Autor: Lim, H. - Prolib Integro

Skocz do pozycji: 1.

Tytuł:: Evaluation of Surface Characteristics and Physical Properties on Biodegradable Magnesium-Calcium Alloys by Anodic Oxidation
Autorzy:: Kim, J.
Lee, J.
Yang, H.
Park, S.
Lim, H.
Oh, G.
Yun, K.
Tematy:: 87.85.jj
87.85.jc; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/1191716.pdf Link otwiera się w nowym oknie
Opis:: The purpose of this study was to determine the effect of calcium (Ca) on the surface characteristics and physical properties of magnesium-calcium alloys after anodization. A novel binary alloy Mg-xCa (in which x=0.5, 1, or 5 wt.%) was cast by combining magnesium (99.9%) and calcium (99.9%) in an argon gas (99.99%) atmosphere. A magnesium alloy rod having a diameter of 15 mm was cut into discs, each 2 mm thick. The specimens were subjected to anodic oxidation at 120 V for 15 minutes at room temperature in an electrolyte solution consisting of calcium gluconate, sodium hexametaphosphate, and sodium hydroxide. Surface and cross-sectional morphological changes were observed using scanning electron microscopy, and the microstructures and phases were detected by means of X-ray diffraction. Hardness and surface roughness were assessed by means of a Vickers hardness tester and a surface roughness meter, respectively. The results show that the physical properties of these magnesium-calcium alloys have been improved, because it was possible to control the dissolution rate according to the amount of calcium added.
Dostawca treści:: Biblioteka Nauki

Artykuł

na półce

Skocz do pozycji: 2.

Tytuł:: Combined Effect of Zr and Si on Isothermal Oxidation of Ti
Autorzy:: Ha, S.-H.
Kim, B.-H.
Yoon, Y.-O.
Lim, H.-K.
Kim, S. K.
Tematy:: Ti
Zr
Si
silicide
oxidation; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Czytelnia Czasopism PAN
Powiązania:: https://bibliotekanauki.pl/articles/353260.pdf Link otwiera się w nowym oknie
Opis:: In this study, the combined effect of Zr and Si on isothermal oxidation of Ti for 25 and 50h at 820°C, which is the temperature related to exhaust valves operation, was investigated. Si addition into Ti-5mass%Zr alloy led to a distribution of silicide Ti₅Si₃ phase formed by a eutectic reaction. The Ti sample containing only Zr showed more retarded oxidation rate than Ti-6Al-4V, the most prevalent Ti alloy, at the same condition. However, while a simultaneous addition of Zr and Si resulted in greater increase of oxidation resistance. The oxide layer formed after the addition of Zr and Si comprised TiO₂, ZrO₂, and SiO₂.
Dostawca treści:: Biblioteka Nauki

Artykuł

na półce

Skocz do pozycji: 3.

Tytuł:: Biological Evaluation of Anodized Biodegradable Magnesium-Calcium Alloys
Autorzy:: Kim, J.
Lee, J.
Lee, K.
Park, S.
Lim, H.
Park, C.
Bae, J.
Yun, K.
Tematy:: 87.85.jj
87.85.J-; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/1398763.pdf Link otwiera się w nowym oknie
Opis:: The objective of this study was to evaluate the biocompatibility of studied binary magnesium-calcium (Mg-Ca) alloys for biodegradable intraosseous implants. Mg is necessary for health and is a non-toxic biodegradable material that decomposes naturally in the body. Nevertheless, Mg has been implicated in problems including diminished physical properties and corrosion resistance when degradation is too rapid prior to bone healing. This study has explored the effect of Ca on the corrosion resistance and biological evaluation after anodizing treatment with different contents of Ca alloy. Binary Mg-0.5Ca, Mg-1Ca and Mg-5Ca alloys were prepared by the casting method under an argon atmosphere and cut into disc-shaped pieces. Pure Mg alloy was used as the control. Anodic oxidation was performed for 15 minutes at a voltage of 120 V using an electrolyte solution containing Ca gluconate, sodium hexametaphosphate, and sodium hydroxide at room temperature. Corrosion resistance was analyzed using a corrosion tester. After a hydrogen evolution test, the surface pattern and phase changes were observed on a scanning electron microscop (SEM) and energy dispersive spectroscop (EDS). Microscopic evaluation of the adhesion and cell biological functions of Mg was conducted by observing the response of human fetal osteoblastic 1.19 cells with regard to changes in surface film properties, depending on the amount of Ca. Our results support the view that in Mg-xCa alloys (x=0.5, 1, 5 wt.%) treated using anodic oxidation, the increasing Ca content controls the rate of decomposition and improves corrosion resistance.
Dostawca treści:: Biblioteka Nauki

