Synthesis of the Magnesium-Based Nano/Amorphous-Composite Alloy Powder by the Combination Method of Melt-Spinning and Mechanical Alloying

2006 ◽  
Vol 313 ◽  
pp. 97-104 ◽  
Author(s):  
L.J. Chang ◽  
J.H. Young ◽  
Jason S.C. Jang ◽  
J.C. Huang ◽  
Chi Y.A. Tsao
Keyword(s):  
Mechanical Alloying ◽  
Alloy Powder ◽  
Melt Spinning ◽  
Amorphous Matrix ◽  
Average Particle Size ◽  
Amorphous State ◽  
Combination Method ◽  
Average Particle ◽  
Composite Alloy

A series of Mg-based alloys with composition of Mg65Y10Cu25-XAgX, x = 0, 5, 10, were selected for investigating the microstructure evolution of the Mg-based nano/amorphous-composite alloy powder synthesized by the combination method of melt-spinning and mechanical alloying (MA). The microstructure characterization of the alloy powders was conducted by means of DSC, XRD, FEG-SEM, and TEM techniques. The result of XRD reveals that the entire as-quenched alloy ribbons exhibit a broaden diffraction pattern of amorphous phase. After 50 hours milling the mixture of amorphous alloy ribbons with 5 vol.% of nano-sized ZrO2 by planetary mill, the ZrO2 dispersed magnesium composite alloy powder can reach to a homogeneous size distribution. In parallel, the MA composite Mg-based alloy powders still remain an amorphous state by the characterization of X-ray diffraction and the DSC analysis. A clear Tg (glass transition temperature) and most wide supercooled region (about 44 K) were revealed for both the Mg65Y10Cu20Ag5 alloy ribbon and the MA magnesium composite powder. In addition, the result of TEM observation also revealed that the ZrO2 with average particle size of 80 nm distributed homogeneously in the amorphous matrix of the Mg65Y10Cu20Ag5 /5 vol.% ZrO2 composite alloy powder. The interface between the ZrO2 dispersoid and the amorphous matrix of the composite alloy powder exhibits a very good bonding condition.

scholarly journals DESIGN, FORMULATION, AND CHARACTERIZATION OF STEARIC ACID-BASED SOLID LIPID NANOPARTICLES OF CANDESARTAN CILEXETIL TO AUGMENT ITS ORAL BIOAVAILABILITY

2018 ◽  
Vol 11 (4) ◽  
pp. 344 ◽  
Author(s):  
Anu Mahajan ◽  
Satvinder Kaur ◽  
Satvinder Kaur
Keyword(s):  
Stearic Acid ◽  
Oral Bioavailability ◽  
Candesartan Cilexetil ◽  
Average Particle Size ◽  
Amorphous State ◽  
Free Drug ◽  
Pharmacokinetic Studies ◽  
Average Particle ◽  
Solid Lipid

 Objective: Poor aqueous solubility and suboptimal oral bioavailability hamper the therapeutic efficacy of candesartan cilexetil (CDC). This study is designed to prepare solid lipid nanoparticle (SLN) of CDC and to enhance the oral absorption of CDC compared with free drug suspension.Methods: The development and characterization of CDC-loaded SLN, using stearic acid as main encapsulating lipid, stabilized with poloxamer188 using “modified emulsification-ultrasonication technique.”Results: CDC-SLN with a total drug content of 88.33±1.23% and entrapment efficiency of 78.28±1.91%, with an average particle size of 197.9 nm and zeta potential value −21.3 mV, was prepared. Differential scanning calorimetry and powder X-ray diffraction (PXRD) results confirmed the molecular encapsulation of the drug in amorphous state. CDC-SLN released 60.43% of drug in comparison to 17.11% released by CDC suspension in 24 h (p<0.05). The results of pharmacokinetic studies in rat showed that AUC0−t of CDC-SLN was significantly enhanced over 3-folds than that of free drug suspension (p<0.05).Conclusion: SLN of CDC could be successful in improving the oral bioavailability of poorly soluble CDC.

Magnetic and Thermal Studies of Iron-Based Amorphous Alloys Produced by a Combination of Melt-Spinning and Ball Milling

2021 ◽  
Vol 1163 ◽  
pp. 99-105
Author(s):  
Zahra Allafe Razzaghi ◽  
Abbas Kianvash ◽  
Abolfazl Tutunchi
Keyword(s):  
Particle Size ◽  
Mechanical Alloying ◽  
Ball Milling ◽  
Melt Spinning ◽  
Thermal Studies ◽  
Average Particle Size ◽  
Ferromagnetic Behavior ◽  
Average Particle ◽  
Mechanically Alloyed ◽  
Melt Spun

