Effect of Heating Rate on Sintered Microstructure of W-Cu Nanocomposite Powder Produced Using W-CuO Mixture

2004 ◽  
Vol 449-452 ◽  
pp. 1125-1128
Author(s):  
Dae Gun Kim ◽  
Gil Su Kim ◽  
Jin Chun Kim ◽  
Sung Tag Oh ◽  
Young Do Kim
Keyword(s):  
Heating Rate ◽  
Nanocomposite Powder ◽  
Lower Heating Rate ◽  
Nanocomposite Powders ◽  
Heating Up ◽  
Lower Heating

The sintered microstructure homogeneity of W-15wt%Cu nanocomposite powders prepared from W-CuO mixture was investigated. The increment of heating rate considerably affected the homogeneity of sintered microstructure. In case of the higher heating rate, the microstructure was more homogeneous than that of the lower heating rate by reason of Cu- exudation during heating-up process.

"Scan" behaviour in Podarcis muralis: the use of vantage points by an actively foraging lizard

1993 ◽  
Vol 14 (3) ◽  
pp. 247-259 ◽  
Author(s):  
Roger Avery ◽  
Annabel Basker ◽  
Claudia Corti
Keyword(s):  
Heating Rate ◽  
Rapid Heating ◽  
Thin Strip ◽  
Podarcis Muralis ◽  
Podarcis Sicula ◽  
Lacerta Viridis ◽  
Lower Heating Rate ◽  
Vantage Points ◽  
Rapid Heating Rate ◽  
Lower Heating

AbstractTwo adult Podarcis muralis whose normal movements incorporated the flat top of a wall, frequently paused so that they were looking outwards from an edge ("scan" posture), especially during longer (≥9 s) periods immobile. Investigations of the posture on raised wooden platforms in outdoor enclosures, using two juvenile lizards, showed that (1) lizards spent significantly more time on platforms than would be expected from random movement, and this was not because wood is a favoured substrate for basking; (2) lizards which were immobile on platforms spent significantly more time at edges than would be expected by chance; (3) body orientations at 67.5-112.5° to the edge were the most frequent and these were maintained for significantly longer periods than the remaining orientations; exceptions were from 0800-0900 h when orientation was often parallel to the edge facing the sun and from 1200-1300 h with only a thin strip of shade at 45°, into which the lizards fitted themselves. Lizards basking in the laboratory beneath a tungsten bulb at the edge of a raised platform adopted outward-facing orientations when the platform height was ≥6 mm. When presented with a choice between basking more effectively (i.e. rapid heating rate) or adopting the "scan" posture at an edge with a lower heating rate or with no heating, they opted for the former. Podarcis sicula, P. filfolensis, Lacerta viridis and L. vivipara all showed an excess of outward-facing orientations when the basking bulbs were place near edges of platforms, but Psammodromus hispanicus did not. Only the two Podarcis species, however, spent more time on raised platforms than would be expected by chance when basking was possible at many sites in an arena.

Coalescence of Cu contacted nanoparticles with different heating rates: A molecular dynamics study

2016 ◽  
Vol 30 (30) ◽  
pp. 1650212 ◽  
Author(s):  
Qibin Li ◽  
Tao Fu ◽  
Tiefeng Peng ◽  
Xianghe Peng ◽  
Chao Liu ◽  
...  
Keyword(s):  
Heating Rate ◽  
Gyration Radius ◽  
Cu Nanoparticles ◽  
Heating Rates ◽  
Shrinkage Ratio ◽  
Initial Stage ◽  
Fundamental Understanding ◽  
Lower Heating Rate ◽  
And Diffusion ◽  
Lower Heating

The coalescence, the initial stage of sintering, of two contacted Cu nanoparticles is investigated under different heating rates of 700, 350 and 233 K/ns. The nanoparticles coalesced rapidly at the initial stage when the temperature of the system is low. Then, the nanoparticles collided softly in an equilibrium period. After the system was increased to a high temperature, the shrinkage ratio, gyration radius and atoms’ diffusion started to change dramatically. The lower heating rate can result in smaller shrinkage ratio, larger gyration radius and diffusion of atoms. However, the growth of sintering neck is hardly influenced by the heating rate. The results provide a theoretical guidance for the fundamental understanding and potential application regarding nanoparticle sintering.

