scholarly journals Mechanical Characterization of Cryomilled Al Powder Consolidated by High-Frequency Induction Heat Sintering

2013 ◽  
Vol 2013 ◽  
pp. 1-10 ◽  
Author(s):  
Ehab A. El-Danaf ◽  
Mahmoud S. Soliman ◽  
Abdulhakim A. Almajid ◽  
Khalil Abdelrazek Khalil
Keyword(s):  
Particle Size ◽  
Grain Size ◽  
High Frequency ◽  
X Ray Diffraction ◽  
Induction Heat ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
Thermal Stability Of ◽  
High Frequency Induction

In the present investigation, an aluminum powder of 99.7% purity with particle size of ~45 µm was cryomilled for 7 hours. The produced powder as characterized by scanning, transmission electron microscopy, and X-ray diffraction gave a particle size of ~1 µm and grain (crystallite) size of23±6 nm. This powder, after degassing process, was consolidated using high-frequency induction heat sintering (HFIHS) at various temperatures for short periods of time of 1 to 3 minutes. The present sintering conditions resulted in solid compact with nanoscale grain size (<100 nm) and high compact density. The mechanical properties of a sample sintered at 773 K for 3 minutes gave a compressive yield and ultimate strength of 270 and 390 MPa, respectively. The thermal stability of grain size nanostructured compacts is in agreement with the kinetics models based on the thermodynamics effects.

scholarly journals Nanocrystalline 6061 Al Powder Fabricated by Cryogenic Milling and Consolidated via High Frequency Induction Heat Sintering

2014 ◽  
Vol 2014 ◽  
pp. 1-9 ◽  
Author(s):  
Walid Hanna ◽  
Khinlay Maung ◽  
Ehab A. El-Danaf ◽  
Abdulhakim A. Almajid ◽  
Mahmoud S. Soliman ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Grain Size ◽  
High Frequency ◽  
Milling Time ◽  
X Ray Diffraction ◽  
Induction Heat ◽  
X Ray ◽  
Cryogenic Milling ◽  
Transmission Electron ◽  
High Frequency Induction

Nanocrystalline 6061 Al alloy was synthesized by cryogenic milling (cryomilling). Both transmission electron microscopy and X-ray diffraction were used to monitor the change in grain size as a function of milling time. The results of both techniques demonstrated a close agreement with respect to two observations: (a) during cryomilling, the grain size of 6061 Al decreased with milling time, and (b) after 15 h of milling, the grain size approached a minimum value of about 22 nm. Despite this agreement, there was a discrepancy: for grain sizes > 40 nm, the grain size measured by transmission electron microscopy was appreciably larger than that inferred from X-ray diffraction. It was shown that powders consolidated via high frequency induction heat sintering (HFIHS) at 500 and 550°C maintained close to nanoscale grain sized microstructure in addition to high compact density in bulk samples. This was manifested by high strength values as compared to microscale grain samples.

scholarly journals Characterization of hydroxyapatite-reduced graphene oxide nanocomposites consolidated via high frequency induction heat sintering method

2020 ◽  
Vol 8 (4) ◽  
pp. 1296-1309
Author(s):  
Hassan Nosrati ◽  
Rasoul Sarraf-Mamoory ◽  
Mohammad Hossein Kazemi ◽  
Maria Canillas Perez ◽  
Mahdieh Shokrollahi ◽  
...  
Keyword(s):  
Graphene Oxide ◽  
Reduced Graphene Oxide ◽  
High Frequency ◽  
Induction Heat ◽  
Reduced Graphene ◽  
Sintering Method ◽  
High Frequency Induction

Synthesis and Characterization of Plasma Synthesized Nanostructured Magnesia-Yttria Based Nanocomposites

2007 ◽  
Vol 1056 ◽  
Author(s):  
Jafar F. Al-Sharab ◽  
Rajendra Sadangi ◽  
Vijay Shukla ◽  
Bernard Kear
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Grain Size ◽  
Chemical Mapping ◽  
X Ray Diffraction ◽  
Fine Grained ◽  
Transmission Electron ◽  
Spray Method ◽  
Average Grain Size

ABSTRACTPolycrystalline Y2O3 is the material of choice for IR windows since it has excellent optical properties in the visible, and near infra-red band. However, current processing methods yield polycrystalline Y2O3 with large grain size (> 100 μm), which limits the hardness and erosion resistance attainable. One way to improve strength is to develop an ultra-fine grained material with acceptable optical transmission properties. To realize a fine-grained ceramic, one approach is to develop a composite structure, in which one phase inhibits the growth of the other phase during processing. In this study, Y2O3-MgO nanocomposite with various MgO content (20, 50 and 80 mol%) were synthesized using plasma spray method. Extensive characterization techniques including x-ray diffraction, scanning electron microscopy (SEM), Transmission electron microscopy (TEM) and Energy Dispersive spectrometry (EDS) were employed to study the synthesized powder as well as the consolidated sample. Transmission Electron Microscopy, as well as EDS chemical mapping, revealed that the consolidated sample have bi-continuous MgO-Y2O3 nanostructure with an average grain size of 200 nm.

