Influence of Oxide Nanoparticles of Fe, Al and Si on the Sintered Magnesia for the Production of Refractory Material to Be Used in Secondary Ladle Metallurgy

2012 ◽  
Vol 1371 ◽  
Author(s):  
Cristian Gómez ◽  
Tushar.K. Das ◽  
Sadasivan Shaji ◽  
Edén A. Rodríguez ◽  
Ana M. Guzmán ◽  
...  
Keyword(s):  
Magnesium Oxide ◽  
Refractory Material ◽  
Silicon Oxide ◽  
Spinel Phase ◽  
X Ray Diffraction ◽  
Spinel Type ◽  
X Ray ◽  
Ladle Metallurgy ◽  
The Matrix ◽  
Agglomeration Of Nanoparticles

ABSTRACTIron oxide (Fe2O3, 20-40 nm), aluminum oxide (Al2O3, 50 nm) and silicon oxide (SiO2, 20-60 nm) nanoparticles were mixed in different concentrations (1 to 5 wt %) in a magnesium oxide matrix to develop new refractory matrixes as candidates in the lining of secondary ladle metallurgy. To avoid agglomeration of nanoparticles in the magnesium oxide (MgO) matrix, it was carried out a dispersion method of nanoparticles with different dispersants. After that, the powder mixture was sintered at a temperature of 1300 and 1500 °C for 4 hours. The refractory samples obtained were studied using X-ray diffraction (XRD) and scanning electron microscopy with energy dispersive X-ray spectrometer (SEM-with EDX) and also measured their density and porosity. The results showed that the samples sintered at 1500 °C with 5 wt % of Fe2O3 reached the highest density and presented the MgFe2O4 spinel-type phase. With the addition of Al2O3-nanoparticles in the MgO matrix, there were the formation of MgAl2O4 spinel phase and in the case of SiO2-nanoparticles addition it was observed the formation of Mg2SiO4 forsterite phase. It is well known that with the increase in spinel phase in the matrix, there is a significant help to retain quantities of ions of iron and nickel due to the dissolution of the slag into the refractory material extending their lining life.

scholarly journals Structural, Optical, and Catalytic Properties of MgCr2O4 Spinel-Type Nanostructures Synthesized by Sol–Gel Auto-Combustion Method

Catalysts ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 1476
Author(s):  
Vasyl Mykhailovych ◽  
Andrii Kanak ◽  
Ştefana Cojocaru ◽  
Elena-Daniela Chitoiu-Arsene ◽  
Mircea Nicolae Palamaru ◽  
...  
Keyword(s):  
Tartaric Acid ◽  
Catalytic Properties ◽  
Spinel Phase ◽  
Sol Gel ◽  
Combustion Method ◽  
Temperature Treatment ◽  
X Ray Diffraction ◽  
Spinel Type ◽  
X Ray ◽  
Auto Combustion

Spinel chromite nanoparticles are prospective candidates for a variety of applications from catalysis to depollution. In this work, we used a sol–gel auto-combustion method to synthesize spinel-type MgCr2O4 nanoparticles by using fructose (FS), tartaric acid (TA), and hexamethylenetetramine (HMTA) as chelating/fuel agents. The optimal temperature treatment for the formation of impurity-free MgCr2O4 nanostructures was found to range from 500 to 750 °C. Fourier transform infrared (FTIR) spectroscopy was used to determine the lattice vibrations of the corresponding chemical bonds from octahedral and tetrahedral positions, and the optical band gap was calculated from UV–VIS spectrophotometry. The stabilization of the spinel phase was proved by X-ray diffraction (XRD) and energy-dispersive X-ray (EDX) analysis. From field-emission scanning electron microscopy (FE-SEM), we found that the size of the constituent particles ranged from 10 to 40 nm. The catalytic activity of the as-prepared MgCr2O4 nanocrystals synthesized by using tartaric acid as a chelating/fuel agent was tested on the decomposition of hydrogen peroxide. In particular, we found that the nature of the chelating/fuel agent as well as the energy released during the auto-combustion played an important role on the structural, optical, and catalytic properties of MgCr2O4 nanoparticles obtained by this synthetic route.

