Sulfidation kinetics and mechanism of some Ni-Mo-Al and Ni-Al alloys over the temperature range 600?800�C

1990 ◽  
Vol 33 (5-6) ◽  
pp. 399-423 ◽  
Author(s):  
M. F. Chen ◽  
D. L. Douglass ◽  
F. Gesmundo
Keyword(s):  
Al Alloys ◽  
Kinetics And Mechanism ◽  
Temperature Range ◽  
Sulfidation Kinetics

scholarly journals Pyrolysis of azetidinones. Part 2. Kinetics and mechanism of thermolysis of β-lactams and β-thiolactams

2016 ◽  
Vol 94 (9) ◽  
pp. 788-793 ◽  
Author(s):  
Nouf S. Al-Hamdan ◽  
Alya M. Al-Etaibi ◽  
Rasha F. Al-Bashir ◽  
Yahia A. Ibrahim ◽  
Nouria A. Al-Awadi ◽  
...  
Keyword(s):  
Gas Phase ◽  
Rate Constants ◽  
Kinetics And Mechanism ◽  
Energy Of Activation ◽  
The Novel ◽  
Temperature Range ◽  
Entropy Of Activation ◽  
Kinetics Of ◽  
Thermolysis Reaction

The kinetics of the gas-phase thermolysis reaction of seven β-lactams and their thione analogues were investigated over the temperature range 533–603 K for the β-lactams and 463–542 K for the β-thiolactams. The average values of the energy of activation (Ea) (kJ mol−1) and Arrhenius log A (s–1) were, respectively, 170.8 ± 18.6 and 12.4 ± 1.6 for the lactams and 131.7 ± 18.2 and 11.0 ± 2.0 for the thione analogues. The entropy of activation (ΔS#) was negative for of the substrates and slightly positive for three. The rate constants (k) (s−1) were calculated for 510 K and compared for the two series of azetidinones. The effects of substituents on rates and the novel role played by the C=O and C=S moieties on the relative reactivities of the cyclic amides are rationalized on the basis of a formal retro[2+2]cycloaddition mechanism used earlier to explain the products of the gas-phase thermolysis reaction of the present azetidinones.

Kinetics and Mechanism of the Reaction of Dichlorotetraaquaruthenium(III) and Thiols

2012 ◽  
Vol 65 (2) ◽  
pp. 113 ◽  
Author(s):  
Suprava Nayak ◽  
Gouri Sankhar Brahma ◽  
K. Venugopal Reddy
Keyword(s):  
Electron Transfer ◽  
Ionic Strength ◽  
Equilibrium Constants ◽  
Activation Parameters ◽  
Kinetics And Mechanism ◽  
Intermediate Complex ◽  
Mechanism Of Formation ◽  
Temperature Range ◽  
Temperature Reduction ◽  
Mechanism Of The Reaction

The formation of an intermediate ruthenium(iii) thiolate complex by the interaction of thiols, RSH (R = glutathione and l-cysteine) and dichlorotetraaquaruthenium(iii), [RuIIICl2(H2O)4]+, is reported in the temperature range 25–40°C. The kinetics and mechanism of formation of the intermediate complex were studied as a function of [RuIIICl2(H2O)4]+, [RSH], pH, ionic strength and temperature. Reduction of the intermediate complex takes place slowly and results in the corresponding disulfides RSSR and [RuIICl2(H2O)4]+. The results are interpreted in terms of a mechanism involving a rate-determining inner-sphere one-electron transfer from RSH to the oxidant used in the present investigation and a comparison of rate and equilibrium constants is presented with activation parameters.

Alloying Effect on the Microstructure and Property of Single Crystal Ni3Al Alloys

1988 ◽  
Vol 133 ◽  
Author(s):  
Zhang Jishan ◽  
Zhang Zhiya ◽  
Tang Yajun ◽  
Zhang Jinghua ◽  
Yu Yang ◽  
...  
Keyword(s):  
Single Crystal ◽  
Al Alloys ◽  
Nickel Base Superalloy ◽  
Al Alloy ◽  
Alloying Effect ◽  
Temperature Range ◽  
Cr Content ◽  
Nickel Base ◽  
Alloying Effects ◽  
Base Superalloy

ABSTRACTThe alloying effects of Cr, Zr, Ta, Nb and B on the microstructure and properties of single crystal Ni3Al alloys have been studied. The strength of the alloys has been improved markedly with promising plasticity. The 0.2% yield stress of some of these alloys is higher than that of IN713C, a typical cast nickel-base superalloy, in the temperature range from 25 to 950°C and some of them reach the strength level of advanced cast nickel-base alloys such as IN100 in the high temperature range. The creep strength of these alloys is also improved markedly. The single crystal Ni3Al alloy with a high Cr content ( 7 at-%) obviously shows an intermediate temperature low plasticity behavior. Although heat treatment can only slightly improve the strength, it can double the elongation of the alloy from 25% to 50%. In the Ni3Al monocrystal containing 1.2at%Zr there exist great amounts of the low melting point Ni5 Zr-γ eutectics around the ordinary γ/γ′ eutectics. This makes it difficult to homogenize the coarse casting structures completely.

Powder Processing of Fe3Al-Based Iron-Aluminide Alloys

1990 ◽  
Vol 213 ◽  
Author(s):  
V.K. Sikka ◽  
R.H. Baldwin ◽  
J.H. Reinshagen ◽  
J.R. Knibloe ◽  
R.N. Wright
Keyword(s):  
Mechanical Properties ◽  
Room Temperature ◽  
Powder Processing ◽  
Al Alloys ◽  
Iron Aluminide ◽  
Temperature Range

ABSTRACTThe production, characterization, and consolidation of Fe3Al-based iron-aluminide powders are described. The consolidated powders were fabricated into sheet. The sheet was tensile tested from room temperature to 800°C and creep tested in the temperature range of 450 to 704°C. Mechanical properties were compared for nitrogen and argon atomized powders. Mechanical properties were also compared for argon atomized powders of Fe3Al alloys containing 2 and 5% Cr.

Pyrolysis of 3-Chloro-3-aryldiazirines, Kinetics and Mechanism

1972 ◽  
Vol 50 (18) ◽  
pp. 3009-3016 ◽  
Author(s):  
Michael T. H. Liu ◽  
K. Toriyama
Keyword(s):  
Thermal Decomposition ◽  
Substituent Effects ◽  
Kinetics And Mechanism ◽  
Temperature Range ◽  
Hammett Correlation

The thermal decomposition of 3-chloro-3-aryldiazirines in various solvents has been investigated over the temperature range 60–100 °C. The intermediate carbenes have been isolated as norcaranes by the use of cyclohexene. Substituent effects on rates of reaction are small and a Hammett correlation was unsuccessful with either σ or σ+ constants. Possible mechanisms for the decompositions are discussed.

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