Pit initiation on nitinol in simulated physiological solutions

Pound, Bruce G.

doi:10.1002/jbm.b.33974

Cited by 12 publications

(8 citation statements)

References 24 publications

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“…The surface in the scratched area could in fact be quite different from that produced by a treatment such as electropolishing or passivation, particularly with regard to inclusions. Pitting appears to initiate at inclusions in EP nitinol and 316 stainless steel . Exposure to a higher concentration of possibly larger inclusions in the scratched area means that the value of E b obtained by the scratch method may not accurately reflect the pitting resistance of an alloy with a treated surface.…”

Section: Methodsmentioning

confidence: 99%

The use of electrochemical techniques to evaluate the corrosion performance of metallic biomedical materials and devices

Pound

2018

J Biomed Mater Res

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The corrosion performance of metallic biomedical materials and devices is commonly evaluated using electrochemical techniques. Although test standards involving such techniques have been released to address some forms of corrosion, a key issue is application of the results with regard to use of an implantable device in vivo. This review focuses on nitinol, 316L/LVM stainless steel, and Co-Cr alloys and is intended to provide some perspective on the significance of results from tests concerning general corrosion, localized corrosion, galvanic corrosion, and fretting corrosion of these alloys in simulated physiological solutions. It also examines the factors that could cause differences in the corrosion performance between in vitro and in vivo exposure, with the goal of providing some rationale for applying electrochemical characteristics obtained from the tests to predict the corrosion performance in vivo. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res B Part B: Appl Biomater, 2018.

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Section: Methodsmentioning

confidence: 99%

The use of electrochemical techniques to evaluate the corrosion performance of metallic biomedical materials and devices

Pound

2018

J Biomed Mater Res

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“…28 Consistent with the results of Tuissi et al for PAM nitinol, other work has shown that pitting is associated with Ti 2 NiO x inclusions on EP nitinol. 22 Pits were observed around oxide inclusions in the nitinol, providing evidence that these inclusions were the sites of pit initiation. Notably, the nitinol contained a similar level of oxygen (0.034 wt.%) but an even lower level of carbon (0.0031 wt.%) compared with the levels in the PAM nitinol (0.0311 wt.% O and 0.0094 wt.% C).…”

Section: Types Of Inclusionmentioning

confidence: 99%

“…19 Even so, there is enough evidence to show that pit initiation can still occur at oxide inclusions. 19,20,22 Size of inclusion is clearly a key factor, 19,29,30 but other factors such as inclusion density and type of inclusion also appear to play a role. 19 4 | CoCr ALLOYS…”

Section: Sun Et Al Found a Correlation Between E B And Inclusion Frac...mentioning

confidence: 99%

“…20 Other work found that pitting occurred at TiC inclusions in mechanically polished (MP) nitinol and, furthermore, that the breakdown potential (E b ) was decreased by the presence of large TiC inclusions, 21 while Ti 2 NiO x inclusions were found to be associated with pit initiation in work involving EP nitinol. 22 The role of TiC inclusions as initiation sites for pitting on nitinol has been established in multiple studies. Neelakantan et al examined the polarization behavior of nitinol with low (0.005 wt.%) and high (0.05 wt.%) carbon.…”

Section: Types Of Inclusionmentioning

confidence: 99%

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Pit initiation on biomedical alloys—A review

Pound

2023

J Biomed Mater Res

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Biomedical alloys, like many engineering alloys, have chemical or physical heterogeneities at the surface, and such heterogeneities can potentially act as sites for pit initiation. Alloys of particular interest are 316/316L (and 316LVM) stainless steel, nitinol, and CoCr alloys. This review focuses on the sites—generally inclusions—that have been associated with pitting in various studies of biomedical alloys in simulated physiological solutions. The effect of these sites is discussed in relation to factors such as type and size. For both 316/316L stainless steel and nitinol, pitting has been found to initiate at two different types of inclusions: sulfide and oxide inclusions in stainless steel, and carbide and oxide inclusions in nitinol. Sulfide inclusions tend to be the predominant sites for pitting on 316/316L stainless steel, while there is some evidence to suggest that carbide inclusions may be more effective than oxide inclusions for pitting on nitinol. CoCrMo alloys differ from the other two alloys in that, although particles can be present in the form of carbides, the carbides typically do not provide sites for pit initiation except possibly for alloys with a high‐C content, certain heat treatments, and when anodically polarized to high potentials. CoNiCrMo differs further in that TiN inclusions can be present in the vicinity of pits and might be associated with them, but irrespective of the initiation site, any pits are unlikely to grow because of repassivation.

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“…In previous studies, electrochemical tests have been used to evaluate the corrosion resistance of nitinol alloys in various physiological environments [5][6][7][8][9][10][11][12][13][14][15][16][17][18]. The correlation of the results from these studies in regards to the corrosion resistance is complex due to different simulated body fluids used as electrolytes and the surface condition, although the chloride content in these physiological solutions remained almost the same.…”

Section: Introductionmentioning

confidence: 99%

In vitro corrosion behaviour of phenolic coated nickel–titanium surfaces

Longela¹,

Chatzitakis²

2020

Biosurface and Biotribology

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The biocompatibility of implantable nickel-titanium biomaterials relies on the quality of their surfaces. In this study, nickel-titanium surfaces are coated with phenolic thin films of tannic acid and pyrogallol with the purpose of studying their corrosion resistance in physiological environments. Three tests are performed: the open-circuit potential test, potentiodynamic polarisation and potentiostatic electrochemical impedance spectroscopy. Polarisation measurements are scrutinised in order to gain knowledge concerning the kinetics of the cathodic and anodic reactions, while the open-circuit potentials and impedance spectroscopy help to study the electrolyte-surficial interactions. It is found that coating nitinol with polyphenols results in the depletion of the native oxide layer and thus a decrease of corrosion resistance. Pyrogallic treated nitinol surfaces (with a corrosion rate of 0.119 mm/year) are half as electrochemically corrosion resistive as tannic acid-coated substrate. Therefore, it is proposed that tannic treated nitinol would be a better option if implanted on biomaterial surfaces. † first, in 70% vol. ethanol; † second, for 5 min at 40°C in an ultrasonic bath with deionised water Milli-Q Direct (Millipore, Billerica, MA) with a resistivity of 18.2 MΩ cm at 25°C; † third, in 40% NaOH and water bath for 5 min; † fourth, sonicated in deionised water for 5 min with a subsequent rinse with deionised water for 5 min; † fifth, immersed for 10 min in 50% vol. HNO 3 , then sonicated in deionised water for 5 min, and then rinsed in deionised water until reaching a neutral pH, and finally, stored in 70% vol. ethanol. 2.1 Polyphenolic coatings Samples were either treated with pyrogallol (PG) diluted in 100 mM BisTris buffer pH 7.0 with 100 mM magnesium chloride at a concentration of 1 mg ml −1 or with tannic acid (TA) diluted in Biosurface and Biotribology

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Pit initiation on nitinol in simulated physiological solutions

Cited by 12 publications

References 24 publications

The use of electrochemical techniques to evaluate the corrosion performance of metallic biomedical materials and devices

The use of electrochemical techniques to evaluate the corrosion performance of metallic biomedical materials and devices

Pit initiation on biomedical alloys—A review

In vitro corrosion behaviour of phenolic coated nickel–titanium surfaces

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