Improvement of the Corrosion Resistance of NiTi Stents by Surface Treatments

1996 ◽  
Vol 459 ◽  
Author(s):  
C. Trépanier ◽  
M. Tabrizian ◽  
LH. Yahia ◽  
L. Bilodeau ◽  
D. L. Piron
Keyword(s):  
Corrosion Resistance ◽  
Oxide Layer ◽  
Corrosion Behavior ◽  
Surface Characteristics ◽  
Salt Bath ◽  
Surface Treatments ◽  
Nickel Titanium ◽  
Treatment Results ◽  
Porous Oxide

ABSTRACTBecause of its optimal radiopacity, superelasticity and shape memory properties Nickel-Titanium (NiTi) is an ideal material for the fabrication of stents. Indeed, these properties can facilitate the implantation and precise positioning of those devices. However, in vitro studies on NiTi report the dependency of the alloy biocompatibility and corrosion behavior to surface treatments. Oxidation of the surface seems to be very promising to improve both the corrosion resistance and the biocompatibility of NiTi. The present study investigate the effect of electropolishing, heat treatment (in air and in a salt bath) and nitric acid passivation to modify the oxide layer on NiTi stents. Techniques such as potentiodynamic polarization tests, Scanning Electron Microscopy (SEM) and Auger Electron Spectroscopy (AES) have been used to develop relationships between corrosion behavior, surface characteristics and surface treatment. Results show that all surface treatments improve the corrosion behavior of the alloy. SEM results indicate that treated stents which exhibit a smooth and uniform surface show a higher corrosion resistance than non treated stents which possess a very porous oxide layer. AES results, indicate that the best corrosion behavior was observed for the stents which exhibit the thinnest oxide layer (electropolished and passivated samples).

scholarly journals Assessment of nickel titanium and beta titanium corrosion resistance behavior in fluoride and chloride environments

2013 ◽  
Vol 83 (5) ◽  
pp. 864-869 ◽  
Author(s):  
Elisa J. Kassab ◽  
José Ponciano Gomes
Keyword(s):  
Corrosion Resistance ◽  
Corrosion Behavior ◽  
Electrochemical Impedance ◽  
Fluoride Concentration ◽  
Nickel Titanium ◽  
Localized Corrosion ◽  
General Corrosion ◽  
Nacl Solution ◽  
Galvanic Coupling ◽  
Beta Titanium

ABSTRACT Objective: To assess the influence of fluoride concentration on the corrosion behavior of nickel titanium (NiTi) superelastic wire and to compare the corrosion resistance of NiTi with that of beta titanium alloy in physiological solution with and without addition of fluoride. Materials and Methods: NiTi corrosion resistance was investigated through electrochemical impedance spectroscopy and anodic polarization in sodium chloride (NaCl 0.15 M) with and without addition of 0.02 M sodium fluoride (NaF), and the results were compared with those associated with beta titanium. The influence of fluoride concentration on NiTi corrosion behavior was assessed in NaCl (0.15 M) with and without 0.02, 0.04, 0.05, 0.07, and 0.12 M NaF solution. Galvanic corrosion between NiTi and beta titanium were investigated. All samples were characterized by scanning electron microscopy. Results: Polarization resistance decreased when NaF concentration was increased, and, depending on NaF concentration, NiTi can suffer localized or generalized corrosion. In NaCl solution with 0.02 M NaF, NiTi suffer localized corrosion, while beta titanium alloys remained passive. Current values near zero were observed by galvanic coupling of NiTi and beta titanium. Conclusions: There is a decrease in NiTi corrosion resistance in the presence of fluoride. The corrosion behavior of NiTi alloy depends on fluoride concentration. When 0.02 and 0.04 M of NaF were added to the NaCl solution, NiTi presented localized corrosion. When NaF concentration increased to 0.05, 0.07, and 0.12 M, the alloy presented general corrosion. NiTi corrosion resistance behavior is lower than that of beta titanium. Galvanic coupling of these alloys does not increase corrosion rates.

Corrosive behaviour of Amplatzer® devices in experimental and biological environments

2002 ◽  
Vol 12 (3) ◽  
pp. 260-265 ◽  
Author(s):  
Huafu Kong ◽  
James L. Wilkinson ◽  
James Y. Coe ◽  
Xiaoping Gu ◽  
Myra Urness ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Oxide Layer ◽  
Titanium Oxide ◽  
Saline Solution ◽  
Nickel Titanium ◽  
Cardiac Transplant ◽  
Titanium Oxide Layer ◽  
Device Placement

