scholarly journals Reducibility study of Rossetta ilmenite ore briquettes and powder with coke breeze at 800-1100°C

2013 ◽  
Vol 45 (1) ◽  
pp. 79-88 ◽  
Author(s):  
el Abd ◽  
N.A. El-Hussiny ◽  
Marguerite Wassef ◽  
M.G. Khalifa ◽  
Aly Soliman ◽  
...  
Keyword(s):  
Organic Materials ◽  
Nitrogen Atmosphere ◽  
Coke Breeze ◽  
Reasonable Condition ◽  
Temperature Range ◽  
Controlling Mechanism

Ilmenite ore fine and coke breeze as reduced material were briquetted with different amounts of organic materials such as molasses or pitch were studied in this investigation. The produced briquettes at reasonable condition were reduced in nitrogen atmosphere at temperature range 800 - 1100oC to determine the factors controlling the reduction and to determine the controlling mechanism. Also ilmenite ore fine with coke breeze were reduced at the same temperature range in nitrogen atmosphere without briquetting process, for the sake of comparison.

scholarly journals Studying the pelletization of rosseta ilmenite concentrate with coke breeze using molasses and reduction kinetics of produced pellets at 800-1150ºC

2012 ◽  
Vol 44 (1) ◽  
pp. 113-126 ◽  
Author(s):  
N.A. El-Hussiny ◽  
M.E.H. Shalabi
Keyword(s):  
Optimum Condition ◽  
Reaction Rate ◽  
Nitrogen Atmosphere ◽  
Coke Breeze ◽  
Reduction Kinetics ◽  
Solid Reaction ◽  
Ilmenite Concentrate ◽  
Controlling Mechanism ◽  
Mechanism Of Reaction ◽  
Kinetics Of

Ilmenite ore fine and coke breeze as reduced material which were pelletized with different amounts of molasses were studied in this investigation. The produced pellets at optimum condition were reduced in nitrogen atmosphere at temperature range 800-1150?C to determine the controlling mechanism. The reduction indicated that the reduction rates increased as the temperature increased and the controlling mechanism of reaction rate is solid-solid reaction.

scholarly journals Studies on Pyrolysis Kinetic of Newspaper Wastes in a Packed Bed Reactor: Experiments, Modeling, and Product Characterization

2015 ◽  
Vol 2015 ◽  
pp. 1-8 ◽  
Author(s):  
Aparna Sarkar ◽  
Sudip De Sarkar ◽  
Michael Langanki ◽  
Ranjana Chowdhury
Keyword(s):  
Packed Bed ◽  
Nitrogen Atmosphere ◽  
Packed Bed Reactor ◽  
Experimental Conditions ◽  
Deactivation Model ◽  
Temperature Range ◽  
Product Characterization ◽  
Kinetic Rate Constants ◽  
Ft Ir ◽  
Pyrolysis Kinetic

Newspaper waste was pyrolysed in a 50 mm diameter and 640 mm long reactor placed in a packed bed pyrolyser from 573 K to 1173 K in nitrogen atmosphere to obtain char and pyro-oil. The newspaper sample was also pyrolysed in a thermogravimetric analyser (TGA) under the same experimental conditions. The pyrolysis rate of newspaper was observed to decelerate above 673 K. A deactivation model has been attempted to explain this behaviour. The parameters of kinetic model of the reactions have been determined in the temperature range under study. The kinetic rate constants of volatile and char have been determined in the temperature range under study. The activation energies 25.69 KJ/mol, 27.73 KJ/mol, 20.73 KJ/mol and preexponential factors 7.69 min−1, 8.09 min−1, 0.853 min−1of all products (solid reactant, volatile, and char) have been determined, respectively. A deactivation model for pyrolysis of newspaper has been developed under the present study. The char and pyro-oil obtained at different pyrolysis temperatures have been characterized. The FT-IR analyses of pyro-oil have been done. The higher heating values of both pyro-products have been determined.

Influence of Oxygen and Titanium Modification of AlN Surface on the Properties of Direct Bonded AlN-Cu Joints

2006 ◽  
Vol 45 ◽  
pp. 1537-1542 ◽  
Author(s):  
W. Olesinska ◽  
D. Kalinski ◽  
M. Chmielewski
Keyword(s):  
Ion Implantation ◽  
Thermal Oxidation ◽  
Barrier Layer ◽  
Oxidation Process ◽  
Isothermal Oxidation ◽  
Nitrogen Atmosphere ◽  
Phase Changes ◽  
Process Temperature ◽  
Experimental Conditions ◽  
Temperature Range

The paper presents the results concerning the formation of a ‘barrier’ layer on AlN ceramic during its joining with copper by the Copper Direct Bonding (CDB) technique. Prior to the joining, the AlN surface was modified by isothermal oxidation or by titanium ion implantation. The effects of the oxidation process temperature were examined within the temperature range from 673 to 1473K. The surface of the ceramic was modified by titanium ion implantation at various ion doses and various accelerating voltages. The modified ceramic was joined with oxidized copper in a nitrogen atmosphere with about 1.5ppm of oxygen, using a belt-type furnace at a temperature of 1323K. The microstructure and phase changes induced on the surfaces of the joints were examined. The modification yielded a ‘barrier’ layer (TiN), which ensured a continuous pore-less contact between the materials being joined. The results obtained under all the experimental conditions indicate that the implantation gives better effects than thermal oxidation. Ion implantation seems to be ideally suited for these purposes. The preferential dose appears to be 5*E16ions/cm2 and the preferential accelerating voltage – 15kV.

