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Wyszukujesz frazę "Nitinol" wg kryterium: Temat


Wyświetlanie 1-3 z 3
Tytuł:
On the Nitinol properties improvement after electrochemical treatments
Autorzy:
Hryniewicz, Tadeusz
Rokicki, Ryszard
Powiązania:
https://bibliotekanauki.pl/articles/1178042.pdf
Data publikacji:
2018
Wydawca:
Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
Tematy:
Nitinol
SMA
electropolishing (EP)
fatigue resistance
inclusions
magnetoelectropolishing (MEP)
Opis:
Shape Memory Alloys (SMAs) are a group of intermetallic compounds, which can undergo deformation at one temperature, and then recover their original undeformed shape upon heating above their transformation temperature. Superelasticity occurs just above the alloy’s transformation temperature in a very narrow range. In this case no heating is necessary to cause the deformed shape to recover upon load relieve to its original undeformed shape. It has to be emphasized that nitinol exhibits enormous elasticity when compared with other medical metal alloys. In recent years, the use of nitinol (NiTi), almost equiatomic binary (50:50 ratio) intermetallic compound of nickel and titanium, has been steadily growing, particularly in medical and dental devices markets. However, broader and further application of nitinol has been slowed down by leaking nickel and unavoidable inclusions during producing in this compound. This work is to present some electrochemical treatment methods in view of reducing of both these phenomena. It appears that changing electrical conditions of electropolishing (EP) above the plateau region (EP+) may improve the quality of surface obtained on NiTi of over 60% in comparison with as-received (AR) nitinol part. What’s more, introducing a magnetic field into the electrolysis system results in numerous positive features of nitinol surface and increase of mechanical properties. Thus the magnetoelectropolishing (MEP) process appears to increase higher the fatigue resistance of the treated NiTi part. The experiments carried out on chirurgical needles show an unusual triple (and higher) growth in resistance to bending until fracture. Further increase in fatigue resistance is usually limited by different size inclusions appearing on the nitinol part surface under magnetoelectropolishing (MEP).
Źródło:
World Scientific News; 2018, 95; 52-63
2392-2192
Pojawia się w:
World Scientific News
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Highly improved Nitinol biomaterial devices by magnetoelectropolishing (MEP)
Autorzy:
Hryniewicz, Tadeusz
Rokicki, Ryszard
Powiązania:
https://bibliotekanauki.pl/articles/1166214.pdf
Data publikacji:
2018
Wydawca:
Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
Tematy:
Biocompatibility
Fatigue resistance
Nitinol biomaterial
Surface roughness
XPS
magnetoelectropolishing
Opis:
In recent years, the use of Nitinol as a metallic biomaterial being compound of nickel and titanium, has been steadily growing, particularly in medical and dental devices markets. However, further application of Nitinol has been slowed down due to leaching nickel and unavoidable inclusions appearing on the surface during manufacture of this intermetallic compound. Electropolishing of Nitinol biomaterial samples as-received (AR) was carried out under different conditions: (a) on the plateau level (EP), (b) above the plateau (EP+), and (c) in the magnetic field (MEP). This work is to present magnetoelectropolishing (MEP) as an electrochemical processing method able to significantly improve the Nitinol biomaterial properties. Following our previous SEM/EDS studies, and corrosion resistance improvement of Nitinol, in this work XPS and XRD study methods were used. First of all, as indicated by XPS study results concerning biocompatibility, it was proved that MEP leaves Nitinol surface enriched in oxygen and with nickel reduced to zero. Thus the titanium oxides, generally TiO2, are formed on Nitinol surface. It appears that by introducing a magnetic field into the electrolysis system, another effect relying on a considerable increase of Nitinol mechanical properties is obtained. The experiments carried out on surgical needles show an unusual multiple growth in resistance to bending until fracture. Further increase in fatigue resistance is usually limited by different size of inclusions which happen to appear on the Nitinol part surface. Moreover, in this work also a simple method is proposed to reject the Nitinol parts, with the inclusions detected on the biomaterial surface, before their application.
Źródło:
World Scientific News; 2018, 106; 175-193
2392-2192
Pojawia się w:
World Scientific News
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Modification of Nitinol Biomaterial for Medical Applications
Autorzy:
Hryniewicz, Tadeusz
Rokicki, Ryszard
Powiązania:
https://bibliotekanauki.pl/articles/1177981.pdf
Data publikacji:
2018
Wydawca:
Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
Tematy:
Nitinol biomaterial
electropolishing
fatigue resistance
magnetoelectropolishing (MEP)
modification methods
sterilization
Opis:
In the paper, a review of modification methods which have been applied to Nitinol intermetallic compound used as biomaterial for medical applications, is carried out. A variety of methods used for Nitinol improvement, beginning from its manufacture, covers mechanical treatment, heat treatment, chemical processing including water boiling, electropolishing, plasma ion implantation, coating to improve the corrosion resistance, minimize nickel leaching, improve osseointegration, and/or vascular compatibility, sterilization and disinfection. Nitinol alloying by addition of a third element to replace Ti or Ni has an enormous effect on phase transformation, corrosion resistance and biocompatibility of the newly created ternary Nitinol alloy. Unfortunately, the ternary nitinol alloys – apart from NiTiCu in actuators and NiTiCr in wires used as a pulling-pushing tool in minimally invasive spine operation – have not found a widespread industrial application yet. One of the most effective surface finishing operations used for metallic biomaterials, with a special attention directed to Nitinol, appears to be magnetoelectropolishing (MEP). A uniform magnetic field used in MEP process can be generated by permanent magnets or by electromagnets. MEP leads to refinement of surface chemical composition impossible to achieve by standard electropolishing. During MEP of alloys and intermetallic compounds, ferromagnetic elements, such as Fe (from stainless steels) or Ni, are primarily removed from the surface so that the passive film on Nitinol is totally composed of titanium oxide. One more unique feature of metal samples after MEP is their de-hydrogenation noticed both in stainless steels, niobium, titanium and Nitinol. In fact, the fatigue resistance of Nitinol after MEP referred to as-received, dependent on the refinement and displacement of inclusions, increases from three to seven times.
Źródło:
World Scientific News; 2018, 96; 35-58
2392-2192
Pojawia się w:
World Scientific News
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-3 z 3

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