Purpose: Nitinol, a nickel-titanium alloy, is a valuable material in the construction of interventional endoluminal devices because of its biocompatibility, super elasticity, high resiliency and shape memory. The possibility of nickel toxicity has been raised with devices constructed of Nitinol. Our investigation examines the long-term corrosive behavior of this alloy in experimental and biological environments. Methods: We performed three levels of study. Microscopic examination was made of 64 devices of various sizes, randomly selected from 240 Amplatzer® Septal Occluders that had been exposed to saline solution at 37°C for fourteen months. All samples were studied by electron microscopy ranging from 50 to 5000 times magnification. We also studied microscopically 3 Amplatzer® devices explanted 18–36 months after implantation in dogs, and 2 Amplatzer Septal Occluders removed from patients 18 months (cardiac transplant) and 19 months (died of causes unrelated to device placement) after implantation, which were examined grossly and by electron microscopy up to 5000 times magnification. We then measured the levels of nickel in the blood using inductive plasma mass spectroscopy in 19 patients with implanted Amplatzer® devices, making measurements before and 6 months after implantation. Results: Electron microscopy showed an intact titanium oxide layer with no evidence of corrosion in vitro and in vivo. One explanted device in direct contact with the platinum leads of a pacemaker for eighteen months showed minor pitting of the titanium oxide layer believed to be galvanic in nature. No wire fractures were found in vitro after cycle testing with 400 million cycles, nor in devices taken from the animals and humans. Biochemical studies showed no significant elevation of levels of nickel levels after implantation. Conclusion: Nitinol wire of Amplatzer® septal occlusion devices is resistant to corrosion when exposed to physiologic saline solution, and in experimental animals as well as humans. A device in contact with a platinum pacemaker electrode developed minimal pitting of the titanium oxide layer, believed to be galvanic in nature and of no structural or clinical significance. There is no increase of concentrations of nickel in the blood of patients who have received Amplatzer® nitinol devices. These favorable testing results reveal that nickel-titanium is an inert, corrosion resistant alloy.

scholarly journals Electrochemical Anodizing Treatment to Enhance Localized Corrosion Resistance of Pure Titanium

2017 ◽  
Vol 15 (1) ◽  
pp. 19-24 ◽  
Author(s):  
Davide Prando ◽  
Andrea Brenna ◽  
Fabio M. Bolzoni ◽  
Maria V. Diamanti ◽  
Mariapia Pedeferri ◽  
...  
Keyword(s):  
Corrosion Resistance ◽  
Titanium Alloys ◽  
Oxide Layer ◽  
Corrosion Behavior ◽  
Pure Titanium ◽  
Localized Corrosion ◽  
Anodic Current Density ◽  
Anodic Current ◽  
Protective Oxide ◽  
Pitting Potential

Background Titanium has outstanding corrosion resistance due to the thin protective oxide layer that is formed on its surface. Nevertheless, in harsh and severe environments, pure titanium may suffer localized corrosion. In those conditions, costly titanium alloys containing palladium, nickel and molybdenum are used. This purpose investigated how it is possible to control corrosion, at lower cost, by electrochemical surface treatment on pure titanium, increasing the thickness of the natural oxide layer. Methods Anodic oxidation was performed on titanium by immersion in H2SO4 solution and applying voltages ranging from 10 to 80 V. Different anodic current densities were considered. Potentiodynamic tests in chloride- and fluoride-containing solutions were carried out on anodized titanium to determine the pitting potential. Results All tested anodizing treatments increased corrosion resistance of pure titanium, but never reached the performance of titanium alloys. The best corrosion behavior was obtained on titanium anodized at voltages lower than 40 V at 20 mA/cm2. Conclusions Titanium samples anodized at low cell voltage were seen to give high corrosion resistance in chloride- and fluoride-containing solutions. Electrolyte bath and anodic current density have little effect on the corrosion behavior.

Effects of hydroxyapatite content on mechanical properties and in-vitro corrosion behavior of ZK60/HA composites

2020 ◽  
Vol 111 (8) ◽  
pp. 621-631
Author(s):  
Jie Teng ◽  
Zili Xu ◽  
Jinlong Su ◽  
Yuan Li
Keyword(s):  
Mechanical Properties ◽  
Corrosion Resistance ◽  
Corrosion Behavior ◽  
Electrochemical Measurement ◽  
X Ray Diffraction ◽  
Corrosion Morphology ◽  
Hardness Tests ◽  
Zk60 Alloy ◽  
Immersion Testing

Abstract In this study, hydroxyapatite-reinforced ZK60 Mg alloybased composites were fabricated via a powder metallurgy route. The mechanical properties of these composites were studied by compressive tests and hardness tests. The in-vitro corrosion behavior was also investigated using immersion testing and electrochemical measurement. The influence of hydroxyapatite content on the mechanical properties and invitro corrosion behavior was evaluated. The microstructure and corrosion morphology were characterized by means of X-ray diffraction, optical and scanning electron microscopy. The results showed that the composite materials with 10 wt.% hydroxyapatite exhibited a better combination of mechanical strength and corrosion resistance. Compared with ZK60 alloy, the addition of 10 wt.% hydroxyapatite resulted in an increase in corrosion resistance by 38.6%.

