scholarly journals A Multifaceted Kinetic Model for the Thermal Decomposition of Calcium Carbonate

Crystals ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 849
Author(s):  
Jingxue Zheng ◽  
Junchen Huang ◽  
Lin Tao ◽  
Zhi Li ◽  
Qi Wang
Keyword(s):  
Thermal Decomposition ◽  
Calcium Carbonate ◽  
Pore Structure ◽  
Kinetic Models ◽  
Decomposition Reaction ◽  
Main Body ◽  
Structure Model ◽  
Thermal Decomposition Process ◽  
Proposed Model ◽  
Improved Model

The existing kinetic models often consider the influence of a single factor alone on the chemical reaction and this is insufficient to completely describe the decomposition reaction of solids. Therefore, the existing kinetic models were improved using the pore structure model. The proposed model was verified using the thermal decomposition experiment on calcium carbonate. The equation has been modified as fα=n1−α1−1n−ln1−α−1m1−ψln1−α12. This led to the conclusion that the pore structure, generated during the thermal decomposition of calcite, has an important influence on the decomposition kinetics. The existing experimental data show that the improved model, with random pores as the main body, reasonably describes the thermal decomposition process of calcite.

scholarly journals Study of GaN-Based Thermal Decomposition in Hydrogen Atmospheres for Substrate-Reclamation Processing

Materials ◽  
2018 ◽  
Vol 11 (11) ◽  
pp. 2082
Author(s):  
Shih-Yung Huang ◽  
Jian-Cheng Lin ◽  
Sin-Liang Ou
Keyword(s):  
Thermal Decomposition ◽  
Decomposition Reaction ◽  
Hydrogen Atmosphere ◽  
Thermal Decomposition Process ◽  
Hydrogen Flow ◽  
Thermal Decomposition Behavior ◽  
Transmission Electron ◽  
Furnace Tube ◽  
Decomposition Behavior ◽  
Patterned Sapphire Substrates

This study investigates the thermal decomposition behavior of GaN-based epilayers on patterned sapphire substrates (GaN-epi/PSSs) in a quartz furnace tube under a hydrogen atmosphere. The GaN-epi/PSS was decomposed under different hydrogen flow rates at 1200 °C, confirming that the hydrogen flow rate influences the decomposition reaction of the GaN-based epilayer. The GaN was completely removed and the thermal decomposition process yielded gallium oxyhydroxide (GaO2H) nanostructures. When observed by transmission electron microscopy (TEM), the GaO2H nanostructures appeared as aggregates of many nanograins sized 2–5 nm. The orientation relationship, microstructure, and formation mechanism of the GaO2H nanostructures were also investigated.

Kinetic Investigation of Thermal Decomposition Reaction of Ethane-1,2-Diamine Copper(II) Chloride, C2H8N2CuCl2

2014 ◽  
Vol 665 ◽  
pp. 255-259
Author(s):  
Pu Hong Wen
Keyword(s):  
Thermal Decomposition ◽  
Kinetic Parameters ◽  
Decomposition Reaction ◽  
Kinetic Investigation ◽  
Thermal Decomposition Process ◽  
Exponential Factor ◽  
Free Energy Of Activation ◽  
Enthalpy Of Activation ◽  
Entropy Of Activation ◽  
Temperature Programmed

:The thermal behavior and thermal decomposition kinetic parameters of ethane-1,2-diamine copper (II) chloride (EDCC) in a temperature-programmed mode have been investigated by mean of TG-DTG. There are four stages in the thermal decomposition process. The kinetic parameters of the apparent activation energyEa(130.2, 143.6 and 158.9 KJ·mol–1) and per-exponential factorA(1011.80, 1012.18and 1011.83s–1) in II, III and IV stages were obtained from analysis of the TG-DTG curves by Kissinger method. The values ofEaindicated that the difficulty coefficient of pyrolysis in II, III and IV stages was increased in the order: II < III < IV. The values of the entropy of activation ΔS≠, enthalpy of activation ΔH≠and free energy of activation ΔG≠of the reaction were estimated.

