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.

Interdiffusion in Nb-Mo, Nb-Ti and Nb-Zr Systems

2012 ◽  
Vol 323-325 ◽  
pp. 491-496 ◽  
Author(s):  
Soma Prasad ◽  
Aloke Paul
Keyword(s):  
Activation Energy ◽  
Diffusion Coefficient ◽  
Diffusion Couple ◽  
Impurity Diffusion ◽  
Impurity Diffusion Coefficient ◽  
Different Temperatures ◽  
Diffusion Couple Technique ◽  
Interdiffusion Coefficients

Diffusion couple technique is used to study interdiffusion in Nb-Mo, Nb-Ti and Nb-Zr systems. Interdiffusion coefficients at different temperatures and compositions are determined using the relation developed by Wagner. The change in activation energy for interdiffusion with composition is determined. Further, impurity diffusion coefficient of the species are determined and compared with the available data in literature.

Diffusion Behavior of Carbon Atoms in Austenite Region of SCM435 Steel

2016 ◽  
Vol 850 ◽  
pp. 266-270 ◽  
Author(s):  
Dong Xu ◽  
Bing Zheng ◽  
Xing Liang Gao ◽  
Miao Yong Zhu
Keyword(s):  
Activation Energy ◽  
Diffusion Coefficient ◽  
Arrhenius Equation ◽  
Diffusion Constant ◽  
Carbon Diffusion ◽  
Diffusion Activation Energy ◽  
Diffusion Behavior ◽  
Scm435 Steel ◽  
The Relationship ◽  
Diffusion Activation

The research on the decarbonizing behavior of the austenite region of SCM435 steel was carried out. And the experimental results shewed that the relationship between the diffusion coefficient and temperature totally agreed with the Arrhenius equation and that the diffusion constant and the diffusion activation energy were uniform within the temperature range of 900-1100°C. However, when the austenite reached certain temperature, the carbon diffusion coefficient decreased significantly as temperature increased and its relationship with temperature no longer agreed with 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.

Infrared absorption spectroscopy of hydrogen and deuterium in CaO and SrO crystals

1989 ◽  
Vol 4 (1) ◽  
pp. 224-231 ◽  
Author(s):  
J. L. Park ◽  
R. González
Keyword(s):  
Activation Energy ◽  
Diffusion Coefficient ◽  
Absorption Spectra ◽  
Infrared Absorption ◽  
Diffusion Coefficients ◽  
Elevated Temperatures ◽  
Arrhenius Equation ◽  
Lithium Concentration ◽  
Infrared Absorption Spectroscopy ◽  
Infrared Absorption Spectra

Infrared absorption spectra have been used to characterize OH− and OD− ions at the surface and the bulk of undoped CaO, lithium doped CaO, and SrO crystals. Diffusion of deuterons from D2O vapor into these crystals was performed at elevated temperatures. Diffusion coefficients were obtained to be D (CaO) = 3 ⊠ 10−6 cm2/sec at 1773 K and D (SrO) = 4 ⊠ 10−7 cm2/sec at 1523 K. For the doped CaO crystal with lithium concentration of 310 ppm, the diffusion coefficient was measured to be D (CaO:Li) = 4 ⊠ 10−7 cm2/sec at 1473 K and the activation energy in the Arrhenius equation was estimated to be 1.7 eV.

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.

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 Physical-chemical characterization of yellow mombin (Spondias mombin L.) foam-mat drying at different temperatures

2018 ◽  
Vol 22 (6) ◽  
pp. 430-435 ◽  
Author(s):  
Bheatriz S. M. de Freitas ◽  
Maisa D. Cavalcante ◽  
Caroline Cagnin ◽  
Richard M. da Silva ◽  
Geovana R. Plácido ◽  
...  
Keyword(s):  
Activation Energy ◽  
Diffusion Coefficient ◽  
Effective Diffusion ◽  
Chemical Characterization ◽  
Titratable Acidity ◽  
Soluble Solids ◽  
Different Temperatures ◽  
Solids Content ◽  
Fresh Pulp ◽  
Physical And Chemical

ABSTRACT The objective of this work was to perform foam-mat drying of yellow mombin pulp, verifying the kinetics and mathematical modeling of the process, and characterizing the obtained product with respect to physical and chemical characteristics, compared with the fresh pulp. Foam-mat drying was carried out with the aid of the foam agent Emustab®, at temperatures of 50, 60, 70 and 80 °C. The drying data were analyzed and fitted to four mathematical models (Wang & Singh, Verma, Page and Midilli). Effective diffusion coefficient and activation energy were determined. Titratable acidity, pH, soluble solids content and vitamin C content, as well as the solubility in water of yellow mombin powder and color variance (L*, a*, b*) were analyzed in both fresh and dehydrated pulp. The Wang & Singh model showed best fit at the temperature of 50 °C, whereas the Midilli model showed the best mathematical fit at temperatures of 60, 70 and 80 °C. Net diffusion coefficient and activation energy values were proportional to the drying temperature. Drying of the foam at 60 °C indicated guarantee of quality of yellow mombin pulp with respect to titratable acidity, pH and color of the a* coordinate.

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.

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 Surface Thermodynamics, Viscosity, Activation Energy of N-Methyldiethanolamine Aqueous Solutions Promoted by Tetramethylammonium Arginate

Entropy ◽  
2020 ◽  
Vol 22 (12) ◽  
pp. 1337
Author(s):  
Xiangfeng Tian ◽  
Lemeng Wang ◽  
Pan Zhang ◽  
Dong Fu
Keyword(s):  
Activation Energy ◽  
Surface Tension ◽  
Diffusion Coefficient ◽  
Aqueous Solutions ◽  
Quantitative Relationship ◽  
Viscosity Data ◽  
Surface Thermodynamics ◽  
Surface Entropy ◽  
Operation Conditions ◽  
Surface Enthalpy

The surface tension and viscosity values of N-methyldiethanolamine (MDEA) aqueous solutions promoted by tetramethylammonium arginate ([N1111][Arg]) were measured and modeled. The experimental temperatures were 303.2 to 323.2 K. The mass fractions of MDEA (wMDEA) and [N1111][Arg] (w[N1111][Arg]) were 0.300 to 0.500 and 0.025 to 0.075, respectively. The measured surface tension and viscosity values were satisfactorily fitted to thermodynamic models. With the aid of experimentally viscosity data, the activation energy (Ea) and H2S diffusion coefficient (DH2S) of MDEA-[N1111][Arg] aqueous solution were deduced. The surface entropy and surface enthalpy of the solutions were calculated using the fitted model of the surface tension. The quantitative relationship between the calculated values (surface tension, surface entropy, surface enthalpy, viscosity, activation energy, and H2S diffusion coefficient) and the operation conditions (mass fraction and temperature) was demonstrated.

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