Reaction Synthesis of MoSi2-Al2O3 Composite Using MoO3, Al and Si Powders

1994 ◽  
Vol 365 ◽  
Author(s):  
Seetharama C. Deevi ◽  
Sarojini Deevi
Keyword(s):  
In Situ Synthesis ◽  
Heating Rates ◽  
X Ray ◽  
Thermite Mixture ◽  
Rate Determining Step ◽  
Simultaneous Oxidation ◽  
Al2o3 Composite ◽  
Different Temperatures

ABSTRACTIn-situ synthesis of a composite of MoSi2-Al2O3 was carried out by reacting a thermite mixture consisting of MoO3, Al, and Si powders. The reaction was found to be extremely fast and violent, and a diluent was required to moderate the reaction. Thermal behavior of the thermite mixture was studied using DTA at different heating rates, and DTA was interrupted at different temperatures to determine the reaction mechanism. X-ray characterization of the products obtained at different temperatures reveals that the mechanism consists of a reduction of MoO3 by Al to MoO2 followed by a simultaneous oxidation of Al to Al2O3 and synthesis reaction between reduced Mo and Si to form MoSi2. The rate determining step is found to be reduction of MoO2 by Al and oxidation of Al to Al2O3. The thermite reaction was moderated by adding Mo and Si to the mixture of MoO3, Al, and Si such that the ratio of MoSi2 to the thermite was in the range of 60:40 to 90:10.

scholarly journals Preparation and Characterization of Chitosan Nanocomposite Based on Nanoscale Silver and Nanomontmorillonite

2019 ◽  
Vol 2 (2) ◽  
pp. 5-12 ◽  
Author(s):  
Fatemeh- Sadat Ebnerasool ◽  
Negar Motakef Kazemi
Keyword(s):  
Food Packaging ◽  
Solution Method ◽  
In Situ Synthesis ◽  
Diffusion Method ◽  
X Ray ◽  
E Coli ◽  
Packaging Industry ◽  
Scanning Electron

The chitosan nanocomposites were rapidly prepared by simple solution method. This biopolymer matrix was modified by prepared nanoscale silver (Ag) using in situ synthesis from precursor and nanomontmorillonite (NMMT). The samples were characterized by Fourier transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA), field emission scanning electron microscopy (FESEM), and energy dispersive x-ray spectroscopy (EDX). The water vapor properties (WVP) of nanocomposites were investigated using gravimetric standard. The antibacterial activity of nanocomposite was measured by the well diffusion method on Muller–Hinton Agar against Escherichia coli (E. coli) by zone inhibition. Based on the obtained results, the nanocomposite can have a good candidate for different applications and food packaging industry.

scholarly journals Synthesis and characterization of sol-gel derived monophasic mullite powder

Cerâmica ◽  
2020 ◽  
Vol 66 (379) ◽  
pp. 307-313
Author(s):  
A. Jana ◽  
D. Ray
Keyword(s):  
Sol Gel ◽  
Grain Morphology ◽  
Precursor Powder ◽  
Bet Surface Area ◽  
X Ray Diffraction ◽  
Heating Rates ◽  
X Ray ◽  
Heat Treated ◽  
Different Temperatures

Abstract High-purity microfine mullite precursor powder of stoichiometric chemical composition, 3Al2O3.2SiO2, was synthesized through the sol-gel route using aluminum isopropoxide and tetraethyl orthosilicate. The derived mullite precursor powder was characterized by BET surface area, particle size distribution, Fourier-transform infrared spectroscopy, thermogravimetry-differential thermal analysis (TG-DTA), X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy. Phase analysis of the precursor powder and calcined samples at different temperatures was done by XRD. Non-isothermal crystallization kinetics of mullite precursor was studied by TG-DTA in static air using heating rates of 5.0, 7.5, 10.0, 12.5, and 15 K.min-1. Grain morphology was studied by SEM. The results showed that synthesized mullite precursor powder possessed homogeneity of Al and Si components, and the amorphous precursor powder was converted to monophasic mullite crystal when heat-treated at 970 °C. Based on Flynn-Wall-Ozawa and Kissinger equations, the activation energy associated with the crystallization of mullite was determined to be 1189.8 and 1189.0 kJ.mol-1, respectively.

The Use of Advanced Analytical Techniques for Characterization of the Chemical, Physical, and Crystallographic Nature of a Surface

1973 ◽  
Vol 31 ◽  
pp. 132-133 ◽  
Author(s):  
R. E. Herfert
Keyword(s):  
Surface Characterization ◽  
Analytical Techniques ◽  
X Ray Diffraction ◽  
Depth Of Penetration ◽  
X Ray ◽  
The Past ◽  
Transmission Electron ◽  
Scanning Electron

Studies of the nature of a surface, either metallic or nonmetallic, in the past, have been limited to the instrumentation available for these measurements. In the past, optical microscopy, replica transmission electron microscopy, electron or X-ray diffraction and optical or X-ray spectroscopy have provided the means of surface characterization. Actually, some of these techniques are not purely surface; the depth of penetration may be a few thousands of an inch. Within the last five years, instrumentation has been made available which now makes it practical for use to study the outer few 100A of layers and characterize it completely from a chemical, physical, and crystallographic standpoint. The scanning electron microscope (SEM) provides a means of viewing the surface of a material in situ to magnifications as high as 250,000X.

scholarly journals In-situ characterization of highly reversible phase transformation by synchrotron X-ray Laue microdiffraction

