scholarly journals PHASE TRANSFORMATION IN THE FORMATION OF FAUJASITE FROM FLY ASH

2010 ◽  
Vol 5 (3) ◽  
pp. 278-282 ◽  
Author(s):  
Sutarno Sutarno ◽  
Yateman Arryanto
Keyword(s):  
Phase Transformation ◽  
Fly Ash ◽  
Specific Surface ◽  
Alkaline Solution ◽  
Weight Ratio ◽  
Diffraction Method ◽  
Hydrothermal Time ◽  
X Ray Diffraction ◽  
X Ray ◽  
Ash Weight

Faujasite was hydrothermally synthesized from fly ash at 100oC in alkaline solution by reflux with 5M HCl and fusion with NaOH pretreatments. Phase transformation in the formation of faujasite was performed by variation of NaOH/fly ash weight ratios and hydrothermal times. The solid products were characterized by X-ray diffraction method. Results showed that faujasite was formed through dissolution of fly ash components such as quartz, mullite and amorphous aluminosilicates followed by crystallization to form faujasite. Arranging the NaOH/fly ash weight ratio as well as hydrothermal time can selectively form faujasite. Faujasite with crystallinity of 97.06%, Si/Al ratio of 2.68, and specific surface area of 452.93 m2/g was successfully formed using NaOH/fly ash weight ratio of 1.2 for hydrothermal time of 72 hours. In more concentrated alkaline solution as well as for longer hydrothermal time, faujasite was completely transformed into hydroxysodalite as the final product. Keywords: fly ash, faujasite, and phase transformation.

scholarly journals SINTESIS DAN KARAKTERISASI FAUJASIT DARI ABU LAYANG : Kajian Pengaruh Waktu Sintesis Terhadap Stabilitas Termal Struktur Faujasit (Kinetics of Faujasite Formation from Fly Ash)

2019 ◽  
Vol 2 (2) ◽  
pp. 10
Author(s):  
Sutarno Sutarno ◽  
Arief Budyantoro
Keyword(s):  
Thermal Stability ◽  
Fly Ash ◽  
Amorphous Phase ◽  
Zeolite Y ◽  
Weight Ratio ◽  
Hydrothermal Time ◽  
X Ray Diffraction ◽  
X Ray ◽  
Kinetics Of ◽  
Thermal Stability Of

Faujasite was hydrothermally synthesized from fly ash at 100oC in alkaline solution by reflux with 5M HCl and fusion with NaOH (weight ratio of NaOH/fly ash = 1.2) pretreatments. Kinetics of faujasite formation was performed by variation of hydrothermal time (0-120 hours). Thermal stability of faujasite from fly ash was tested at 400-900oC and was compared with commercial zeolite Y. The solid products were characterized by X-ray diffraction method. Results showed that faujasite was formed through dissolution of fly ash components such as quartz, mullite and amorphous aluminosilicates (0-3 hours) followed by crystallization to form faujasite (6-48 hours). In longer hydrothermal time (48-72 hours), faujasite transformed into zeolite P and completely formed hydroxysodalite after 120 hours. X-ray diffraction pattern showed that thermal stability of faujasite from fly ash was relatively lower than that of commercial zeolite Y. Faujasite from fly ash transformed into amorphous phase at 800oC whereas commercial zeolite Y transformed into amorphous phase at 900oC.

Phase Transformation in Mechanically Alloyed and Hot-Pressed Nb-4Si-8B and Nb-8Si-16B Alloys

2014 ◽  
Vol 802 ◽  
pp. 14-19
Author(s):  
Carlos Edilson Chiaradia ◽  
Luciano Braga Alkmin ◽  
Carlos Ângelo Nunes ◽  
Vinícius André Rodrigues Henriques ◽  
Gilda Maria Cortez Pereira ◽  
...  
Keyword(s):  
Phase Transformation ◽  
Energy Dispersive Spectrometry ◽  
Weight Ratio ◽  
Wet Milling ◽  
X Ray Diffraction ◽  
Mechanically Alloyed ◽  
X Ray ◽  
Equilibrium Structures ◽  
Steel Balls ◽  
Milled Powders

The work reports on the phase transformation in mechanically alloyed and hot-pressed Nb-4Si-8B and Nb-8Si-16B (at-%) alloys. Elemental powder mixtures were processed in a planetary ball mill under argon atmosphere using 300 rpm, stainless steel balls (19 mm diameter) and vials (225 mL), and a ball-to-powder weight ratio of 10:1. After dry milling for 7h, wet milling with isopropyl alcohol for more 20 min was adopted to increase the recovering of previously cold-welded Nb-4Si-8B powders. To obtain the equilibrium structures the as-milled powders were hot-pressed under vacuum at 1200oC for 1 h. The as-milled powders and hot-pressed samples were characterized by X-ray diffraction, scanning electron microscopy, and energy dispersive spectrometry. XRD results revealed the presence of metastable phases in as-milled Nb-Si-B powders. The hot pressing has produced dense Nb-Si-B samples, which were formed by the Nbss, Nb3B2and Fe2Nb phases beside of other unknown Si-rich phase.