Artykuł

na półce

Skocz do pozycji: 4.

Tytuł:: Fabrication of a Spherical Titanium Powder by Combined Combustion Synthesis and DC Plasma Treatment
Autorzy:: Choi, S. H.
Ali, B.
Hyun, S. K.
Sim, J. J.
Choi, W. J.
Joo, W.
Lim, J. H.
Lee, Y. J.
Kim, T. S.
Park, K. T.
Tematy:: combustion synthesis
DC plasma treatment
titanium powder
3D printing process
combustion parameters; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Czytelnia Czasopism PAN
Powiązania:: https://bibliotekanauki.pl/articles/356067.pdf Link otwiera się w nowym oknie
Opis:: Combustion synthesis is capable of producing many types of refractory and ceramic materials, as well as metals, with a relatively lower cost and shorter time frame than other solid state synthetic techniques. TiO₂ with Mg as reductant were dry mixed and hand compacted into a 60 mm diameter mold and then combusted under an Ar atmosphere. Depending on the reaction parameters (Mg concentration 2 ≤ α ≤ 4), the thermocouples registered temperatures between 1160°C and 1710°C . 3 mol of Mg gave the optimum results with combustion temperature (T_c) and combustion velocity (U_c) values of 1372°C and 0.26 cm/s respectively. Furthermore, this ratio also had the lowest oxygen concentration in this study (0.8 wt%). After combustion, DC plasma treatment was carried out to spheroidize the Ti powder for use in 3D printing. The characterization of the final product was performed using X-ray diffraction, scanning electron microscopy, energy dispersive spectroscopy, and N/O analysis.
Dostawca treści:: Biblioteka Nauki

Artykuł

na półce

Skocz do pozycji: 5.

Tytuł:: Reaction Kinetics and Morphological Study of TiNb2O7 Synthesized by Solid-State Reaction
Autorzy:: Choi, S. H.
Ali, B.
Choi, K. S.
Hyun, S. K.
Sim, J. J.
Choi, W. J.
Joo, W.
Lim, J. H.
Lee, T. H.
Kim, T. S.
Park, K. T.
Tematy:: solid state reaction
kinetic analysis
quantitative phase analysis
TiNb2O7 synthesis; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Czytelnia Czasopism PAN
Powiązania:: https://bibliotekanauki.pl/articles/355326.pdf Link otwiera się w nowym oknie
Opis:: Although TiNb₂O₇ is regarded as a material with high application potential in lithium-ion batteries (LIBs) and solid-oxide fuel cells (SOFCs), it has been difficult to find suitable cost-effective conditions for synthesizing it on a commercial scale. In this study, TiNb₂O₇ compounds were synthesized by a solid state synthesis process. For stoichiometrically precise synthesis of the TiNb₂O₇ phase, the starting materials, TiO₂ and Nb₂O₅ were taken in a 1:1 molar ratio. Activation energy and reaction kinetics of the system were investigated at various synthesis temperatures (800,1000,1200, and 1400°C) and for various holding durations (1,5,10, and 20 h). Furthermore, change in the product morphology and particle size distribution were also evaluated as a function of synthesis temperature and duration. Additionally, quantitative phase analysis was conducted using the Rietveld refinement method. It was found that increases in the synthesis temperature and holding time lead to increase in the mean particle size from 1 to 4.5 μm. The reaction rate constant for the synthesis reaction was also calculated.
Dostawca treści:: Biblioteka Nauki