In this study, we demonstrate the synthesis of an Fe78Si9B10P3 amorphous alloy by three pathways: mechanical alloying, melt-spinning and a combination of melt-spinning and ball milling. Microstructure, thermal stability and soft magnetic properties of the melt-spun and mechanically alloyed powders are comparatively studied. Ball milling of previously melt-spun samples led to an amorphous powder with an average particle size of ~2.4 μm after 20 hrs of milling. Mechanical alloying of elemental Fe-Si-B-P powders in a planetary ball mill for up to 100 hrs led only to a partial amorphisation of powder with a median particle size of ~1.3 μm. Differential thermal analysis of the amorphous ribbon revealed that the amorphous phase was stable up to ~520 °C, at which the crystallization process occurred. The melt spun ribbons exhibited excellent soft ferromagnetic behavior, including high saturation magnetization (Ms) of ~171 emu/g and a low coercivity (Hc) of ~2.8 Oe. In the 20 hrs milled ribbons, due to a probable partial anisotropy which induced by ball milling stress, the Ms value decreased slightly to ~161 emu/g but the Hc increased to ~38 Oe. The mechanically alloyed samples present a relatively lower Ms of ~154 emu/g and higher Hc of ~43 Oe. It is to be noted that the milling of ribbons is usually inevitable due to their technological restrictions in use.

Synthesis and Characterization of Water-Soluble Monolayer-Protected Gold Nanoparticles

2011 ◽  
Vol 415-417 ◽  
pp. 617-620 ◽  
Author(s):  
Yan Su ◽  
Ying Yun Lin ◽  
Yu Li Fu ◽  
Fan Qian ◽  
Xiu Pei Yang ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Particle Size ◽  
Gold Nanoparticles ◽  
Average Particle Size ◽  
Water Soluble ◽  
Synthesis And Characterization ◽  
Average Particle ◽  
Transmission Electron

Water-soluble gold nanoparticles (AuNPs) were prepared using 2-mercapto-4-methyl-5- thiazoleacetic acid (MMTA) as a stabilizing agent and sodium borohydride (NaBH4) as a reducing agent. The AuNPs product was analyzed by transmission electron microscopy (TEM), UV-vis absorption spectroscopy and Fourier transform infrared spectroscopy (FTIR). The TEM image shows that the particles were well-dispersed and their average particle size is about 5 nm. The UV-vis absorption and FTIR spectra confirm that the MMTA-AuNPs was stabilized by the carboxylate ions present on the surface of the AuNPs.

scholarly journals Characterization of dispersion strengthened copper with 3wt%Al2O3 by mechanical alloying

2004 ◽  
Vol 36 (3) ◽  
pp. 205-211 ◽  
Author(s):  
Viseslava Rajkovic ◽  
Olivera Eric ◽  
Dusan Bozic ◽  
M. Mitkov ◽  
Endre Romhanji
Keyword(s):  
Mechanical Alloying ◽  
Structural Changes ◽  
Early Stage ◽  
Structure Refinement ◽  
Average Particle Size ◽  
Copper Matrix ◽  
Alumina Powder ◽  
Average Particle ◽  
Micro Hardness ◽  
Electrolytic Copper Powder

The copper matrix has been dispersion strengthened with 3wt.%Al2O3 by mechanical alloying. Commercial alumina powder with an average particle size of 0.75mm was used for alloying. The mechanical alloying process was performed in a planetary ball mill up to 20h in air. After milling all powders were treated in H2 at 4000C for 1h, and finally hot pressing was used for compaction (800oC, 3h, Ar). Structure observations revealed a lamellar structure (Al2O3 particles largely restricted to interlamellar planes between adjacent copper lamellae) accompanied also by structure refinement. These structural changes were mostly completed in the early stage of milling, and retained after compaction. Micro hardness was found to progressively increase with milling time. So, after 5h of milling the micro hardness of the Cu+3twt%Al2O3 compact was 1540MPa, i.e. 2.5 times greater than for the as-received electrolytic copper powder (638MPa) compacted under identical conditions, while after 20h of milling it was 2370 MPa. However after exposing the tested compact at 800oC up to 5h, the achieved hardening effect vanished.

scholarly journals Preparation and characterization of domperidone nanoparticles for dissolution improvement

2018 ◽  
Vol 27 (1) ◽  
pp. 39-52
Author(s):  
Mohammed Sabar Al-lami ◽  
Malath H. Oudah ◽  
Firas A. Rahi
Keyword(s):  
Particle Size ◽  
Average Particle Size ◽  
In Vitro Release ◽  
Methyl Cellulose ◽  
Precipitation Method ◽  
Average Particle ◽  
Antisolvent Precipitation ◽  
Stirring Time