scholarly journals Study of Concrete Strength and Pore Structure Model Based on Grey Relation Entropy

Materials ◽  
2021 ◽  
Vol 14 (2) ◽  
pp. 432
Author(s):  
Min Zhang ◽  
Xianhua Yao ◽  
Junfeng Guan ◽  
Lielie Li ◽  
Juan Wang ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Pore Structure ◽  
Pore Size ◽  
Concrete Strength ◽  
Sensitivity Coefficient ◽  
Structure Model ◽  
Proposed Model ◽  
Compressive Strength Of Concrete ◽  
The Relationship ◽  
Grey Relation

The Grey Relation Entropy (GRE) theory is used to analyze the sensitive pore size that affects the compressive strength of concrete. The relationship between the strength and pore structure is revised based on the sensitivity coefficient. The revised model is used to calculate the compressive strength of concrete. In order to verify the validity of the proposed model, the calculated results are compared with experimental ones, showing satisfactory agreement with a larger correlation than existing methods.

scholarly journals Thermal behavior and decomposition kinetics of rifampicin polymorphs under isothermal and non-isothermal conditions

2010 ◽  
Vol 46 (2) ◽  
pp. 343-351 ◽  
Author(s):  
Ricardo Alves ◽  
Thaís Vitória da Silva Reis ◽  
Luis Carlos Cides da Silva ◽  
Silvia Storpírtis ◽  
Lucildes Pita Mercuri ◽  
...  
Keyword(s):  
Thermal Decomposition ◽  
Thermal Behavior ◽  
Melting Process ◽  
Decomposition Process ◽  
Stable Form ◽  
Thermal Decomposition Process ◽  
Mean Values ◽  
Conversion Level ◽  
Polymorphic Forms ◽  
Crystalline Forms

The thermal behavior of two polymorphic forms of rifampicin was studied by DSC and TG/DTG. The thermoanalytical results clearly showed the differences between the two crystalline forms. Polymorph I was the most thermally stable form, the DSC curve showed no fusion for this species and the thermal decomposition process occurred around 245 ºC. The DSC curve of polymorph II showed two consecutive events, an endothermic event (Tpeak = 193.9 ºC) and one exothermic event (Tpeak = 209.4 ºC), due to a melting process followed by recrystallization, which was attributed to the conversion of form II to form I. Isothermal and non-isothermal thermogravimetric methods were used to determine the kinetic parameters of the thermal decomposition process. For non-isothermal experiments, the activation energy (Ea) was derived from the plot of Log β vs 1/T, yielding values for polymorph form I and II of 154 and 123 kJ mol-1, respectively. In the isothermal experiments, the Ea was obtained from the plot of lnt vs 1/T at a constant conversion level. The mean values found for form I and form II were 137 and 144 kJ mol-1, respectively.

scholarly journals An Improved Approach for Reduction of Defect Density Using Optimal Module Sizes

2014 ◽  
Vol 2014 ◽  
pp. 1-7 ◽  
Author(s):  
Dinesh Verma ◽  
Shishir Kumar
Keyword(s):  
Goodness Of Fit ◽  
Defect Density ◽  
Optimal Size ◽  
Data Sets ◽  
Density Parameter ◽  
Proposed Model ◽  
Module Size ◽  
Curve Fitting Method ◽  
Improved Model ◽  
Effective Distribution

Nowadays, software developers are facing challenges in minimizing the number of defects during the software development. Using defect density parameter, developers can identify the possibilities of improvements in the product. Since the total number of defects depends on module size, so there is need to calculate the optimal size of the module to minimize the defect density. In this paper, an improved model has been formulated that indicates the relationship between defect density and variable size of modules. This relationship could be used for optimization of overall defect density using an effective distribution of modules sizes. Three available data sets related to concern aspect have been examined with the proposed model by taking the distinct values of variables and parameter by putting some constraint on parameters. Curve fitting method has been used to obtain the size of module with minimum defect density. Goodness of fit measures has been performed to validate the proposed model for data sets. The defect density can be optimized by effective distribution of size of modules. The larger modules can be broken into smaller modules and smaller modules can be merged to minimize the overall defect density.

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