Kinetic isotherms of cyclohexane on active carbon supersorbon

1979 ◽  
Vol 44 (12) ◽  
pp. 3464-3468
Author(s):  
Zdeněk Sedláček
Keyword(s):  
Activation Energy ◽  
Diffusion Coefficient ◽  
Temperature Dependence ◽  
Active Carbon ◽  
Enthalpy Of Vaporization ◽  
Probable Mechanism

The kinetic isotherm makes it possible to compute the value of diffusion coefficient and, from its temperature dependence, to calculate the activation energy of the adsorbate transfer in the adsorbent pores. The data of kinetic isotherms have been taken over from our previous paper. On the basis of comparison of the activation energy with the isosteric heats and with enthalpy of vaporization we can judge of a probable mechanism of transfer.

The influence of monomer and polymer properties on the removal of organic vehicle from ceramic and metal moldings

1995 ◽  
Vol 10 (8) ◽  
pp. 2060-2072 ◽  
Author(s):  
S.A. Matar ◽  
J.R.G. Evans ◽  
M.J. Edirisinghe ◽  
E.H. Twizell
Keyword(s):  
Activation Energy ◽  
Diffusion Coefficient ◽  
Degradation Products ◽  
Diffusion Constant ◽  
Enthalpy Of Vaporization ◽  
Organic Vehicle ◽  
Polymer Properties ◽  
Plastic Forming ◽  
Successful Removal ◽  
Ceramic Suspensions

This paper describes the effects of monomer and polymer properties on the competition between degradation of organic vehicle and transport of degradation products in ceramic moldings during pyrolysis. An experimentally tested model is studied systematically for ranges of material and process parameters characteristic of known polymers and their degradation products. The work highlights the properties having the greatest influence on the successful removal of organic vehicle from molded ceramics. The polymer properties controlling the diffusion constant are linked to the temperature dependence of viscosity of the molten suspension. Enthalpy of vaporization of the organic vehicle and the activation energy for the diffusion coefficient have a commanding influence on the critical heating rate for avoidance of defects. Preliminary guidelines emerge for the design of polymers for plastic forming of ceramic suspensions.

The Temperature Dependence of the Atoms Co Diffusion Coefficient in Pt80Co20(111) Alloy

2007 ◽  
Vol 265 ◽  
pp. 19-23
Author(s):  
M. Vasylyev ◽  
Vitaliy A. Tinkov ◽  
Sergey I. Sidorenko ◽  
S.M. Voloshko
Keyword(s):  
Activation Energy ◽  
Diffusion Coefficient ◽  
Temperature Dependence ◽  
Surface Segregation ◽  
Surface Region ◽  
Near Surface ◽  
Kinetics Of

The method of Ionization Spectroscopy is used to study the thermo-induced kinetics of surface segregation of the Pt80Co20(111) alloy components. The temperature dependence of the Co diffusion coefficient in this alloy is determined. It is found that the value of the activation energy for the segregation of Co atoms in the near-surface region is close to the heat of sublimation of pure Co.

About Fe Diffusion in Cu

2012 ◽  
Vol 323-325 ◽  
pp. 171-176 ◽  
Author(s):  
D. Prokoshkina ◽  
A.O. Rodin ◽  
V. Esin
Keyword(s):  
Activation Energy ◽  
Diffusion Coefficient ◽  
Grain Boundary ◽  
Temperature Dependence ◽  
Boundary Diffusion ◽  
Bulk Diffusion ◽  
Grain Boundary Diffusion ◽  
Radiotracer Technique ◽  
Exponential Factor ◽  
Temperature Range

The temperature dependence of the bulk diffusion coefficient of Fe in Cu is determined by EDX in the temperature range from 923 to 1273 K, , m2/s. These results are different from that obtained earlier by radiotracer technique: activation energy is less by 30 kJ/mol and pre-exponential factor is 50 times smaller. Deviations from ideality of investigated solutions do not explain the differences; consequently, the thermodynamical factor would not responsible for such an effect. Fast grain boundary diffusion of Fe in Cu was not observed in the temperature range from 823 to 1073 K.