A Comparative Analysis of the Kinetic Experiments in Polyethylene Pyrolysis

2013 ◽  
Vol 136 (2) ◽  
Author(s):  
Pravin Kannan ◽  
Salisu Ibrahim ◽  
K. Suresh Kumar Reddy ◽  
Ahmed Al Shoaibi ◽  
C. Srinivasakannan
Keyword(s):  
Kinetic Parameters ◽  
Heating Rate ◽  
Kinetic Data ◽  
Mass Transfer Resistance ◽  
Review Of Literature ◽  
Transfer Resistance ◽  
Lower Heating Rate ◽  
Polymer Pyrolysis ◽  
The Difference ◽  
Lower Heating

A review of literature has been conducted to survey the kinetic data of low-density polyethylene (LDPE) pyrolysis. The review reveals large variations in the reported global kinetic parameters. The cause of variation has been identified to be the difference in the experimental techniques, including thermogravimetric analysis (TGA) and non-TGA methods. Even within the nonisothermal TGA data, large variations have been observed at heating rate of 20 K/min, while the variations are insignificant at lower heating rate regimes (2–10 K/min), indicating the influence of heat/mass transfer resistance controlling the kinetics. Detailed analysis revealed that most of the current techniques are unable to capture all the relevant data necessary for estimating the kinetic parameters of the aforementioned process. The outcome of this review work thrusts the need for a better experimental technique to estimate the kinetic parameters of complex reactions, such as polymer pyrolysis.

Development of Electroless Ni-P/NRAM Nanocomposite Powder with Enhanced Microwave Absorption Properties

2009 ◽  
Vol 67 ◽  
pp. 59-64 ◽  
Author(s):  
Rahul Sharma ◽  
Ramesh Chandra Agarwala ◽  
Vijaya Agarwala
Keyword(s):  
Electron Microscope ◽  
Microwave Absorption ◽  
Radiation Power ◽  
Nanocomposite Powder ◽  
Absorption Properties ◽  
Microwave Absorption Properties ◽  
Radar Absorbing Material ◽  
Transmission Electron ◽  
Absorbing Material ◽  
Nanocomposite Powders

Nano radar absorbing material (NRAM) i.e. BaMe2Fe16O27 (Me2+=Fe2+) powder (10 nm) is coated with amorphous Ni-P nano layer (5-10 nm) by using electroless (EL) technology to develop EL Ni-P/NRAM nanocomposite powder. The experimental processes parameters and EL Ni-P bath composition were optimized to obtain the deposition. As-deposited nanocomposite powder was microwave annealed (MWA) with increasing radiation power from 160 to 760 watts for 5 minutes. The surface morphology, elemental contents, phase transformation and magnetic properties of NRAM powders were examined under field emission scanning electron microscope (FESEM), transmission electron microscope (TEM), X-ray diffraction (XRD) and vibrating sample magnetometer (VSM) respectively. Maximum reflection loss (RL) 33.75 dB at 15.80 GHz for nanocomposite powder MWA at 760 watt was obtained the absorption range under −15 dB is from 13.76 to 16.77 GHz with 2 mm thickness layer in Ku Band. Excellent microwave absorption properties due to accurate electromagnetic (EM) match in the nanocomposite microstructure, a strong natural resonance and multipolarization. Such (Ni+ Ni3P)/NRAM nanocomposite powders may be attractive candidates for EM absorption.

scholarly journals Effects of heating rate and heating up time to central biomass particles for bio-oil production

2016 ◽  
Vol 51 (1) ◽  
pp. 13-22
Author(s):  
MB Ahmed ◽  
ATMK Hasan ◽  
M Mohiuddin ◽  
M Asadullah ◽  
MS Rahman ◽  
...  
Keyword(s):  
Heating Rate ◽  
Particle Temperature ◽  
Product Distribution ◽  
Heating Rates ◽  
Final Temperature ◽  
Central Mass ◽  
Bio Oil ◽  
Reactor Temperature ◽  
Biomass Particles ◽  
Heating Up