Thermal and Structural Characterization of Nanocomposite Iron Nitride - Alumina and Iron Nitride - Silica Particles

2001 ◽  
Vol 703 ◽  
Author(s):  
Ann M. Viano ◽  
Sanjay R. Mishra
Keyword(s):  
Particle Size ◽  
Milling Time ◽  
Iron Nitride ◽  
X Ray Diffraction ◽  
X Ray ◽  
Thermal Peak ◽  
Transmission Electron ◽  
Diffraction Patterns ◽  
The One

ABSTRACTNanocomposite iron nitride based powders are known to have enhanced magnetic and other physical properties. To further explore their potential for application in various fields, we have performed a systematic study of the iron nitride - alumina and iron nitride - silica systems. Iron nitride powder of composition FexN (2 < x < 4), containing both Fe3N and Fe4N phases, was mechanically milled with Al2O3 or SiO2 powder for 4, 8, 16, 32, and 64 hours at the following compositions; (FexN)0.2(Al2O3)0.8, (FexN)0.6(Al2O3)0.4, (FexN)0.2(SiO2)0.8, and (FexN)0.6(SiO2)0.4. Differential thermal analysis and X-ray diffraction were performed to investigate thermal and structural transitions as a function of milling time. As the milling time is increased, the thermal peak corresponding to Fe4N is diminished, while the one corresponding to Fe3N is enhanced. These transitions are correlated with X-ray diffraction patterns. All XRD peaks broaden as a function of milling time, corresponding to smaller particle size. Transmission electron microscopy also reveals a decrease in particle size as the milling time in increased.

Preparation, Characterization of Co3O4 Nano-Particles and its Catalytic Effect on the Combustion of Fuel Rich Propellants

2012 ◽  
Vol 560-561 ◽  
pp. 284-288 ◽  
Author(s):  
Wei Qiang Pang ◽  
Xiao Bing Shi ◽  
Yang Li
Keyword(s):  
Particle Size ◽  
Catalytic Effect ◽  
Solid Phase ◽  
Particle Size Analysis ◽  
Nano Particles ◽  
Size Analysis ◽  
X Ray Diffraction ◽  
Transmission Electron ◽  
Wide Size Distribution

The mono-dispersed Co3O4 nano-particles were prepared by means of solid phase synthetical method. The particle size, specific surface area, crystal structure and morphology of the samples were characterized by laser particle size analysis, x-ray diffraction (XRD) and transmission electron microscopy (TEM), respectively. The catalytic effects of nano-particles on the combustion of fuel rich propellant were investigated. The results show that the Co3O4 nano-particles prepared are uniform and with relatively wide size distribution curve. The catalytic effect of Co3O4 nano-particles on the fuel rich propellant is stronger than those of micro-sized Co3O4 particles and CuO nano-particles.

Synthesis and Characterization of Li-Ti-O Nano-Composites and Their Doped BaTiO3 Based X7R-Type Ceramics

2010 ◽  
Vol 148-149 ◽  
pp. 1575-1579
Author(s):  
Qing Zhang ◽  
Rui Yuan Niu ◽  
Min Wang ◽  
Bin Cui ◽  
Zhu Guo Chang
Keyword(s):  
Particle Size ◽  
Dielectric Properties ◽  
Ph Value ◽  
Sol Gel ◽  
Nano Composites ◽  
X Ray Diffraction ◽  
Transmission Electron ◽  
Minimum Particle Size ◽  
Sol Gel Process

Li-Ti-O (abbreviated as LTO) nano-composites were synthesized via sol-gel process, and then doped BaTiO3 based X7R type ceramics. The LTO nano-composites and their ceramics were characterized by means of thermaogravimetric, Fourier-transform infrared, X-ray diffraction methods, transmission electron microscopy. We also characterized the dielectric properties of the LTO doped BaTiO3 based ceramics of X7R type. The results indicated that LTO nano-composites were nanometer scale powders. The pH value and calcining temperature had an influence on particle size of LTO sintering aids. At pH about 3 and with calcining at 600 °C, the nano-composites attained minimum particle size (about 10 nm). By adding 0.10 wt% of the LTO nano-composites, the temperature permittivity achieved about 4200 when sintered at 1240 °C for 4 h, and the dielectric properties met X7R standard.

