| Title: | Corrosion behavior of nickel–titanium continuous-casted alloys |
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| Authors: | ID Miličić Lazić, Minja (Author)
ID Mitić, Dijana (Author)
ID Radović, Katarina (Author)
ID Djordjević, Igor (Author)
ID Majerič, Peter (Author)
ID Rudolf, Rebeka (Author)
ID Grgur, Branimir (Author) |
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| Files: |  metals-14-00088.pdf (14,90 MB)
MD5: 0B8CBCA47FDF8F601518FEAE298DA50B
 https://www.mdpi.com/2075-4701/14/1/88
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| Language: | English |
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| Work type: | Article |
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| Typology: | 1.01 - Original Scientific Article |
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| Organization: | FS - Faculty of Mechanical Engineering
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| Abstract: | Variations in the corrosion behavior of biomedical NiTi alloys in Cl− containing and acidic
environments present a problem with their biological implantation. The objective of this research
was to evaluate the synergy of the microstructure, the corrosion behavior, and the biocompatibility of
novel continuous-cast NiTi alloys and to compare them with commercial NiTi alloys. The two alloys
have a practically identical nominal chemical composition, but they differ in production technology.
The continuous casting technology involved vacuum induction melting of the basic components
and vertical continuous casting, while the commercial NiTi alloy was produced through a process of
casting, hot rolling, and forming into square shapes. The microstructure was revealed to determine
the surface area and size of grains. The corrosion of a commercial nickel–titanium alloy and one
prepared by a novel continuous casting method in acidic and chloride-containing solutions was
studied via analytical and electrochemical tests. Localized corrosion characteristics related to oxide
properties, when exposed to 9 g L−1 NaCl solution, were examined with focused ion beam analysis
and subsequent microchemical analysis of the formed corrosive products. Corrosion potential over
time and the oxide film resistance were analyzed using linear polarization measurements. To obtain
a preliminary estimate of biocompatibility, human fibroblast cells were used in indirect contact,
i.e., alloy conditioning medium. The continuous casting method resulted in a reduction in the
average grain size in comparison to the commercial sample and better corrosion stability of the
sample in an acidic environment. Also, in a solution of 9 g L−1 NaCl the commercial sample showed
high values for the corrosion current density (jcorr = 6 µA cm−2), which indicated low corrosion
resistance, while the continuous casting sample possessed much better corrosion stability and lower
values for the corrosion current density (jcorr = 0.2 µA cm−2). In line with that, elemental analysis of
the corroded surfaces showed higher Cl− ion deposition over the surface layer of the commercial
sample, suggesting local oxide breakdown. Moreover, NiTicc reached a value three times higher
for polarization resistance (Rp = 270 kΩ cm2) over time in comparison to the commercial sample
(Rp~100 kΩ cm2). Biocompatibility evaluation showed that human fibroblast cells exhibited altered
metabolic activity. An MTT assay showed that cells’ mitochondrial activity dropped below that of
control cells in the presence of both materials’ supernatants. |
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| Keywords: | nickel–titanium, corosion behaviour, electrochemical testing, NiTi biocompatibility |
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| Publication status: | Published |
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| Publication version: | Version of Record |
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| Submitted for review: | 27.10.2023 |
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| Article acceptance date: | 28.12.2023 |
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| Publication date: | 11.01.2024 |
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| Publisher: | MDPI AG |
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| Year of publishing: | 2024 |
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| Number of pages: | 16 str. |
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| Numbering: | Vol. 14, iss. 1, [article no.] 88 |
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| PID: | 20.500.12556/DKUM-93511  |
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| UDC: | 621.833.1:539.4 |
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| ISSN on article: | 2075-4701 |
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| COBISS.SI-ID: | 181212163 |
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| DOI: | 10.3390/met14010088 |
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| Copyright: | © 2024 by the authors |
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| Publication date in DKUM: | 30.06.2025 |
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| Views: | 171 |
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| Downloads: | 11 |
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| Metadata: |    |
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| Categories: | Misc.
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