Characterization of Ni-CNTs Nanocomposites Produced by Mechanical Alloying

2013 ◽  
Vol 829 ◽  
pp. 515-519 ◽  
Author(s):  
Shaghayegh Gharegozloo ◽  
Hossein Abdizadeh ◽  
Abolghasem Ataie
Keyword(s):  
Mechanical Milling ◽  
Milling Time ◽  
High Energy ◽  
X Ray Diffraction ◽  
Metal Matrix Nanocomposites ◽  
X Ray ◽  
Milling Method ◽  
Particle Refinement ◽  
Matrix Nanocomposites

The interest in using CNTs as the reinforcement of metal matrix nanocomposites has been growing considerably due to their enhanced properties. In the present work, nickel was reinforced by carbon nanotubes (CNTs) via high energy mechanical milling method. The effects of various amounts of CNTs (5%, 10%, 20% and 30%) and different milling times (1, 5, 10 and 15 hours) were investigated. X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) and vibrating sample magnetometer (VSM) analysis were used for evaluation of phase composition, morphology and magnetic properties of the samples, respectively. The results showed a homogeneous dispersion of CNTs into the nickel matrix phase by mechanical milling. It was observed that the increase in the milling time, for a particular amount of CNTs, caused a decrease of mean crystallite size from 56 nm to 35 nm. The increase of CNTs amount also resulted in the powder particle refinement. VSM analysis showed that with the increase of CNTs from 0% to 30%, the magnetization of the samples decreases from 52.36 to 30.74 emu/g, and the coercivity of the nanocomposites increases from 61.45 to 114 Oe.

DSC-TGA Hydrogen Evaluation during Mechanical Milling of AlFe Intermetallic

2013 ◽  
Vol 755 ◽  
pp. 105-110 ◽  
Author(s):  
E. García de León M. ◽  
O. Téllez-Vázquez ◽  
C. Patiño-Carachure ◽  
G. Rosas
Keyword(s):  
Mechanical Milling ◽  
Milling Time ◽  
Hydrogen Generation ◽  
Pure Aluminum ◽  
High Energy ◽  
Milling Process ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Diffraction Patterns

Fe40Al60 (at%) intermetallic alloy composition was obtained by conventional casting methods and subsequently subjected to high-energy mechanical milling under different conditions of humidity. All samples were characterized by X-ray diffraction patterns (XRD), transmission electron microcopy (TEM) and DSC-TGA thermogravimetric experiments. After the milling process, the amount of hydrogen generated was determined using thermogravimetric analysis and chemical reactions (stoichiometry). All techniques confirm the formation of bayerite phase which is attributed to the hydrogen embrittlement reaction between the intermetallic material and water to release hydrogen. It was observed that the hydrogen generation is increased as the ball milling time is increased. The quantity of hydrogen evaluated is similar to that obtained in previous reported experiments with pure aluminum and some of its alloys.

Mechanochemical Synthesis and Characterization of FeNi-Al2O3 Nanocomposites

2011 ◽  
Vol 413 ◽  
pp. 109-116 ◽  
Author(s):  
Seyyed Abdalkarim Sajjadi ◽  
Hossein Beygi ◽  
Mansour Zare
Keyword(s):  
Milling Time ◽  
Phase Evolution ◽  
Synthesis And Characterization ◽  
Maximum Hardness ◽  
X Ray Diffraction ◽  
X Ray ◽  
Mixture Characterization ◽  
Matrix Nanocomposites ◽  
Scanning Electron

In this Study, FeNi-Al2O3 nanocomposites with three different compositions were successfully synthesized through mechanical alloying of Fe2O3, Ni and Al powders mixture. Characterization of the products was accomplished by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX) and X-ray diffraction (XRD). The effect of various parameters such as chemical composition of starting materials, milling time and annealing on the phase evolution, morphology and microhardness of samples was investigated. It was found that FeNi matrix nanocomposites reinforced with 10, 15 and 30wt.% of Al2O3 were fabricated in 300, 240 and 180 min of milling, respectively. The crystallite size of the intermetallic FeNi phase and particle size of Al2O3 in the 720 min milled FeNi-30wt.%Al2O3 nanocomposite sample were calculated 28nm and 5.15 µm, respectively. Microhardness results also showed the same sample had the maximum hardness value of 790 HV.

scholarly journals Structural, magnetic properties and microwave absorbing behavior of iron based carbon nanocomposites