Synthesis and Characterization of Structure Controlled Nano-cobalt Particles

2002 ◽  
Vol 755 ◽  
Author(s):  
Shiqiang Hui ◽  
Mingzhong Wu ◽  
Shihui Ge ◽  
Dajing Yan ◽  
Y.D. Zhang ◽  
...  
Keyword(s):  
Grain Size ◽  
Magnetic Properties ◽  
Silica Coating ◽  
Face Centered Cubic ◽  
X Ray Diffraction ◽  
Transmission Electron ◽  
Average Grain Size ◽  
Wet Chemical ◽  
Face Centered

ABSTRACTNanostructured cobalt particles with and without a ceramic coating have been synthesized using a wet chemical method. The structure and magnetic properties of synthesized powder were characterized using x-ray diffraction (“XRD”), high-resolution transmission electron microscopy (“HRTEM”), and a Quantum Design (SQUID) magnetometer. The cobalt nanoparticles are of either face-centered cubic (“fcc”) and/or hexagonally close-packed (“hcp”) crystalline structures. The average grain size is ∼14 nm for cobalt (either fcc or hcp) with an amorphous silica coating, and the average grain size is ∼9 nm for hcp cobalt and 26 nm for fcc cobalt without a silica coating. The effect of annealing temperature on grain size and magnetic properties are addressed.

Mechanical Properties and Consolidation of WC-8wt.%Ni Hard Materials by HFIHS and PCAS

2007 ◽  
Vol 124-126 ◽  
pp. 1153-1156 ◽  
Author(s):  
In Kyoon Jeong ◽  
Hwan Cheol Kim ◽  
Jung Mann Doh ◽  
Jin Kook Yoon ◽  
In Yong Ko ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Particle Size ◽  
Grain Size ◽  
High Frequency ◽  
Sintering Behavior ◽  
Pulsed Current ◽  
Hard Materials ◽  
Short Time ◽  
High Frequency Induction

Two methods, High-Frequency Induction-Heated Sintering (HFIHS) and Pulsed Current Activated Sintering (PCAS), were utilized to consolidate WC-8wt.%Ni hard materials. The demonstrated advantages of these processes are rapid densification to near theoretical density in a relatively short time and with insignificant change in grain size. The hardness, fracture toughness, and the relative density of the dense WC–8Ni composites produced by HFIHS and PCAS were investigated. And the effect of variation in particle size of WC powder on the sintering behavior and mechanical properties were investigated.

scholarly journals Obtaining and Characterization of TiO2-GO Composites for Photocatalytic Applications

2020 ◽  
Vol 2020 ◽  
pp. 1-9 ◽  
Author(s):  
D. K. Calvo Ramos ◽  
M. Vega González ◽  
R. A. Esparza Muñóz ◽  
J. Santos Cruz ◽  
F. J. De Moure-Flores ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Uv Radiation ◽  
Uv Light ◽  
Sol Gel ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Scanning Transmission

Titanium dioxide (TD) and graphene oxide (GO) were synthesized by sol-gel and improved Hummers method, respectively. This study shows the results of the incorporation through four different conditions (sol-gel, sol-gel and ultrasonic, annealed, and UV radiation, C1 to C4, respectively). It was observed that a homogeneous incorporation of TD on sheets of GO was obtained satisfactorily. The composites of TiO2/GO were characterized using different techniques such as X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), scanning transmission electron microscopy (STEM), energy dispersive X-ray spectroscopy (EDS), Raman spectroscopy, and infrared spectroscopy (IR). The photocatalytic activity of the composites was determined from the degradation of the dye azo tartrazine using UV and solar radiation. The best incorporation of TD nanoparticles on GO was obtained with condition C3 (thermal incorporation method) at a temperature of 65°C. This shows a uniformity in the size and shape of the TD as well as an excellent adherence to the sheet of GO. This addition is accomplished by ionic bonding in the presence of electrostatic Coulomb forces. The C3 composite degraded the tartrazine dye using UV radiation and sunlight. With the latter, the degradation time was three times faster than using UV light.

TEM and HRTEM Characterization of TiAl Diffusion Bonds Using Ni/Al Nanolayers

2014 ◽  
Vol 21 (1) ◽  
pp. 132-139 ◽  
Author(s):  
Sónia Simões ◽  
Filomena Viana ◽  
Ana S. Ramos ◽  
Maria T. Vieira ◽  
Manuel F. Vieira
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Grain Size ◽  
Bonding Temperature ◽  
Microstructural Characterization ◽  
Thin Layers ◽  
Phase Identification ◽  
Transmission Electron ◽  
Scanning Transmission

AbstractDiffusion bonding of TiAl alloys can be enhanced by the use of reactive nanolayer thin films as interlayers. Using these interlayers, it is possible to reduce the conventional bonding conditions (temperature, time, and pressure) and obtain sound and reliable joints. The microstructural characterization of the diffusion bond interfaces is a fundamental step toward understanding and identifying the bonding mechanisms and relating them to the strength of the joints. The interface of TiAl samples joined using Ni/Al nanolayers was characterized by transmission electron microscopy and scanning transmission electron microscopy. Microstructural characterization of the bond revealed that the interfaces consist of several thin layers of different composition and grain size (nanometric and micrometric). The bonding temperature (800, 900, or 1,000°C) determines the grain size and thickness of the layers present at the interface. Phase identification by high-resolution transmission electron microscopy combined with fast Fourier transform and electron energy-loss spectroscopy analyses reveals the presence of several intermetallic compounds: AlTiNi, NiAl, and Al2TiNi. For bonds produced at 800 and 900°C, nanometric grains of Ti were detected at the center of the interface.

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