Achieving theoretical thermal conductivity and coeffieicent of thermal expansion in a W-Cu composite sheet

2019 ◽  
Author(s):  
Xingang Wang ◽  
Peng Cao
Keyword(s):  
Thermal Conductivity ◽  
Thermal Expansion ◽  
Coefficient Of Thermal Expansion ◽  
Thin Sheet ◽  
Rolling Direction ◽  
Thickness Reduction ◽  
Full Density ◽  
Infiltration Process ◽  
Good Surface ◽  
Composite Samples

W-20wt.%Cu composite sheets with full density and good surface quality were successfully fabricated through an infiltration process followed by a hot rolling. After a total thickness reduction of 75%, the majority of the tungsten (W) particles have been deformed and elongated along the rolling direction. The aspect ratio of the W particles in the composite has reached 2.5. The relative density increases considerably to a maximum value of 99.8% when the rolling ratio increases. The thermal conductivity and microhardness of the W-Cu composites increase significantly with the rolling reduction. On the contrary, the coefficient of thermal expansion (CTE) of the composite samples decreases with the rolling ratio. Specifically, after subjected to 75% of thickness reduction, we obtained a large W-Cu thin sheet. This thin sheet demonstrates a low CTE of 7.27×10^-6/K and the highest thermal conductivity of 224.91 W/(m-K); both values are close to the respective theoretical ones.

Diamond/Al metal matrix composites formed by the pressureless metal infiltration process

1993 ◽  
Vol 8 (5) ◽  
pp. 1169-1173 ◽  
Author(s):  
William B. Johnson ◽  
B. Sonuparlak
Keyword(s):  
Thermal Conductivity ◽  
Thermal Expansion ◽  
Metal Matrix Composites ◽  
Metal Matrix ◽  
Coefficient Of Thermal Expansion ◽  
Matrix Composites ◽  
Infiltration Process ◽  
Point Bend ◽  
Aluminum Metal Matrix Composites ◽  
Metal Infiltration

Diamond particles are unique fillers for metal matrix composites because of their extremely high modulus, high thermal conductivity, and low coefficient of thermal expansion. Diamond reinforced aluminum metal matrix composites were prepared using a pressureless metal infiltration process. The diamond particulates are coated with SiC prior to infiltration to prevent the formation of Al4C3, which is a product of the reaction between aluminum and diamond. The measured thermal conductivity of these initial diamond/Al metal matrix composites is as high as 259 W/m-K. The effects of coating thickness on the physical properties of the diamond/Al metal matrix composite, including Young's modulus, 4-point bend strength, coefficient of thermal expansion, and thermal conductivity, are presented.

Effects of Cu Powder Size on the Microstructure of TiB2/Cu Composites Fabricated by Reactive Infiltration Process

2010 ◽  
Vol 654-656 ◽  
pp. 2724-2727 ◽  
Author(s):  
Shinji Kato ◽  
Makoto Kobashi ◽  
Naoyuki Kanetake
Keyword(s):  
Thermal Conductivity ◽  
Thermal Expansion ◽  
Volume Fraction ◽  
Coefficient Of Thermal Expansion ◽  
Electronic Devices ◽  
Processing Method ◽  
Powder Size ◽  
Infiltration Process ◽  
Reactive Infiltration ◽  
Tib2 Particles

Recently, industrial technology for both improving thermal conductivity and controlling the coefficient of thermal expansion of heat sink materials has became an important issuebecause of the downsizing of electronic devices. We have been investigating the innovative processing method for TiB2 dispersed Cu matrix composite by reactive infiltration process in which the combustion reaction of elemental powders (Ti+2B+Cu → TiB2+Cu) and pressureless infiltration of molten Cu into porous reaction product (TiB2/Cu composite) are combined. By this process, fine TiB2particles (2~3µm) can be dispersed in Cu matrix homogeneously. However, for better thermal conductivity and reduced thermal expansion, 3-dimentionally continuous inter-penetrating structure of TiB2 and Cu phases is suitable. In this study, we researched the effects of Cu powder size and volume fraction in Ti,B,Cu green powder compact on the microstructure of the combustion synthesized TiB2/Cu composite. When Cu powders were smaller than 45µm, TiB2 particles were uniformly dispersed in Cu matrix. However, when Cu powders were larger than 150µｍ, monolithic Cu area without TiB2 dispersion was formed. The monolithic Cu area tended to be connected each other by increasing the amount of Cu powders. This resulted in the formation of 3-dimensionally continuous inter-penetrating TiB2/Cu microstructure.