On the mechanism of formation of the granular structure and interfaces in self-reinforced aluminum nitride

2021 ◽  
Vol 2021 (2) ◽  
pp. 63-71
Author(s):  
G. S. Oleynik ◽  
◽  
A. V. Kotko ◽  
Keyword(s):  
Solid Solution ◽  
Aluminum Nitride ◽  
Sintering Temperature ◽  
High Mobility ◽  
Nitrogen Atmosphere ◽  
Width Ratio ◽  
Mechanism Of Formation ◽  
Common Boundary ◽  
Temperature Range ◽  
The Common

Results of an investigation by scanning electron microscopy methods of the microstructure of self-reinforced aluminum nitride obtained on the basis of aluminum nitride powder and containing 3 mass.% oxygen by plasma-chemical synthesis in the temperature range 1700-2000 °C are presented. Initial aluminum nitride was represented by the wurtzite (2H) phase. Samples were obtained by free sintering in a nitrogen atmosphere. It was established that, during sintering of AlN in the indicated temperature range, three microstructural types of the material and six types of interfaces (three types of intergranular and three types of intragranular ones) formed. The features of the microstructure of the materials are fully determined by the development of intergranular crystal-oriented polytype transitions of 2H AlNmultilayer polytypes (MP) in sintering. The sequence of successive structural transformations that determine the development of polytype transitions was established. 1. Formation of initial 2H AlN grains of the solid solution 2H AlN-O. The substitution of nitrogen by oxygen takes place. 2. The development of isomorphous delamination of the solid solution in every grain with the precipitation of an interlayer enriched in oxygen. 3. In interlayers, polytypes consisting of a series of polytypes with different number of layers (MP) form. Such an interlayer has developed base surfaces and propagates from one boundary to another in the grain, which determines the formation of a special structural state of fragments of boundaries, that border interlayers in the direction <hk0>. 4. The high mobility of the indicated fragments of boundaries determines their break-off from the common boundary and formation of a grain nucleus of anisometric (plate-like) shape. This process begins already at a sintering temperature Tsint. = 1800 °C, and, at Tsint. = 2000 °C, polycrystals practically entirely consist of grains of plate-like shape. In this case, with increase in the sintering temperature, the aspect ratio (the length-to-width ratio) of such grains rises. Keywords: aluminum nitride, polytype transformations, grains, microstructure, boundaries, self-reinforcement.

Phenomenological Model for Creep Behaviour in Cu-8.5at%Al Alloy

2006 ◽  
Vol 251-252 ◽  
pp. 89-96
Author(s):  
M. Abo-Elsoud
Keyword(s):  
Melting Temperature ◽  
Phenomenological Model ◽  
Creep Behaviour ◽  
Intermediate Temperature ◽  
Al Alloy ◽  
Dislocation Glide ◽  
Temperature Range ◽  
Intermediate Temperature Range ◽  
Controlling Mechanism ◽  
Creep Regime

Creep experiments were conducted on Cu-8.5at.% Al alloy in the intermediate temperature range from 673 to 873K, corresponding to 0.46-0.72 Tm where Tm is the absolute melting temperature. The present analysis reveals the presence of two distinct deformation regions (climb and viscous glide) in the plot of log ε vs. log σ. The implications of these results on the transition from powerlaw to exponential creep regime are examined. The results indicated that the rate controlling mechanism for creep is the obstacle-controlled dislocation glide. A phenomenological model is proposed which assumes that cell boundaries with sub-grains act as sources and obstacles to gliding dislocations.

Investigation of Thermal Stability of Zn(II), Pt(II) and Pd(II) Complexes with (E)-2-oxo-2-{N'-[1-(pyridin-2-yl)ethylidene]hydrazino}acetamide

2005 ◽  
Vol 494 ◽  
pp. 375-380
Author(s):  
Tamara R. Todorović ◽  
K.K. Andjelković ◽  
D.M. Sladić ◽  
D.A. Jeremić ◽  
D. Minić
Keyword(s):  
Thermal Stability ◽  
Thermal Degradation ◽  
Structural Transformation ◽  
Structural Rearrangement ◽  
Nitrogen Atmosphere ◽  
Crystal Water ◽  
Temperature Range ◽  
Square Planar ◽  
Thermal Stability Of

Thermal stability of neutral Zn(II), Pd(II) and Pt(II) complexes of formulae [Zn(apsox)2]·3H2O and [M(apsox)Cl] (M=Pd(II), Pt(II), HL=(E)-2-oxo-2-{N ’-[1-(pyridin-2- yl)ethylidene]hydrazino}acetamide) were studied. The results of DSC and TG analyses within the temperature range from 20 to 600 °C in nitrogen atmosphere showed that the loss of crystal water represents the first step during decomposition of the octahedral Zn(II) complex followed by structural rearrangement of its anhydrous form. After that the complex remained stable to about 330 °C. Different from neutral square-planar Pd(II) and Pt(II) complexes, a satisfactory resolution of the peaks in DSC of the Zn(II) complex enabled determination of the activation energies of its structural transformation and thermal degradation.

