scholarly journals Carbothermal reduction of mill scales formed on steel billets during continuous casting

2021 ◽  
Vol 242 (1) ◽  
Author(s):  
S. M. Espinoza Suarez ◽  
L. E. Borja-Castro ◽  
M. I. Valerio-Cuadros ◽  
A. Bustamante Domínguez ◽  
H. A. Cabrera-Tinoco ◽  
...  
Keyword(s):  
Iron Oxides ◽  
Carbothermal Reduction ◽  
Room Temperature ◽  
Reduction Process ◽  
Ferromagnetic State ◽  
Argon Atmosphere ◽  
X Ray Diffraction ◽  
Spectroscopy Analysis ◽  
Crude Steel ◽  
X Ray

AbstractA billet is a bar made from crude steel which surface contains scales which are rich in iron oxides. This study presents the carbothermal reduction of the scales formed in steel billets. The process included the reaction of the iron oxides contents with carbon (in ratio 5:1) and annealing in a tubular furnace under argon atmosphere. The occurred reactions are discussed using thermodynamic calculations and thermal analysis which indicate a three-stage reduction process Fe3O4 ➔ FeO ➔ Fe3C ➔α-Fe with intermediate reactions at the interval temperature 960 and 1300 °C. The X-ray diffraction confirms the reduction to α-Fe with minor presence of unreacted C, magnetite and wustite. Mössbauer spectroscopy analysis was performed at room temperature where a typical sextet corresponding to the dominant α-Fe is shown as well as wustite, magnetite and cementite to a lesser extent. The magnetization measurements confirm the ferromagnetic state corresponding to the α-Fe.

Synthesis and Magnetic Properties of CoAl2O4 Coated Co Solid Solution Nanocapsules

2010 ◽  
Vol 663-665 ◽  
pp. 1256-1259
Author(s):  
Gui Mei Shi ◽  
Ge Song ◽  
Shu Lian ◽  
Jin Bing Zhang
Keyword(s):  
Solid Solution ◽  
Photoelectron Spectrum ◽  
Room Temperature ◽  
Ferromagnetic State ◽  
Antiferromagnetic Order ◽  
X Ray Diffraction ◽  
X Ray ◽  
The Core ◽  
New Type ◽  
The Magnetic Field

A new type of antiferromagnetic CoAl2O4 coated ferromagnetic Co solid solution is synthesized by arc-discharging. Typical HRTEM images show that the nanocapsules form in a core-shell structure. The size of the nanocapsules is in range of 10-90 nm and the thickness of the shell is about 3-10 nm. X-ray photoelectron spectrum (XPS) and X-ray diffraction (XRD) reveal that the core consists of Co solid solution, while the shell is CoAl2O4. The magnetic field and temperature dependence of magnetizations confirm that the Co solid solution nanocapsules are basically in the ferromagnetic state below Curie temperature. In addition, the antiferromagnetic order occurs with Neél temperature TN of about 5 K. The saturation magnetization of Ms = 76.1 Am2/kg and the coercive force of Hc= 23.28 kA/m are achieved at room temperature for the Co solid solution nanocapsules.

scholarly journals Sintering and dielectric properties of a technical porcelain prepared from economical natural raw materials

Cerâmica ◽  
2016 ◽  
Vol 62 (364) ◽  
pp. 405-412 ◽  
Author(s):  
S. Kasrani ◽  
A. Harabi ◽  
S.-E. Barama ◽  
L. Foughali ◽  
M. T. Benhassine ◽  
...  
Keyword(s):  
Dielectric Constant ◽  
Room Temperature ◽  
Raw Materials ◽  
Dielectric Measurements ◽  
X Ray Diffraction ◽  
Potash Feldspar ◽  
Spectroscopy Analysis ◽  
X Ray ◽  
Microscopy Images ◽  
Technical Porcelain

Abstract In this study, the production of a technical porcelain, for the ceramic dielectric applications by using economical natural raw materials, was investigated. The basic porcelain composition was selected consisting of 30 wt% kaolin, 45 wt% potash-feldspar and 25 wt% quartz. The obtained phases in the sintered samples were investigated by X-ray diffraction, Fourier transform infrared spectroscopy analysis, and scanning electron microscopy images. It has been confirmed by these techniques that the main crystalline phases were quartz and mullite. Dielectric measurements of technical porcelains have been carried out at 1 kHz from room temperature to 200 °C. The dielectric constant, loss factor, dielectric loss tangent, and resistivity of the porcelain sample sintered at 1160 °C were 22-25, 0.32-1.80, 0.006-0.07, and 0.2-9 x 1013 Ω.cm, respectively. The value of dielectric constant was significantly high when compared to that of conventional porcelains which did not exceed generally 9.