Effect of Ultrasonication on Synthesis of Forsterite Ceramics

2012 ◽  
Vol 576 ◽  
pp. 252-255 ◽  
Author(s):  
K.Y. Sara Lee ◽  
K.M. Christopher Chin ◽  
Ramesh Singh ◽  
C.Y. Tan ◽  
M.A. Hassan ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Crystallite Size ◽  
Ball Milling ◽  
Magnesium Oxide ◽  
X Ray Diffraction ◽  
X Ray ◽  
Heat Treated ◽  
The Matrix ◽  
Processing Steps

The current study is to examine the effect of ultrasonication on the synthesis of forsterite (Mg2SiO4) powder. Ultrasonication and ball milling were performed using talc and magnesium oxide as starting precursors, followed by heat treatment to obtain forsterite. The X-ray diffraction results of the powders heat treated at 1200°C showed that the 2 hours ultrasonication followed by 3 hours ball milling was beneficial in retaining the forsterite phase in the matrix. The results were similar to ball milling for 10 hours prior to heat treatment. The derived powders also exhibited very fine crystallite size in the range of 28 to 35 nm thus indicating the viability of using ultrasonication as part of the processing steps in the synthesizing of forsterite ceramics.

Characteristics of Ni–Cr–Fe laser clad layers on EA4T steel

2017 ◽  
Vol 31 (16-19) ◽  
pp. 1744031
Author(s):  
Wenjing Chen ◽  
Hui Chen ◽  
Yongjing Wang ◽  
Congchen Li ◽  
Xiaoli Wang
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
X Ray Diffraction ◽  
X Ray ◽  
Cladding Layer ◽  
Metallurgical Bonding ◽  
The Matrix ◽  
Feeding Speed ◽  
Upper Bainite ◽  
Scanning Electron

The Ni–Cr–Fe metal powder was deposited on EA4T steel by laser cladding technology. The microstructure and chemical composition of the cladding layer were analyzed by optical microscopy (OM), scanning electron microscopy (SEM) and X-ray diffraction (XRD). The bonding ability between the cladding layer and the matrix was measured. The results showed that the bonding between the cladding layer and the EA4T steel was metallurgical bonding. The microstructure of cladding layer was composed of planar crystals, columnar crystals and dendrite, which consisted of Cr2Ni3, [Formula: see text] phase, M[Formula: see text]C6 and Ni3B phases. When the powder feeding speed reached 4 g/min, the upper bainite occurred in the heat affected zone (HAZ). Moreover, the tensile strength of the joint increased, while the yield strength and the ductility decreased.

Detection of Compositional Fluctuations in High Temperature Exposed Waspaloy

2001 ◽  
Vol 699 ◽  
Author(s):  
Xiaodong Zou ◽  
Tariq Makram ◽  
Rosario A. Gerhardt
Keyword(s):  
Exposure Time ◽  
Structural Integrity ◽  
Thermal Exposure ◽  
X Ray Diffraction ◽  
X Ray ◽  
Gamma Prime ◽  
Distribution Shape ◽  
The Matrix ◽  
Quantitative Stereology ◽  
Nickel Base

AbstractWaspaloy is a nickel base super-alloy used in aircraft engines. When this alloy is placed in service, it is subjected to long term exposure at high temperatures, which can cause the reinforcing gamma prime precipitate population to fluctuate and thus affect its structural integrity. The population fluctuates as a result of coarsening, dissolution or re-precipitation. Samples exposed to 1200° F for times ranging from 0 to 12626 hours were characterized using impedance spectroscopy, microhardness measurements, x-ray diffraction and quantitative stereology. Two important parameters were derived from the impedance measurements: (1) the imaginary admittance peak magnitude (Ymax) and (2) the associated relaxation frequency (fmax). As the distribution, shape and size of the precipitates change with exposure time, these parameters were also found to vary. In addition to the changes in precipitate geometry, lattice constant changes detected by analyzing x-ray diffraction data suggest that there are compositional shifts in the matrix as well as the gamma prime precipitates. Furthermore, the preferred orientation of the precipitates can also be seen to change with exposure time. These changes in composition, size and shape as a function of thermal exposure time are accompanied by changes in the volume fractions of primary and secondary gamma prime particles present. Using effective medium models, it is possible to predict that the measured properties are related to the gamma prime population. The grain boundary carbides do not appear to play any role at the conditions presented.