Diffusion of 57Co in amorphous Fe–RE (RE = Dy, Tb, and Ce) and Fe–Si–B alloys

1993 ◽  
Vol 8 (9) ◽  
pp. 2231-2238 ◽  
Author(s):  
Kazumasa Yamada ◽  
Yoshiaki Iijima ◽  
Kazuaki Fukamichi
Keyword(s):  
Activation Energy ◽  
Diffusion Coefficient ◽  
Temperature Dependence ◽  
Tracer Diffusion ◽  
Atomic Size ◽  
Exponential Factor ◽  
Dc Sputtering ◽  
The Matrix ◽  
Diffusion Temperature ◽  
Order Of Magnitude

Tracer diffusion of 57Co in amorphous Fe100−xDyx (x = 20–40), Fe75Tb25, Fe67Ce33, and Fe80Si6B14 alloys prepared by dc sputtering has been studied at temperatures of 523 and 573 K. In the Fe–Dy alloys the diffusion coefficient of 57Co shows a maximum at 33 at.% Dy. The magnitude of the diffusion coefficient of 57Co in Fe75Tb25 is nearly equal to that in Fe75Dy25, while those in Fe67Ce33 and Fe80Si6B14 are about one order of magnitude less than the values in Fe67Dy33 and Fe80Dy20. This suggests that the atomic size of the diffusant and the density of the matrix are dominant in the diffusion. Temperature dependence of the diffusion coefficient D of 57Co in the amorphous Fe75Dy25 alloy has been determined in the range from 493–673 K. It shows a linear Arrhenius relationship expressed by D = 5.7 × 10−2 exp(−199 kJ mol−1/RT) m2 s−1. The magnitudes of the pre-exponential factor and the activation energy suggest that the cobalt tracer atoms in the amorphous Fe75Dy25 alloy diffuse by an interstitial-like mechanism.

Radiotracer Measurements of Sulfur Diffusion in Rubbers

1971 ◽  
Vol 44 (5) ◽  
pp. 1307-1315 ◽  
Author(s):  
M. Mozisek
Keyword(s):  
Activation Energy ◽  
Diffusion Coefficient ◽  
Temperature Dependence ◽  
Diffusion Coefficients ◽  
Elemental Sulfur ◽  
Butyl Rubber ◽  
In Cis ◽  
Sulfur Diffusion

Abstract The object of measurement was the diffusion of elemental sulfur labeled with the radioisotope S in representative types of rubber. The highest values of diffusion coefficient were found in cis-1,4 polybutadiene. The lowest measured value was found for butyl rubber. The activation energy, expressing the temperature dependence of the diffusion coefficients, ranges from 4 to 10 kcal mol-1. For some rubbers studied, the activation energy is to a certain degree dependent upon temperature. The values of the diffusion coefficients and the characteristic constants for their temperature dependence are related to the mobility of the macromolecular segments.

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.

P+ implanted 6H-SiC n+-i-p diodes: evidence for a post-implantation-annealing dependent defect activation

2014 ◽  
Vol 1693 ◽  
Author(s):  
R. Nipoti ◽  
M. Puzzanghera ◽  
F. Moscatelli
Keyword(s):  
Activation Energy ◽  
Temperature Dependence ◽  
Ideality Factor ◽  
Low Voltage ◽  
Reverse Current ◽  
Forward Current ◽  
Current Region ◽  
Recombination Centers ◽  
Energy Dependent ◽  
Post Implantation

ABSTRACTTwo n+-i-p 6H-SiC diode families with P+ ion implanted emitter have been processed with all identical steps except the post implantation annealing: 1300°C/20min without C-cap has been compared with 1950°C/10min with C-cap. The analysis of the temperature dependence of the reverse current at low voltage (-100V) in the temperature range 27-290°C shows the dominance of a periphery current which is due to generation centers with number and activation energy dependent on the post implantation annealing process. The analysis of the temperature dependence of the forward current shows two ideality factor n region, one with n = 1.9/2 at low voltage and the other one with 1 < n < 2 without passing through 1 for increasing voltages. For both the diode families the current with n = 1.9/2 is a periphery current due to recombination centers with a thermal activation energy near the 6H-SiC mid gap. In the forward current region of 1 < n < 2, the two diode families show different ideality factor values which could be attributed to a different post implantation annealing defect activation.

Diffusion of Ce-Al Melts Measured by Sliding Cell Technique

2017 ◽  
Vol 898 ◽  
pp. 679-683
Author(s):  
Cheng Chen ◽  
Jin Liang Hu ◽  
Lang Xiang Zhong ◽  
Bo Zhang
Keyword(s):  
Activation Energy ◽  
Temperature Dependence ◽  
Strong Interaction ◽  
Al Alloy ◽  
Diffusion Behavior ◽  
Diffusion Constants

The diffusion behavior of Ce-Al alloy melt at three temperatures of 943K, 953K and 963K was investigated by sliding shear method. The inter-diffusion constants D show Arrhenius-type temperature dependence in the investigated regimes. Compared with the previous results achieved in Ce-Cu melt, liquid Ce-Al displays a much slower diffusion behavior and rather higher activation energy ED, which was caused by the strong interaction between Ce and Al.

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