Material

Preparation, Structural and Microstructural Characterization of Ti-30NB-10ta-5ZR alloy for biomedical applications

Publication date: Available online 20 November 2020

Source: Journal of Materials Research and Technology

Author(s): Sergey V. Gudkov, Alexander V. Simakin, Sergey V. Konushkin, Alexander Yu. Ivannikov, Elena O. Nasakina, Lyudmila A. Shatova, Alexey G. Kolmakov, Mikhail A. Sevostyanov

Published

1 week ago

November 21, 2020

Republished by Plato

Available online 20 November 2020

Journal of Materials Research and Technology

open access

Abstract

Ti-30Nb-10Ta-5Zr alloy was produced and studied in the work. Plates and wires were made of this alloy. The alloy was shown to have pure β-crystalline phase and to possess the required mechanical properties. Microstructures with a height of the order of several hundred nm, located at a distance of 1.5-2.0 μm were observed on the surface of the alloy. From the point of view of reactive oxygen species generation and long-lived reactive protein species formation, the Ti-30Nb-10Ta-5Zr alloy is more preferrable than nitinol. Cultivation of cell cultures on Ti-30Nb-10Ta-5Zr surfaces resulted in high mitotic index (2%) and low content of non-viable cells (<5%). The cells were actively attaching and spreading on the alloy. Biocompatibility of Ti-30Nb-10Ta-5Zr was confirmed by the experiments on implantation of the alloy as plates and coiled wires. The surface morphology of the specimens did not alter significantly after the biological trials. It can be suggested that Ti-30Nb-10Ta-5Zr alloy is an appropriate material for potential medical applications.

Keywords

Titanium

tantalum

niobium

zirconium

biocompatibility

mechanical properties

Source: https://www.sciencedirect.com/science/article/pii/S2238785420320020?dgcid=rss_sd_all

Related Topics:cultivation material medical product research

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Material

Improving the mechanical strength of carbon-carbon composites by oxidative stabilization

Publication date: Available online 28 November 2020

Source: Journal of Materials Research and Technology

Author(s): Ji Hong Kim, Ayoung Jo, Yun Jeong Choi, Ki Bong Lee, Ji Sun Im, Byong chol Bai

Published

18 hours ago

November 29, 2020

Republished by Plato

Available online 28 November 2020

open access

Abstract

Carbon/carbon composite has superior properties, so it has been expected to use various industrial fields. However, low mechanical strength (than conventional structural materials) works as a hurdle, so the use of oxidative stabilization to improve the mechanical strength of carbon/carbon composites was studied. The oxidation process was performed at 220∼350 °C based on thermogravimetric analysis (TGA). The compressive strength of the oxidized sample at 290 °C was 212 MPa, which is 2.5 times greater than that of the non-oxidized sample (84 MPa). However, the oxidation temperature of more than 290 °C decreased the compressive strength (199 MPa at 350 °C). This tendency was in accordance with the TGA and X-ray photoelectron spectroscopy (XPS) results. The effect of oxidative stabilization can be explained by two factors: the polymerization of the used binder pitch by the crosslinking effect by induced oxygen and improvement of the affinity between the coke and binder pitch.

Keywords

Carbon-carbon composite

Oxidative stabilization

Mechanical strength

Oxygen crosslinking

Coke/Pitch affinity

Source: https://www.sciencedirect.com/science/article/pii/S2238785420320317?dgcid=rss_sd_all

Material

Impact of alkaline and acid treatment on the surface chemistry of a hot-dip galvanized Zn-Al-Mg coating

Publication date: Available online 28 November 2020

Source: Journal of Materials Research and Technology

Author(s): Burak William Çetinkaya, Fabian Junge, Gregor Müller, Florian Haakmann, Klaus Schierbaum, Miroslaw Giza

Published

18 hours ago

November 29, 2020

Republished by Plato

Available online 28 November 2020

open access

Abstract

The surface chemistry of an exemplary hot-dip galvanized Zn-Al-Mg coating comprising 1.6 wt.% aluminum and 1.1 wt.% magnesium was characterized by means of secondary and transmission electron microscopy as well as synchrotron radiation X-ray photoelectron spectroscopy. Lamellae of the coating prepared via focused ion beam technique were examined through energy dispersive X-ray analysis. Further the effect of alkaline and acid treatment respectively was investigated by employing time of flight secondary ion mass spectroscopy, energy dispersive X-ray analysis and glow discharge optical emission spectroscopy. Throughout this work it is shown that both alkaline (NaOH) and acid (H₂SO₄) solutions alter the chemical composition when applied to the coating surface. With the native Zn-Al-Mg system yielding a complex microstructure covered by a magnesium and aluminum rich oxide film, highly alkaline surroundings (pH > 13) caused a decrease of aluminum at the uppermost surface. Every deployed acid solution (pH < 2.4) lead to a preferred pickling of the magnesium compounds including the oxide layer plus the intermetallic MgZn₂ phases of the coating. Exposure to both highly alkaline and acid environments corresponded to a higher proportion of zinc at the coating surface measured by all applied surface analytical tools indicating that the modification of the chemical composition took place on both nanoscopic and microscopic scale.

Keywords

hot-dip galvanizing

Zn-Al-Mg coating

surface characterization

alkaline cleaning

acid treatment

Source: https://www.sciencedirect.com/science/article/pii/S2238785420320366?dgcid=rss_sd_all

Material

High-temperature thermodynamics of ZnO–NH4Cl–H2O system

Publication date: Available online 28 November 2020

Source: Journal of Materials Research and Technology

Author(s): Duoqiang Zhao, Shenghai Yang, Yongming Chen, Yafei Jie, Jing He, Chaobo Tang

Published

18 hours ago

November 29, 2020

Republished by Plato

Available online 28 November 2020

open access

Abstract

On the basis of the principles of simultaneous equilibrium, conservation of mass, and aqueous electronic charge neutrality and the correspondence principle of ion entropy, the high-temperature thermodynamics of the ZnO–NH₄Cl–H₂O system was studied to predict solubility and construct Zn species distribution. The model was constructed precisely by using the MATLAB program. The total Zn²⁺ concentration in the solution was affected significantly by temperature and total ammonium concentration. ZnNH₃Cl₃⁻ was the predominant species in the ZnO–NH₄Cl–H₂O system. The solubility of zinc diammine chloride in NH₄Cl solution (>2 mol·L^-1) in the temperature range of 303–353 K was determined using equilibrium experiments, which had results that agreed well with the theoretical value. The data and high-temperature thermodynamic model used in this paper are reliable.