Spreading Kinetics of Molten 60Sn40Pb on Higher Melting Temperature Pb-Sn Alloy Substrates

1995 ◽  
Vol 390 ◽  
Author(s):  
H. Conrad ◽  
Z. Guo ◽  
D. Y. Jung
Keyword(s):  
Activation Energy ◽  
Contact Angle ◽  
Melting Point ◽  
Kcal Mole ◽  
Depth Of Penetration ◽  
Spherical Cap ◽  
Solid Diffusion ◽  
Time Exponent ◽  
Image Position ◽  
Kinetics Of

ABSTRACTThe spreading of molten 60Sn40Pb drops on higher melting point Pb-Sn alloy substrates (3 to 10 wt.% Sn) was investigated for reflow temperatures of 205° to 300°C. Following melting the drop assumed the form of a slightly flared, spherical cap with some penetration into the substrate beneath the contact area. The effects of time and temperature on the contact angle θ and the depth of penetration h were of the formwhere the apparent activation energy Q was 4.2 kcal/mole for θ and 16 kcal/mole for h. The time exponent m (negative for θ and positive for h) decreased with temperature from ∼ 0.2–0.3 at 205°C to ∼0.05 at 260° and then increased again at higher temperatures. The magnitude of Q for θ is in accord with that for the viscosity of molten Pb-Sn alloys and that for h with a combined liquid-solid diffusion involved in the dissolution. Further work is however needed to identify unequivocally the mechanisms which govern the wetting in these duplex Pb-Sn alloy systems.

Vulcanization of Elastomers. 23. The Chemical Kinetics of Vulcanization Reactions and The Physical Properties of The Vulcanizates. I

1960 ◽  
Vol 33 (2) ◽  
pp. 335-341
Author(s):  
Walter Scheele ◽  
Karl-Heinz Hillmer
Keyword(s):  
Activation Energy ◽  
Physical Properties ◽  
Chemical Kinetics ◽  
Kcal Mole ◽  
First Order ◽  
Equilibrium Swelling ◽  
Kinetics Of ◽  
Kinetics Of Vulcanization ◽  
Limiting Value ◽  
Good Agreement

Abstract As a complement to earlier investigations, and in order to examine more closely the connection between the chemical kinetics and the changes with vulcanization time of the physical properties in the case of vulcanization reactions, we used thiuram vulcanizations as an example, and concerned ourselves with the dependence of stress values (moduli) at different degrees of elongation and different vulcanization temperatures. We found: 1. Stress values attain a limiting value, dependent on the degree of elongation, but independent of the vulcanization temperature at constant elongation. 2. The rise in stress values with the vulcanization time is characterized by an initial delay, which, however, is practically nonexistent at higher temperatures. 3. The kinetics of the increase in stress values with vulcanization time are both qualitatively and quantitatively in accord with the dependence of the reciprocal equilibrium swelling on the vulcanization time; both processes, after a retardation, go according to the first order law and at the same rate. 4. From the temperature dependence of the rate constants of reciprocal equilibrium swelling, as well as of the increase in stress, an activation energy of 22 kcal/mole can be calculated, in good agreement with the activation energy of dithiocarbamate formation in thiuram vulcanizations.

Insect blood-brain barrier: a radioisotope study of the kinetics of exchange of a liposoluble molecule (n-butanol)

1976 ◽  
Vol 64 (1) ◽  
pp. 119-130
Author(s):  
M. V. Thomas
Keyword(s):  
Activation Energy ◽  
Temperature Sensitivity ◽  
Nerve Cord ◽  
Previous Investigation ◽  
Time Course ◽  
Kcal Mole ◽  
Similar Time ◽  
Kinetics Of ◽  
Butanol Concentration ◽  
Good Agreement

About 90% of the butanol uptake by the cockroach abdominal nerve cord washed out with half-times of a few seconds, in good agreement with an electrophysiological estimate, and the temperature sensitivity suggested an activation energy of 3 Kcal mole-1. The remaining activity washed out far more slowly, with a similar time course to that observed in a previous investigation which had not detected the fast fraction. Its size was similar to the non-volatile uptake, and was considerably affected by the butanol concentration and incubation period. It apparently consisted of butanol metabolites, which could be detected by chromatography.

