Thermal Properties of Si Mechanically Alloyed with FeSi2 and CrSi2

2015 ◽  
Vol 799-800 ◽  
pp. 207-211
Author(s):  
Konstantin N. Galkin ◽  
Andrey Usenko ◽  
Andrey Voronin ◽  
Dmitriy Moskovskikh ◽  
Andrey Korotitskiy ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Thermal Properties ◽  
Size Effect ◽  
Band Gap ◽  
Lattice Thermal Conductivity ◽  
Volume Fraction ◽  
Reference Sample ◽  
The Other ◽  
Mechanically Alloyed ◽  
Silicon Structures

Thermal properties of Si mechanically alloyed with FeSi2 and CrSi2 were characterized for the samples with different volume fraction of the disilicides. An anomalously low thermal conductivity observed in the FeSi2-doped samples was ascribed to an enhanced porosity of the samples which triggered the size effect on the lattice thermal conductivity reported previously for nanomeshed and “holey” silicon structures. It was also found that alloying of Si with FeSi2 led to a reduction of thermal conductivity as compared to the reference sample of pure Si prepared under the same conditions. On the other hand, alloying of Si with CrSi2 resulted in an increase in the thermal conductivity as compared to the reference sample of pure Si. The observed trends in the thermal conductivity were ascribed to the formation of impurity levels in the band gap.

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.

Influence of Mesocarp Fibre Inclusion on Thermal Properties of Foamed Concrete

2021 ◽  
Vol 87 (1) ◽  
pp. 1-11
Author(s):  
Siti Shahirah Suhaili ◽  
Md Azree Othuman Mydin ◽  
Hanizam Awang
Keyword(s):  
Thermal Conductivity ◽  
Heat Capacity ◽  
Thermal Properties ◽  
Thermal Diffusivity ◽  
Specific Heat ◽  
Specific Heat Capacity ◽  
Volume Fraction ◽  
Thermal Constant ◽  
Volume Fractions ◽  
Foamed Concrete

The addition of mesocarp fibre as a bio-composite material in foamed concrete can be well used in building components to provide energy efficiency in the buildings if the fibre could also offer excellent thermal properties to the foamed concrete. It has practical significance as making it a suitable material for building that can reduce heat gain through the envelope into the building thus improved the internal thermal comfort. Hence, the aim of the present study is to investigate the influence of different volume fractions of mesocarp fibre on thermal properties of foamed concrete. The mesocarp fibre was prepared with 10, 20, 30, 40, 50 and 60% by volume fraction and then incorporated into the 600, 1200 and 1800 kg/m3 density of foamed concrete with constant cement-sand ratio of 1:1.5 and water-cement ratio of 0.45. Hot disk thermal constant analyser was used to attain the thermal conductivity, thermal diffusivity and specific heat capacity of foamed concrete of various volume fractions and densities. From the experimental results, it had shown that addition of mesocarp fibre of 10-40% by volume fraction resulting in low thermal conductivity and specific heat capacity and high the thermal diffusivity of foamed concrete with 600 and 1800 kg/m3 density compared to the control mix while the optimum amount of mesocarp fibre only limit up to 30% by volume fraction for 1200 kg/m3 density compared to control mix. The results demonstrated a very high correlation between thermal conductivity, thermal diffusivity and specific heat capacity which R2 value more than 90%.

Numerical Solution of Transient Heat Conduction Equation for Heat-Treatable Alloys Whose Thermal Properties Change With Time and Temperature

1977 ◽  
Vol 99 (3) ◽  
pp. 471-478 ◽  
Author(s):  
K. Farnia ◽  
J. V. Beck
Keyword(s):  
Thermal Conductivity ◽  
Thermal Properties ◽  
Differential Equations ◽  
Numerical Solution ◽  
Precipitation Hardening ◽  
Elevated Temperatures ◽  
Volume Fraction ◽  
Transient Heat Conduction ◽  
Computer Assisted ◽  
Al 2024

