XRD Studies on Transformation of Dolomite under CO2 and N2 Atmosphere

In this study, dolomite was heated under CO2 and N2 gases using fluidized bed reactor from 85 °C to 835 °C. Dolomite under N2 atmosphere did not show any significant changes on its crystallite size, suggesting there is no significant chemical reaction. On the other hand, dolomite under CO2 atmosphere shows no significant changes on its crystallite size until it reaches high temperature (> 800 °C) where MgO started to be observed in X- ray diffraction. This shows that few chemical reactions started to happen in this reaction condition.

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In-Situ Isothermal Crystallization of Poly(l-lactide)

Polymers ◽

10.3390/polym13193377 ◽

2021 ◽

Vol 13 (19) ◽

pp. 3377

Author(s):

Zirui Huang ◽

Meiling Zhong ◽

Haibo Yang ◽

Enqin Xu ◽

Dehui Ji ◽

...

Keyword(s):

High Temperature ◽

Nucleation Rate ◽

Low Temperatures ◽

Isothermal Crystallization ◽

The Other ◽

Wide Angle ◽

X Ray Diffraction ◽

X Ray ◽

Different Temperatures

The isothermal crystallization of poly(l-lactide) (PLLA) has been investigated by in-situ wide angle X-ray diffraction (WAXD) and polarized optical microscopes (POM) equipped with a hot-stage accessory. Results showed that the spherulites of PLLA were formed at high temperature, whereas irregular morphology was observed under a low temperature. This can be attributed to the varying rates of crystallization of PLLA at different temperatures. At low temperatures, the nucleation rate is fast and hence the chains diffuse very slow, resulting in the formation of imperfect crystals. On the other hand, at high temperatures, the nucleation rate is slow and the chains diffuse fast, leading to the formation of perfect crystals. The change in the value of the Avrami exponent with temperature further verifies the varying trend in the morphological feature of the crystals.

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Behavior of Two Foundry Cobalt-Based Alloys Exposed to a Hot Complex Gaseous Mixture Simulating the Atmosphere in a Waste-to-Energy Boiler. Part 1: Case of the Alloy Exposed to the Complex Gas Stream

Journal of Material Science and Technology Research ◽

10.31875/2410-4701.2018.05.1 ◽

2018 ◽

Vol 5 ◽

pp. 1-5

Author(s):

Lionel Aranda ◽

Thierry Schweitzer ◽

Patrice Berthod ◽

Christophe Rapin ◽

Didier Souchon ◽

...

Keyword(s):

Water Vapor ◽

High Temperature ◽

Working Conditions ◽

Gaseous Mixture ◽

The Other ◽

Waste To Energy ◽

Gas Mixture ◽

Refractory Materials ◽

X Ray Diffraction ◽

X Ray

The refractory materials required for waste-to-energy boilers endure severe working conditions, such as exposure to heat and hot oxidation / corrosion. Thanks to their high temperature properties cobalt-based alloys may respond to these properties requirements. In this work two model alloys based on cobalt and rich in chromium were elaborated by casting and samples were prepared by cutting and polishing. These samples were exposed, one to a hot complex gaseous mixture particularly aggressive reproducing the atmosphere in WtE boilers in service (presence of water vapor, di-oxygen, carbon di-oxide, hydrogen chloride), and the other to synthetic ashes, both for more than two hundreds hours. After test the samples were characterized by X-ray diffraction and SEM observations. On sample exposed to the complex gas stream a {10 to 15μm}-thick oxide scale formed on the surface of the sample exposed to the gas mixture. It involved all the elements of the alloy and it obviously developed both inwards and outwards as suggested by the position of the oxidized carbides.

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Nanophase Copper Ferrite Using an Organic Gelation Technique

MRS Proceedings ◽

10.1557/proc-457-81 ◽

1996 ◽

Vol 457 ◽

Cited By ~ 1

Author(s):

D. Sriram ◽

R. L. Snyder ◽

V. R. W. Amarakoon

Keyword(s):

High Temperature ◽

Low Temperature ◽

Crystallite Size ◽

Polyacrylic Acid ◽

Size Analysis ◽

Copper Ferrite ◽

Carboxylic Group ◽

X Ray Diffraction ◽

X Ray ◽

Nano Size

ABSTRACTNanocrystalline copper ferrite (Cu0.5Fe2.5O4) was synthesized using a forward strike gelation method with polyacrylic acid (PAA) as a gelating agent. The dried gel was calcined at a low temperature of 400 °C to get the final powder. The effect of pH and the ratio of the cation to the carboxylic group in the initial gel were studied with respect to both the phases and the crystallite size of the final powders synthesized. Phase and crystallite size analysis were done using x-ray diffraction and TEM. Saturation magnetization results were obtained using a SQUID magnetometer. The reactions occurring in the nano-size copper ferrite, in air as a function of temperature, were tracked using adynamic high temperature x-ray diffraction (HTXRD) system.

