scholarly journals Research of high-speed HFC-boriding kinetics

2021 ◽  
Vol 285 ◽  
pp. 07038
Author(s):  
Vladimir Malikov ◽  
Alexander Shegolev ◽  
Alexey Ishkov
Keyword(s):  
Activation Energy ◽  
Chemical Reactions ◽  
High Frequency ◽  
High Speed ◽  
Arrhenius Equation ◽  
Main Element ◽  
Kinetic Curves ◽  
Boride Coatings ◽  
Different Temperatures ◽  
Boriding Process

The paper presents studies boride coatings, which were created using high-frequency treatment with currents. Chemical reactions characterized the boriding procedure at various temperatures are show. The choice of the main element, of the reaction-boriding scheme is characterize, their role is revealed, and the probable processes leading to the realization of topochemical boriding initiated by HFC-heating are established. The kinetic curves received during the test at different temperatures are showed. Anamorphoses of the kinetic curves are showed, and the values of activation energy and parameters of the boriding process using HFC-heating are calculated on the basis of linearization of the Arrhenius equation.

scholarly journals Instantaneous activation energy of alkali activated materials

2019 ◽  
Vol 3 ◽  
pp. 121-123
Author(s):  
Shiju Joseph ◽  
Siva Uppalapati ◽  
Ozlem Cizer
Keyword(s):  
Activation Energy ◽  
Apparent Activation Energy ◽  
Reaction Rate ◽  
Arrhenius Equation ◽  
Isothermal Calorimetry ◽  
Traditional Methods ◽  
Cement Based Materials ◽  
Different Temperatures ◽  
Higher Temperature ◽  
Alkali Activated

Alkali activated materials (AAM) are generally cured at high temperatures to compensate for the low reaction rate. Higher temperature accelerates the reaction of AAM as in cement-based materials and this effect is generally predicted using Arrhenius equation based on the activation energy. While apparent activation energy is calculated from parallel isothermal calorimetry measurements at different temperatures, instantaneous activation energy is typically measured using a differential scanning calorimeter. Compared to the apparent activation energy, instantaneous activation energy has minimal effects on the microstructural changes due to the variation in temperature. In this work, the evolution of activation energy was determined by traditional methods and was compared with the instantaneous activation energy. It was found that while the activation energy changed with the progress of reaction over traditional methods, the instantaneous activation energy did not show any changes / or remained the same. The instantaneous activation energy was also found to be higher compared to the apparent activation energy determined with traditional methods.

scholarly journals Chemical reactions at high-speed HFC-boriding

2019 ◽  
Vol 135 ◽  
pp. 01067
Author(s):  
Alexander Katasonov ◽  
Vladimir Malikov ◽  
Alexey Ishkov
Keyword(s):  
Service Life ◽  
Ternary System ◽  
Chemical Reactions ◽  
High Frequency ◽  
High Speed ◽  
Chemical Interaction ◽  
Matrix Composites ◽  
Solid Media ◽  
Diffusion Boriding ◽  
Main Components

Strengthening of parts and units of machines, increased reliability and longer service life is an important task of modern industry. As an promising materials for protective-strengthening coatings, offered matrix composites based on the ternary system Fe-B-FenB. The article is proposed the complex heating of steel being borated and imbued medium by high frequency currents (HFC), and to combine the diffusion boriding from liquid and solid media and the transition of the diffusion boriding to chemical interaction between the elements of Fe and B. We determined the main components of the reaction-boronizing system, as well as their roles and possible processes that lead to the implementation of topochemical boriding initiated by HFC-heating. Confirmed the course of the reaction leading to the occurrence of reducing agents Ca, Si and active boron in the boronizing mixture.

