scholarly journals Influence of high heating rates on evolution of oxides on directed laser energy additively fabricated IN718

2021 ◽  
Vol 5 (1) ◽  
Author(s):  
Sangram Mazumder ◽  
Mangesh V. Pantawane ◽  
Narendra B. Dahotre
Keyword(s):  
Photoelectron Spectroscopy ◽  
Room Temperature ◽  
Experimental Approach ◽  
Laser Energy ◽  
Isothermal Treatment ◽  
Thermal Treatments ◽  
Heating Rates ◽  
Temperature Oxidation ◽  
Fe Oxides ◽  
Kinetics Of

AbstractThe effect of non-isothermal treatment in oxygen-containing air, via heating rates of 10, 50, and 1000 °C/min until 1000 °C followed by furnace cooling to room temperature on oxides formed on directed laser energy additively fabricated IN718 was studied. Another set of samples heated up to 1000 °C using the same heating rates were isothermally held at 1000 °C for 1 hr followed by furnace cooling to room temperature. X-ray photoelectron spectroscopy indicated the presence of NiO on samples only heated at 1000 °C/min. Also, results indicated the absence of Fe-oxides on non-isothermally treated samples, irrespective of heating rate. However, isothermal treatment confirmed the presence of NiO on all samples and Fe-oxides on samples heated via 50 and 1000 °C/min. The durations in complement with the kinetics of the thermal treatments influenced oxide evolution in the samples. Such an experimental approach was adopted to study the material response under dynamic short duration-high temperature oxidation.

Pyrolysis of Sugarcane Bagasse: A Consecutive Reactions Kinetic Model from TGA Experiments

2010 ◽  
Vol 660-661 ◽  
pp. 593-598 ◽  
Author(s):  
Kássia Graciele dos Santos ◽  
Taisa S. Lira ◽  
Valéria V. Murata ◽  
Marco Gianesella ◽  
Marcos A.S. Barrozo
Keyword(s):  
Kinetic Model ◽  
Sugarcane Bagasse ◽  
Room Temperature ◽  
Linear Method ◽  
Pyrolysis Kinetics ◽  
Heating Rates ◽  
Exponential Factor ◽  
Consecutive Reactions ◽  
Kinetics Of ◽  
Good Agreement

The pyrolysis kinetics of sugarcane bagasse in nitrogen flow was studied by thermogravimetric analysis from room temperature to 1173 K at different heating rates (1.5, 3, 5, 10, 15, 20, 30 and 50 K/min). As there are three distinct devolatilization peaks in the DTG curve, each peak was associated to thermal decomposition of an individual biomass subcomponent (hemicellulose, cellulose and lignin). The kinetic model adopted was a consecutive reactions model. The kinetic parameters of the pyrolysis process, such as activation energy and pre-exponential factor, were calculated by least squares non-linear method and Scilab are used as the simulation tool. The simulated results showed a good agreement with the experimental data and the parameters found are similar to reported by the literature.

Kinetics of Thermal Decomposition of Group-Hi Metal Alkyls on GaAs(100)

1990 ◽  
Vol 204 ◽  
Author(s):  
V. M. Donnelly ◽  
J. A. Mccaulley ◽  
R. J. Shul
Keyword(s):  
Thermal Decomposition ◽  
Low Temperature ◽  
Photoelectron Spectroscopy ◽  
Chemical Vapor ◽  
Semiconductor Films ◽  
Heating Rates ◽  
Kinetics Of Thermal Decomposition ◽  
Cracking Pattern ◽  
Kinetics Of ◽  
Metal Alkyls