2016 ◽  
Vol 12 (1) ◽  
Author(s):  
Mashadi Sunandar
Keyword(s):  
Magnetic Properties ◽  
Mechanical Milling ◽  
Room Temperature ◽  
High Energy ◽  
Frequency Range ◽  
X Ray Diffraction ◽  
X Ray ◽  
Microwave Absorbing Materials ◽  
Milling Method ◽  
Microwave Absorbing

Nanocomposite of α-Fe/C was successfully synthesized by mechanical milling method. Analytical-grade of α-Fe and graphite powders with a purity of greater than 99% were mixed. The mixture was milled for 50 hours at room temperature using High Energy Milling (HEM). The refinement results of X-ray diffraction pattern shows that the α-Fe/C nanocomposite consists of 20 wt% Fe and 80 wt% C. The mechanical milling resulted in α-Fe/C powders with mean particle size ~900 nm. The image reveals the morphology of particle and the particles that exist is aggregates of fine grains. The magnetic properties of the particle α-Fe/C nanocomposite showed low coercivity and high remanent magnetization. The α-Fe/C nanocomposite has certain microwave absorber properties in the frequency range of 9 – 15 GHz, with the maximum reflection loss reaches -10 dB at 12 GHz and the absorption range under −4 dB is from 11.2 to 15.5 GHz with 2 mm thickness. The study concluded that the α-Fe/C nanocomposite shows good candidate materials for microwave absorbing materials applications. 

Influence of Milling Time on the Homogeneity of the Al2O3/Ni Composite Powders Obtained by Mechanical Milling

2014 ◽  
Vol 216 ◽  
pp. 146-150 ◽  
Author(s):  
Cristina Voicu ◽  
Florin Popa ◽  
Petru Pascuta ◽  
Ionel Chicinaş
Keyword(s):  
Mechanical Milling ◽  
Milling Time ◽  
High Energy ◽  
X Ray Diffraction ◽  
Nanocomposite Powder ◽  
Composite Powders ◽  
X Ray ◽  
Two Phases ◽  
The Stability ◽  
High Level

Al2O3/Ni nanocomposite powder was obtained by high-energy mechanical milling starting from a mixture of Al2O3 and Ni commercially powders. The Al2O3+15%vol. Ni mixture was homogenized for 15 minutes in the Turbula-type blender and then was milled in a planetary ball mill (Fritsch, Pulverisette 4) under argon atmosphere up to 120 min. Several milling times were used: 10, 30, 60, 90 and 120 minutes respectively. The evolution of the powders during milling and the stability of the composite phases were investigated by X-ray diffraction (XRD), optical microscopy (OM), scanning electron microscopy (SEM) and energy dispersive X-ray microanalysis (EDX). The SEM and OM images show a high level of homogenization of the Ni and Al2O3 phases for milling times larger than 90 minutes. The X-ray studies indicate no mixing between the two phases. The crystallite grain size is decreasing with the milling time.

Microstructure Evolution of a Fine Grain Al-50wt%Si Alloy Fabricated by High Energy Milling

2011 ◽  
Vol 479 ◽  
pp. 54-61 ◽  
Author(s):  
Fei Wang ◽  
Ya Ping Wang
Keyword(s):  
Grain Growth ◽  
Microstructure Evolution ◽  
Room Temperature ◽  
Milling Time ◽  
High Energy ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Laser Method ◽  
X Ray ◽  
Fine Grain

Microstructure evolution of high energy milled Al-50wt%Si alloy during heat treatment at different temperature was studied. Scanning electron microscope (SEM) and X-ray diffraction (XRD) results show that the size of the alloy powders decreased with increasing milling time. The observable coarsening of Si particles was not seen below 730°C in the high energy milled alloy, whereas, for the alloy prepared by mixed Al and Si powders, the grain growth occurred at 660°C. The activation energy for the grain growth of Si particles in the high energy milled alloy was determined as about 244 kJ/mol by the differential scanning calorimetry (DSC) data analysis. The size of Si particles in the hot pressed Al-50wt%Si alloy prepared by high energy milled powders was 5-30 m at 700°C, which was significantly reduced compared to that of the original Si powders. Thermal diffusivity of the hot pressed Al-50wt%Si alloy was 55 mm2/s at room temperature which was obtained by laser method.