Synthesis of Al2OC Ceramic Powder by a Carbothermal Reduction Process

2014 ◽  
Vol 881-883 ◽  
pp. 1017-1020
Author(s):  
Shuang Shuang Ding ◽  
Peng Cui ◽  
Hong Xi Zhu ◽  
Cheng Ji Deng ◽  
Chao Yu
Keyword(s):  
Carbothermal Reduction ◽  
Raw Materials ◽  
Heating Temperature ◽  
Ceramic Powder ◽  
Reduction Process ◽  
Synthesis Temperature ◽  
X Ray Diffraction ◽  
X Ray ◽  
Argon Flow ◽  
Micro Morphology

A12OC ceramic powder was successfully synthesized via a carbothermal reduction method using Al2O3, B2O3 and activated carbon powders as raw materials. The effects of synthesis temperature on the phase transformation and micro-morphology of A12OC were investigated by means of X-ray diffraction (XRD) and scanning electron microscopy (SEM). The results indicated that the content of A12OC in the products was increased with the increasing heating temperature. The optimized process for preparing A12OC was heating the mixtures at 1700 °C for 2 h in argon flow. A12OC particles synthesized at 1700 °C were hexagon plate-like with thickness of 5 μm and size of about 50 μm. Keywords: A12OC, synthesis, microstructure

Y-Type Hexaferrites: Structural, Dielectric and Magnetic Properties

2012 ◽  
Vol 189 ◽  
pp. 209-232 ◽  
Author(s):  
Rajshree B. Jotania ◽  
Hardev Singh Virk
Keyword(s):  
Magnetic Properties ◽  
Quantum Interference ◽  
Room Temperature ◽  
Structural Changes ◽  
Ferromagnetic State ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Lcr Meter ◽  
Co Precipitation

This paper attempts to provide a historical survey of structure of various types of hexaferrites. It provides information about synthesis, characterization, structural, magnetic and dielectric properties of Y-type hexagonal ferrites using various chemical routes. We have prepared a series of cobalt doped Sr2Cu2-xCoxFe12O22(x = 0.0 to 1.0) hexaferrites using a wet chemical co-precipitation technique. The prepared hexaferrite precursors were calcined at 950 °C for 4 hours in a furnace and slowly cooled to room temperature. The crystal structure of Y-type hexaferrites is rather complicated. The chemical and structural changes were examined in detail by X-ray diffraction (XRD), Differential scanning calorimetry (DSC), Scanning electron microscopy (SEM), and Fourier transform infra-red (FTIR) spectroscopy. X-ray diffraction studies showed that sintering temperature as low as 950°C was sufficient to produce a single-phase Y-type hexaferrite material. The dielectric measurements were carried out over the frequency range of 100 Hz to 2 MHz at room temperature using an LCR meter to study the variation of dielectric constant and loss tangent with frequency. The magnetic properties of hexaferrite samples were investigated using a vibration sample magnetometer (VSM), and a superconducting quantum interference device (SQUID) magnetometer in the temperature range 30K to 200K. A change from ferromagnetic state to super paramagnetic state has been observed in Co doped Sr2Cu2-xCoxFe12O22(x= 0.6 to 1.0) hexaferrite. The novel applications of all types of hexaferrite materials have been described.

