Novel Polymer Electrets

1999 ◽  
Vol 600 ◽  
Author(s):  
G. M. Sessler ◽  
J. Hillenbrand
Keyword(s):  
Thermal Stability ◽  
Theoretical Model ◽  
Porous Structure ◽  
Piezoelectric Properties ◽  
Experimental Results ◽  
Charge Densities ◽  
New Family ◽  
Thermal Stability Of ◽  
Good Agreement ◽  
Polymer Electrets

AbstractPermanently charged films with a cellular or porous structure represent a new family of polymer electrets. These materials show piezoelectric properties with high transducer constants. The electromechanical response equations of such films are derived for their operation as sensors and as actuators. Experimental results are also presented for cellular polypropylene. In particular, measurements of the direct and inverse transducer constants, the thermal stability of the charge, and Young's modulus are discussed. Assuming reasonable charge distributions and charge densities, the calculated transducer constants are in good agreement with the measured values. Both the theoretical model and the measurements show the reciprocity of the transducer constants.

Nanocomposite Epoxy Resin for SiC Module

2011 ◽  
Vol 2011 (HITEN) ◽  
pp. 000196-000200 ◽  
Author(s):  
Kenji Okamoto ◽  
Yuji Takematsu ◽  
Miyako Hitomi ◽  
Yoshinari Ikeda ◽  
Yoshikazu Takahashi
Keyword(s):  
Thermal Stability ◽  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Epoxy Resin ◽  
Molecular Motion ◽  
Experimental Results ◽  
Power Module ◽  
Operation Temperature ◽  
Thermal Stability Of

There is a demand to improve the thermal stability of epoxy molding resins used in the power module of SiC power chips operating at temperatures of 200°C or more. This paper describes a technique for increasing the thermal stability of the resin by decreasing molecular motion through the addition of nanofiller. The experimental results showed that the glass transition temperature (Tg) of the epoxy resin increased by approximately 30°C when the silica nanofiller was added. The epoxy resin added nanofiller was investigated in order to achieve the operation temperature 200°C of power module.

scholarly journals Thermal Characteristics of Spindle Supported with Water-Lubricated Hydrostatic Bearings

2019 ◽  
Vol 13 (5) ◽  
pp. 602-609 ◽  
Author(s):  
Yohichi Nakao ◽  
Rei Kirigaya ◽  
Dmytro Fedorynenko ◽  
Akio Hayashi ◽  
Kenji Suzuki ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Water Flow ◽  
Temperature Increase ◽  
Power Loss ◽  
Thermal Characteristics ◽  
Experimental Results ◽  
Total Power ◽  
Cooling Efficiency ◽  
Power Losses ◽  
Thermal Stability Of

Characteristics of a spindle supported with water-lubricated hydrostatic bearings were experimentally investigated. In particular, this paper focuses on the thermal characteristics of the spindle. The flowrates of water as the lubricating fluid were measured separately for the radial and thrust bearings, in relation to the supply pressure. Fluid power losses owing to pressure losses of the lubricating fluid were then introduced. Furthermore, the power losses owing to the water viscosity were determined by measuring the spindle torque and angular velocity. The experiments revealed that the total power loss of the spindle is approximately 300 W. The cooling effect of the lubricating water was then examined by introducing a temperature increase between the supply and drain water. The experimental results verified that the water temperature increased by approximately 0.8°C, at a spindle speed of 3000 min-1. Based on the temperature increase of the water, the power removed from the spindle by the water flow was estimated. By comparing the generated total power loss and the power transferred by the water flow, the cooling efficiency of the flow of lubricating-water was defined in this paper. If the cooling efficiency is 100%, the temperature change of the spindle can be zero regardless of the power loss, achieving ideal thermal stability of the spindle. Experimental results revealed that the cooling efficiency of the tested spindle was over 80%. This indicates that the flow of water as a lubricating fluid removes generated heat from the spindle effectively, and achieves improved thermal stability of the spindle.

Theoretical Model of Plastic Hysteresis in Spherical Contact Under Combined Normal and Tangential Loading

2008 ◽  
Author(s):  
Yuri Kligerman ◽  
Izhak Etsion
Keyword(s):  
Theoretical Model ◽  
Stress State ◽  
Friction Force ◽  
Contact Area ◽  
Contact Condition ◽  
Experimental Results ◽  
Tangential Displacement ◽  
Elastic Plastic ◽  
Plastic Sphere ◽  
Good Agreement

The behavior of an elastic-plastic contact between a deformable sphere and a rigid flat under combined constant normal and reciprocating tangential loading is investigated in the present work. The theoretical model is based on the assumptions of full stick contact condition and two kinds of the sphere material hardening. Hysteretic change of friction force versus tangential displacement during reciprocating tangential loading is investigated along with the study of the change of the contact area and stress state in the elastic-plastic sphere. Good agreement between theoretical and experimental results is obtained.