scholarly journals Влияние режима получения образцов и термообработки на локальную структуру халькогенидного полупроводника Ge-=SUB=-2-=/SUB=-Sb-=SUB=-2-=/SUB=-Te-=SUB=-5-=/SUB=-

2022 ◽  
Vol 56 (3) ◽  
pp. 291
Author(s):  
С.Н. Гарибова ◽  
А.И. Исаев ◽  
С.И. Мехтиева ◽  
С.У. Атаева ◽  
Р.И. Алекперов
Keyword(s):  
Heat Treatment ◽  
Thermal Processing ◽  
Thermal Evaporation ◽  
Amorphous State ◽  
Hexagonal Structure ◽  
Structural Elements ◽  
X Ray Diffraction ◽  
X Ray ◽  
The Matrix ◽  
Close Range

Specifics of "amorphous state - crystal" phase transitions in dependence on the samples obtaining method and thermal processing, as well as changes in the structure and close range order in the arrangement of the atoms of Ge20Sb20.5Te51 chalcogenide semiconductors have been studied by the x-ray diffraction and Raman spectroscopy. It has been shown that Ge20Sb20.5Te51 films obtained by thermal evaporation on an unheated substrate are amorphous; after heat treatment at 220 and 400 °C, transform into a crystalline phase with a cubic and hexagonal structure. The chemical bonds and the main structural elements that form the matrix of the investigated objects, as well as the changes that occur in them during heat treatment, have been determined.

scholarly journals Thermal History of Matrix Forsterite Grains from Murchison Based on High-resolution Tomography

2021 ◽  
Vol 922 (2) ◽  
pp. 256
Author(s):  
Giulia Perotti ◽  
Henning O. Sørensen ◽  
Henning Haack ◽  
Anja C. Andersen ◽  
Dario Ferreira Sanchez ◽  
...  
Keyword(s):  
High Resolution ◽  
Electron Density ◽  
Chemical Compositions ◽  
X Ray Diffraction ◽  
X Ray ◽  
Density Maps ◽  
Thermally Processed ◽  
The Matrix ◽  
History Of ◽  
Chondrule Formation

Abstract Protoplanetary disks are dust- and gas-rich structures surrounding protostars. Depending on the distance from the protostar, this dust is thermally processed to different degrees and accreted to form bodies of varying chemical compositions. The primordial accretion processes occurring in the early protoplanetary disk such as chondrule formation and metal segregation are not well understood. One way to constrain them is to study the morphology and composition of forsteritic grains from the matrix of carbonaceous chondrites. Here, we present high-resolution ptychographic X-ray nanotomography and multimodal chemical microtomography (X-ray diffraction and X-ray fluorescence) to reveal the early history of forsteritic grains extracted from the matrix of the Murchison CM2.5 chondrite. The 3D electron density maps revealed, at unprecedented resolution (64 nm), spherical inclusions containing Fe–Ni, very little silica-rich glass and void caps (i.e., volumes where the electron density is consistent with conditions close to vacuum) trapped in forsterite. The presence of the voids along with the overall composition, petrological textures, and shrinkage calculations is consistent with the grains experiencing one or more heating events with peak temperatures close to the melting point of forsterite (∼2100 K), and subsequently cooled and contracted, in agreement with chondrule-forming conditions.

