TY  - JOUR
AU  - Miličić Lazić, Minja
AU  - Mitić, Dijana
AU  - Radović, Katarina
AU  - Đorđević, Igor
AU  - Majerič, Peter
AU  - Rudolf, Rebeka
AU  - Grgur, Branimir N.
PY  - 2024
UR  - http://TechnoRep.tmf.bg.ac.rs/handle/123456789/7189
AB  - 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.
PB  - MDPI
T2  - Metals
T1  - Corrosion Behavior of Nickel–Titanium Continuous-Casted Alloys
IS  - 1
SP  - 88
VL  - 14
DO  - 10.3390/met14010088
ER  - 

@article{
author = "Miličić Lazić, Minja and Mitić, Dijana and Radović, Katarina and Đorđević, Igor and Majerič, Peter and Rudolf, Rebeka and Grgur, Branimir N.",
year = "2024",
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.",
publisher = "MDPI",
journal = "Metals",
title = "Corrosion Behavior of Nickel–Titanium Continuous-Casted Alloys",
number = "1",
pages = "88",
volume = "14",
doi = "10.3390/met14010088"
}

Miličić Lazić, M., Mitić, D., Radović, K., Đorđević, I., Majerič, P., Rudolf, R.,& Grgur, B. N.. (2024). Corrosion Behavior of Nickel–Titanium Continuous-Casted Alloys. in Metals
MDPI., 14(1), 88.
https://doi.org/10.3390/met14010088

Miličić Lazić M, Mitić D, Radović K, Đorđević I, Majerič P, Rudolf R, Grgur BN. Corrosion Behavior of Nickel–Titanium Continuous-Casted Alloys. in Metals. 2024;14(1):88.
doi:10.3390/met14010088 .

Miličić Lazić, Minja, Mitić, Dijana, Radović, Katarina, Đorđević, Igor, Majerič, Peter, Rudolf, Rebeka, Grgur, Branimir N., "Corrosion Behavior of Nickel–Titanium Continuous-Casted Alloys" in Metals, 14, no. 1 (2024):88,
https://doi.org/10.3390/met14010088 . .

TY  - JOUR
AU  - Rudolf, Rebeka
AU  - Majerič, Peter
AU  - Lazić, Vojkan
AU  - Grgur, Branimir
PY  - 2022
UR  - http://TechnoRep.tmf.bg.ac.rs/handle/123456789/5219
AB  - In this paper, we present the idea and development of a new gold-copper-zinc-germanium (AuCuZnGe) alloy, which is related to the method of production and research of its key properties, so that the new Au alloy could be used for jewelry production and in dental technology. The research design was associated with the determination of appropriate chemical composition, manufacturing technology, and performing the characterization. Melting and casting technologies were used to cast the AuCuZnGe alloy while rolling was used to prepare the cylinders and cutting to make square plates with a = 10 mm and thickness of 1 mm. Such plates were provided for corrosion testing. Observation of the plate′s microstructure was performed with Scanning Electron Microscopy (SEM) equipped by Energy-Dispersive X-ray spectrometry (EDS) and X-ray diffraction (XRD). Corrosion testing involved performing the following measurements: Polarization, the open circuit potentials, and linear polarization resistance. Based on the SEM, EDS, XRD, and results of corrosion testing it can be concluded that the new AuCuZnGe alloy possesses high corrosion stability and can be classified as a high noble alloy.
PB  - MDPI
T2  - Metals
T1  - Development of a New AuCuZnGe Alloy and Determination of Its Corrosion Properties
IS  - 8
SP  - 1284
VL  - 12
DO  - 10.3390/met12081284
ER  - 

@article{
author = "Rudolf, Rebeka and Majerič, Peter and Lazić, Vojkan and Grgur, Branimir",
year = "2022",
abstract = "In this paper, we present the idea and development of a new gold-copper-zinc-germanium (AuCuZnGe) alloy, which is related to the method of production and research of its key properties, so that the new Au alloy could be used for jewelry production and in dental technology. The research design was associated with the determination of appropriate chemical composition, manufacturing technology, and performing the characterization. Melting and casting technologies were used to cast the AuCuZnGe alloy while rolling was used to prepare the cylinders and cutting to make square plates with a = 10 mm and thickness of 1 mm. Such plates were provided for corrosion testing. Observation of the plate′s microstructure was performed with Scanning Electron Microscopy (SEM) equipped by Energy-Dispersive X-ray spectrometry (EDS) and X-ray diffraction (XRD). Corrosion testing involved performing the following measurements: Polarization, the open circuit potentials, and linear polarization resistance. Based on the SEM, EDS, XRD, and results of corrosion testing it can be concluded that the new AuCuZnGe alloy possesses high corrosion stability and can be classified as a high noble alloy.",
publisher = "MDPI",
journal = "Metals",
title = "Development of a New AuCuZnGe Alloy and Determination of Its Corrosion Properties",
number = "8",
pages = "1284",
volume = "12",
doi = "10.3390/met12081284"
}

Rudolf, R., Majerič, P., Lazić, V.,& Grgur, B.. (2022). Development of a New AuCuZnGe Alloy and Determination of Its Corrosion Properties. in Metals
MDPI., 12(8), 1284.
https://doi.org/10.3390/met12081284

Rudolf R, Majerič P, Lazić V, Grgur B. Development of a New AuCuZnGe Alloy and Determination of Its Corrosion Properties. in Metals. 2022;12(8):1284.
doi:10.3390/met12081284 .

Rudolf, Rebeka, Majerič, Peter, Lazić, Vojkan, Grgur, Branimir, "Development of a New AuCuZnGe Alloy and Determination of Its Corrosion Properties" in Metals, 12, no. 8 (2022):1284,
https://doi.org/10.3390/met12081284 . .