Aluminothermic Synthesis of Al2O3/ZrO2/SiC Composite Powders

1991 ◽  
Vol 249 ◽  
Author(s):  
J.P. Erauw
Keyword(s):  
Morphological Characteristics ◽  
Xrd Analysis ◽  
Reaction Scheme ◽  
Adiabatic Temperature ◽  
Experimental Results ◽  
Aluminothermic Reduction ◽  
Reaction Products ◽  
Composite Powders

ABSTRACTThe synthesis of Al2O3/ZrO2/ SiC composite powders by aluminothermic reduction of zircon in the presence of carbon is reported. The effect of the temperature on the progress of the reaction, as assessed by XRD analysis, is outlined. The morphological characteristics of the reaction products are described. Based on the experimental results, a reaction scheme is proposed. The possible propagation of the reaction is discussed in terms of the adiabatic temperature.

Aluminothermic Reduction of Niobium Pentoxide in a Hydrogen Plasma Furnace

2006 ◽  
Vol 514-516 ◽  
pp. 599-603
Author(s):  
Marcio W.D. Mendes ◽  
António Carlos P. Santos ◽  
Francisca de Fatima P. Medeiros ◽  
Clodomiro Alves Jr. ◽  
A.G.P. Silva ◽  
...  
Keyword(s):  
Hydrogen Plasma ◽  
Xrd Analysis ◽  
High Energy ◽  
Steel Tube ◽  
Aluminothermic Reduction ◽  
Powder Layer ◽  
Stainless Steel Tube ◽  
Reaction Products ◽  
X Ray Diffraction ◽  
New Process

The aluminothermic reduction is a highly exothermal reaction between a metal oxide and aluminium. Conventionally this reaction is ignited by an electric resistance and the reaction products after cooling are in the form of a rigid block of mixed metal and aluminium oxide. In this work a new process of aluminothermic reduction is presented, in which the reaction is ignited by a hydrogen plasma. The niobium oxide and aluminium powders are high energy milled for six hours to form particles constituted of oxide and aluminum. Stoichiometric, substoichiometric and superstoichiometric mixtures were prepared. The mixture was placed in a stainless steel tube (the hollow cathode) inside the reactor chamber. The chamber was firstly evacuated. Then hydrogen at low pressure was introduced. In the following an electric discharge between the cathode and the anode localized just above the cathode ignites the plasma. The plasma heats the particles on the surface of the powder layer and starts the reaction that proceeds in each particle since the reactants are intimately mixed. The heat generated by the reaction propagates deeper in the layer until the whole mixture reacts. Substoichiometric mixtures can be used because hydrogen takes part of the reduction. The Nb2O5 – Al starting powder mixture and the products of the reaction are characterized by laser grain size measurement and X-Ray diffraction (XRD). The products are in form of powder or agglomerates of particles. Phases of reaction products was determined by XRD analysis and the particle size trough SEM.

scholarly journals Effect of Mg Concentration on the Aluminothermic Reduction of Mn2O3 Particles Obtained from Cathodes of Discharged Alkaline Batteries: Mathematical Modeling and Experimental Results

Metals ◽  
2019 ◽  
Vol 9 (1) ◽  
pp. 49
Author(s):  
Orlando Flores Dávila ◽  
Jesús Torres Torres ◽  
Alfredo Flores Valdes
Keyword(s):  
Molten Aluminum ◽  
Treatment Time ◽  
Chemical Reduction ◽  
Reduction Reaction ◽  
Solid Particles ◽  
Experimental Results ◽  
Aluminothermic Reduction ◽  
Magnesium Concentration ◽  
Reaction Products ◽  
Alkaline Batteries

This paper aimed at studying the effect of magnesium concentration in molten aluminum produced from beverage cans on the process of aluminothermic reduction of Mn2O3 particles obtained from the cathodes of discharged alkaline batteries. The experimental results were analyzed by using thermodynamic fundamentals and kinetic modeling, while the characterization of the reaction products obtained allowed the mechanism of the process to be described. It was found that the addition of magnesium improves the wettability of solid particles by molten aluminum, thus increasing the reaction and its subsequent incorporation into the molten aluminum solution of Mn released from the reduction reaction. This work was carried out using several initial magnesium concentrations; 1.0, 2.0, 3.0, and 4.0 wt %, under a constant temperature of 1073 K, a constant treatment time of 240 min, and a constant agitation speed of 200 rpm. The results show that the higher the initial magnesium concentration in the molten alloy, the higher the speed of the chemical reduction reaction of the Mn2O3 particles.

Growth mechanism and PL properties of β-sialon nanobelts/nanowires synthesized by a process of aluminothermic reduction nitridation of zircon

CrystEngComm ◽  
2015 ◽  
Vol 17 (7) ◽  
pp. 1591-1596 ◽  
Author(s):  
Haitao Liu ◽  
Fanrong Meng ◽  
Qing Li ◽  
Zhaohui Huang ◽  
Shunqin Luo ◽  
...  
Keyword(s):  
Growth Mechanism ◽  
Large Scale ◽  
Aluminothermic Reduction ◽  
Composite Powders

Large scale β-sialon nanobelts/nanowires and ZrN–sialon composite powders were prepared via aluminothermic reduction nitridation with flowing N2.