This study was carried out to prepare and characterize domperidone nanoparticles to enhance solubility and the release rate. Domperidone is practically insoluble in water and has low and an erratic bioavailability range from 13%-17%. The domperidone nanoparticles were prepared by solvent/antisolvent precipitation method at different polymer:drug ratios of 1:1 and 2:1 using different polymers and grades of poly vinyl pyrolidone, hydroxy propyl methyl cellulose and sodium carboxymethyl cellulose as stabilizers. The effect of polymer type, ratio of polymer:drug, solvent:antisolvent ratio, stirring rate and stirring time on the particle size, were investigated and found to have a significant (p? 0.05) effect on particle size. The best formula was obtained with lowest average particle size of 84.05. This formula was studied for compatibility by FTIR and DSC, surface morphology by FESEM and crystalline state by XRPD. Then domperidone nanoparticles were formulated into a simple capsule dosage form in order to study of the in vitro release of drug from nanoparticles in comparison raw drug and mixture of polymer:drug ratios of 2:1. The release of domperidone from best formula was highly improved with a significant (p? 0.05) increase.

Formation of Fe3AlC Base Alloy by Mechanical Alloying and Vacuum Hot Pressing

2007 ◽  
Vol 534-536 ◽  
pp. 189-192 ◽  
Author(s):  
Kazuo Isonishi
Keyword(s):  
Mechanical Alloying ◽  
Hot Pressing ◽  
Base Alloy ◽  
Average Particle Size ◽  
Processing Route ◽  
Full Density ◽  
Second Phase ◽  
Average Particle ◽  
Vacuum Hot Pressing ◽  
Metallurgical Processing

Fabrication of Fe3AlC matrix in-situ composite, reinforced by a FeAl phase, was studied by using the powder metallurgical processing route. Especially, in order to disperse the second phase more finely, we chose the mechanical alloying process. We investigated the microstructural and mechanical properties of the consolidated material. After consolidation by vacuum hot pressing, the compact showed almost full density and consisted of a Fe3AlC matrix and FeAl second phase (average particle size was less than 1μm). The compact showed HV746, which was higher than that of the arc melted Fe3AlC monolithic material, HV650.

CONTROLLED SYNTHESIS AND CHARACTERIZATION OF CERIUM-DOPED ZnS NANOPARTICLES IN HMTA MATRIX

2011 ◽  
Vol 10 (03) ◽  
pp. 487-493 ◽  
Author(s):  
K. VIJAI ANAND ◽  
R. MOHAN ◽  
R. MOHAN KUMAR ◽  
M. KARL CHINNU ◽  
R. JAYAVEL
Keyword(s):  
Quantum Confinement Effect ◽  
Average Particle Size ◽  
Surface States ◽  
Deep Trap ◽  
Average Particle ◽  
Zns Nanoparticles ◽  
Selected Area Electron Diffraction ◽  
Luminescence Process ◽  
Photoluminescence Studies

Cerium-doped ZnS nanoparticles have been synthesized through hydrothermal method. The nanoparticles were stabilized using hexamethylenetetramine (HMTA) as surfactant in aqueous solution. The average particle size of the prepared samples is about 2 nm. The structure of the as-prepared ZnS nanoparticles is cubic (zinc blende) as demonstrated by X-ray powder diffraction (XRD) and selected area electron diffraction (SAED) analysis. TEM results showed that the synthesized nanoparticles were uniformly dispersed in the HMTA matrix without aggregation. The UV–Vis absorption spectra of the prepared ZnS nanoparticles show a considerable blueshift in the absorption band edge compared to bulk ZnS indicating a strong quantum confinement effect. Formation of HMTA-capped ZnS nanoparticles was confirmed by FTIR studies. Photoluminescence studies showed that the relative emission intensity of Ce3+ -doped ZnS nanoparticles is higher than that of undoped ZnS nanoparticles, which is due to the enhancement of radiative recombination in the luminescence process. The PL spectra showed two emission peaks at around 420 nm and 442 nm, which may be attributed to deep-trap emission or defect-related emission of ZnS and presence of various surface states.

The Aggregation Study and Characterization of Silver Nanoparticles

2017 ◽  
Vol 263 ◽  
pp. 165-169
Author(s):  
Silvia Chowdhury ◽  
Faridah Yusof ◽  
Nadzril Sulaiman ◽  
Mohammad Omer Faruck
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Particle Size ◽  
Silver Nanoparticles ◽  
Absorption Spectrum ◽  
Average Particle Size ◽  
Average Particle ◽  
Transmission Electron ◽  
Vis Spectroscopy

In this article, we have studied the process of silver nanoparticles (AgNPs) aggregation and to stop aggregation 0.3% Polyvinylpyrrolidone (PVP) was used. Aggregation study carried out via UV-vis spectroscopy and it is reported that the absorption spectrum of spherical silver nanoparticles were found a maximum peak at 420 nm wavelength. Furthermore, Transmission Electron Microscopy (TEM) were used to characterized the size and shape of AgNPs, where the average particle size is around 10 to 25 nm in diameter and the AgNPs shape is spherical. Next, Dynamic Light Scattering (DLS) were used, owing to observed size distribution and self-correlation of AgNPs.

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