Single Crystal Wurtzitic Aluminum Nitride Growth on Silicon Using Supersonic Gas Jets

1995 ◽  
Vol 395 ◽  
Author(s):  
S. A. Ustin ◽  
L. Lauhon ◽  
K. A. Brown ◽  
D. Q. Hu ◽  
W. Ho
Keyword(s):  
Aluminum Nitride ◽  
Growth Rates ◽  
High Energy ◽  
X Ray Diffraction ◽  
Rutherford Back Scattering ◽  
X Ray ◽  
Supersonic Molecular Beam ◽  
Supersonic Beams ◽  
Wide Range

ABSTRACTHighly oriented aluminum nitride (0001) films have been grown on Si(001) and Si (111) substrates at temperatures between 550° C and 775° C with dual supersonic molecular beam sources. Triethylaluminum (TEA;[(C2H5)3Al]) and ammonia (NH3) were used as precursors. Hydrogen, helium, and nitrogen were used as seeding gases for the precursors, providing a wide range of possible kinetic energies for the supersonic beams due to the disparate masses of the seed gases. Growth rates of AIN were found to depend strongly on the substrate orientation and the kinetic energy of the incident precursor; a significant increase in growth rate is seen when seeding in hydrogen or helium as opposed to nitrogen. Growth rates were 2–3 times greater on Si(001) than on Si(111). Structural characterization of the films was done by reflection high energy electron diffraction (RHEED) and x-ray diffraction (XRD). X-ray rocking curve (XRC) full-width half-maxima (FWHM) were seen as small as 2.5°. Rutherford back scattering (RBS) was used to determine the thickness of the films and their chemical composition. Films were shown to be nitrogen rich, deviating from perfect stoichiometry by 10%–20%. Surface analysis was performed by Auger electron spectroscopy (AES).

Effect of Process on the Dielectric Properties of BaTiO3-Based X9R Ceramics

2014 ◽  
Vol 906 ◽  
pp. 18-24 ◽  
Author(s):  
Bao Lin Zhang ◽  
Bin Bin Zhang ◽  
Ning Ning Wang ◽  
Jing Ming Fei
Keyword(s):  
Particle Size ◽  
Dielectric Properties ◽  
Milling Time ◽  
Sintering Temperature ◽  
Sintering Process ◽  
X Ray Diffraction ◽  
Sintered Ceramic ◽  
X Ray ◽  
Particle Size Analyzer

The effect of milling time and sintering process on the dielectric properties of BaTiO3-based X9R ceramics was investigated. The characterization of the raw powders and the sintered ceramic was carried out by X-ray diffraction and scanning electron microscopy. The particle size distribution of the mixed powders was examined by Laser Particle Size Analyzer. The results shown that with the milling time extended, the Cruie Peak was depressed, or even disappeared. Moreover, with the rise of sintering temperature, the dielectric constant of the ceramics increased and the dielectric loss decreased gradually. Eventually, by milling for 11h and sintering at 1090°Cfor 2h, good dielectric properties were obtained, which were ε25°C≥ 2526, εr/εr25°C≤± 12% (–55~200°C), tanδ≤1.12% (25°C).

Synthesis and Characterization of Nanostructured Mechanical Cu-Fe-Co Alloy

2018 ◽  
Vol 941 ◽  
pp. 1232-1237
Author(s):  
Alisiya Biserova-Tahchieva ◽  
Isabel López-Jiménez ◽  
Núria Llorca-Isern
Keyword(s):  
Defect Density ◽  
Nanocrystalline Structure ◽  
High Energy ◽  
Magnetic Behaviour ◽  
X Ray Diffraction ◽  
X Ray ◽  
Soft Ferromagnetic ◽  
Hours Of Work ◽  
And Diffusion

Nanocrystalline structure of CuFeCo (50:25:25 wt%) alloy has been obtained by high energy mechanical milling from elemental metal powder mixture during large hours of work. Phase transformations and diffusion in the system subjected to heat treatment are discussed. Thermal stability at high temperatures is analysed and considered of importance for several applications. The nanostructure was studied by employing X-Ray diffraction and electron microscopy. It has been determined the reduction in crystallite size and the induced microstrain by the milling time. The solid solution achievement through the increment of defect density was confirmed by Mössbauer analysis. Magnetic behaviour was analysed through magnetization technique entailing their soft ferromagnetic behaviour related to the microstructural changes.

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