2016 ◽  
Vol 108 (21) ◽  
pp. 211902 ◽  
Author(s):  
Xian Chen ◽  
Nobumichi Tamura ◽  
Alastair MacDowell ◽  
Richard D. James
Keyword(s):  
Phase Transformation ◽  
In Situ Characterization ◽  
X Ray ◽  
Reversible Phase ◽  
Laue Microdiffraction

scholarly journals A Superhydrophobic, Antibacterial, and Durable Surface of Poplar Wood

Nanomaterials ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 1885
Author(s):  
Xinyu Wu ◽  
Feng Yang ◽  
Jian Gan ◽  
Zhangqian Kong ◽  
Yan Wu
Keyword(s):  
Stearic Acid ◽  
Antibacterial Properties ◽  
Alkali Resistance ◽  
Poplar Wood ◽  
X Ray Diffraction ◽  
X Ray ◽  
Different Temperatures ◽  
Acid And Alkali Resistance ◽  
The Stability

The silver particles were grown in situ on the surface of wood by the silver mirror method and modified with stearic acid to acquire a surface with superhydrophobic and antibacterial properties. Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and X-ray energy spectroscopy (XPS) were used to analyze the reaction mechanism of the modification process. Scanning electron microscopy (SEM) and contact angle tests were used to characterize the wettability and surface morphology. A coating with a micro rough structure was successfully constructed by the modification of stearic acid, which imparted superhydrophobicity and antibacterial activity to poplar wood. The stability tests were performed to discuss the stability of its hydrophobic performance. The results showed that it has good mechanical properties, acid and alkali resistance, and UV stability. The durability tests demonstrated that the coating has the function of water resistance and fouling resistance and can maintain the stability of its hydrophobic properties under different temperatures of heat treatment.

scholarly journals Structural Characterization of Heterodinuclear ZnII-LnIII Complexes (Ln = Pr, Nd) with a Ring-Contracted H2valdien-Derived Schiff Base Ligand

2021 ◽  
Author(s):  
Shabana Noor ◽  
Richard Goddard ◽  
Fehmeeda Khatoon ◽  
Sarvendra Kumar ◽  
Rüdiger W. Seidel
Keyword(s):  
Molecular Structure ◽  
Schiff Base ◽  
Structural Characterization ◽  
Schiff Base Ligand ◽  
Crystal And Molecular Structure ◽  
X Ray ◽  
X Ray Crystallography ◽  
Imidazoline Ring

AbstractSynthesis and structural characterization of two heterodinuclear ZnII-LnIII complexes with the formula [ZnLn(HL)(µ-OAc)(NO3)2(H2O)x(MeOH)1-x]NO3 · n H2O · n MeOH [Ln = Pr (1), Nd (2)] and the crystal and molecular structure of [ZnNd(HL)(µ-OAc)(NO3)2(H2O)] [ZnNd(HL)(OAc)(NO3)2(H2O)](NO3)2 · n H2O · n MeOH (3) are reported. The asymmetrical compartmental ligand (E)-2-(1-(2-((2-hydroxy-3-methoxybenzylidene)amino)-ethyl)imidazolidin-2-yl)-6-methoxyphenol (H2L) is formed from N1,N3-bis(3-methoxysalicylidene)diethylenetriamine (H2valdien) through intramolecular aminal formation, resulting in a peripheral imidazoline ring. The structures of 1–3 were revealed by X-ray crystallography. The smaller ZnII ion occupies the inner N2O2 compartment of the ligand, whereas the larger and more oxophilic LnIII ions are found in the outer O2O2’ site. Graphic Abstract Synthesis and structural characterization of two heterodinuclear ZnII-LnIII complexes (Ln = Pr, Nd) bearing an asymmetrical compartmental ligand formed in situ from N1,N3-bis(3-methoxysalicylidene)diethylenetriamine (H2valdien) through intramolecular aminal formation are reported.

In situsmall-angle X-ray scattering characterization of X-ray-induced local heating

2014 ◽  
Vol 47 (6) ◽  
pp. 2078-2080 ◽  
Author(s):  
Monika Witala ◽  
Jun Han ◽  
Andreas Menzel ◽  
Kim Nygård
Keyword(s):  
Local Heating ◽  
Liquid Mixtures ◽  
Glass Capillary ◽  
Sample Container ◽  
X Ray ◽  
X Ray Scattering ◽  
Synchrotron Light ◽  
Ray Scattering

It is shown that small-angle X-ray scattering from binary liquid mixtures close to the critical point of demixing can be used forin situcharacterization of beam-induced heating of liquid samples. For demonstration purposes, the proposed approach is applied on a well studied critical mixture of water and 2,6-lutidine. Given a typical incident X-ray flux at a third-generation synchrotron light source and using a 1.5 mm-diameter glass capillary as sample container, a beam-induced local temperature increase of 0.45 ± 0.10 K is observed.

Anin situatomic force microscope for normal-incidence nanofocus X-ray experiments

2016 ◽  
Vol 23 (5) ◽  
pp. 1110-1117 ◽  
Author(s):  
M. V. Vitorino ◽  
Y. Fuchs ◽  
T. Dane ◽  
M. S. Rodrigues ◽  
M. Rosenthal ◽  
...  
Keyword(s):  
Thin Film ◽  
Atomic Force Microscope ◽  
High Speed ◽  
Normal Incidence ◽  
Organic Thin Film ◽  
X Ray ◽  
Atomic Force ◽  
Synchrotron Beamlines

A compact high-speed X-ray atomic force microscope has been developed forin situuse in normal-incidence X-ray experiments on synchrotron beamlines, allowing for simultaneous characterization of samples in direct space with nanometric lateral resolution while employing nanofocused X-ray beams. In the present work the instrument is used to observe radiation damage effects produced by an intense X-ray nanobeam on a semiconducting organic thin film. The formation of micrometric holes induced by the beam occurring on a timescale of seconds is characterized.

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