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Sorption of Hydrogen Chloridein The Fluidized Bed Reactor

Ecological Chemistry and Engineering S ◽

10.1515/eces-2019-0006 ◽

2019 ◽

Vol 26 (1) ◽

pp. 69-80

Author(s):

Małgorzata Olek ◽

Witold Żukowski ◽

Jerzy Baron

Keyword(s):

Thermal Decomposition ◽

Thermal Treatment ◽

Fluidized Bed ◽

Methylene Chloride ◽

Fluidized Bed Reactor ◽

Molar Ratio ◽

X Ray Diffraction ◽

Reversible Process ◽

X Ray ◽

Bubbling Bed

Abstract Combustion of fuels, including renewable fuels and thermal treatment of waste (CFCs, pesticides), is associated with emissions of pollutants including halogens. The reversible process of sorption/desorption of HCl, in a fluidized (bubbling) bed reactor (BFB), during co-combustion of Cl-materials, was carried out. The thermal decomposition of methylene chloride (DCM, CH2Cl2) in an inert sand bed with the addition of the hydroxyapatite sorbent (HAp, Ca5(PO4)3(OH)) was investigated. The process parameters were as follows: temperature - 930 °C, the air excess - 1.3, stream rate of CH2Cl2 - 50 cm3/h. The concentration of HCl, CCl4, CHCl3, CH2Cl2, CH3Cl, COCl2 in the exhaust gases were monitored online with FTIR spectroscopy. The main chlorine product was hydrogen chloride. Samples of unprocessed HAp, taken from the bed during the process, and solid apatite residues were analyzed by X-ray diffraction (XRD). The content of chlorapatite (Ca5(PO4)3Cl) in the analyzed samples was respectively 11, 53 and 19 %. X-ray fluorescence (XRF) analysis showed the molar ratio of Ca:P:Cl was: 1.00:0.36:0.01, 1.00:0.36:0.09, 1.00:0.37:0.04 respectively. The HAp could be used as an sorbent of the HCl(g) during combustion of materials containing chlorine.

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Phase Transition and Thermal Expansion of Ba3RB3O9 (R = Sm–Yb, and Y)

High Temperature Materials and Processes ◽

10.1515/htmp-2015-0290 ◽

2017 ◽

Vol 36 (8) ◽

pp. 763-769 ◽

Cited By ~ 1

Author(s):

Rayko Simura ◽

Shohei Kawai ◽

Kazumasa Sugiyama

Keyword(s):

Phase Transition ◽

Thermal Expansion ◽

High Temperature ◽

Thermal Expansion Coefficient ◽

Room Temperature ◽

The Other ◽

X Ray Diffraction ◽

X Ray ◽

Melting Temperatures ◽

Type Phase

AbstractHigh temperature powder X-ray diffraction measurements of Ba3RB3O9 (R=Sm–Yb, and Y) were carried out at temperatures ranging from room temperature to just below the corresponding melting temperatures (1,200–1,300 °C). No phase transition was found for the H-type phase (R$\overline 3 $) with R=Sm–Tb and the L-type phase (P63 cm) with R=Tm–Yb. On the other hand, phase transition from the L phase to the H phase was observed for R=Dy–Er, and Y at around 1,100–1,200 °C. The obtained axial thermal expansion coefficient (ATEC) of the a-axis was larger than that of the c-axis for the H phase, and the ATEC of the c-axis was larger than that of the a-axis for the L phase. The observed anisotropic nature of ATEC is attributed to the distribution of the BO3 anionic group with rigid boron–oxygen bonding in the structures of the H and L phases.

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Aluminum Nitridation in a Solar-Heated Vibrating Fluidized Bed Reactor

Journal of Solar Energy Engineering ◽

10.1115/1.2888171 ◽

1999 ◽

Vol 121 (4) ◽

pp. 224-227 ◽

Cited By ~ 1

Author(s):

John P. Lock ◽

Brennan L. Peterson ◽

Alan W. Weimer ◽

Roland J. Pitts ◽

Carl E. Bingham ◽

...