The Reactivity of CaTi4(PO4)6 with Alumina and Y-TZP Ceramics

2007 ◽  
Vol 361-363 ◽  
pp. 787-790
Author(s):  
Sabina Beranič Klopčič ◽  
Irena Pribošič ◽  
Tomaž Kosmač ◽  
Ute Ploska ◽  
Georg Berger
Keyword(s):  
Room Temperature ◽  
Xrd Analysis ◽  
Second Phase ◽  
Reaction Products ◽  
Stabilized Zirconia ◽  
Monoclinic Zro2 ◽  
Commercial Alumina ◽  
The Matrix ◽  
Different Temperatures ◽  
Edx Analyses

The reactivity of CaTi4(PO4)6 (CTP) with alumina and yttria-stabilized zirconia (Y-TZP) ceramics was studied. CTP powder was synthesized and composites with commercial alumina or zirconia matrices containing 10 wt% of CTP were prepared. They were sintered at different temperatures and characterized using XRD, SEM, and EDX analyses. The results showed that the alumina/CTP and Y-TZP/CTP composites start to react below 1000 °C. In the alumina/CTP composite the first reaction product, detected at 970 °C, was AlPO4. At temperatures above 1280 °C TiO2 and CaTiO3 were also formed and no CTP peaks could be detected using XRD analysis. The composite sintered at 1500 °C consisted of Al2O3 matrix, AlPO4, TiO2, CaTiO3 and Al2TiO5. The reaction products formed in the Y-TZP/CTP composite at 970 °C were TiO2 and Ca2Zr7O16. At higher sintering temperatures, 1280 °C and above, CTP was no longer present, Ca2Zr7O16 decomposed, forming CaO2 and ZrO2, and Y2O3 was consumed to form YPO4. Consequently, upon cooling to room temperature the matrix phase transformed to monoclinic ZrO2. Based on these results it can be concluded that CTP is not a suitable bioactive second phase for the fabrication of CTP composites with alumina or zirconia matrices.

Mechanofusion Processing of Metal-Oxide Composite Powders for Plasma Spraying

2010 ◽  
Vol 1276 ◽  
Author(s):  
Ricardo Cuenca-Alvarez ◽  
Carmen Monterrubio-Badillo ◽  
Hélêne Ageorges ◽  
Pierre Fauchais
Keyword(s):  
Mechanical Energy ◽  
Xrd Analysis ◽  
Composite Particles ◽  
Composite Powders ◽  
Steel Core ◽  
No Formation ◽  
Particle Coating ◽  
Plasma Sprayed Coatings ◽  
Plasma Sprayed ◽  
Sprayed Coatings

AbstractComposite particles destined to build plasma sprayed coatings, are prepared by the mechanofusion process (MF). These particles consist of a stainless steel core particle coated by finer particles of alumina. Changes induced by the MF process are monitored by SEM, DRX, and laser granulometry, revealing that the dry particle coating process is governed by agglomeration and rolling phenomena. Simultaneously, the MF performance is controlled by the operating parameters such as the compression gap, the mass ratio of host to guest particle, and the powder input rate. The mechanical energy input leads to a nearly rounded shape of the final composite particles; however, no formation of new phases or components decomposition is detected by XRD analysis. The resulting composite powder features optimal characteristics, concerning particle shape and phases distribution, to be plasma sprayed in air.

The Influence of Technological Medium Composition on the Structure-Related Morphological Characteristics of Al–2B Composite Powders

2020 ◽  
Vol 82 (4) ◽  
pp. 403-407
Author(s):  
A. I. Malkin ◽  
A. D. Aliev ◽  
V. A. Klyuev ◽  
V. I. Savenko ◽  
A. A. Shiryaev ◽  
...  
Keyword(s):  
Morphological Characteristics ◽  
Medium Composition ◽  
Composite Powders ◽  
Technological Medium

Preparation of LiFePO4/C Composite Powders

2011 ◽  
Vol 391-392 ◽  
pp. 377-380
Author(s):  
Guo Jun Li ◽  
Ming Yang ◽  
Hai Li Jing ◽  
Rui Ming Ren
Keyword(s):  
Citric Acid ◽  
Oxalic Acid ◽  
Specific Capacity ◽  
Xrd Analysis ◽  
X Ray Diffraction ◽  
Composite Powders ◽  
Charge Capacity ◽  
X Ray ◽  
Initial Charge

LiFePO4/C composite powders were prepared by a simple reaction of as-synthesized FePO4•2H2O, LiOH•H2O, oxalic acid and citric acid. The influence of oxalic acid and citric acid in different ratios was investigated on morphology and electrochemical performance of LiFePO4/C composite powders. The characterization of the composites included X-ray diffraction (XRD) and scanning electron microscopy (SEM). The XRD analysis indicates that the material is well crystallized without impurities. The obtained LiFePO4/C composite powders with well dispersion at CA/OA ratio of 1:1.50 and the initial charge capacity reached 159.3 mAhg-1 at 0.1C rate, meanwhile, the particles prepared at 1:0.75 were close to spherical in shape and the specific capacity value was 149.8 mAhg-1 at 0.1C rate, with a slight decrease on greater C-rates reaching 141.3 mAhg-1 at 1C.