Evaluation of Thermal Stability of Porous Material by Sintering Stress

2006 ◽  
Vol 317-318 ◽  
pp. 683-688
Author(s):  
Fumihiro Wakai ◽  
Yutaka Shinoda ◽  
Takashi Akatsu
Keyword(s):  
Thermal Stability ◽  
Porous Material ◽  
Porous Structure ◽  
Porous Materials ◽  
Difference Method ◽  
Energy Difference ◽  
Force Balance ◽  
Pore Surface ◽  
Porous Structures ◽  
Thermal Stability Of

The sintering stress is related to the thermal stability of porous structure. The sintering stress for a given porous structure in equilibrium can be calculated by three methods theoretically; the energy difference method, the curvature method, and the force balance method. The sintering stresses by three different methods were exactly the same for the idealized porous materials in equilibrium, in which the pore surface had a constant curvature at any point. The porous material does not spontaneously shrink when the sintering stress becomes zero or negative. The sintering stress will be used to design optimal porous structures with improved thermal stability.

ELECTRON-PHONON INTERACTION WITHIN THE FRAMEWORK OF THE FLUCTUATING VALENCE OF COPPER ATOMS — A THEORETICAL MODEL FOR HIGH TEMPERATURE SUPERCONDUCTIVITY

1990 ◽  
Vol 04 (05) ◽  
pp. 325-331
Author(s):  
SURESH V. VETTOOR ◽  
V. M. NANDAKUMARAN
Keyword(s):  
High Temperature ◽  
Theoretical Model ◽  
Green's Function ◽  
High Temperature Superconductivity ◽  
Experimental Results ◽  
Function Technique ◽  
Phonon Interaction ◽  
Electron Phonon Interaction ◽  
Good Agreement ◽  
Quasiparticle Excitations

Electron-phonon interaction is considered within the framework of the fluctuating valence of Cu atoms. Anderson's lattice Hamiltonian is suitably modified to take this into account. Using Green's function technique the possible quasiparticle excitations are determined. The quantity 2∆k(0)/k B T c is calculated for T c = 40 K . The calculated values are in good agreement with the experimental results.

Phase Transition, Piezoelectric Properties, and Thermal Stability of (1−x−y)BiScO3-yBiGaO3-xPbTiO3Ceramics

2008 ◽  
Vol 91 (9) ◽  
pp. 2943-2946 ◽  
Author(s):  
Yihang Jiang ◽  
Baoquan Qin ◽  
Yi Zhao ◽  
Yuzhi Jiang ◽  
Wei Shi ◽  
...  
Keyword(s):  
Phase Transition ◽  
Thermal Stability ◽  
Piezoelectric Properties ◽  
Thermal Stability Of

Helium and Hydrogen Induced Growth of Microcavities in Silicon; Application to Gas And Impurity Collection

1994 ◽  
Vol 373 ◽  
Author(s):  
A. Van Veen ◽  
H. Schut ◽  
R.A. Hakvoort ◽  
A. Fedorov ◽  
K.T. Westerduin
Keyword(s):  
Thermal Stability ◽  
Room Temperature ◽  
Positron Beam ◽  
Experimental Results ◽  
Subsequent Annealing ◽  
Sharp Threshold ◽  
Vacancy Clusters ◽  
Beam Analysis ◽  
Atomistic Calculations ◽  
Thermal Stability Of

AbstractThermal helium desorption spectrometry and positron beam analysis have been used to monitor the growth of helium vacancy clusters during room temperature helium irradiation of silicon and during subsequent annealing to 1300 K. Experimental results obtained with hydrogen irradiation show that also hydrogen can be used to create cavities. There is a rather sharp threshold dose for creating cavities that will survive 1300 K annealing. It appears that positrons form a sensitive probe for the trapping and release of impurities inside the cavities. Results of atomistic calculations are used to discuss thermal stability of helium vacancy complexes. The results are related to recent impurity gettering studies based on impurity trapping at helium induced gettering centers.

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