ABSTRACTWe report studies of the kinetics of thermal decomposition of triethylgallium (TEGa), trimethylgallium (TMGa), and trimethylindium (TMIn) adsorbed on GaAs(100) in ultrahigh vacuum. The adsorbed layers were prepared by dosing GaAs(100) at room temperature, to either saturated coverage or coverages below saturation. Subsequent heating leads to loss of adsorbed hydrocarbons. The relative coverage of carbon was monitored by X-ray photoelectron spectroscopy (XPS), and products were detected with a differentially pumped quadrupole mass spectrometer. The kinetic analysis also includes measurements of laser-induced, rapid thermal decomposition (heating rates of ∼1011°C/s).TEGa dissociatively chemisorbs on GaAs(100). Heating the substrate results in desorption of diethylgallium radicals at low temperature and C2H4 (and some C2H5) at higher temperatures, after most of the diethylgallium has desorbed. TMGa decomposes to yield a Ga-alkyl desorption product (either dimethylgallium, or a mixture of dimethylgallium and TMGa) at low temperature and CH3 at higher temperature. TMIn undergoes a methyl exchange reaction on GaAs(100) where a Ga-alkyl desorbs with the same cracking pattern as in TMGa decomposition. Decomposition mechanisms for these group-III metal alkyls are proposed, Arrhenius parameters are presented, and some implications are discussed for growth of Ga-containing III-V compound semiconductor films from these precursors by chemical vapor deposition and molecular beam techniques.

scholarly journals Study on the thermal kinetics of anthracite oxidation induced by water and associated pyrite

2020 ◽  
Author(s):  
Caiping Wang ◽  
Xiadan Duan ◽  
Zujin Bai ◽  
Yang Xiao ◽  
Jun Deng
Keyword(s):  
Coal Sample ◽  
Spontaneous Combustion ◽  
Oxidation Process ◽  
Great Influence ◽  
Oxygen Absorption ◽  
Heating Rates ◽  
Temperature Oxidation ◽  
Mechanism Model ◽  
Gain Stage ◽  
Kinetics Of

Abstract Pyrite and water in coal have considerable influence on coal spontaneous combustion and threaten the safety of mine production gravely. To reveal the influence mechanism of water and associated pyrite on oxidation kinetics of coal–oxygen composite reaction, the pyrite of 0%, 1%, 2%, 4%, 6% and the moisture of 1%, 5%, 10%, 15% and 20% were mixed with the coal samples to obtain 25 coal samples. Thermogravimetric analysis technology was conducted to explore the changes of mass and characteristic temperatures of coal samples treated with water and associated pyrite during the low–temperature oxidation, and kinetic analysis of the oxidation process was discussed based on multiple heating rates(5 °C/min, 10 °C/min and15 °C/min).The results show that water and associated pyrite had a great influence on coal in oxygen absorption and weight gain stage ( T 3 ~ T 5 ), and there was a proportion range with the largest synergistic oxidation contribution. The apparent activation energy of the coal sample appeared changes, but the mechanism model did not, indicating that water and pyrite could affect the oxidation process of the coal sample externally. When water and associated pyrite exhibit synergistic interaction, there have a range that water was 10~15% and associate pyrite was 2~4% had the largest promotion and contribution to anthracite oxidation. The results have important scientific value and practical guiding significance for the further study on prediction, prevention and control of high sulfur anthracite spontaneous combustion.

scholarly journals Kinetic analysis of oil palm empty fruit bunch (OPEFB) pellets as feedstock for pyrolysis

2015 ◽  
Author(s):  
Bemgba Bevan Nyakuma
Keyword(s):  
Activation Energy ◽  
Oil Palm ◽  
Room Temperature ◽  
Energy Requirement ◽  
Inert Atmosphere ◽  
Decomposition Kinetics ◽  
The Other ◽  
Empty Fruit Bunch ◽  
Heating Rates ◽  
Kinetics Of

The thermal behaviour and decomposition kinetics of pelletized oil palm empty fruit bunch (OPEFB) was investigated in this study using thermogravimetric analysis (TGA). The OPEFB pellets were heated from room temperature to 1000 ºC at different heating rates; 5, 10 and 20 °C min-1 under inert atmosphere. Thermal degradation occurred in three steps; drying, devolatization and char decomposition. Subsequently, the Popescu method was applied to the TG/DTG data to determine the kinetic parameters of the OPEFB pellets. The activation energy, E, for different degrees of conversion, α = 0.05 to 0.7 are 36.60 kJ/mol to 233.90 kJ/mol with high correlation R2 values. In addition, the drying and decomposition of lignin reactions displayed lower E values compared to the devolatization characterized by high E value of 233 kJ/mol at α = 0.2. This indicates that the devolatization process is slower and requires higher energy requirement to reach completion than the other stages of thermal decomposition of the fuel under inert atmosphere. Keywords: decomposition, kinetics, oil palm, empty fruit bunch, pyrolysis.