scholarly journals Phase Transformation of Alumina, Silica and Iron Oxide during Carbothermic Reduction of Fly Ash for Ceramics Production

Metals ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 1165
Author(s):  
Qingchun Yu ◽  
Yong Deng ◽  
Yuebin Feng ◽  
Ziyong Li
Keyword(s):  
Phase Transformation ◽  
Fly Ash ◽  
Carbothermic Reduction ◽  
Energy Dispersive Spectrometry ◽  
Intermediate Compound ◽  
Added Value ◽  
X Ray Diffraction ◽  
X Ray ◽  
Reduced Products ◽  
Electronic Microscope

Fly ash is a by-product from burning of coal. Utilization of fly ash by carbothermic reduction is an effective way to recover aluminum, silicon, and iron to enhance product-added value. This work is focused on the phase transformation of Al2O3, SiO2 and Fe2O3 during carbothermic reduction of fly ash in air. A comparative analysis of carbothermic reduction of fly ash in air and in nitrogen was made. Thermodynamics analysis was performed to illustrate the possible reactions for residue and condensate. X-ray diffraction (XRD), scanning electronic microscope (SEM), and energy dispersive spectrometry (EDS) were employed to characterize the phase composition, surface morphology, and microstructure of the reduced products. Results show that Fe3Si and Fe2Si appear sequentially with increasing of temperature. Al5O6N is an intermediate compound. Residue of Al9FeSi3, Al, and Si, and condensate of SiC, AlN and C are obtained. β-SiAlON was not found in the residue. Nitrogen is involved in the reduction of Al2O3 but not in the reduction of SiO2 and Fe2O3. Carbothermic reduction of fly ash in air did not behave the same as fly ash in nitrogen.

scholarly journals Zirconium Phase Transformation under Static High Pressure and ω-Zr Phase Stability at High Temperatures

Materials ◽  
2019 ◽  
Vol 12 (14) ◽  
pp. 2244 ◽  
Author(s):  
Lucyna Jaworska ◽  
Jolanta Cyboron ◽  
Slawomir Cygan ◽  
Adam Zwolinski ◽  
Boguslaw Onderka ◽  
...  
Keyword(s):  
High Pressure ◽  
Phase Transformation ◽  
High Temperatures ◽  
High Purity ◽  
Stress Measurement ◽  
Diffraction Method ◽  
Quantitative Phase Analysis ◽  
X Ray Diffraction ◽  
X Ray ◽  
Ω Phase

High-purity Zr has been observed to undergo a phase transformation from the α-phase to the hexagonal ω-phase under high pressure generated either statically or by shock loading. The transition pressure from α-Zr to ω-Zr at 300 K is 2.10 GPa. The main aim of this research was to determine the conditions of α-Zr in ω-Zr transformation and the state of stresses after the high-pressure pressing and sintering of zirconium powders. Commercially acquired zirconium powders of 99.9% and 98.8% purity were used in this study. Qualitative and quantitative phase analysis of the materials was carried out using X-ray diffraction. The materials were statically pressed and sintered using a Bridgman-type toroidal apparatus at under 4.0 and 7.8 GPa. After pressing, the transformation proceeded for the zirconium powder containing 98.8% purity (with hydrides admixture) but did not occur for the high-purity zirconium powders with 99.9% purity. The zirconium powders were sintered using the HPHT (High Pressure—High Temperature) method at temperatures of 1273 K and 1473 K. The transformation proceeded for both powders. The highest contribution of the ω-Zr phase was obtained in the zirconium (98.8% purity with the hydrides contents) sintered for 1 min at a temperature of 1473 K and a pressure of 7.8. The ω-phase content was 87 wt.%. The stress measurement was performed for the pressed and sintered materials using the sin2ψ X-ray diffraction method. The higher sintering temperature resulted in a decrease of the residual stresses in the ω-Zr phase for the sintered zirconium. The higher levels of stress limited the transformation of the α-Zr phase into the ω-Zr phase. Investigated materials characterized by higher compressive macrostresses were also typical of the greater stability of the ω-Zr phase at high temperatures.

scholarly journals SYNTHESIS OF FAUJASITE WITH HIGH THERMAL STABILITY FROM FLY ASH

2010 ◽  
Vol 4 (1) ◽  
pp. 26-32
Author(s):  
Sutarno Sutarno ◽  
Yateman Arryanto
Keyword(s):  
Thermal Stability ◽  
Fly Ash ◽  
Zeolite Y ◽  
Weight Ratio ◽  
Diffraction Method ◽  
Nitrogen Adsorption ◽  
X Ray Diffraction ◽  
Zeolite Nay ◽  
Naoh Pretreatment ◽  
Thermal Stability Of