scholarly journals Corrosion Resistance of Cr–Co Alloys Subjected to Porcelain Firing Heat Treatment—In Vitro Study

Processes ◽  
2021 ◽  
Vol 9 (4) ◽  
pp. 636
Author(s):  
Dorota Rylska ◽  
Bartłomiej Januszewicz ◽  
Grzegorz Sokołowski ◽  
Jerzy Sokołowski
Keyword(s):  
Heat Treatment ◽  
Corrosion Resistance ◽  
Corrosion Behavior ◽  
In Vitro Study ◽  
Alloying Elements ◽  
Dental Ceramics ◽  
Cobalt Chromium ◽  
Corrosion Properties ◽  
Manufacturing Method

The procedure of ceramics fusion to cobalt–chromium (Co–Cr) base dental crowns affects their corrosion behavior and biological tolerance. This study’s purpose was to comparatively evaluate the effect of heat treatment (HT) applicable for dental ceramics firing on the corrosion properties among Co–Cr base alloys fabricated via different methods: casting (CST), milling soft metal and post sintering (MSM), and selective laser melting (SLM). All specimens were subjected to a heat treatment corresponding to a full firing schedule. The microstructure and elemental composition of oxidized surfaces were investigated by scanning electron microscopy and energy dispersive spectroscopy. Corrosion properties were examined by electrochemical potentiodynamic polarization tests. The values of jcorr, Ecorr, Rp, and breakdown potential Ebr were estimated. The oxide layers formed during the HT process corresponded to the composition of the original alloys’ structure. Among the thermal treated alloys, SLM showed the highest corrosion resistance, followed by the MSM and CST. This may be attributed to uniform distribution of alloying elements in homogenous structure and to the reduced porosity, which enhances corrosion resistance and decreases the risk of crevice corrosion. The overall corrosion behavior was strongly influenced by the segregation of alloying elements in the microstructure, thus, is directly determined by the manufacturing method.

Effect of RE Elements Addition on Corrosion Behavior of Mg-Zn-Ca Amorphous Alloys for Biomedical Applications

2021 ◽  
Vol 1035 ◽  
pp. 501-510
Author(s):  
Yu Chen Chi ◽  
Bao Ru Guan ◽  
Feng Chen ◽  
Feng Xinag Qin
Keyword(s):  
Thermal Stability ◽  
Corrosion Resistance ◽  
Rare Earth ◽  
Oxide Layer ◽  
Corrosion Behavior ◽  
Amorphous Alloys ◽  
Biomedical Applications ◽  
Good Thermal Stability ◽  
Re Elements

The effects of rare earth (RE) elements (La, Y) addition on thermal stability and corrosion behavior of Mg68Zn28Ca4 amorphous alloys were investigated in this paper. The investigated Mg-Zn-Ca-RE amorphous alloys exhibit good thermal stability and enhanced corrosion resistance. The enhanced corrosion resistance of the RE-containing amorphous alloys is owing to the enrichment of the Zn and RE elements in the oxide layer. The corrosion resistance is further improved with the increasing of RE content.

Corrosion Behavior of Various Surface Treatments Ti-6Al-4V Alloy - A Review

2013 ◽  
Vol 849 ◽  
pp. 58-61 ◽  
Author(s):  
Yusliza Yusuf ◽  
Nooririnah Binti Omar ◽  
Muhamad Azwar Azhari ◽  
Md Ashadi Bin Md Johari
Keyword(s):  
Wear Resistance ◽  
Corrosion Resistance ◽  
Corrosion Behavior ◽  
Biomedical Application ◽  
Plasma Nitriding ◽  
Surface Hardness ◽  
Surface Treatments ◽  
Wear Properties ◽  
Resistance Property ◽  
Corrosion Resistance Property

A Ti-6Al-4V alloy has been widely used as suitable materials for several of application such as aerospace, marine and biomedical application. Although this alloy is excellent in its properties and good corrosion resistance, the applications are limited because of their poor tribological property referring to the wear resistance property due to their low surface hardness. Therefore, it is inevitable to improve the wear properties of Ti-6Al-4V without detrimental the initial corrosion resistance properties even increasing it for better result. Over the years, various methods of surface treatments for Ti-6Al-4V have been studied and most frequently used are laser treatment, plasma nitriding process, PVD coating and also duplex coating. For each of the surface treatment discussed, several type of corrosion behavior have been studied with the conclusion is comparable to each other. In general, throughout these techniques, the wear resistance property of Ti-6Al-4V was improved and simultaneously improving the corrosion resistance property.

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