Changes in microstructure occur in as-received aluminum alloy (Al-2024-T351) when it is subjected to elevated temperatures (150–260°C). These changes, which are called precipitation hardening, in turn influence the thermal properties, making them time as well as temperature dependent. A computer-assisted transient experimental procedure has been developed to determine the values of thermal conductivity of as-received Al-2024-T351 under the influence of precipitation-hardening. Based on isothermal experimental data and related algebraic modeling of the thermal conductivity, a mathematical model in the form of two differential equations is proposed. Instantaneous values of volume fraction of precipitate and thermal conductivity can be predicted using this model. A method for the simultaneous numerical solution of the partial differential equation of conduction and the proposed differential equations of precipitation are also given. The influence of precipitation—hardening on temperature distribution and on values of thermal conductivity is shown graphically for several cases involving the Al-2024-T351 material.

Thermal properties of kinetic spray Al–SiC metal-matrix composite

2003 ◽  
Vol 18 (4) ◽  
pp. 855-860 ◽  
Author(s):  
Gary L. Eesley ◽  
Alaa Elmoursi ◽  
Nilesh Patel
Keyword(s):  
Thermal Conductivity ◽  
Thermal Expansion ◽  
Thermal Properties ◽  
Metal Matrix ◽  
Volume Fraction ◽  
Spray Deposition ◽  
Deposition Process ◽  
Matrix Composites ◽  
Kinetic Spray ◽  
Compositional Variations

Kinetic spray deposition provides a new means for producing composite materials with tailored physical properties. We report on measurements of the thermal conductivity and thermal-expansion coefficient for several compositional variations of kinetically sprayed Al–SiC metal-matrix composites. As a result of the deposition process, inclusion of SiC particles saturates in the 30–40% volume fraction range.

Correlating Microscale Thermal Conductivity of Heavily-Doped Silicon With Simultaneous Measurements of Stress

2011 ◽  
Vol 133 (4) ◽  
Author(s):  
Ming Gan ◽  
Vikas Tomar
Keyword(s):  
Thermal Conductivity ◽  
Thermal Properties ◽  
Compressive Strain ◽  
Integrated System ◽  
Nanoindentation Test ◽  
Crystal Silicon ◽  
Increase With Increase ◽  
Temperature Detector ◽  
Silicon Structures ◽  
Measured Thermal Conductivity

The functioning and performance of today’s integrated circuits and sensors are highly affected by the thermal properties of microscale silicon structures. Due to the well known size effect, the thermal properties of microscale silicon structures are not the same as those of the bulk silicon. Furthermore, stress/strain inside microscale silicon structures can significantly affect their thermal properties. This article presents the first thermal conductivity measurements of a microscale silicon structure under applied compressive stress at 350 K. Atomic force microscope (AFM) cantilevers made of doped single-crystal silicon were used as samples. A resistance temperature detector (RTD) heater attached to another RTD sensor was used as the heating module, which was mounted onto a nanoindentation test platform. This integrated system applied compressive load to the cantilever in the longitudinal direction while supplying heat. The thermal conductivity of the cantilevers was calculated using steady state heat conduction equation. The result shows that the measured thermal conductivity varies from 110 W/(m·K) to 140 W/(m·K) as compressive strain varies from 0.1% to 0.3%. Thermal conductivity is shown to increase with increase in compressive strain. These results match with the published simulation values. The measured thermal conductivity and stress values vary in the similar manner as a function of applied strain.

Thermal Properties of Rubber Compounds. II. Heat Generation of Pigmented Rubber Compounds

1935 ◽  
Vol 8 (1) ◽  
pp. 138-149 ◽  
Author(s):  
C. E. Barnett ◽  
W. C. Mathews
Keyword(s):  
Thermal Conductivity ◽  
Thermal Properties ◽  
Laboratory Test ◽  
Heat Generation ◽  
The Other ◽  
Moving Plate ◽  
Rubber Compounds ◽  
Time Required ◽  
Two Machines ◽  
Rubber Block

