL OF BIOMEDICAL ENGINEERING
SUMMER 2009
, Volume 3
, Number 2; Page(s) 0 To 0. |
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Paper: CORROSION BEHAVIOR OF SHAPE MEMORY NI-TI ALLOYS IN THE PHYSIOLOGICAL ENVIRONMENT SIMULATED BY BODY FLUIDS FOR MEDICAL APPLICATION |
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| Author(s): ZARE M., KHALIL ALLAFI J.*, AMIN AHMADI B., HADAVI S.M.M. |
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| * RESEARCH CENTER FOR ADVANCE MATERIALS, FACULTY OF MATERIALS ENGINEERING, SAHAND UNIVERSITY OF TECHNOLOG, TABRIZ, IRAN |
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| Abstract:
Ni-Ti shape memory alloys display unique properties such as high corrosion resistance, biocompatibility, super elasticity and shape memory behavior. They also are suitable materials for medical applications. In spite of high Ni content (above 50%) of Ni-Ti shape memory alloys, these materials represent good biocompatibility due to formation of Titanium oxide (TiO2) passive layer. Although TiO2 passive layer in these alloys can prevent releasing nickel to the environment, high nickel content and stability of passive layer in these alloys are very debatable subjects. In this study a Ni-Ti shape memory alloy with nominal composition of 50.7 atom% Ni was produced by vacuum induction melting (VIM) process. Homogenization treatments of samples were performed at 1050C for 24 hours. Microstructure and chemical composition of specimens were analyzed. Electrochemical tests were performed in two physiological environments of Ringer solution and NaCl 0.9% solution. In order to determine the amount of released Ni, the solution after potentiostatic tests was analyzed by atomic absorption spectroscopy. The samples after corrosion tests were investigated using Scanning Electron Microscopy (SEM). Furthermore corrosion products were analyzed by X-Ray Diffraction (XRD). Results indicate that the breakdown potential of the Ni-Ti alloy in NaCl 0.9% solution is higher than that in ringer solution. Topographical evaluations show that corrosion products are nearly the same in all samples.
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| Keyword(s): NI-TI SHAPE MEMORY ALLOY, POTENTIOSTATIC, POTENTIODYNAMIC, NICKEL RELEASE, NACL AND RINGER SOLUTION |
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