Effects of Temperature and Heating Rate on the Precipitation of 3C-SiC Islands on 4H-SiC(0001) from a Liquid Phase

2009 ◽  
Vol 615-617 ◽  
pp. 193-196
Author(s):  
Olivier Kim-Hak ◽  
Gabriel Ferro ◽  
Jacques Dazord ◽  
Patrick Chaudouët ◽  
Didier Chaussende
Keyword(s):  
Liquid Phase ◽  
Heating Rate ◽  
Graphite Crucible ◽  
Heating Rates ◽  
Final Temperature ◽  
Initial Stage ◽  
Vls Growth ◽  
Effects Of Temperature

Like on 6H-SiC substrates, 3C-SiC islands precipitation was found to be the initial stage of the VLS growth of 3C-SiC layers on 4H-SiC surfaces. This precipitation happens between 1100 and 1200°C with a heating rate of 2.8°C.s-1, without addition of propane. The islands size increases in a similar manner whether the final temperature increases (for a given heating rate) or the heating rate decreases (for a given final temperature). This enlargement can give rise to a complete cubic layer for the highest temperatures or the slowest heating rates. It is suggested that the carbon atoms involved in the enlargement process (after the nucleation) come from the graphite crucible.

INVESTIGATION OF THERMAL DEGRADATION OF POULTRY PROCESSING DEWATERED SLUDGE USING THERMOGRAVIMETRIC ANALYSIS METHOD

2015 ◽  
Vol 76 (5) ◽  
Author(s):  
N. Aniza ◽  
S. Hassan ◽  
M. F. M. Nor ◽  
K. E. Kee ◽  
Aklilu T.
Keyword(s):  
Particle Size ◽  
Thermogravimetric Analysis ◽  
Thermal Degradation ◽  
Heating Rate ◽  
Degradation Process ◽  
Heating Rates ◽  
Initial Stage ◽  
Poultry Processing ◽  
Effect Of Particle Size ◽  
Dewatered Sludge

Thermal degradation of Poultry Processing Dewatered Sludge (PPDS) was studied using thermogravimetric analysis (TGA) method. The effect of particle size on PPDS samples and operational condition such as heating rates were investigated. The non-isothermal TGA was run under a constant flow of oxygen at a rate of 30 mL/min with temperature ranging from 30ºC to 800ºC. Four sample particle sizes ranging between 0.425 mm to 2 mm, and heating rate between 5 K/min to 20 K/min were used in this study. The TGA results showed that particle size does not have any significant effect on the thermogravimetry (TG) curves at the initial stage, but the TG curves started to separate explicitly at the second stage. Particle size may affect the reactivity of sample and combustion performance due to the heat transfer and temperature gradient. The TG and peak of derivative thermogravimetry (DTG) curves tend to alter at high temperature when heating rate is increased most likely due to the limitation of mass transfer and the delay of degradation process. 

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

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.

The Effects of Temperature and Heating Rate on the Preparation of Stalk Char

2012 ◽  
Vol 496 ◽  
pp. 88-93
Author(s):  
Jian Pan ◽  
Lin Wang
Keyword(s):  
Heating Rate ◽  
Pyrolysis Temperature ◽  
Calorific Value ◽  
Product Yield ◽  
Proximate Analysis ◽  
High Yield ◽  
Heating Rates ◽  
Fixed Carbon ◽  
Experimental Parameters ◽  
Effects Of Temperature

The pyrolysis of three stalk was studied to estimate the effect of pyrolysis conditions on product yield, calorific value and proximate analysis. Heating rate and pyrolysis temperature were the main experimental parameters. According to the test, when the heating rates were at 5, 10 and 15°C/min, the low heating rate reacted more thoroughly, got high yield and kept more energy. As the pyrolysis temperature rising; namely 200,300,400 and 500°C;the fixed carbon and gross calorific value were increasing to be 68% and 24.72 MJ/Kg respectively, but the yield was decreasing.

Experimental Study on Edible Mushroom Bran Pyrolysis

2014 ◽  
Vol 521 ◽  
pp. 88-92 ◽  
Author(s):  
Xiao Juan Guo ◽  
Yong Jun Xu ◽  
Xiao Xi Yang ◽  
Frank G.F Qin
Keyword(s):  
Weight Loss ◽  
Heating Rate ◽  
Edible Mushroom ◽  
Heating Rates ◽  
Final Temperature ◽  
Pyrolysis Characteristics ◽  
Thermogravimetric Analyzer ◽  
Mass Losses ◽  
Product Distributions ◽  
Third Stage

Pyrolysis characteristics of edible mushroom bran with different heating rates were investigated applying a thermogravimetric analyzer (TG) coupled with a Fourier transform infrared (FTIR) spectrometer. The pyrolysis experiments were performed up to 1073 K at heating rates of 10, 20, 30 K/min in a dynamic nitrogen flow of 20 ml/min. The results show that important differences on the pyrolytic behavior and product distributions are observed when heating rate is changed. At the lower heating rates, the starting temperature, final temperature of pyrolysis and the maximum rates of mass losses were relatively low. When the heating rate was increased, the starting temperature, final temperature of pyrolysis and the maximum rates of mass losses also increased. There have three stages: the first-stage was from the temperature of 20 to110°C with a weight loss of 12.33~14.36%; the second-stage was from 220°C to 400°C with a weight loss of 45.09~49.59%; the third stage was from 400 to 800°Cwith a weight loss of 15.11%~ 15.34%. The main pyrolysis vapour was CO2, phenol , and significant amounts of H2O, hydrocarbon, carbonyl compounds and acids.

