scholarly journals Electrical conductivity, ion pairing, and ion self-diffusion in aqueous NaCl solutions at elevated temperatures and pressures

2019 ◽  
Vol 151 (22) ◽  
pp. 224504 ◽  
Author(s):  
Tae Jun Yoon ◽  
Lara A. Patel ◽  
Matthew J. Vigil ◽  
Katie A. Maerzke ◽  
Alp T. Findikoglu ◽  
...  
Keyword(s):  
Electrical Conductivity ◽  
Elevated Temperatures ◽  
Ion Pairing ◽  
Self Diffusion

Non-Destructive Evaluation of Creep Damage in a Nickel Base Super-Alloy Turbine Bucket

2009 ◽  
Author(s):  
Hector Carreon
Keyword(s):  
Electrical Conductivity ◽  
Eddy Current ◽  
Elevated Temperatures ◽  
Damage Zone ◽  
Creep Damage ◽  
Turbine Engine ◽  
Turbine Component ◽  
Nickel Base ◽  
Turbine Bucket ◽  
Super Alloy

Due to elevated temperatures, excessive stresses and severed corrosion conditions, turbine engine components are subject to creep processes that limit the components life such as a turbine bucket. The failure mechanism of a turbine bucket is related primarily to creep and corrosion and secondarily to thermal fatigue. As a result, it is desirable to assess the current condition of such turbine component. This study uses the eddy current (EC) nondestructive evaluation technique in an effort to monitor the creep damage in a nickel base super-alloy, 7FA stage 2 turbine bucket after service. The experimental results show significative electrical conductivity variations in eddy current images on the creep damage zone of nickel base super-alloy samples cut from a turbine bucket. Thermoelectric power (TEP) measurements were also conducted in order to obtain a direct correlation between the presence of material changes due to creep damage and the electrical conductivity measurements.

Creep of CdZnTe at high homologous temperatures

1999 ◽  
Vol 14 (10) ◽  
pp. 3864-3869 ◽  
Author(s):  
T. E. Stevens ◽  
J. C. Moosbrugger ◽  
F. M. Carlson
Keyword(s):  
Elevated Temperatures ◽  
Small Strain ◽  
Small Sample ◽  
Dislocation Creep ◽  
Etch Pit Density ◽  
Self Diffusion ◽  
Etch Pit ◽  
Before And After ◽  
Low Levels ◽  
Different Sources

The creep behavior of single-crystal Zn-doped CdTe was examined in the small strain regime. Specimens from two different sources, with tensile axes [110] and [112], were deformed at 1073 and 1173 K. Strain rates were of order 10−6 to 10−7 s−1. A laser interferometer was constructed to measure the small sample displacement. Cadmium overpressure was used to inhibit sublimation of test specimens at elevated temperatures. Some tests showed a transition from secondary to tertiary creep at low levels of strain. An activation energy for steady-state creep was calculated as QC = 1.46 eV, and the creep exponent was found to be approximately n = 4.2. These results, coupled with reported activation energies for self-diffusion of Cd in Cd(Zn)Te, indicate a dislocation creep mechanism. Etch pit density was measured before and after deformation and approached a common level regardless of initial etch pit density.

scholarly journals Multicomponent non-aqueous electrolytes for high temperature operation of supercapacitors

2020 ◽  
Vol 61 (1) ◽  
pp. 67-75
Author(s):  
Mikhail V. Astakhov ◽  
◽  
Ludmila A. Puntusova ◽  
Ruslan R. Galymzyanov ◽  
Ilya S. Krechetov ◽  
...  
Keyword(s):  
Electrical Conductivity ◽  
Dielectric Constant ◽  
Propylene Carbonate ◽  
Boiling Point ◽  
Elevated Temperatures ◽  
Specific Conductivity ◽  
Ethylene Carbonate ◽  
Aqueous Electrolytes ◽  
Cyclic Carbonates ◽  
High Boiling Point

Multicomponent non-aqueous electrolytes based on cyclic carbonates and tetraethylammonium tetrafluoroborate have been developed for the operation of supercapacitors at elevated temperatures. Propylene carbonate, which has a high dielectric constant and a high boiling point, was used as the main solvent of electrolytes. However, a significant drawback of propylene carbonate is its high viscosity, which leads to decrease in the electrical conductivity of electrolytes based on it compared to electrolytes based on acetonitrile. To increase the electrical conductivity, an additional component was introduced into the electrolyte – a cosolvent with the necessary set of properties. When choosing cosolvents, two approaches were used. In the first case, to increase the dielectric permittivity of the liquid phase, ethylene carbonate having a higher dielectric constant than propylene carbonate was introduced into the electrolyte. This approach made it possible to significantly increase the electrical conductivity of the electrolyte and to achieve high resource stability of the supercapacitor. The values of the specific capacitance and energy of the supercapacitor with the introduction of ethylene carbonate in the electrolyte practically did not change. In the second case, butyl acetate, which has a low viscosity but has a moderate polarity and a sufficiently high boiling point, was used as a co-solvent. In this case, not only an increase in the electrical conductivity of the electrolyte was observed, but also a significant increase in the capacitive characteristics of the supercapacitor. It is shown that the use of a mixture of cyclic carbonates and esters as a solvent in the composition of the electrolyte can increase its specific conductivity by 40%, and the specific energy consumption of a supercapacitor by 20%. The developed electrolytes provide long-term operation of supercapacitors both at room temperature and at elevated temperatures up to 80 °С.

The Study on EMAT Applied in Nondestructive Testing of Elevated Temperature Material

2015 ◽  
Vol 750 ◽  
pp. 261-265
Author(s):  
Yang Zheng ◽  
Su Jun Li ◽  
Hui Zheng
Keyword(s):  
Electrical Conductivity ◽  
Elevated Temperature ◽  
Magnetic Permeability ◽  
Elevated Temperatures ◽  
Testing Temperature ◽  
Testing System ◽  
Physical Parameters ◽  
Electromagnetic Acoustic Transducers ◽  
Acoustic Transducers ◽  
On Line

Electromagnetic acoustic transducers (EMATs) has overcome many disadvantages of the traditional piezoelectric ultrasonic sensors and can be applied in elevated temperatures and on-line inspection. In an EMAT testing system, the tested material and EMAT itself make up a whole system. So the performance of EMAT is closely depended on some physical parameters of tested material. On the other hand, characteristic parameters of metallic materials are closely related to temperature, such as density, modulus of elasticity, electrical conductivity and magnetic permeability. As the temperature increases, the density of the metal material is reduced, the elastic modulus is reduced, the electrical conductivity is decreased, the magnetic permeability has a consistent increasing trend until the Curie point. Thus the EMAT detection performance affected by the change of temperature should be considered. This paper studied the effects of temperature on EMAT testing. Three materials of 20 # steel, Q235 and 16MnR were investigated. Testing temperature varies from 26 °C to 500 °C. The results show that under elevated temperature condition, EMAT echo signals still have a good waveform and stability. Meanwhile, signals are attenuated less than 2dB. It proved that the EMAT technique has a good steady performance in elevated temperature.

Sign in / Sign up

Export Citation Format

Share Document