scholarly journals MICROSTRUCTURAL STUDY AND RECRYSTALLIZATION KINETICS OF DEFORMED COMMERCIAL COPPER WIRES

2018 ◽  
Vol 24 (1) ◽  
pp. 32 ◽  
Author(s):  
Lahcene Fellah ◽  
Abdallah Diha ◽  
Zakaria Boumerzoug
Keyword(s):  
Activation Energy ◽  
Room Temperature ◽  
Argon Atmosphere ◽  
Recrystallization Temperature ◽  
Heating Rates ◽  
Recrystallization Kinetics ◽  
Slip Bands ◽  
Commercial Copper ◽  
The One ◽  
Kinetics Of

This work aims to investigate the microstructure after cold-wiredrawing process of commercial copper and its recrystallization kinetics under isochronal annealing. In this paper, the samples studied are commercial copper wires reduced at six different reductions by a wiredrawing at room temperature. Optical microscopy, Scanning Electron Microscopy (SEM), and DSC were used as characterization techniques. The samples were annealed under Argon atmosphere with four different heating rates by using DSC. The Kissinger, Ozawa, Boswell, and Starink methods were used to determine the recrystallization kinetics. The results showed that the cold-wiredrawing had caused the elongation of grains along the main axis of the wires also showed the existence of slip bands. It has been found, on the one side, that the recrystallization temperature increased and shifted to higher temperatures as the heating rate increased, which means that this reaction is thermally actived; On the other sidethe recrystallization temperature clearly shifted to lower temperatures as the deformation increased, which indicated that recrystallization is profoundly enhanced by high deforming.We noted a decrease in the activation energy values when the reduction increases, the activation energy for the most reduced materials were lower than that in the less reduced wires.

Oxidation Behavior of Pd-Si Compounds

1982 ◽  
Vol 18 ◽  
Author(s):  
A. Cros ◽  
R. A. Pollak ◽  
K. N. Tu
Keyword(s):  
Chemical Analysis ◽  
Photoelectron Spectroscopy ◽  
Electron Spectroscopy ◽  
Room Temperature ◽  
Oxidation Behavior ◽  
Spillover Effect ◽  
Photoemission Spectroscopy ◽  
Temperature Oxidation ◽  
X Ray ◽  
Oxygen Dissociation

The room temperature oxidation of PdSi, Pd2Si and Pd4Si has been studied using X-ray photoelectron spectroscopy (X-ray photoemission spectroscopy or electron spectroscopy for chemical analysis). We find that only silicon atoms in these silicides are oxidized and the oxidation of Pd4Si surfaces is enhanced compared with that of Pd2Si and PdSi, as is evidenced by both a higher silicon oxidation state and thicker oxide films. This behavior is discussed in terms of silicide stability and a spillover effect where palladium atoms catalyze molecular oxygen dissociation.

Room-temperature oxidation of ultrathin TiB2 films

2002 ◽  
Vol 17 (4) ◽  
pp. 805-813 ◽  
Author(s):  
Feng Huang ◽  
W. J. Liu ◽  
J. F. Sullivan ◽  
J. A. Barnard ◽  
M. L. Weaver
Keyword(s):  
Magnetic Recording ◽  
Photoelectron Spectroscopy ◽  
Room Temperature ◽  
Oxide Thickness ◽  
Temperature Oxidation ◽  
X Ray ◽  
Force Microscopy ◽  
Application Potential ◽  
New Perspective ◽  
Protective Overcoats

Titanium diboride has been claimed as a very promising candidate material for protective applications in the magnetic recording. Its oxidation resistance at room temperature is a critical criterion in assessing this application potential. In this paper, the oxidation characteristics of ultrathin TiB2 thin films, such as overcoat erosion and oxide thickness, are investigated via a combination of x-ray reflectivity, x-ray photoelectron spectroscopy (XPS), and atomic force microscopy. It was found that a <2-h exposure to air at room temperature led to the formation of approximately 15-Å-thick, well-defined oxides at the expense of an approximately 9-Å erosion of the TiB2 overcoats, coupled with the existence of a sharp oxide/TiB2 interface. XPS studies confirmed the existence of the oxides. Considering the decreasing allowable thickness for such protective overcoats, oxidation and the resultant thickness gain negate such a potential of ultrathin TiB2 films. The results in our current report provide a new perspective on its potential as protective overcoats in magnetic recording.

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