Evaluation of CeSZ Thermal Barrier Coatings for Diesels

2000 ◽  
Author(s):  
P.J. Huang ◽  
J.J. Swab ◽  
P.J. Patel ◽  
W.S. Chu
Keyword(s):  
Thermal Conductivity ◽  
Thermal Expansion ◽  
Thermal Barrier Coatings ◽  
Coefficient Of Thermal Expansion ◽  
Fuel Efficiency ◽  
Atmospheric Plasma ◽  
Thermal Barrier ◽  
Mechanical And Thermal Properties ◽  
Barrier Coatings ◽  
Spray Process

Abstract The development of thermal barrier coatings (TBCs) for diesel engines has been driven by the potential improvements in engine power and fuel efficiency that TBCs represent. TBCs have been employed for many years to reduce corrosion of valves and pistons because of their high temperature durability and thermal insulative properties. There are research programs to improve TBCs wear resistance to allow for its use in tribologically intensive areas of the engine. This paper will present results from tribological tests of ceria stabilized zirconia (CeSZ). The CeSZ was applied by atmospheric plasma spray process. Various mechanical and thermal properties were measured including wear, coefficient of thermal expansion, thermal conductivity, and microhardness. The results show the potential use of CeSZ in wear sensitive applications in diesel applications. Keywords: Thermal Barrier Coating, Diesel Engine, Wear, Thermal Conductivity, and Thermal Expansion

Processing of Porous Zirconium Tungstate and Their Thermomechanical Properties

2014 ◽  
Author(s):  
Mingang Wang ◽  
Truong Do ◽  
Patrick Kwon
Keyword(s):  
Thermal Expansion ◽  
Coefficient Of Thermal Expansion ◽  
Processing Technique ◽  
Thermomechanical Properties ◽  
Processing Route ◽  
Full Density ◽  
Ceramic Powders ◽  
Zirconium Tungstate ◽  
Spherical Graphite ◽  
New Processing

This paper explores a new processing method to fabricate porous zirconium tungstate (ZrW2O8 or ZT) with the porosity content up to 40% in volume. The method uses spherical graphite powders that are mechanically stable, allowing us to compact with ceramic powders in dry condition. Thus, the ceramic powders mixed with spherical graphite powders can be compacted and sintered to a near full density. During sintering, the graphite powders burn out without damaging the powder compact due to their inherent near-zero thermal expansion. The processing route discussed in this paper is applicable to all oxide ceramics where the sintering can take place in air and above 700°C to dissociate the graphite. In this paper, we have applied this processing technique to fabricate porous ZrW2O8. Many porous ZrW2O8 with a range of porosity levels were fabricated and tested for their theromomechanical properties including elastic modulus (E) and coefficient of thermal expansion (CTE). The experimentally determined properties were compared with the predictions based on the micromechanical Mori-Tanaka scheme.

scholarly journals A Comprehensive Review on Theoretical Aspects of Nanofluids: Exact Solutions and Analysis

Symmetry ◽  
2020 ◽  
Vol 12 (5) ◽  
pp. 725 ◽  
Author(s):  
Nadeem Ahmad Sheikh ◽  
Dennis Ling Chuan Ching ◽  
Ilyas Khan
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Thermal Expansion ◽  
Exact Solutions ◽  
Transfer Rate ◽  
Coefficient Of Thermal Expansion ◽  
Literature Survey ◽  
Heat Transfer Characteristics ◽  
Hybrid Nanofluids ◽  
Mass Expansion

In the present era, nanofluids are one of the most important and hot issue for scientists, physicists, and mathematicians. Nanofluids have many important and updated characteristics compared to conventional fluids. The thermal conductivity, thermal expansion, and the heat transfer rate of conventional fluids are not up to the mark for industrial and experimental uses. To overcome these deficiencies, nanoparticles have been dispersed into base fluids to make them more efficient. The heat transfer characteristics through symmetry trapezoidal-corrugated channels can be enhanced using nanofluids. In the present article, a literature survey has been presented for different models of nanofluids and their solutions—particularly, exact solutions. The models for hybrid nanofluids were also mentioned in the present study. Furthermore, some important and most used models for the viscosity, density, coefficient of thermal expansion, coefficient of mass expansion, heat capacitance, electrical conductivity, and thermal conductivity are also presented in tabular form. Moreover, some future suggestions are also provided in this article.