Machinability and Microstructure of SiC/h-BN Nano-Composites

2008 ◽  
Vol 569 ◽  
pp. 45-48
Author(s):  
Hai Yun Jin ◽  
Guan Jun Qiao ◽  
Zong Ren Peng ◽  
Ji Qiang Gao
Keyword(s):  
Fracture Strength ◽  
Nano Composites ◽  
Weak Interface ◽  
X Ray Diffraction ◽  
X Ray ◽  
Sic Particles ◽  
N2 Atmosphere ◽  
The Matrix ◽  
Better Than

SiC particles coated with nano-BN were synthesized and the machinable SiC/BN ceramic nano-composites were fabricated by Plasma Active Sintering (PAS) in N2 atmosphere. The existing and distribution of h-BN phase were revealed by X-ray diffraction (XRD), and SEM. For the existing of weak interface between h-BN and SiC grains, the machinability of both SiC/BN micro-composites and nano-composites were improved obviously. Because the nano-sized h-BN crystals were homogeneously dispersed around the SiC grains of the matrix, the fracture strength of the nano-composites was better than the SiC/h-BN micro-composite.

Aspects of the structure and composition of baleen, and some effects of exposure to petroleum hydrocarbons

1984 ◽  
Vol 62 (2) ◽  
pp. 193-198 ◽  
Author(s):  
D. J. St. Aubin ◽  
R. H. Stinson ◽  
J. R. Geraci
Keyword(s):  
Petroleum Hydrocarbons ◽  
Trichloroacetic Acid ◽  
Breaking Strength ◽  
X Ray Diffraction ◽  
Balaenoptera Physalus ◽  
Fin Whale ◽  
X Ray ◽  
The Matrix ◽  
Spilled Oil ◽  
Iron And Calcium

The structure and composition of baleen from seven species of whales was studied using tensiometry. X-ray diffraction, and elemental analysis. Baleen was found to be composed principally of amorphous and α-keratin. Hydroxyapatite (bone mineral, Ca10 (PO4)6 OH2) was present in all species. Certain elements, notably manganese, copper, boron, iron, and calcium were more highly concentrated in the fibers than in the matrix of the plate. The breaking strength of baleen plates from fin (Balaenoptera physalus), sei (B. borealis), and grey (Eschrichtius robustus) whales was comparable to that of buffalo horn, in the range of 2−9 × 106 N∙m−2. The stiffness of baleen was somewhat less than that of other keratinized tissues. Treatment with 10% (v/v) trichloroacetic acid for 8 days removed most of the calcium salts, denatured α-keratin, and made fin whale plates stronger and stiffer. Exposure to gasoline for 1.5 h or 14 days, crude oil for 8 days, or tar for 21 days resulted in loss of trace elements from baleen, and inconsistent changes in keratin organization. After tar exposure, fin whale baleen plates were stiffer and stronger. We presume that at sea, baleen would be relatively resistant to damage by spilled oil.

Investigations on Cu2+-substituted Ni–Zn ferrite nanoparticles

2016 ◽  
Vol 30 (32n33) ◽  
pp. 1650347
Author(s):  
Amarjeet ◽  
Vinod Kumar
Keyword(s):  
Spinel Phase ◽  
Thermo Gravimetric Analysis ◽  
Peak Position ◽  
Precipitation Method ◽  
Gravimetric Analysis ◽  
Frequency Range ◽  
X Ray Diffraction ◽  
Absorption Bands ◽  
X Ray ◽  
Zn Ferrite

[Formula: see text] ([Formula: see text] = 0.1, 0.3 and 0.5) nanoparticles were prepared by chemical co-precipitation method. The developed nanoparticles were characterized for structural properties by powder X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) techniques. Peak position in the X-ray diffraction pattern confirmed the single spinel phase of the developed particles. Infrared (IR) spectroscopy in mid-IR range showed the presence of characteristic absorption bands corresponding to octahedral and tetrahedral bonds in the spinel structure of prepared samples. Thermo-gravimetric analysis (TGA) measurements showed a considerable weight loss in the developed samples above 700[Formula: see text]C. Frequency dependence of the electrical properties of the developed material pellets was studied in the frequency range of 1 kHz–5 MHz. Temperature dependence of the dielectric constant of [Formula: see text] was studied at different temperatures, i.e. at 425, 450 and 475 K, in the frequency range of 1 kHz–5 MHz. It was found that the electrical conductivity decreases with increasing Cu[Formula: see text] ion content while it increases with the increase in temperature.

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