Creep and Creep Recovery of 2618-T61 Aluminum Under Variable Temperature

1984 ◽  
Vol 51 (4) ◽  
pp. 816-820 ◽  
Author(s):  
U. W. Cho ◽  
W. N. Findley
Keyword(s):  
Activation Energy ◽  
Aluminum Alloy ◽  
Apparent Activation Energy ◽  
Variable Temperature ◽  
Constant Stress ◽  
Temperature History ◽  
Effect Of Temperature ◽  
Creep Recovery ◽  
Dependent Theory ◽  
Using Data

Creep and creep recovery data are reported for pure tension of 2618-T61 aluminum alloy under variable temperature between 200° C and 230° C. Varying temperature experiments involved an abrupt temperature increase and a linearly increasing and decreasing temperature at a constant stress of 137.9 MPa (20 ksi). A temperature-compensated time by Sherby and Dorn was employed to represent the effect of temperature. A temperature-history-dependent theory using data from constant stress creep and creep recovery together with the apparent activation energy was used to predict the creep under variable temperature. The predictions agreed quite well with the observed data. The apparent activation energy of this alloy was found to be 49,000 cal/mole°K.

Variable Temperature Creep and Creep Recovery of 304 Stainless Steel

1984 ◽  
Vol 106 (4) ◽  
pp. 393-396 ◽  
Author(s):  
U. W. Cho ◽  
W. N. Findley
Keyword(s):  
Stainless Steel ◽  
Temperature Increase ◽  
Variable Temperature ◽  
Superposition Principle ◽  
304 Stainless Steel ◽  
Temperature History ◽  
Effect Of Temperature ◽  
Creep Recovery ◽  
Temperature Creep ◽  
Dependent Theory

Creep and creep recovery data are reported for pure tension of 304 stainless steel under variable temperature between 593°C and 649°C. Varying temperature experiments involved multiple steps of abrupt temperature increase and decrease at a constant stress of 86.2 MPa (12.5 ksi). A temperature-compensated time proposed by Sherby and Dorn was employed to represent the effect of temperature. The temperature history dependent theory combined with the modified superposition principle was used to predict the variable temperature creep and creep recovery from data under constant temperature. The test data were predicted reasonably well by the theory.

scholarly journals Effect of Temperature on the Creep of Ice

1969 ◽  
Vol 8 (52) ◽  
pp. 131-145 ◽  
Author(s):  
Malcolm Mellor ◽  
Richard Testa
Keyword(s):  
Activation Energy ◽  
Creep Rate ◽  
Single Crystal ◽  
Apparent Activation Energy ◽  
Creep Curve ◽  
Effect Of Temperature ◽  
Temperature Dependent ◽  
Creep Tests ◽  
Polycrystalline Ice ◽  
Rate Relation

Creep tests on homogeneous, isotropic polycrystalline ice gave an apparent activation energy for creep of 16.4 kcal/mol (68.8 kJ/mol) over the temperature range −10° to −60° C. Above −10° C the Arrhenius relation for temperature dependence is invalid, and creep rate becomes progressively more temperature dependent as the melting point is approached. Between −20° and −50° C the apparent activation energy for creep of a single crystal of ice was found to be 16.5 kcal/mol (69.1 kJ/mol). A complete creep curve for a single crystal loaded in uniaxial compression parallel to the basal plane was qualitatively similar to the classical creep curve; creep rate at all stages was very much faster than for polycrystalline ice under the same conditions. Creep tests on polycrystalline ice at 0° C gave a stress/strain-rate relation for that temperature, but its precise meaning is unclear, since recrystallization complicated the results.

Reactions of thiyl radicals. II. The photolysis of methyl disulfide vapor

1967 ◽  
Vol 45 (12) ◽  
pp. 1369-1374 ◽  
Author(s):  
P. M. Rao ◽  
J. A. Copeck ◽  
A. R. Knight
Keyword(s):  
Nitric Oxide ◽  
Activation Energy ◽  
Apparent Activation Energy ◽  
Pressure Range ◽  
Excess Energy ◽  
Inert Gases ◽  
Effect Of Temperature ◽  
Primary Process ◽  
Direct Production ◽  
Thiyl Radicals

The photolysis of methyl disulfide vapor in the pressure range 2–25 Torr at wavelengths between 2 300 and 2 800 and at 2 288 Å has been examined and the effect of temperature, pressure, added inert gases, ethyl disulfide, and nitric oxide determined.The primary process is a direct production of two CH3S radicals which have excess energy and which can be observed as methyl thionitrite when NO is present during the decomposition. When pure disulfide is photolyzed the major observable product is methanethiol, although this material accounts for only a small fraction of the primarily produced thiyl radicals whose principal fate is recombination in a substrate-reforming reaction producing excited disulfide molecules. The latter species are deactivated by added gases, or by the substrate itself. The mode of mercaptan formation is by abstraction of H atoms from the substrate by excited CH3S radicals with an apparent activation energy of 1.5 kcal.

scholarly journals Effect of Temperature on the Creep of Ice

1969 ◽  
Vol 8 (52) ◽  
pp. 131-145 ◽  
Author(s):  
Malcolm Mellor ◽  
Richard Testa
Keyword(s):  
Activation Energy ◽  
Creep Rate ◽  
Single Crystal ◽  
Apparent Activation Energy ◽  
Creep Curve ◽  
Effect Of Temperature ◽  
Temperature Dependent ◽  
Creep Tests ◽  
Polycrystalline Ice ◽  
Rate Relation

