Wyniki wyszukiwania - BazTech

1

Loading Effect of Ag Nanoparticles on Photocatalytic Activity of TiO2 Nanorod Arrays Prepared by Hydrothermal Method

Lee Kwangmin, Yoo Daeheung, Zakiyuddin Ahmad

Archives of Metallurgy and Materials

|

2021

|

Vol. 66, iss. 3

751--754

EN

Rutile-TiO2 nanorod thin films were formed on Ti disks via alkali treatment in NaOH solutions followed by heat treatment at 700°C. Ag nanoparticles were loaded on nanorods using a photo-reduction method to improve the photocatalytic properties of the prepared specimen. The surface characterization and the photo-electrochemical properties of the Ag-loaded TiO2 nanorods were investigated using a field-emission scanning electron microscope (FE-SEM), X-ray photoelectron spectroscopy (XPS), UV-Vis spectroscopy and electrochemical impedance spectroscopy (EIS). The TiO2 nanorods obtained after the heat treatment were 80 to 180 nm thick and 1 μm long. The thickness of the nanorods increased with the NaOH concentration. The UV-Vis spectra exhibit a shift in the absorption edge of the Ag-loaded TiO2 to the visible light range and further narrowing of the bandgap. The decrease in the size of the capacitive loops in the EIS spectra showed that the Ag loading effectively improved the photocatalytic activity of the TiO2 nanorods.

2

Degradation Characterization and Mechanisms of Warm Rolled Mg-1.6Gd with 95% Reduction Ratio for Biodegradable Implant Applications

Zakiyuddin Ahmad, Irawan Arya Abietta, Susanti Oknovia, Harjanto Sri

Archives of Metallurgy and Materials

|

2020

|

Vol. 65, iss. 3

1015--1018

EN

Mg-1.6Gd binary alloy was subjected to uniaxial warm rolling at a unidirectional and cross-sectional with a reduction ratio of 95% in order to observe the relationship between its microstructural changes to the degradation behavior. The warm rolling was performed at a temperature range of its recrystallization temperature, which were 400°C and 560°C, and a feed rate of 10 mm/min. Degradation behaviors of Mg-1.6Gd binary alloy was evaluated by means of potentiodynamic polarization and hydrogen evolution test in modified Kokubo’s SBF solution at temperature of 37 ± 1ºC. The lowest corrosion rate of 0.126 mm/year derived from potentiodynamic polarization test was showed by unidirectional-rolled specimen at temperature of 560°C. Hydrogen evolution test results showed the lowest hydrogen gas formed during 24 hours of immersion was found on unidirectional-rolled specimen at temperature of 560°C with a rate of 0.268 cc/cm2/hours. While cross rolled specimens showed a high corrosion and hydrogen evolution rate of 20 mm/year and 0.28 cc/cm2/hours.

3

Effect of Cold Rolling on Electrochemical Impedance Behavior of New β-Type Ti-6Mo-6V-5Cr-3Sn-2.5Zr Alloy

Song Hocheol, Zakiyuddin Ahmad, Kim Sinhye, Lee Kwangmin

Archives of Metallurgy and Materials

|

2019

|

Vol. 64, iss. 2

487--490

EN

In this study, the corrosion properties of Ti-6Mo-6V-5Cr-3Sn-2.5Zr alloy were investigated as a function of the cold rolling ratio and annealing temperature. The annealing treatment was carried out at temperature of 680°C, 730°C, and 780°C. The highest corrosion potential observed in the specimen with a 10% rolling ratio was 179 mV, which was more positive than that of the nonrolled specimen (–0.214 VSSC). The lowest corrosion current density (1.30×10-8 A/cm2) was observed in the non-rolled specimen which suggested that the integrity of its passive oxide layer was superior to that of the cold-rolled specimens. Time-dependent EIS evaluation revealed that the consistency of the passive oxide layer was highly affected by the subjected rolling ratio over time.