Faujasite was hydrothermally synthesized from fly ash at 100oC in alkaline solution by reflux with various concentration of HCl and fusion with NaOH (weight ratio of NaOH/fly ash = 1.2) pretreatments. Thermal stability of faujasite from fly ash was tested at 400-900oC and was compared with commercial zeolite Y. The solid products were characterized by X-ray diffraction method, chemical analysis and nitrogen adsorption (BET). Results showed that synthesis of faujasite from fly ash via fusion pretreatment with NaOH has resulted faujasite selectively, however, the faujasite obtained still showed relatively low thermal stability due to its relatively low of Si/Al mol ratio. Reflux pretreatment with HCl was an effective method not only to increase the Si/Al mol ratio but also to decrease the metal impurities in the fly ash sample. Synthesis of faujasite from fly ash via combination of reflux with HCl and fusion with NaOH pretreatment has resulted faujasite selectively with higher Si/Al mol ratio. Faujasite obtained from fly ash via combination of reflux with HCl and fusion with NaOH pretreatment showed thermal stability as high as commercial zeolite NaY.   Keywords: fly ash, reflux with HCl, fusion with NaOH, faujasite and thermal stability

scholarly journals Growth of sillenite Bi12FeO20 single crystals: structural, thermal, optical, photocatalytic features and first principle calculations

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Durga Sankar Vavilapalli ◽  
Ambrose A. Melvin ◽  
F. Bellarmine ◽  
Ramanjaneyulu Mannam ◽  
Srihari Velaga ◽  
...  
Keyword(s):  
Single Crystal ◽  
Single Crystals ◽  
Photoelectron Spectroscopy ◽  
Diffraction Method ◽  
Lattice Parameter ◽  
First Principle ◽  
X Ray Diffraction ◽  
X Ray ◽  
First Principle Calculations ◽  
Photodegradation Efficiency

AbstractIdeal sillenite type Bi12FeO20 (BFO) micron sized single crystals have been successfully grown via inexpensive hydrothermal method. The refined single crystal X-ray diffraction data reveals cubic Bi12FeO20 structure with single crystal parameters. Occurrence of rare Fe4+ state is identified via X-ray photoelectron spectroscopy (XPS) and X-ray absorption spectroscopy (XAS). The lattice parameter (a) and corresponding molar volume (Vm) of Bi12FeO20 have been measured in the temperature range of 30–700 °C by the X-ray diffraction method. The thermal expansion coefficient (α) 3.93 × 10–5 K−1 was calculated from the measured values of the parameters. Electronic structure and density of states are investigated by first principle calculations. Photoelectrochemical measurements on single crystals with bandgap of 2 eV reveal significant photo response. The photoactivity of as grown crystals were further investigated by degrading organic effluents such as Methylene blue (MB) and Congo red (CR) under natural sunlight. BFO showed photodegradation efficiency about 74.23% and 32.10% for degrading MB and CR respectively. Interesting morphology and microstructure of pointed spearhead like BFO crystals provide a new insight in designing and synthesizing multifunctional single crystals.

scholarly journals Study of Corrosion Resistance and Degradation Mechanisms in LiTiO2-Li2TiO3 Ceramic

Crystals ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 753
Author(s):  
Dmitriy Shlimas ◽  
Artem L. Kozlovskiy ◽  
Maxim Zdorovets
Keyword(s):  
Degradation Mechanism ◽  
Diffraction Method ◽  
Large Mass ◽  
Time Frame ◽  
X Ray Diffraction ◽  
Acidic Media ◽  
X Ray ◽  
Mass Losses ◽  
The Stability ◽  
Thermal Sintering

The interest in lithium-containing ceramics is due to their huge potential as blanket materials for thermonuclear reactors for the accumulation of tritium. However, an important factor in their use is the preservation of the stability of their strength and structural properties when under the influence of external factors that determine the time frame of their operation. This paper presents the results of a study that investigated the influence of the LiTiO2 phase on the increasing resistance to degradation and corrosion of Li2TiO3 ceramic when exposed to aggressive acidic media. Using the X-ray diffraction method, it was found that an increase in the concentration of LiClO4·3H2O during synthesis leads to the formation of a cubic LiTiO2 phase in the structure as a result of thermal sintering of the samples. During corrosion tests, it was found that the presence of the LiTiO2 phase leads to a decrease in the degradation rate in acidic media by 20–70%, depending on the concentration of the phase. At the same time, and in contrast to the samples of Li2TiO3 ceramics, for which the mechanisms of degradation during a long stay in aggressive media are accompanied by large mass losses, for the samples containing the LiTiO2 phase, the main degradation mechanism is pitting corrosion with the formation of pitting inclusions.

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