Abstract THE first paper (1) of this series discussed thermal conductivity of rubber and a number of compounding ingredients which were measured using the electric current as the source of heat. In this article the fundamental factors controlling the generation of heat and the variations possible by pigmentation are being studied. Results obtained for pigmented rubber in the pendulum and flexometer will be discussed and correlated. In the writers' laboratory two machines have been used extensively in studying the temperature developed in rubber compounds subjected to distortion by compressive forces. The first of these is a flexometer described by Cooper (2), and the second a compression machine in which a rubber block 14 cm. (5.5 inches) in diameter and 9.53 cm. (3.75 inches) high is pounded with a definite load a specified number of times per minute. The laboratory test block used in the flexometer is in the shape of a frustrum of a rectangular pyramid, of which the base is 5.4 × 2.86 cm. (2.126 × 1.125 inches), the top 5.08 × 2.54 cm. (2 × 1 inches), and the altitude 3.81 cm. (1.5 inches). This block of rubber is compressed between two plates under definite load, one of the plates being stationary while the other travels in a circular motion of definite magnitude. After the sample has been placed in the machine, the moving plate is set to one side of the center. Both the loading and the amount of offset may be varied within wide limits. With this machine one may study either the temperature developed over a period of flexing or the time required to compress the sample a predetermined amount.

scholarly journals Influence of Pd Doping on Electrical and Thermal Properties of n-Type Cu0.008Bi2Te2.7Se0.3 Alloys

Materials ◽  
2019 ◽  
Vol 12 (24) ◽  
pp. 4080 ◽  
Author(s):  
Se Yun Kim ◽  
Hyun-Sik Kim ◽  
Kyu Hyoung Lee ◽  
Hyun-jun Cho ◽  
Sung-sil Choo ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Thermal Properties ◽  
Carrier Concentration ◽  
Figure Of Merit ◽  
Lattice Thermal Conductivity ◽  
Phonon Scattering ◽  
Energy Conversion Efficiency ◽  
Thermoelectric Figure ◽  
Pd Doping ◽  
Effect Of Pd

Doping is known as an effective way to modify both electrical and thermal transport properties of thermoelectric alloys to enhance their energy conversion efficiency. In this project, we report the effect of Pd doping on the electrical and thermal properties of n-type Cu0.008Bi2Te2.7Se0.3 alloys. Pd doping was found to increase the electrical conductivity along with the electron carrier concentration. As a result, the effective mass and power factors also increased upon the Pd doping. While the bipolar thermal conductivity was reduced with the Pd doping due to the increased carrier concentration, the contribution of Pd to point defect phonon scattering on the lattice thermal conductivity was found to be very small. Consequently, Pd doping resulted in an enhanced thermoelectric figure of merit, zT, at a high temperature, due to the enhanced power factor and the reduced bipolar thermal conductivity.

Lattice Thermal Conductivity of Fe-Cr Alloys With 〈001〉 Tilt Boundaries: An Atomistic Study

2014 ◽  
Author(s):  
Ishraq Shabib ◽  
Mohammad Abu-Shams ◽  
Mujibur R. Khan
Keyword(s):  
Thermal Conductivity ◽  
Molecular Dynamics ◽  
Single Crystal ◽  
Grain Boundaries ◽  
Lattice Thermal Conductivity ◽  
The Other ◽  
Tilt Boundaries ◽  
Cr Concentration ◽  
Non Equilibrium Molecular Dynamics ◽  
Atomistic Study

The objective of this study is to examine lattice thermal conductivity (κ) of Fe-Cr alloys containing different 〈001〉 tilt grain boundaries (GBs). The effects of Cr concentration (2 and 10%) and three different 〈001〉 tilt boundaries (Σ5{310}, Σ13{510}, and Σ17{530}) have been examined at 70K using the reverse non-equilibrium molecular dynamics (rNEMD) simulation technique. The results exhibit higher κ for Fe or Fe-Cr models with Σ5[310] GB. The values are 2–4% and 12–16% more than those of models with Σ13[510] and Σ17[530] GBs, respectively. Pure Fe single crystal models exhibit higher conductivities than Fe/Fe-Cr models with various Σ tilt boundaries. κ decreases 7–9% as GBs are introduced into the pure Fe single crystal models. On the other hand, the conductivities of Fe-Cr models are affected more by the Cr concentration than the presence of a particular GB. As 10% Cr is added into the system the conductivity decreases by 7.6–9.4% compared to the pure Fe models.

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