Influence of the Temperature on the Diffusion Coefficient Value during the Cobalt Electrodeposition on Different Substrates

2014 ◽  
Vol 976 ◽  
pp. 144-147
Author(s):  
Nancy Ramos Lora ◽  
Luis Humberto Mendoza Huizar ◽  
Clara Hilda-Rios-Reyes ◽  
Carlos Andrés Galán-Vidal
Keyword(s):  
Activation Energy ◽  
Diffusion Coefficient ◽  
Temperature Effect ◽  
Glassy Carbon ◽  
Arrhenius Equation ◽  
Voltammetric Techniques ◽  
Different Temperatures ◽  
Cobalt Electrodeposition

Cobalt electrodeposition on palladium and glassy carbon was studied at different temperatures by using voltammetric techniques. Temperature effect on the diffusion coefficient value was analyzed. The results clearly showed that cobalt electrodeposition is a diffusioncontrolled process. The temperature effect on the values of the diffusion coefficient was analyzed through the Arrhenius equation. The value of the activation energy was calculated as 21.56 kJ mol-1and 25.73 kJ mol1for palladium and glassy carbon respectively.

Kinetics of Hydrothermal Decomposition of Potassium Feldspar with Calcium Hydroxide

2012 ◽  
Vol 549 ◽  
pp. 65-69 ◽  
Author(s):  
Yu Qin Liu ◽  
Hong Tu Xia ◽  
Hong Wen Ma
Keyword(s):  
Activation Energy ◽  
Kinetic Equation ◽  
Calcium Hydroxide ◽  
Arrhenius Equation ◽  
Hydrothermal Reaction ◽  
Potassium Feldspar ◽  
Different Temperatures ◽  
Temperature Ranges ◽  
Dissolution Ratio ◽  
Kinetics Of

The aegirine-augite syenite potash ore, taken from Changling, Luonan in Shannxi province, were hydrothermally decomposed over the temperature ranges of 533 K to 563 K using calcium hydroxide as additive. The dissolution ratio of the K2O at different reaction temperature and time was determined. Analysis of the experimental results revealed that the dissolution rate of potash ore satisfies the chemical reaction controlled kinetic equation. The rate constant of hydrothermal reaction at different temperatures was obtained. The activation energy was calculated using the Arrhenius equation. The hydrothermal decomposition mechanism of microcline was proposed.

Note: Color development rate in dulce de leche

1995 ◽  
Vol 1 (2-3) ◽  
pp. 137-140 ◽  
Author(s):  
M.S. Pauletti ◽  
E. Castelao ◽  
N. Sabbag ◽  
Y S. Costa
Keyword(s):  
Experimental Data ◽  
Activation Energy ◽  
Formation Process ◽  
Arrhenius Equation ◽  
Development Rate ◽  
Sensorial Analysis ◽  
Color Formation ◽  
Color Development ◽  
Global Rate ◽  
Different Temperatures

The time necessary to obtain the characteristic dulce de leche color at different temperatures was studied. Samples were held at constant temperature until they reached a standard prescribed color. Sensorial analysis of the final color of the samples was performed in order to detect any difference. Results showed that color among samples was not significantly different (p = 0.95). Arrhenius equation was used to correlate the kinetics results. Variance analysis showed a very good correlation of experimental data (r2 = 0.98). The apparent activation energy values for both studied systems were similar (13.88–14.45 kcal mol–1) but somewhat smaller than those given by other authors for similar systems. The global rate constant value of color formation process at any temperature was slightly larger when the protein/carbohydrate ratio was higher.

The deuterium interaction with tungsten and iridium in the UHV system

1985 ◽  
Vol 50 (12) ◽  
pp. 2656-2664
Author(s):  
Karel Kuchynka ◽  
Zlatko Knor
Keyword(s):  
Partial Pressure ◽  
Chemical Reactions ◽  
Pressure Range ◽  
Tungsten Filament ◽  
Different Temperatures ◽  
Pressure Changes

The behaviour of hydrogen, in its contact with the iridium and the tungsten filament kept at different temperatures, was studied in the pressure range 1.3 . 10-6 - 1.3 . 10-3 Pa, in a glass apparatus. The effects of adsorption, atomization, desorption, recombination of atoms and chemical reactions were investigated as a function of temperature of the filaments. The named individual processes were used for interpretation of the partial pressure changes in the apparatus. The significance of the above individual phenomena in the UHV experiments is pointed out in this paper.