Keyword(s):

Aluminum Nitride ◽

Fluidized Bed ◽

Fluidized Bed Reactor ◽

Solar Furnace ◽

National Renewable Energy Laboratory ◽

High Flux ◽

Complete Conversion ◽

X Ray Diffraction ◽

X Ray ◽

Fluidization Process

A vibrating fluidized bed reactor was constructed and interfaced with the High-Flux Solar Furnace at the National Renewable Energy Laboratory in Golden, CO. Various precursor mixtures of aluminum and aluminum nitride were heated for approximately 10 to 15 minutes using focused sunlight with an intensity as high as 2000 kW/m2. Particles ranging in size from 2 μm to 10 μm were produced with the heating and fluidization process. X-ray diffraction and chemical composition analyses of the product indicate virtually complete conversion of aluminum to aluminum nitride for some precursor mixtures. High conversion was also achieved using multi-pass processing.

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Vysokoteplotní fázové transformace kaolinitu v závislosti na krystalinitě

Geologické výzkumy na Moravě a ve Slezsku ◽

10.5817/gvms2020-12674 ◽

2020 ◽

Vol 27 (1-2) ◽

Author(s):

Petr Štursa ◽

Dalibor Všianský ◽

Karel Lang ◽

Lenka Nevřivová ◽

Lukáš Tvrdík ◽

...

Keyword(s):

High Temperature ◽

Crystallite Size ◽

Rietveld Method ◽

Exothermic Effect ◽

X Ray Diffraction ◽

Spinel Type ◽

X Ray ◽

Heat Flow Curve ◽

Two Samples ◽

Low Crystallinity

Although kaolinite is one the most important industrial minerals, the processes of its transformation to mullite have not been completely explained so far. The study is focused on kaolinite crystallinity calculation and its effect on high-temperature phases transitions in the series kaolinite-mullite. Samples of purified natural kaolins from several sites were analysed using X-ray diffraction (XRD). Besides the determination of the complex mineral composition, kaolinite crystallite size was calculated from XRD data by the Rietveld method, Scherrer equation and using the Hinckley crystallinity index. Thermal analysis (DSC/TG) was used as the principal approach to examine endothermic and exothermic effects of kaolinite transformations. The course and maximum temperatures of the observed effects were correlated with the original crystallite size of kaolinite. Two samples with different kaolinite crystallinity were also analysed by high-temperature X-ray diffraction (ht-XRD) to study the formation of mullite. Scanning electron microscope (SEM) was used to visualize morphology of kaolinite.It was found out that the original crystallinity of kaolinite affects all three examined processes-kaolinite dehydroxylation, formation of crystalline phases from metakaolinite and development of mullite crystal structure. Dehydroxylation of samples with higher kaolinite crystallinity takes place at higher temperatures. Similar effect applies for the reaction(-s) at the temperature about 980 °C observed at heat flow curve where crystallization of spinel type phase and mullite with very low crystallinity occurs. Broadening of FWHM of the exothermic effect points to decreasing kaolinite crystallinity. Crystallization of mullite exhibits different dependence on kaolinite crystallinity than the previous processes. The results show that mullite with larger crystallite size develops faster from kaolinite of low crystallinity and vice versa.

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Nb and Ta Substituted Bi(Pb)-Sr-Ca-Cu-O Superconductors

International Journal of Modern Physics B ◽

10.1142/s0217979298002581 ◽

1998 ◽

Vol 12 (29n31) ◽

pp. 3335-3337 ◽

Cited By ~ 2

Author(s):

O. Smrčková ◽

D. Sýkorová ◽

P. Vaśek

Keyword(s):

Magnetic Susceptibility ◽

High Temperature ◽

Critical Current Density ◽

High Temperature Phase ◽

The Other ◽

Weak Links ◽

Temperature Phase ◽

Superconducting Properties ◽

X Ray Diffraction ◽

X Ray

The influence of stoichiometric replacement of Bi by Nb and Ta in the Bi(Pb)-based superconducting system has been investigated. The properties were detected by the measurement of resistivity, magnetic susceptibility and critical current density. X-ray diffraction technique has been used for crystallographic and phase analysis. The study reveals that for both substituents an addition of small amount of them enhances the content of the high temperature phase and improves superconducting properties. On the other hand greater amount of substituents deteriorates weak links in the sample.

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