Objective of this work was to pyrolysis woody biomass. Experiments were carried out at 300 to 500oC. Relatively bigger particles were used. Special emphasis was given to investigate the effects of heating rate and heating up time of the central mass of the particles on the product distribution. Surface temperature reached to the reactor set temperature immediately while the temperature at the central part was as low as 50oC. The center temperature gradually increased to the final temperature within 3 to 8 minutes, depending on the wood types and the reactor set temperature. For ipil-ipil wood the heating rate of the central mass was much faster than krishnachura and koroi woods, and thus the heating up time was lower. Ipil-ipil wood was experienced higher yield (65%) even at lower reactor temperature 300oC with particle temperature 450oC. In the case of krishnachura and koroi woods, the bio-oil yields were lower under the same condition due to the heating rates of the central parts were much slower. Further researchon different biomasses may be necessary to demonstrate overall process.Bangladesh J. Sci. Ind. Res. 51(1), 13-22, 2016

The Effect of Reinforcement Phase on the Microstructure of Al-SiC Nanocomposite Powder Prepared via Mechanical Alloying

2009 ◽  
Vol 83-86 ◽  
pp. 764-770
Author(s):  
Taha Rostamzadeh ◽  
H. Shahverdi ◽  
R. Sarraf-Mamoory ◽  
A. Shanaghi
Keyword(s):  
Electron Microscopy ◽  
Mechanical Alloying ◽  
Metal Matrix ◽  
Milling Time ◽  
Lattice Strain ◽  
Volume Fraction ◽  
Aluminum Matrix ◽  
High Energy ◽  
Nanocomposite Powder ◽  
Nanocomposite Powders

Mechanical alloying is one of the most successful methods for the manufacturing of metal matrix nanocomposite powders. In this study, Al/SiC metal matrix composite (MMCp) powders with volume fractions of 5, 10, and 15 percent SiC were successfully obtained after milling the powder for a period of 25 hours at a ball to powder ratio of 15:1 using high energy planetary milling. The Scanning electron microscopy (SEM) and X-ray diffraction (XRD) analyses were conducted to investigate the lattice strain of the matrix phase and the microstructure of the nanocomposite powders after 1, 10, and 25 hours of milling time. Also, the morphology of the Al-5%SiC nanocomposite powder was investigated using transmission electron microscopy (TEM). The results show that with the increase of both milling time and the reinforcement phase volume fraction, the lattice strain increases and the average size of aluminum phase crystallites decreases. Eventually, after 25 hours of milling, the nanocomposite powders show a spherical-like morphology and SiC particles were distributed in an aluminum matrix with appropriate order.

scholarly journals Optimized Heating Rate and Soot-catalyst Ratio for Soot Oxidation over MoO3 Catalyst

2017 ◽  
Vol 12 (3) ◽  
pp. 408 ◽  
Author(s):  
Congwei Mei ◽  
Deqing Mei ◽  
Shan Yue ◽  
Zong Chen ◽  
Yinnan Yuan
Keyword(s):  
Heating Rate ◽  
Soot Oxidation ◽  
Transfer Effect ◽  
Reaction Engineering ◽  
Heating Rates ◽  
Thermogravimetric Analyzer ◽  
Ft Ir ◽  
Surface Microstructures ◽  
And Diffusion ◽  
Lower Heating

MoO3 is now utilized as a promising catalyst due to its high activity and favorable mobility at low temperature. Its spectral data and surface microstructures were characterized by Fourier transform infrared spectra (FT-IR) and Field emission scanning electron microscope (FESEM). Thermo-analysis of the carbon black was performed over nano-MoO3 catalyst in a thermogravimetric analyzer (TGA) at various heating rates and soot-catalyst ratios. Through the analysis of kinetic parameters, we found that the heat transfer effect and diffusion effect can be removed by setting lower heating rates and soot-catalyst ratios. Therefore, a strategy for selecting proper thermogravimetric parameters were established, which can contribute to the better understanding of thermo-analytical process. Copyright © 2017 BCREC Group. All rights reservedReceived: 4th December 2016; Revised: 13rd June 2017; Accepted: 9th April 2017; Available online: 27th October 2017; Published regularly: December 2017How to Cite: Mei, C., Mei, D., Yue, S, Chen, Z., Yuan, Y. (2017). Optimized Heating Rate and Soot-catalyst Ratio for Soot Oxidation over MoO3 Catalyst. Bulletin of Chemical Reaction Engineering & Catalysis, 12 (3): 408-414 (doi:10.9767/bcrec.12.3.845.408-414 

scholarly journals Transient Liquid Phase Sintering of PM Steel—A Matter of the Heating Rate

