Temperature and Pressure Dependence of Self Diffusion in Long Liquid n-Alkanes

1991 ◽  
Vol 95 (8) ◽  
pp. 859-865 ◽  
Author(s):  
T. Vardag ◽  
N. Karger ◽  
H.-D. Lüdemann
Keyword(s):  
Pressure Dependence ◽  
Self Diffusion ◽  
Temperature And Pressure

Temperature and pressure dependence of self diffusion in nonassociating liquids

1992 ◽  
Vol 54 (4) ◽  
pp. vii-ix ◽  
Author(s):  
F. Bachl ◽  
T. Vardag ◽  
S. Wappmann ◽  
H.-D. Lüdemann
Keyword(s):  
Pressure Dependence ◽  
Self Diffusion ◽  
Temperature And Pressure

Temperature and Pressure Dependence of Self Diffusion in Octamethylcyclotetrasiloxane and Hexamethylcyclotrisilazane

1990 ◽  
Vol 45 (11-12) ◽  
pp. 1281-1284 ◽  
Author(s):  
A. Greiner-Schmid ◽  
M. Has ◽  
H.-D. Lüdemann
Keyword(s):  
Magnetic Field ◽  
Pressure Dependence ◽  
Spin Echo ◽  
The Self ◽  
Self Diffusion ◽  
Field Gradients ◽  
Magnetic Field Gradients ◽  
Temperature And Pressure ◽  
Spin Echo Technique ◽  
Self Diffusion Coefficient

AbstractThe pressure dependence of the self diffusion coefficient D for octamethylcyclotetrasiloxane and hexamethylcyclotrisilazane has been determined by the NMR spin echo technique with pulsed magnetic field gradients at pressures up to 200 MPa and at temperatures between 490 K and 290 K. The data extend partially into the deeply supercooled range. The isobaric temperature dependence of these data is quantitatively described by the empirical Vogel-Fulcher-Tammann equation. For both substances the melting pressure curves were determined in addition.

Measurements of real non-Newtonian response for liquid lubricants under moderate pressures

2001 ◽  
Vol 215 (3) ◽  
pp. 223-233 ◽  
Author(s):  
S Bair
Keyword(s):  
Numerical Simulation ◽  
Kinetic Theory ◽  
Simple Shear ◽  
Pressure Dependence ◽  
Shear Stresses ◽  
Current Interest ◽  
Flow Properties ◽  
Power Law Fluid ◽  
Temperature And Pressure

A thorough characterization of all viscous flow properties relevant to steady simple shear was carried out for five liquid lubricants of current interest to tribology. Shear stresses were generated to values significant to concentrated contact lubrication. Two types of non-Newtonian response were observed: shear-thinning as a power-law fluid and near rate-independence. Functions and parameters were obtained for the temperature and pressure dependence of the viscosity and of the time constant for the Carreau-Yasuda equation. Results are consistent with free volume and kinetic theory, but directly contradict many assumptions currently utilized for numerical simulation and for extracting rheological properties from contact measurements.

Doping Effect in Nickel Oxide

2009 ◽  
Vol 289-292 ◽  
pp. 775-782 ◽  
Author(s):  
Zbigniew Jurasz ◽  
Krzysztof Adamaszek ◽  
Romuald Janik ◽  
Zbigniew Grzesik ◽  
Stanisław Mrowec
Keyword(s):  
Activation Energy ◽  
Nickel Oxide ◽  
High Temperatures ◽  
Oxygen Pressure ◽  
Pressure Dependence ◽  
Oxidation Rate ◽  
Doping Effect ◽  
Self Diffusion ◽  
Electron Holes ◽  
Influence Of Impurities

Detailed investigations of nonstoichiometry as well as chemical and self-diffusion in nickel oxide have shown that doubly ionised cation vacancies and electron holes are the predominant defects in this material. The present work is an attempt to demonstrate that aliovalent impurities (Cr, Al, Na and Li) may considerably influence the concentration of these defects and, consequently, the oxidation rate of nickel at high temperatures. It has been shown that small amounts of tri-valent impurities (Cr, Al) bring about an increase of the oxidation rate, while mono-valent ones (Li, Na) decrease the rate of oxidation. These phenomena may satisfactorily be explained in terms of a doping effect. All experiments have been carried out as a function of temperature (1373-1673 K) and oxygen pressure (1-105 Pa) and consequently, it was possible to determine the influence of impurities not only on the oxidation rate but also on the activation energy of reaction and its pressure dependence. The results of these investigations could again be elucidated in terms of doping effect.

Pressure Dependence of Self Diffusion in Some Neat Alkanes and Binary Mixtures

1990 ◽  
Vol 94 (3) ◽  
pp. 336-342 ◽  
Author(s):  
T. Vardag ◽  
F. Bachl ◽  
S. Wappmann ◽  
H.-D. Lüdemann
Keyword(s):  
Binary Mixtures ◽  
Pressure Dependence ◽  
Self Diffusion
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