Kinetics of the addition of acids to olefins with and without boron fluoride catalysis

1967 ◽  
Vol 45 (1) ◽  
pp. 11-16 ◽  
Author(s):  
G. A. Latrèmouille ◽  
A. M. Eastham
Keyword(s):  
Activation Energy ◽  
Acetic Acid ◽  
Apparent Activation Energy ◽  
Trifluoroacetic Acid ◽  
Similar Rate ◽  
Ethylene Dichloride ◽  
Kcal Mole ◽  
Rate Law ◽  
Boron Fluoride ◽  
Kinetics Of

Isobutene reacts readily with excess trifluoroacetic acid in ethylene dichloride solution at ordinary temperatures to give t-butyl trifluoroacetate. The rate of the reaction is given, within the range of the experiments, by the expression d[ester]/dt = k[acid]2[olefin], and the apparent activation energy is about 6 kcal/mole. The rate of addition is markedly dependent on the strength of the reacting acid and is drastically reduced in the presence of mildly basic materials, such as dioxane. The boron fluoride catalyzed addition of acetic acid to 2-butene can be considered to follow a similar rate law, i.e. d[ester]/dt = k[acid·BF3]2[olefin], but only if some assumptions are made about the position of the equilibrium [Formula: see text]since only the 1:1 complex is reactive.

Chemical Vapor Deposition of SiO2 from Ozone-Organosilane Mixtures near Atmospheric Pressure

1992 ◽  
Vol 282 ◽  
Author(s):  
K. V. Guinn ◽  
J. A. Mucha
Keyword(s):  
Activation Energy ◽  
Chemical Vapor Deposition ◽  
Vapor Deposition ◽  
Atmospheric Pressure ◽  
Chemical Vapor ◽  
Zero Order ◽  
Kcal Mole ◽  
Consumption Ratio ◽  
Zero Order Kinetics ◽  
Kinetics Of

ABSTRACTThe kinetics of deposition of SiO2 by the reaction of tetramethylsilane (TMS) with ozone (O3) has been studied over the temperature range 180 – 380° C and compared with available data for the same process using tetraethoxysilane (TEOS). Both processes exhibit the same activation energy (17 kcal/mole) below 300 ° C which falls-off at higher temperatures due to transport limitations. Transition from first- to zero-order kinetics occurs with increasing concentrations of TMS and O3, which gives an overall O3/TMS consumption ratio of 10 at 258° C and5 at 325° C. TEOS is estimated to be 5 times more reactive than TMS above 300° C and over 10 times more reactive in the kinetically-limited regime below 300° C. Results suggest that O3-induced SiO2 deposition proceeds via surface reactions and is limited by heterogeneous decomposition of ozone.

scholarly journals Frequency Dependent Kinetics of the CW CO2 Laser Induced Reaction of CF3CF2Cl

1987 ◽  
Vol 7 (5-6) ◽  
pp. 271-277
Author(s):  
R. N. Zitter ◽  
D. F. Koster ◽  
N. Siddiqua
Keyword(s):  
Activation Energy ◽  
Absorption Band ◽  
Co2 Laser ◽  
Laser Frequency ◽  
Kcal Mole ◽  
Band Center ◽  
Laser Frequencies ◽  
Cw Co2 Laser ◽  
Kinetics Of ◽  
Induced Reaction

Kinetics of the decomposition of CF3CF2Cl at 50 torr by a cw CO2 laser have been studied over a range of laser frequencies extending 36 cm−1 below an absorption band center at 980 cm−1. At constant translational temperature, the change in the rate constant with laser frequency is a factor of 100, comparable to the effect previously observed in CF2ClCF2Cl. Arrhenius plots show an activation energy of 86.2 kcal/mole, independent of frequency.

Vulcanization of Elastomers. 40. Vulcanization of Natural Rubber and Synthetic Rubber with Sulfur in Presence of Sulfenamides. III

1965 ◽  
Vol 38 (1) ◽  
pp. 189-203 ◽  
Author(s):  
W. Scheele ◽  
J. Helberg
Keyword(s):  
Activation Energy ◽  
Reaction Mechanism ◽  
Natural Rubber ◽  
Rate Constants ◽  
Sulfur Concentration ◽  
Kcal Mole ◽  
Synthetic Rubber ◽  
Chemical Constitution ◽  
Induction Times ◽  
Kinetics Of

Abstract Vulcanization of natural rubber with sulfur was studied in presence of six sulfenamides, to determine the effect of the chemical constitution of the sulfenamide on sulfur decrease and on crosslinking. The results can be condensed as follows: (1) The kinetics of sulfur disappearance is in every respect qualitatively independent of the chemical constitution of the sulfenamide. (2) For the sulfenamides investigated, the smallest and largest rate constants for sulfur decrease differed only by a factor of two. (3) Greater differences are encountered in the induction times for sulfur decrease and for crosslinking. The latter are notably longer than those for sulfur disappearance. (4) The same activation energy, 23 kcal/mole, is derived from the temperature dependence of the induction times for all the sulfenamides. (5) The dissociation of sulfenamides in solution and their reaction with mercaptobenzothiazole were investigated further. The results provide the basis for a proposed reaction mechanism, which is presented in detail and can account for a number of the features typical of sulfenamide-accelerated vulcanization. (6) The drop in sulfur concentration goes at practically the same rate, if one introduces, instead of N, N-dicyclohexyl-2-benzothiazolesulfenamide, the corresponding ammonium mercaptide in equimolar concentration.