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.

Maximum heating rates for producing undistorted glassy carbon ware determined by wedge-shaped samples

1996 ◽  
Vol 11 (9) ◽  
pp. 2368-2375 ◽  
Author(s):  
Hossein Maleki ◽  
Lawrence R. Holland ◽  
Gwyn M. Jenkins ◽  
R. L. Zimmerman ◽  
Wally Porter
Keyword(s):  
Heating Rate ◽  
Treatment Process ◽  
Gaseous Product ◽  
Pyrolysis Mass Spectrometry ◽  
Heating Rates ◽  
Gaseous Products ◽  
Volatile Products ◽  
Solid Bodies ◽  
Polymeric Carbon ◽  
Maximum Heating

Polymeric carbon artifacts are particularly difficult to make in thick section. Heating rate, temperature, and sample thickness determine the outcome of carbonization of resin leading to a glassy polymeric carbon ware. Using wedge-shaped samples, we found the maximum thickness for various heating rates during gelling (300 K–360 K), curing (360 K–400 K), postcuring (400 K–500 K), and precarbonization (500 K–875 K). Excessive heating rate causes failure. In postcuring the critical heating rate varies inversely as the fifth power of thickness; in precarbonization this varies inversely as the third power of thickness. From thermogravimetric evidence we attribute such failure to low rates of diffusion of gaseous products of reactions occurring within the solid during pyrolysis. Mass spectrometry shows the main gaseous product is water vapor; some carboniferous gases are also evolved during precarbonization. We discuss a diffusion model applicable to any heat-treatment process in which volatile products are removed from solid bodies.

scholarly journals Production of ceramics from coal fly ash

2012 ◽  
Vol 18 (2) ◽  
pp. 245-254 ◽  
Author(s):  
Biljana Angjusheva ◽  
Emilija Fidancevska ◽  
Vojo Jovanov
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Solid State ◽  
Liquid Phase ◽  
Bending Strength ◽  
Coal Fly Ash ◽  
Liquid Phase Sintering ◽  
Heating Rates ◽  
Republic Of Macedonia ◽  
The Subject

Dense ceramics are produced from fly ash from REK Bitola, Republic of Macedonia. Four types of fly ash from electro filters and one from the collected zone with particles < 0.063 mm were the subject of this research. Consolidation was achieved by pressing (P= 133 MPa) and sintering (950, 1000, 1050 and 11000C and heating rates of 3 and 100/min). Densification was realized by liquid phase sintering and solid state reaction where diopside [Ca(Mg,Al)(Si,Al)2O6] was formed. Ceramics with optimal properties (porosity 2.96?0.5%, bending strength - 47.01?2 MPa, compressive strength - 170 ?5 MPa) was produced at 1100?C using the heating rate of 10?C/min.

scholarly journals Towards a better representation of the solar cycle in general circulation models

2007 ◽  
Vol 7 (20) ◽  
pp. 5391-5400 ◽  
Author(s):  
K. M. Nissen ◽  
K. Matthes ◽  
U. Langematz ◽  
B. Mayer
Keyword(s):  
Solar Cycle ◽  
Heating Rate ◽  
General Circulation ◽  
Temperature Response ◽  
General Circulation Models ◽  
Short Wave ◽  
Radiative Transfer Model ◽  
Transfer Model ◽  
Heating Rates ◽  
Radiation Scheme

Abstract. We introduce the improved Freie Universität Berlin (FUB) high-resolution radiation scheme FUBRad and compare it to the 4-band standard ECHAM5 SW radiation scheme of Fouquart and Bonnel (FB). Both schemes are validated against the detailed radiative transfer model libRadtran. FUBRad produces realistic heating rate variations during the solar cycle. The SW heating rate response with the FB scheme is about 20 times smaller than with FUBRad and cannot produce the observed temperature signal. A reduction of the spectral resolution to 6 bands for solar irradiance and ozone absorption cross sections leads to a degradation (reduction) of the solar SW heating rate signal by about 20%. The simulated temperature response agrees qualitatively well with observations in the summer upper stratosphere and mesosphere where irradiance variations dominate the signal. Comparison of the total short-wave heating rates under solar minimum conditions shows good agreement between FUBRad, FB and libRadtran up to the middle mesosphere (60–70 km) indicating that both parameterizations are well suited for climate integrations that do not take solar variability into account. The FUBRad scheme has been implemented as a sub-submodel of the Modular Earth Submodel System (MESSy).

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