Preparation and Thermoelectric Properties of AgPb18SbTe20 Materials via Hydrothermal Synthesis Method

2008 ◽  
Vol 368-372 ◽  
pp. 550-552 ◽  
Author(s):  
H. Li ◽  
Ke Feng Cai ◽  
H.F. Wang ◽  
L. Wang ◽  
X.L. Li
Keyword(s):  
Hydrothermal Synthesis ◽  
Thermal Effects ◽  
Room Temperature ◽  
Synthesis Method ◽  
Argon Atmosphere ◽  
Pressureless Sintering ◽  
X Ray Diffraction ◽  
Bulk Materials ◽  
X Ray ◽  
Maximum Power Factor

AgPb18SbTe20 nano-powders have been synthesized by a hydrothermal synthesis method at 180 °C for 20 h, using AgNO3, Pb(NO3)2, Sb(NO3)3, Na2TeO3 as starting materials and KBH4 as a reductant. AgPb18SbTe20 bulk thermoelectric materials were obtained by pressureless sintering at 450 °C or 520 °C under argon atmosphere, after uniaxial pressing the as-synthesized powders into pellets. The phase composition and thermal effects of as-prepared powders were characterized by X-ray diffraction (XRD) and DSC-TG analyses, respectively. Electrical properties of the as-prepared bulk materials were measured from room temperature to about 700 K, and the maximum power factor of 85 μW/mK2 was achieved at 600 K for the sample sintered at 723 K for 3 h.

scholarly journals The behavior of the lattice parameters in the Bi-Sn-Zn system

2007 ◽  
Vol 43 (2) ◽  
pp. 151-159 ◽  
Author(s):  
Helena Braga ◽  
J. Ferreira ◽  
L.F. Malheiros
Keyword(s):  
Room Temperature ◽  
Mass Density ◽  
Phase Region ◽  
Argon Atmosphere ◽  
Lattice Parameters ◽  
Crystalline Solid ◽  
X Ray Diffraction ◽  
X Ray ◽  
Three Phase ◽  
Expansion Coefficients

Lattice parameters, coefficients of thermal expansion and mass density were determined by means of X-ray powder diffraction between 30 and 180?C (or 240?C - depending on samples' composition). Rietveld refinement was performed in order to obtain phases' lattice parameters at each temperature. The Panalytical X' Pert Pro MPD was used for room temperature X-ray diffraction experiments (RTXRD) with bulk samples. The aim was to identify the phases that were present in the sample, as well as, their lattice parameters. For some samples, powder high temperature X-ray diffraction measurements (HT-XRD) were also performed, under a vacuum of 10-5 mbar or an argon atmosphere. It was found that the lattice parameters of (Bi), (Sn) and (Zn) don't change with the composition, at room temperature, as expected since all samples belong to the three phase region. It was also concluded that (Bi) behaves like an isometric crystalline solid on the contrary of (Zn) that has different expansion coefficients for different crystallographic directions a (= b) and c.

Influence of CeO2 Additive on the Phase Transformations of Zirconia from Zircon Ore by Carbothermal Reduction Process

2014 ◽  
Vol 602-603 ◽  
pp. 238-241 ◽  
Author(s):  
Teng Yu Wang ◽  
You Guo Xu ◽  
Zhao Hui Huang ◽  
Ming Hao Fang ◽  
Yan Gai Liu ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Phase Transformations ◽  
Carbothermal Reduction ◽  
Heating Temperature ◽  
Reduction Process ◽  
X Ray Diffraction ◽  
Stabilized Zirconia ◽  
X Ray ◽  
Additive Increase ◽  
Scanning Electron

This paper mainly discusses the influences of heating temperatures and CeO2 additive contents on the phase transformations of zirconia from zircon ore by carbothermal reduction. The phase transformations of zirconia from zircon ore by carbothermal reduction were monitored by X-ray diffraction. The microstructure of the product was characterized by scanning electron microscopy. The results show that without adding CeO2, the optimized heating temperature of zircon carbothermal reduction was 1600 °C and the main phases of the product were m-ZrO2, ZrC and β-SiC, t-ZrO2; After adding CeO2, the main phase of the products consists of t-ZrO2, m-ZrO2, ZrC and β-SiC when the heating temperature is 1600 °C. CeO2 additive can be introduced into zirconia lattice and can cause it to form cerium stabilized zirconia. Zirconia in the product would be turned into partially stabilized zirconia with cerium addition from 5 wt% to 20 wt%. However, the form of zirconia in the product is not changed greatly with the amount of CeO2 additive increase.

scholarly journals Synthesis of Y- Ni alloy by calciothermic reduction diffusion process

