Kinetic Study on Microwave Magnetizing Roast of Fe2O3 Powders

In this paper, the reaction kinetic mechanism of Fe2O3 powder containing carbon was studied by microwave magnetizing roast. Based on the temperature-rise curve and weight loss curve of Fe2O3 powder by microwave magnetizing roast, the kinetic parameters of Fe2O3 powder microwave magnetizing roast were calculated by non-isothermal methods. The controlling steps of different temperature-rising periods in microwave magnetizing roast process of Fe2O3 powder were calculated by the Achar-Brindley-Sharp-Wendworth method. The results indicated that the controlling step of microwave magnetizing roast was phase boundary reaction control of contracted cylinder in 250~450°C, and it was three-dimensional diffusion control of spherical symmetry in 450~650°C. The results showed that the starting temperature of reduction roasting of Fe2O3 powder was 250°C, which was lower than that under electrical heating, thereby, it proved in theory that microwave heating can enhance reaction rate.

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Electrodeposition of cobalt nanoparticles: An analysis of the mechanisms behind the deviation from three-dimensional diffusion-control

Journal of Electroanalytical Chemistry ◽

10.1016/j.jelechem.2019.113413 ◽

2019 ◽

Vol 851 ◽

pp. 113413 ◽

Cited By ~ 3

Author(s):

Pietro Altimari ◽

Pier Giorgio Schiavi ◽

Antonio Rubino ◽

Francesca Pagnanelli

Keyword(s):

Three Dimensional ◽

Cobalt Nanoparticles ◽

Diffusion Control ◽

Dimensional Diffusion

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Study on Smelting Metallic Magnesium by Siliconthermic Reducing Method and its Reaction Kinetics

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.129-131.1133 ◽

2010 ◽

Vol 129-131 ◽

pp. 1133-1137

Author(s):

Feng Gao ◽

Wang Guo Sheng ◽

Liu Yun Yi ◽

Ying Xin Ge ◽

Wang Zhu Min

Keyword(s):

Activation Energy ◽

Raw Materials ◽

Three Dimensional ◽

Reduction Rate ◽

Reduction Process ◽

Frequency Factor ◽

Reduction Temperature ◽

Metallic Magnesium ◽

Boundary Reaction ◽

Phase Boundary Reaction

The metallic magnesium by siliconthermic reducing method was studied by magnetite as raw materials. The Mg reduction rate, such as reduction temperature and time, Si-Fe added mount, mineralize CaF2 added, briquette pressure, were discussed by experiments. Through siliconthermic reducing process analyzed, the result showed reduction process was in line with three-dimensional phase boundary reaction D3 model and kinetic equitation were expressed as , with an apparent activation energy 313.58 KJ/mol, frequency factor 2.7×106 s-1.

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Kinetics of Chemical Vapor Deposition of Sic Between 750 and 850°C at 1 Bar Total Pressure

MRS Proceedings ◽

10.1557/proc-250-41 ◽

1991 ◽

Vol 250 ◽

Cited By ~ 6

Author(s):

Dieter Neuschütz ◽

Farzin Salehomoum

Keyword(s):

Deposition Rate ◽

Total Pressure ◽

Reaction Rate ◽

Chemical Vapor ◽

Deposition Mechanism ◽

Reaction Orders ◽

Si Content ◽

Boundary Reaction ◽

Phase Boundary Reaction ◽

Kinetics Of

AbstractThe deposition rate from mixtures of methyltrichlorosilane (MTS), hydrogen and methane was measured thermogravimetrically using a hot wall vertical reactor and planar SiC substrates. Below 850 °C and at sufficiently high gas velocities, the rate of the phase boundary reaction could be determined. In the absence of CH4 and at H2 :MTS=55, Si was deposited together with SiC. Addition of CH4 lowered the Si content, pure SiC being deposited at CH4 :MTS above 10. The deposition rate j in the range 750 to 850 °C follows the equation with E(Si) = 160 and E(SiC) = 300 kJ/mol. Reaction mechanisms are presented to account for the observed reaction orders with respect to MTS. Between 900 and 970 °C, the reaction rate decreased with temperature indicating a change in the deposition mechanism.

