scholarly journals Sound velocities and thermal properties of BeX (X=S, Se and Te) alkaline-earth chalcogenides

2016 ◽  
Vol 5 (1) ◽  
pp. 9
Author(s):  
Salah Daoud
Keyword(s):  
Thermal Conductivity ◽  
Thermal Properties ◽  
Elastic Wave ◽  
Alkaline Earth ◽  
Theoretical Data ◽  
Elastic Stiffness ◽  
Band Gaps ◽  
Wave Velocities ◽  
Beryllium Chalcogenides ◽  
Sound Velocities

The sound velocities and some thermal properties of BeX (X=S, Se and Te) beryllium-chalcogenides large band gaps semiconductors have been estimated by employing some usual theoretical and emperical formulas. The lattice parameters and the elastic stiffness constants used here are taken from the literature. The longitudinal, transverse and average elastic wave velocities, the Debye temperature, the melting temperature, the thermal conductivity and the Grüneisen parameter are successfully predicted and analyzed in comparison with the available experimental and theoretical data. In general, our obtained results of these quantities agree well with the experimental and other theoretical data of the literature.

An empirical relationship between thermal conductivity and elastic wave velocities in sandstone

1993 ◽  
Vol 20 (16) ◽  
pp. 1679-1682 ◽  
Author(s):  
Maria Zamora ◽  
Dung Vo-Thanh ◽  
Gérard Bienfait ◽  
Jean Paul Poirier
Keyword(s):  
Thermal Conductivity ◽  
Elastic Wave ◽  
Empirical Relationship ◽  
Wave Velocities

scholarly journals Sound velocities and Debye temperature of BeSe under high pressure up to 50 GPa

2016 ◽  
Vol 5 (1) ◽  
pp. 7
Author(s):  
Salah Daoud
Keyword(s):  
High Pressure ◽  
Elastic Wave ◽  
Mechanical Behavior ◽  
Debye Temperature ◽  
Elastic Constants ◽  
Structural Parameters ◽  
Theoretical Data ◽  
Elastic Wave Velocity ◽  
Brittle Behavior ◽  
Sound Velocities

The mechanical behavior, sound velocities and Debye temperature of beryllium-selenide (BeSe) semiconductor under pressure up to 50 GPa have been estimated using the structural parameters and elastic constants of Fanjie Kong and Gang Jiang (Physica B 404 (2009) 3935-3940). The Pugh ratio, the directional dependence of elastic wave velocity, the longitudinal, transverse and average sound velocities, and the Debye temperature are successfully predicted and analyzed in comparison with the available theoretical data. The analysis of the Pugh ratio indicates that this compound is prone to brittle behavior. Our obtained results of the longitudinal, transverse and average sound velocities at high pressure indicate that these of Kong and Jiang (Physica B 404 (2009) 3935-3940) are not correctly predicted.

scholarly journals Prediction of rocks thermal conductivity from elastic wave velocities, mineralogy and microstructure

2014 ◽  
Vol 197 (2) ◽  
pp. 860-874 ◽  
Author(s):  
Lucas Pimienta ◽  
Joel Sarout ◽  
Lionel Esteban ◽  
Claudio Delle Piane
Keyword(s):  
Thermal Conductivity ◽  
Elastic Wave ◽  
Wave Velocities

Effect of Sc, Y, Yb, Hf, Ce on Mechanical and Thermal Properties of La2Zr2O7: First-Principles Calculations

2015 ◽  
Vol 1120-1121 ◽  
pp. 85-93 ◽  
Author(s):  
Lei Jin ◽  
Pei Zhong Li ◽  
Chun Zhu Jiang ◽  
Guo Dong Zhou ◽  
Hai Bin Zhou ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Thermal Properties ◽  
Sound Velocity ◽  
Young’S Modulus ◽  
Debye Temperature ◽  
Elastic Constants ◽  
First Principles ◽  
Young's Modulus ◽  
Elastic Stiffness ◽  
Mechanical And Thermal Properties