The thermal decomposition of RDX at temperatures below the melting point. II. Activation energy

1970 ◽  
Vol 23 (4) ◽  
pp. 749 ◽  
Author(s):  
JJ Batten ◽  
DC Murdie
Keyword(s):  
Activation Energy ◽  
Thermal Decomposition ◽  
Melting Point ◽  
Kinetic Parameter ◽  
Arrhenius Equation ◽  
Kcal Mole ◽  
Decomposition Products ◽  
Sample Geometry ◽  
Temperature Range ◽  
Definition Of

The activation energy has been determined in the temperature range 170-198�. If the sample was spread the activation energy was independent of the definition of the kinetic parameter substituted in the Arrhenius equation and was 63 kcal mole-1. In the case of the unspread samples the activation energies of the induction, acceleration, and maximum rates were 49, 43, and 62 kcal mole-1 respectively. The effect that sample geometry has on the activation energy is attributed to gaseous decomposition products influencing the reaction.

Gas phase photochlorination of perfluorocyclohexene

1969 ◽  
Vol 47 (6) ◽  
pp. 1067-1069 ◽  
Author(s):  
J. J. Cosa ◽  
C. A. Vallana ◽  
E. H. Staricco
Keyword(s):  
Activation Energy ◽  
Quantum Yield ◽  
Gas Phase ◽  
Photochemical Reaction ◽  
Total Pressure ◽  
Square Root ◽  
Kcal Mole ◽  
Kinetics Of

The kinetics of the gas phase photochemical reaction between perfluorocyclohexene and chlorine was studied between 10 and 50 °C. The system was irradiated with light of 4360 Å. The rate of the photochlorination was independent of the perfluorocyclohexene pressure and of the total pressure. It was found to be proportional to the first power of the pressure of Cl2 and to the square root of the intensity of absorbed light. At 30 °C, the quantum yield was found to be 200 when the initial Cl2 pressure was 100 Torr, and intensity of light absorbed 9.89 × 10−9 einstein l−1s−1.An activation energy of 5.1 kcal/mole could be assigned to the reaction C6F10Cl + Cl2.

THE NON-ENZYMATIC HYDROLYSIS OF ADENOSINE DIPHOSPHATE

1957 ◽  
Vol 35 (12) ◽  
pp. 1496-1503 ◽  
Author(s):  
K. A. Holbrook ◽  
Ludovic Ouellet
Keyword(s):  
Activation Energy ◽  
Aqueous Solution ◽  
Enzymatic Hydrolysis ◽  
Inorganic Phosphate ◽  
Adenosine Diphosphate ◽  
Hydrogen Ions ◽  
Kcal Mole ◽  
First Order ◽  
Kinetics Of ◽  
Hydrolysis Of

The kinetics of the non-enzymatic hydrolysis of adenosine diphosphate in aqueous solution have been studied at pH 3.5 to 10.5 and temperatures from 80° to 95 °C. The reaction has been followed by measuring colorimetrically the inorganic phosphate liberated according to the over-all reaction[Formula: see text]The reaction has been found to be first order with respect to ADP concentration and to be catalyzed by hydrogen ions. From rate studies at pH 8.0 an activation energy of 24.2 kcal./mole was derived. A mechanism is proposed to account for the observed facts and the mechanism for the hydrolysis of adenosine triphosphate is also discussed.

Kinetics of the Reaction between Silver and Nitric Acid

1962 ◽  
Vol 15 (2) ◽  
pp. 181 ◽  
Author(s):  
JJ Batten
Keyword(s):  
Activation Energy ◽  
Nitric Acid ◽  
Induction Period ◽  
Acid Concentration ◽  
Maximum Rate ◽  
Kcal Mole ◽  
Temperature Range ◽  
Induction Rate ◽  
Rate Of Dissolution ◽  
Kinetics Of

The rate of dissolution of silver gauze in nitric acid at various concentrations and temperatures was measured in a static system. The solution process was measured by the weight of silver dissolved in various time intervals. In general, induction periods were observed, but after this period the dissolution proceeded with an appreciable velocity. To examine the influence of acid concentration and temperature on the kinetics of the reaction, the duration of the induction period, the rate of dissolution during this period, and the subsequent maximum rate were taken as kinetic parameters of the reaction. The induction rate was found to be highly dependent on the initial acid concentration (approx. seventh power), whereas over most of the concentration range accessible to study, the maximum rate was proportional to the square of the concentration. It was also observed that increase in temperature sharply increases the induction rate, but has little effect upon the subsequent maximum rate over most of the temperature range studied. The activation energy of the induction rate was greater than 20 kcal/mole, whereas that of the maximum rate was about 4 kcal/mole over most of the temperature range studied. This difference in the activation energy during and after the induction period is explained by a shift in the mechanism controlling the rate of the process from a chemical reaction at the surface to a diffusion process.

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