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Non-Isothermal Decomposition Kinetic of Polypropylene/Hydrotalcite Composite

Journal of Nanoscience and Nanotechnology ◽

10.1166/jnn.2019.16675 ◽

2019 ◽

Vol 19 (11) ◽

pp. 7493-7501 ◽

Cited By ~ 1

Author(s):

Sheng Xu ◽

Min Zhang ◽

Siyu Li ◽

Moyu Yi ◽

Shigen Shen ◽

...

Keyword(s):

Thermal Stability ◽

Thermal Decomposition ◽

Nitrogen Atmosphere ◽

Heating Rates ◽

Decomposition Reactions ◽

Kinetic And Thermodynamic Parameters ◽

Málek Method ◽

Boundary Reaction ◽

Phase Boundary Reaction ◽

Thermal Stability Of

P3O5-10 pillared Mg/Al hydrotalcite (HTs) as a functional fire-retarding filler was successfully prepared by impregnation-reconstruction, where the HTs was used to prepare polypropylene (PP) and HTs composite (PP/HTs). Thermal decomposition was crucial for correctly identifying the thermal behavior for the PP/HTs, and studied using thermogravimetry (TG) at different heating rates. Based on single TG curves and Málek method, as well as 41 mechanism functions, the thermal decompositions of the PP/HTs composite and PP in nitrogen atmosphere were studied under non-isothermal conditions. The mechanism functions of the thermal decomposition reactions for the PP/HTs composite and PP were separately “chemical reaction F3” and “phase boundary reaction R2,” which were also in good agreement with corresponding experimental data. It was found that the addition of the HTs increased the apparent activation energy Ea of the PP/HTs comparing to the PP, which improved the thermal stability of the polypropylene. A difference in the set of kinetic and thermodynamic parameters was also observed between the PP/HTs and PP, particularly with respect to lower ΔS≠ value assigned to higher thermal stability of the PP/HTs composite.

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A noninvasive fluorescence imaging-based platform measures 3D anisotropic extracellular diffusion

Nature Communications ◽

10.1038/s41467-021-22221-0 ◽

2021 ◽

Vol 12 (1) ◽

Author(s):

Peng Chen ◽

Xun Chen ◽

R. Glenn Hepfer ◽

Brooke J. Damon ◽

Changcheng Shi ◽

...

Keyword(s):

Anisotropic Diffusion ◽

Biological Systems ◽

Three Dimensional ◽

Molecular Transport ◽

Light Sheet ◽

Fundamental Limitations ◽

Disease Mechanisms ◽

Dimensional Diffusion ◽

Compositional Changes ◽

Diffusion Tensors

AbstractDiffusion is a major molecular transport mechanism in biological systems. Quantifying direction-dependent (i.e., anisotropic) diffusion is vitally important to depicting how the three-dimensional (3D) tissue structure and composition affect the biochemical environment, and thus define tissue functions. However, a tool for noninvasively measuring the 3D anisotropic extracellular diffusion of biorelevant molecules is not yet available. Here, we present light-sheet imaging-based Fourier transform fluorescence recovery after photobleaching (LiFT-FRAP), which noninvasively determines 3D diffusion tensors of various biomolecules with diffusivities up to 51 µm2 s−1, reaching the physiological diffusivity range in most biological systems. Using cornea as an example, LiFT-FRAP reveals fundamental limitations of current invasive two-dimensional diffusion measurements, which have drawn controversial conclusions on extracellular diffusion in healthy and clinically treated tissues. Moreover, LiFT-FRAP demonstrates that tissue structural or compositional changes caused by diseases or scaffold fabrication yield direction-dependent diffusion changes. These results demonstrate LiFT-FRAP as a powerful platform technology for studying disease mechanisms, advancing clinical outcomes, and improving tissue engineering.

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