Metals ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 1662
Author(s):  
Stefan Geroldinger ◽  
Raquel de Oro Calderon ◽  
Christian Gierl-Mayer ◽  
Herbert Danninger
Keyword(s):  
Liquid Phase ◽  
Heating Rate ◽  
Transient Liquid Phase ◽  
Liquid Phase Sintering ◽  
Alloying Elements ◽  
Heating Rates ◽  
Different Temperatures ◽  
Transient Liquid Phase Sintering ◽  
Heating Up ◽  
Cct Diagrams

Powder metallurgy (PM) offers several variants to introduce alloying elements for establishing the desired final composition. One route is the master alloy (MA) approach. The composition and the elements contained in the MA can be adjusted to obtain a liquid phase that penetrates through the interconnected pore network and thus enhances the distribution of the alloying elements and the homogenization of the microstructure. Such a liquid phase is often of a transient character, and therefore the amount of liquid formed and the time the liquid is present during the sintering are highly dependent on the heating rates. The heating rate has also an impact on the reaction temperatures, and therefore, by properly adjusting the heating rate, it is possible to sinter PM-steels alloyed with Fe-Cr-Si-C-MA at temperatures below 1250 °C. The present study shows the dependence of the melting regimes on the heating rate (5, 10, 20, 120 K/min) represented by “Kissinger plots”. For this purpose, liquid phase formation and distribution were monitored in quenching dilatometer experiments with defined heating up to different temperatures (1120 °C, 1180 °C, 1250 °C, 1300 °C) and subsequent quenching. Optimum sintering conditions for the materials were identified, and the concept was corroborated by C and O analysis, CCT diagrams, metallographic sections, and hardness measurements.

Reaction Sintering of Mg2Si Intermetallic Compound by Microwave Irradiation

2012 ◽  
Vol 512-515 ◽  
pp. 1683-1686
Author(s):  
Chang Kun Du ◽  
Shu Cai Zhou
Keyword(s):  
Solid State ◽  
Intermetallic Compound ◽  
Microwave Field ◽  
Phase Reaction ◽  
Reaction Sintering ◽  
Green Density ◽  
Power Setting ◽  
Lower Heating Rate ◽  
Lower Heating ◽  
Heating Profile

In order to reduce the oxidizing and volatilizing caused by Mg element in the traditional methods for synthesizing Mg2Si compounds, solid state phase reaction at low temperature was introduced by microwave field. XRD was used to characterize the powders. At the same time, the influences of parameters during the synthesis processing were discussed. The results suggest that the heating profile is also dependent on the initial green density and higher green density provides lower heating rate while power setting are fixed and the oxidation of Mg can be rest rained by changing microwave heating programs. It was found that high purity Mg2Si intermetallic compound can be obtained with excessive content of 8at% Mg from the stoichiometric Mg2Si, 853K and 30min

Chemical synthesis and densification of a novel Ag/Cr2O3-AgCrO2 nanocomposite powder

2018 ◽  
Vol 25 (4) ◽  
pp. 739-743 ◽  
Author(s):  
Mohammad Ardestani ◽  
Farshid Karpasand
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Synthesis Method ◽  
Chemical Precipitation ◽  
Precipitation Method ◽  
Nanocomposite Powder ◽  
Dense Microstructure ◽  
Air Atmosphere ◽  
Nanocomposite Powders ◽  
Scanning Electron

Abstract Ag/Cr2O3-AgCrO2 nanocomposite powders were chemically synthesized using a chemical precipitation method. The synthesis method stages included precipitation and calcination. The initial precipitates contained Cr(OH)3·3H2O and Ag2CO3 compounds. Calcination of the initial precipitates led to thermal decomposition of the precipitates and evaporation of volatile compounds such as H2O and CO2. The calcined precipitates contained silver, chromium oxide, and silver-chromia. The crystallite size of Ag2CO3 and Ag were determined as 18.9 and 45 nm, respectively. The scanning electron microscopy investigations showed that the particle size of the initial precipitates was lower than 100 nm. The calcined powders were sintered at 550°C in air atmosphere. The sintered samples were cold-repressed under 300 and 550 MPa. It was found that by increasing the repressing compaction magnitudes, the density and hardness of the sintered samples were increased. The scanning electron microscopy evaluation of the densified samples showed nearly dense microstructure.

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