Glide Mechanisms of Dislocations in NiAl

1998 ◽  
Vol 552 ◽  
Author(s):  
D. Caillard
Keyword(s):  
Room Temperature ◽  
Cross Slip ◽  
Friction Forces ◽  
Temperature Range ◽  
Controlling Mechanism ◽  
Atomistic Calculations ◽  
Good Agreement

ABSTRACTThe glide properties of <001> dislocations have been studied by in situ straining experiments at and below room temperature, with the aim of studying slip, cross-slip, Peierls friction forces, and pinning at small obstacles. Most results are in a good agreement with atomistic calculations. It is concluded that unpinning from small extrinsic obstacles is probably the rate controlling mechanism in this temperature range and in the soft orientation.

Mn–In–Co, Mn–Pt and Mn–In–Pt Based Contacts to p–GaAs

1990 ◽  
Vol 181 ◽  
Author(s):  
T. S. Kalkur ◽  
Y. C. Lu ◽  
M. Rowe
Keyword(s):  
Ohmic Contact ◽  
Annealing Temperature ◽  
Heat Pulse ◽  
Nitrogen Atmosphere ◽  
Contact Resistivity ◽  
Pulse System ◽  
Auger Analysis ◽  
Temperature Range ◽  
Contact Metallization ◽  
Surface Morphologies

ABSTRACTMn–In–Co, Mn–In–Pt and Mn–Pt metallizations are used to form ohmic contact on Be-implanted rapid thermally annealed GaAs. The rapid thermal alloying of contact metallizations are performed in A.G. Associates Heat pulse system in nitrogen atmosphere in the temperature range of 350°C to 800°C for 5 seconds. The contacts were found to be ohmic at an annealing temperature of 450°C. The In–Mn–Co metallization showed higher minimum contact resistivity (5 × 10−4 ohm.cm2 ) than In–Mn–Pt metallization (1.5 × 10−5 ohm.cm2 ) for an annealing temperature of 700°C and time 5 seconds. The surface morphologies of In–Mn–Pt metallizations were smooth even after alloying at 700°C for 5 seconds. The Auger analysis shows outdiffusion of Ga and As into the contact metallization and negligible indiffusion of In and Mn into GaAs.

Thermodynamic and Dielectric Properties of MgSiN2 Ceramics

2006 ◽  
Vol 317-318 ◽  
pp. 857-860 ◽  
Author(s):  
Zoltán Lenčéš ◽  
Kiyoshi Hirao ◽  
Pavol Šajgalík ◽  
Michael J. Hoffmann
Keyword(s):  
Bending Strength ◽  
Nitrogen Pressure ◽  
Nitrogen Atmosphere ◽  
Temperature Range ◽  
Free Energy Of Formation ◽  
Wide Range ◽  
Indentation Fracture Toughness ◽  
Stability Examination ◽  
Direct Nitridation ◽  
Energy Of Formation

Reaction bonded MgSiN2 (RBMSN) was prepared by direct nitridation of a Si/Mg2Si/Mg/Si3N4 powder compact in a temperature range of 1350-1550°C. The oxygen content of MgSiN2 was in the range of 0.4 – 0.6 wt%. A thermal stability examination showed that MgSiN2 is stable up to 1400°C at 0.1 MPa N2 pressure. The activation energy of decomposition calculated from the temperature dependence of weight loss is H = 383 kJ⋅mol-1. The time dependence and nitrogen pressure dependence of MgSiN2 decomposition was also investigated at constant temperature. MgSiN2 is stable at 1560°C in 0.6 MPa nitrogen atmosphere. Using these experimental data together with the heat capacity published in a literature the Gibbs free energy of formation of MgSiN2 was calculated in a temperature range 300-2500 K. Dense MgSiN2 ceramics or MgSiN2/Si3N4 composites with fluorine-based additives were prepared by hot pressing. The composite materials had a 4-point bending strength of 427 MPa and Vickers hardness (HV1) of 20.8 GPa, respectively. The indentation fracture toughness was 5.3 MPa.m1/2, due to the presence of elongated β-Si3N4 grains. The dielectric constant of dense reaction bonded MgSiN2 at 100 kHz was 9.5-10, while that of MgSiN2/Si3N4 composite in a wide range 50 – 6000, depending on composition and heat treatment.

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