Interaction between Yttria Fully Stabilized Zirconia or Yttria-Zirconia Blended Face-Coat with Ti6Al4V during Investment Casting

2014 ◽  
Vol 1019 ◽  
pp. 302-310 ◽  
Author(s):  
Kalenda Mutombo ◽  
Christina Kgomo ◽  
P. Rossouw
Keyword(s):  
Electron Microscopy ◽  
Xrd Analysis ◽  
Experimental Results ◽  
X Ray Diffraction ◽  
Stabilized Zirconia ◽  
X Ray ◽  
Hardness Tester ◽  
Alpha Case ◽  
Face Coat ◽  
Scanning Electron

The interaction between the Ti6Al4V alloy and the mould materials was investigated. The alpha-case was characterized by Vickers hardness tester, optical and scanning electron microscopy equipped with electron dispersive X-ray spectrometry (EDX). X-ray diffraction (XRD) analysis was performed on as cast and on YFSZ or YZ-Blended face-coats. From the experimental results, a distinct alpha-case formation was revealed. The YFSZ led to a thicker and harder alpha-case than the YZ-Blended face-coat. The EDX revealed the presence of Zr and Si elements in both alpha-cases. Therefore, from experimental results and thermodynamic calculations, pure ZrO2and SiO2may react with Ti.

scholarly journals Stability of kaolin sand from the Vyšný Petrovec deposit (south Slovakia) in an acid environment

2012 ◽  
Vol 63 (6) ◽  
pp. 503-512 ◽  
Author(s):  
Pentrák Martin ◽  
Madejová Jana ◽  
Andrejkovičová Slávka ◽  
Uhlík Peter ◽  
Komadel Peter
Keyword(s):  
Dissolution Rate ◽  
Xrd Analysis ◽  
Reaction Products ◽  
Solid Reaction ◽  
Oh Groups ◽  
High Dissolution Rate ◽  
Acid Environment ◽  
Mir Spectra ◽  
Gradual Release

Abstract Comprehensive characterization of kaolin sand from the Vyšný Petrovec (VP) deposit in Slovakia by a variety of experimental methods was performed. The quantitative XRD analysis (RockJock software) revealed that the acid-untreated sample contained mainly kaolinite (~60 wt. %), a considerable amount of dioctahedral micas (~32 wt. %) and quartz (~ 7 wt. %). The Hinckley index (HI) and Aparicio-Galán-Ferrel index (AGFI) calculated from the 02l and 11l reflections showed medium-defect kaolinite to be present in the VP kaolin. The influence of the mineral composition of VP kaolin on its stability in 6 mol · dm-3 HCl at 95 °C was investigated. The solid reaction products were examined by chemical analysis; XRD and infrared spectroscopy in both middle (MIR) and near (NIR) regions. Considerably higher dissolution rate of Fe compared to Al indicated that Fe was bounded in a readily soluble phase rather than in kaolinite. While the MIR spectra confirmed the gradual release of the central atoms from the clay minerals layers and creation of amorphous silica upon acid treatment, the NIR spectra revealed the formation of Si-OH groups in the solid reaction product. Relatively high dissolution rate of VP kaolin resulted from the presence of small-grains of mediumdefect kaolinite and clay admixtures in VP kaolin sand.

scholarly journals Intelligent Bionic Optimization Algorithm Based on the Growth Characteristics of Tree Branches

2021 ◽  
Vol 15 (2) ◽  
pp. 34-46
Author(s):  
Fei Tang
Keyword(s):  
Genetic Algorithm ◽  
Tree Growth ◽  
Optimization Algorithm ◽  
Ant Colony Algorithm ◽  
Morphological Characteristics ◽  
Optimal Solution ◽  
Shoot Tip ◽  
Experimental Results ◽  
Ant Colony ◽  
The Individual

To improve the performance of bionic algorithms, an intelligent bionic optimization algorithm is proposed based on the morphological characteristics of trees growing toward light. The growth organ of the tree is mapped into the coding of the tree growth algorithm, and the entire tree is formed by selecting the fastest growing individual to form the next level of the tree. When the tree growth reaches a certain level, the individual code of the shoot tip is added to enhance the search ability of the individual shoot tip in the growth space of the entire tree. This method achieves a near-optimal solution. The experimental results were compared with the optimization results of the genetic algorithm and the ant colony algorithm using the classic optimization function. The experimental results show that this algorithm has fewer iterations, a faster convergence speed, higher precision, and a better optimization ability than the genetic algorithm or the ant colony algorithm.

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