In order to achieve better understanding of the effect of dopant (Sc, Y, Yb, Hf and Ce) on elastic stiffness and thermal properties of La2Zr2O7. The related calculations were performed using the first principles methods. The predicted elastic constants indicate that La2Zr2O7 and oxidations-La2Zr2O7 (oxidations refer to Sc2O3, Y2O3, Yb2O3, HfO2 and CeO2) are mechanically stable structures. And then the numerical estimates of bulk modulus, shear modulus, Young’s modulus were performed using the calculated elastic constants. After these mechanical properties are obtained, sound velocity, Debye temperature and theoretical minimum thermal conductivity of La2Zr2O7 and oxidations-La2Zr2O7 are calculated and analyzed in detail. The available experimental results and our calculations are basically satisfactory. The calculated results indicate that Young’s modulus, mean sound velocity, Debye temperature and minimum thermal conductivity of La2Zr2O7 can be decreased by dopants. CeO2 has extraordinary ability to decrease thermal conductivity in these dopant oxidations.

Thermal Characterization of Carbon-Carbon Composites

2011 ◽  
Author(s):  
Messiha Saad ◽  
Darryl Baker ◽  
Rhys Reaves
Keyword(s):  
Thermal Conductivity ◽  
Thermal Properties ◽  
Thermal Diffusivity ◽  
Specific Heat ◽  
Critical Role ◽  
Carbon Composite ◽  
Flash Method ◽  
Carbon Composites ◽  
Energy Storage Devices ◽  
Graphitized Carbon

Thermal properties of materials such as specific heat, thermal diffusivity, and thermal conductivity are very important in the engineering design process and analysis of aerospace vehicles as well as space systems. These properties are also important in power generation, transportation, and energy storage devices including fuel cells and solar cells. Thermal conductivity plays a critical role in the performance of materials in high temperature applications. Thermal conductivity is the property that determines the working temperature levels of the material, and it is an important parameter in problems involving heat transfer and thermal structures. The objective of this research is to develop thermal properties data base for carbon-carbon and graphitized carbon-carbon composite materials. The carbon-carbon composites tested were produced by the Resin Transfer Molding (RTM) process using T300 2-D carbon fabric and Primaset PT-30 cyanate ester. The graphitized carbon-carbon composite was heat treated to 2500°C. The flash method was used to measure the thermal diffusivity of the materials; this method is based on America Society for Testing and Materials, ASTM E1461 standard. In addition, the differential scanning calorimeter was used in accordance with the ASTM E1269 standard to determine the specific heat. The thermal conductivity was determined using the measured values of their thermal diffusivity, specific heat, and the density of the materials.

scholarly journals Testing a Gypsum Composite Based on Raw Gypsum with a Direct Admixture of Paraffin and Polymer to Improve Thermal Properties

Materials ◽  
2021 ◽  
Vol 14 (12) ◽  
pp. 3241
Author(s):  
Krzysztof Powała ◽  
Andrzej Obraniak ◽  
Dariusz Heim
Keyword(s):  
Thermal Conductivity ◽  
Heat Capacity ◽  
Thermal Properties ◽  
Phase Change ◽  
Large Scale ◽  
Building Materials ◽  
Residential Buildings ◽  
Energy Performance ◽  
Polymer Content ◽  
Volumetric Heat Capacity

The implemented new legal regulations regarding thermal comfort, the energy performance of residential buildings, and proecological requirements require the design of new building materials, the use of which will improve the thermal efficiency of newly built and renovated buildings. Therefore, many companies producing building materials strive to improve the properties of their products by reducing the weight of the materials, increasing their mechanical properties, and improving their insulating properties. Currently, there are solutions in phase-change materials (PCM) production technology, such as microencapsulation, but its application on a large scale is extremely costly. This paper presents a solution to the abovementioned problem through the creation and testing of a composite, i.e., a new mixture of gypsum, paraffin, and polymer, which can be used in the production of plasterboard. The presented solution uses a material (PCM) which improves the thermal properties of the composite by taking advantage of the phase-change phenomenon. The study analyzes the influence of polymer content in the total mass of a composite in relation to its thermal conductivity, volumetric heat capacity, and diffusivity. Based on the results contained in this article, the best solution appears to be a mixture with 0.1% polymer content. It is definitely visible in the tests which use drying, hardening time, and paraffin absorption. It differs slightly from the best result in the thermal conductivity test, while it is comparable in terms of volumetric heat capacity and differs slightly from the best result in the thermal diffusivity test.