Friction and Wearing Behaviour of Sintered Composites Made from Copper Mixed with Carbon Fibers

2015 ◽  
Vol 660 ◽  
pp. 81-85 ◽  
Author(s):  
Radu Caliman
Keyword(s):  
Thermal Conductivity ◽  
Thermal Expansion ◽  
Composite Materials ◽  
Friction Coefficient ◽  
Carbon Fiber ◽  
Carbon Fibers ◽  
Coefficient Of Thermal Expansion ◽  
Density Ratio ◽  
Point Of View ◽  
Short Carbon

This paper presents a study regarding friction and wear comportment of sintered composite materials obtained by mixture of copper with short carbon fibers. Sintered composites are gaining importance because the reinforcement serves to reduce the coefficient of thermal expansion and increase the strength and modulus. In case of composites form by carbon fiber and copper, the thermal conductivity can also be enhanced. The combination of low thermal expansion and high thermal conductivity makes them very attractive for electronic packaging. Besides good thermal properties, their low density makes them particularly desirable for aerospace electronics and orbiting space structures. Compared to the metal itself, a carbon fiber-copper composite is characterized by a higher strength-to-density ratio, a higher modulus-to-density ratio, better fatigue resistance, better high-temperature mechanical properties and better wear resistance. Varying the percentage of short carbon fibers from 7,8% to 2,4%, and the percentage of copper from 92,2% to 97,6%, five dissimilar composite materials have been made and tested from the wear point of view. Friction tests are carried out, at room temperature, in dry conditions, on a pin-on-disc machine. The friction coefficient was measured using abrasive discs made from steel 4340 having the average hardness of 40 HRC, and sliding velocity of 0,6 m/sec. The primary goal of this study work it was to distinguish a mixture of materials with enhanced friction and wearing behaviour. The load applied on the specimen during the tests, is playing a very important role regarding friction coefficient and also the wearing speed.

Non-steady-state measurements of the thermal conductivities of liquid polyphenyls

1963 ◽  
Vol 273 (1353) ◽  
pp. 259-274 ◽  
Keyword(s):  
Thermal Conductivity ◽  
Thermal Expansion ◽  
Steady State ◽  
Temperature Dependence ◽  
Line Source ◽  
Coefficient Of Thermal Expansion ◽  
Liquid Benzene ◽  
Extended Range ◽  
Benzene Toluene ◽  
Effect Of Structure

A line source technique has been developed for non-steady-state measurements of the therm al conductivities of liquids over an extended range of temperature. The accuracy of the method, which is an absolute one, has been critically exam ined. T hermal conductivities of liquid benzene, toluene, diphenyl, o-,m - and^p-terphenyl, estimated to be accurate to + 0*25 % , have been obtained. These results are discussed in terms of the effect of structure on the transport properties of liquids and the relation between the coefficient of thermal expansion and the temperature dependence of thermal conductivity.

scholarly journals Technological Relevance, Research Prospect and Applications of Aluminium-Silicon Carbide-Graphite Hybrid Metal Matrix Composites for Thermal Characterization

2018 ◽  
Vol 8 (02) ◽  
Author(s):  
S A Mohan Krishna ◽  
T N Shridhar ◽  
L Krishnamurthy ◽  
K B Vinay ◽  
G V Naveen Prakash
Keyword(s):  
Mechanical Properties ◽  
Thermal Conductivity ◽  
Silicon Carbide ◽  
Thermal Expansion ◽  
Hybrid Composites ◽  
Coefficient Of Thermal Expansion ◽  
Aluminium Matrix ◽  
Matrix Composites ◽  
Aluminium Matrix Composites ◽  
Research Prospect

Aluminium matrix composites belong to the family of materials whose mechanical, tribological, thermal and electrical properties can be customized effectively. Most of the commercial work on MMCs has been highlighted on Aluminium as the matrix material. The combination of light weight, environmental resistance and beneficial mechanical properties has made Aluminium alloys exceedingly popular; these properties also make Aluminium best suited for use as a matrix metal. The thermophysical properties of these composites can be tailor made and have excellent specific mechanical properties. These composites can be fabricated with ease. Aluminium matrix composites reinforced with the particles of Silicon Carbide possess high yield strength, low coefficient of thermal expansion or thermal expansivity, high modulus of elasticity and excellent wear resistance by maintaining volume proportion up to 20%. Aluminium hybrid composites can be customized to provide moderate Coefficient of Thermal Expansion (CTE) and high thermal conductivity that are favorable for the applications pertaining to thermal management equipment. However, it is necessary to evaluate different percentage combinations of reinforcements with matrix Aluminium to check for thermal stability and to measure thermal conductivity and coefficient of thermal expansion. It is expected that, Aluminium-Silicon Carbide-Graphite hybrid composites can be used as load bearing material for the above applications. In this paper, a review about the said hybrid composites to investigate thermal properties for engineering applications have been discussed based on its technological relevance, applications and research prospect.

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