10.30544/96 ◽  
2015 ◽  
Vol 21 (2) ◽  
pp. 65-72 ◽  
Author(s):  
Marimuthu Ilayaraja ◽  
L. John Berchmans ◽  
Sankara Raman Sankaranarayanan
Keyword(s):  
Electron Microscopy ◽  
Reduction Process ◽  
Argon Atmosphere ◽  
Vibrating Sample Magnetometer ◽  
X Ray Diffraction ◽  
X Ray ◽  
Ni Alloy ◽  
Different Temperatures ◽  
Calciothermic Reduction ◽  
Scanning Electron

In this study, magnetic material of the Yttrium based alloy such as nickel intermetallic compound is prepared by calciothermic reduction process (CRD), at different temperatures, for 7 hours, under Argon atmosphere. Kinetic analyses have been used to calculate the conversion rate and the rate constant at different temperatures. Thermodynamic calculations have been performed to estimate the Gibbs free energy at different temperatures. Scanning Electron Microscopy (SEM), X-ray diffraction and EDX analysis have been performed to characterize the samples produced at 1273 K. Magnetic properties have been estimated using Vibrating Sample Magnetometer.

scholarly journals Room-Temperature Synthesis of the TiC, ZrC, HfC, VC, NbC and TaC Powder Monocarbides

2019 ◽  
Vol 7 (1) ◽  
pp. 113-120
Author(s):  
Olesya I. Nakonechna ◽  
Nadezhda N. Belyavina ◽  
Mykola M. Dashevskyi ◽  
Yuriy A. Titov
Keyword(s):  
Crystal Structure ◽  
Mechanical Alloying ◽  
Ball Mill ◽  
Room Temperature ◽  
Diffraction Method ◽  
High Energy ◽  
Argon Atmosphere ◽  
X Ray Diffraction ◽  
Temperature Synthesis ◽  
X Ray

The nanoscaled (up to 30 nm) TiC, ZrC, HfC, VC, NbC and TaC monocarbides with NaCl-type structure have been synthesized from the elemental metals and the carbon nanotubes (CNTs) by mechanical alloying in a high energy planetary ball mill in an argon atmosphere. The powders obtained were examined by X-ray diffraction method. It is shown that mechanical alloying is accompanied by a decrease in the lattice parameters of MeC carbides formed and by a decrease of the total number of atoms in their crystal structure, i.e. by an increase of structural vacancies in the materials obtained. On the whole, monocarbides obtained can be arranged by the simplicity of their formation in a ball mill as: HfC -> ZrC -> TiC -> TaC -> NbC -> VC.

scholarly journals Synthesis and Magnetic Properties of Hematite Particles in a “Nanomedusa” Morphology

2014 ◽  
Vol 2014 ◽  
pp. 1-9 ◽  
Author(s):  
Jin Bae Lee ◽  
Hae Jin Kim ◽  
Janez Lužnik ◽  
Andreja Jelen ◽  
Damir Pajić ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Room Temperature ◽  
Magnetic Phase ◽  
Hydrothermal Process ◽  
Ferromagnetic State ◽  
X Ray Diffraction ◽  
Morin Transition ◽  
Preferential Direction ◽  
X Ray ◽  
Transmission Electron

We present the synthesis, characterization, and magnetic properties of hematite particles in a peculiar “nanomedusa” morphology. The particles were prepared from an iron-silica complex by a hydrothermal process in a solution consisting of ethyl acetate and ethanol. The particles’ morphology, structure, and chemical composition were investigated by transmission electron microscopy, powder X-ray diffraction, and scanning electron microscope equipped with an energy-dispersive X-ray spectrometer. The “hairy” particles consist of a spherical-like core of about 100 nm diameter and fibrous exterior composed of thin “legs” of 5 nm diameter grown along one preferential direction. The particles’ cores are crystalline and undergo a magnetic phase transition to a weakly ferromagnetic state at a temperature of 930 K that matches reasonably the Néel temperature of bulk hematite. However, unlike bulk hematite that undergoes Morin transition to an antiferromagnetic state around room temperature and small hematite nanoparticles that are superparamagnetic, the “nanomedusa” particles remain weakly ferromagnetic down to the lowest investigated temperature of 2 K. Each particle thus represents a nanodimensional “hairy” ferromagnet in a very broad temperature interval, extending much above the room temperature. Such high-temperature ferromagnetic nanoparticles are not frequently found among the nanomaterials.

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