Assessing rock brittleness and fracability from radial variation of elastic wave velocities from borehole acoustic logging

2016 ◽  
Vol 64 (4) ◽  
pp. 958-966 ◽  
Author(s):  
Xiao-Ming Tang ◽  
Song Xu ◽  
Chun-Xi Zhuang ◽  
Yuan-Da Su ◽  
Xue-Lian Chen
Keyword(s):  
Elastic Wave ◽  
Radial Variation ◽  
Acoustic Logging ◽  
Wave Velocities ◽  
Rock Brittleness

Effect of Coating on the Thermal Conductivities of Diamond/Cu Composites Prepared by Spark Plasma Sintering (SPS)

2014 ◽  
Vol 722 ◽  
pp. 25-29 ◽  
Author(s):  
Q.L. Che ◽  
X.K. Chen ◽  
Y.Q. Ji ◽  
Y.W. Li ◽  
L.X. Wang ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Thermal Properties ◽  
Theoretical Prediction ◽  
Volume Fraction ◽  
Interface Reaction ◽  
Copper Matrix ◽  
Bonding Force ◽  
Ti Alloys ◽  
Plasma Sintering ◽  
Spark Plasma

The carbide forming is proposed to improve interfacial bonding between diamond particles and copper-matrix for diamond/copper composites. The volume fraction of diamond and minor titanium are optimized. The microstructures, thermal properties, interface reaction production and its effect of minor titanium on the properties of the composites are investigated. The results show that the bonding force and thermal conductivity of the diamond/Cu-Ti alloys composites is much weaker and lower than that of the coated-diamond/Cu. the thermal conductivity of coated-60 vol. % diamond/Cu composites is 618 W/m K which is 80 % of the theoretical prediction value. The high thermal conductivity has been achieved by forming the titanium carbide at diamond/copper interface to gain a good interface.

Adhesive penetration of wood cell walls investigated by scanning thermal microscopy (SThM)

Holzforschung ◽  
2008 ◽  
Vol 62 (1) ◽  
pp. 91-98 ◽  
Author(s):  
Johannes Konnerth ◽  
David Harper ◽  
Seung-Hwan Lee ◽  
Timothy G. Rials ◽  
Wolfgang Gindl
Keyword(s):  
Thermal Conductivity ◽  
Thermal Properties ◽  
Surface Temperature ◽  
Cell Walls ◽  
Adhesive Contact ◽  
Wood Adhesive ◽  
Bond Line ◽  
Scanning Thermal Microscopy ◽  
Thermal Probe ◽  
Thermal Microscopy

Abstract Cross sections of wood adhesive bonds were studied by scanning thermal microscopy (SThM) with the aim of scrutinizing the distribution of adhesive in the bond line region. The distribution of thermal conductivity, as well as temperature in the bond line area, was measured on the surface by means of a nanofabricated thermal probe offering high spatial and thermal resolution. Both the thermal conductivity and the surface temperature measurements were found suitable to differentiate between materials in the bond region, i.e., adhesive, cell walls and embedding epoxy. Of the two SThM modes available, the surface temperature mode provided images with superior optical contrast. The results clearly demonstrate that the polyurethane adhesive did not cause changes of thermal properties in wood cell walls with adhesive contact. By contrast, cell walls adjacent to a phenol-resorcinol-formaldehyde adhesive showed distinctly changed thermal properties, which is attributed to the presence of adhesive in the wood cell wall.

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