Creep tests on homogeneous, isotropic polycrystalline ice gave an apparent activation energy for creep of 16.4 kcal/mol (68.8 kJ/mol) over the temperature range −10° to −60° C. Above −10° C the Arrhenius relation for temperature dependence is invalid, and creep rate becomes progressively more temperature dependent as the melting point is approached. Between −20° and −50° C the apparent activation energy for creep of a single crystal of ice was found to be 16.5 kcal/mol (69.1 kJ/mol). A complete creep curve for a single crystal loaded in uniaxial compression parallel to the basal plane was qualitatively similar to the classical creep curve; creep rate at all stages was very much faster than for polycrystalline ice under the same conditions. Creep tests on polycrystalline ice at 0° C gave a stress/strain-rate relation for that temperature, but its precise meaning is unclear, since recrystallization complicated the results.

scholarly journals Study on drying kinetics of summer onion

2015 ◽  
Vol 39 (4) ◽  
pp. 661-673 ◽  
Author(s):  
Md Masud Alam ◽  
Md Nurul Islam ◽  
Md Nazrul Islam
Keyword(s):  
Activation Energy ◽  
Mass Transfer ◽  
Rate Constant ◽  
Variable Temperature ◽  
Air Flow ◽  
Drying Kinetics ◽  
Effect Of Temperature ◽  
Drying Rate ◽  
External Resistance ◽  
Kinetics Of

The present study was concerned with the kinetics of drying of summer onion. Drying was done in a mechanical dryer at constant air flow using blanched and unblanched onion with variable temperature (52, 60 and 680C) and thickness (3, 5 and 7 mm). Drying rate was increased with increase of temperature and decreased with the increase in thickness in blanched and unblanched onion. Blanched onion showed higher drying rate than unblanched onion. Drying rate constant and thickness can be expressed as power low equations. The value of index “n” were found to be 1.277 and 0.845 for onion indicating that the external resistance to mass transfer was highly significant. The effect of temperature on diffusion co-efficient follows an Arrhenius type relationship. The activation energy (Ea) for diffusion of water was found 5.781 Kcal/g-mole for unblanched and 2.46 Kcal/g-mole for blanched onion when onions were dried in mechanical dryer. DOI: http://dx.doi.org/10.3329/bjar.v39i4.22545 Bangladesh J. Agril. Res. 39(4): 661-673, December 2014

scholarly journals Effect of Temperature and pH on Early Hydration Rate and Apparent Activation Energy of Alkali-Activated Slag

2019 ◽  
Vol 2019 ◽  
pp. 1-13
Author(s):  
Ping Li ◽  
Jianhui Tang ◽  
Xudong Chen ◽  
Yin Bai ◽  
Qiyao Li
Keyword(s):  
Activation Energy ◽  
Apparent Activation Energy ◽  
Effect Of Temperature ◽  
Early Hydration ◽  
Alkali Activated Slag ◽  
Hydration Rate ◽  
Different Temperatures ◽  
Shell Forming ◽  
Activated Slag ◽  
Alkali Activated

In order to investigate the effect of temperature and pH on the early hydration rate of alkali-activated slag (AAS), NaOH was used as alkali activator, and the nonevaporable water (NEW) content of the slag paste at different temperatures (5, 20 and 35°C) and pH (12.10, 12.55, 13.02, and 13.58) was measured. On the basis of the Arrhenius formula, the hydration rate of slag was characterized by the content of nonevaporative water, and the apparent activation energy of slag hydration at different pH was also obtained. The early hydration rate of slag was significantly affected by temperature and pH of activator solution. The apparent activation energy Ea of slag decreased with the increase of pH, and there was a good linear relationship between them. When pH was less than 13.02, increasing the temperature can accelerate the hydration rate of slag. However, under the condition of high pH (pH = 13.58), the hydration rate of slag was negatively correlated with temperature, which was related to the “shell forming” phenomenon of slag hydration.

scholarly journals Photodegradation of Rhodamine B Using the Microwave/UV/H2O2: Effect of Temperature

2013 ◽  
Vol 2013 ◽  
pp. 1-12 ◽  
Author(s):  
Carlo Ferrari ◽  
H. Chen ◽  
R. Lavezza ◽  
C. Santinelli ◽  
I. Longo ◽  
...  
Keyword(s):  
Activation Energy ◽  
Hydrogen Peroxide ◽  
Apparent Activation Energy ◽  
Rhodamine B ◽  
Effect Of Temperature ◽  
Microwave Source ◽  
Uv Emission ◽  
Linear Behavior ◽  
C 30 ◽  
Few Data

The oxidative decoloration of Rhodamine B (RhB) was performed in a photochemical reactor which enables microwave (MW) and UV radiation to be applied simultaneously. We used an immersed microwave source, with no need for an oven. Controlling the temperature, MW power, and UV emission of the reactor all led to a greater overall control of the process. Due to the action of highly reactive hydroxyl radicals, the decoloration of RhB was followed online using a spectrograph. Complete decoloration occurred in four minutes, and 92% of mineralisation was obtained in 70 minutes. The experiments were performed at various temperatures (21°C, 30°C, 37°C, and 46°C), with and without hydrogen peroxide. The apparent reaction rate was used to calculate the apparent activation energy of the decoloration process:Ea=38±2 kJ/mol and40±2 kJ/mol with (400 mg/L) or without hydrogen peroxide, respectively. The lack of deviation from the linear behavior of the Arrhenius plot confirms that the application of MW does not affect theEaof the process. The apparent activation energy value found was compared with the few data available in the literature, which were obtained in the absence of MW radiation and are inconsistent.

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