Cr-Substituted Mesoporous Aluminophosphate Molecular Sieve: Synthesis, Characterization, Crystallization Kinetics and Catalytic Activity

2013 ◽  
Vol 316-317 ◽  
pp. 1018-1023
Author(s):  
Xin Zhu Li ◽  
Ji Shi Zhang
Keyword(s):  
Activation Energy ◽  
Catalytic Activity ◽  
Crystal Growth ◽  
Crystallization Kinetics ◽  
Molecular Sieve ◽  
Arrhenius Equation ◽  
Degree Of Crystallinity ◽  
Tert Butylhydroperoxide ◽  
Growth Activation ◽  
Cr Map

Cr-substituted mesoporous aluminophosphate molecular sieve (Cr-MAP) was synthesized and characterized. Crystallization kinetics curves measured as an index to the relative degree of crystallinity, according to the Arrhenius equation to calculate the apparent nucleation activation energy and crystal growth activation energy of Cr-MAP, which was 63.7 and 14.7 kJ• mol-1, respectively. Cr-MAP had highly catalytic activity for fabricating acetophenone by selectively oxizing ethylbenzene. Using tert-butylhydroperoxide as oxidant and chlorobenzene as solvent at 100 °C for 8 h, acetophenone selectivity, acetophenone yield and ethylbenzene conversion reaches 85.4, 62.2 and 72.8 %, respectively.

scholarly journals Kinetics and thermodynamic properties related to the drying of 'Cabacinha' pepper fruits

2016 ◽  
Vol 20 (2) ◽  
pp. 174-180 ◽  
Author(s):  
Hellismar W. da Silva ◽  
Renato S. Rodovalho ◽  
Marya F. Velasco ◽  
Camila F. Silva ◽  
Luís S. R. Vale
Keyword(s):  
Experimental Data ◽  
Activation Energy ◽  
Free Energy ◽  
Thermodynamic Properties ◽  
Gibbs Free Energy ◽  
Removal Rate ◽  
Effective Diffusion ◽  
Drying Time ◽  
Three Samples ◽  
Different Temperatures

ABSTRACT The objective of this study was to determine and model the drying kinetics of 'Cabacinha' pepper fruits at different temperatures of the drying air, as well as obtain the thermodynamic properties involved in the drying process of the product. Drying was carried out under controlled conductions of temperature (60, 70, 80, 90 and 100 °C) using three samples of 130 g of fruit, which were weighed periodically until constant mass. The experimental data were adjusted to different mathematical models often used in the representation of fruit drying. Effective diffusion coefficients, calculated from the mathematical model of liquid diffusion, were used to obtain activation energy, enthalpy, entropy and Gibbs free energy. The Midilli model showed the best fit to the experimental data of drying of 'Cabacinha' pepper fruits. The increase in drying temperature promoted an increase in water removal rate, effective diffusion coefficient and Gibbs free energy, besides a reduction in fruit drying time and in the values of entropy and enthalpy. The activation energy for the drying of pepper fruits was 36.09 kJ mol-1.

scholarly journals Superior Degradation Performance of Nanoporous Copper Catalysts on Methyl Orange

Metals ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 913
Author(s):  
Jinyi Wang ◽  
Sen Yang
Keyword(s):  
Activation Energy ◽  
Methyl Orange ◽  
High Efficiency ◽  
Low Cost ◽  
Degradation Process ◽  
Copper Catalysts ◽  
Reaction Rate Constant ◽  
Nanoporous Structure ◽  
Intra Particle Diffusion ◽  
Different Temperatures

The development of low-cost and high-efficiency catalysts for wastewater treatment is of great significance. Herein, nanoporous Cu/Cu2O catalysts were synthesized from MnCu, MnCuNi, and MnCuAl with similar ligament size through one-step dealloying. Meanwhile, the comparisons of three catalysts in performing methyl orange degradation were investigated. One of the catalysts possessed a degradation efficiency as high as 7.67 mg·g−1·min−1. With good linear fitting by the pseudo-first-order model, the reaction rate constant was evaluated. In order to better understand the degradation process, the adsorption behavior was considered, and it was divided into three stages based on the intra-particle diffusion model. Three different temperatures were applied to explore the activation energy of the degradation. As a photocatalytic agent, the nanoporous structure of Cu/Cu2O possessed a large surface area and it also had low activation energy, which were beneficial to the excellent degradation performance.

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