The effects of particle size and volume fraction of Al2O3 on electronic thermal conductivity of α-Al2O3 particulate reinforced aluminum composites (Al/Al2O3MMC)

2006 ◽  
Vol 29 (3-4) ◽  
pp. 226-229 ◽  
Author(s):  
N. Özdemir ◽  
F. Yakuphanoglu
Keyword(s):  
Thermal Conductivity ◽  
Particle Size ◽  
Volume Fraction ◽  
Aluminum Composites ◽  
Electronic Thermal Conductivity ◽  
Α Al2o3 ◽  
Particulate Reinforced

STUDYING THE EFFECT OF DIFFERENT ADDITIVES ON THE THERMAL CONDUCTIVITY AND MECHANICAL CHARACTERISTICS OF EPOXY-BASED COMPOSITE MATERIALS

2021 ◽  
Vol 25 (Special) ◽  
pp. 2-72-2-77
Author(s):  
Hassanein M. Nhoo ◽  
◽  
Raad. M. Fenjan ◽  
Ahmed A. Ayash ◽  
◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Thermal Conductivity ◽  
Particle Size ◽  
Tensile Strength ◽  
Mechanical Characteristics ◽  
Volume Fraction ◽  
Pyrolysis Process ◽  
Volume Percent ◽  
Fair Comparison ◽  
Filler Level

The current paper deals with investigating the effect of two different fillers on the thermal and mechanical characteristics of epoxy-based composite. The filler used throughout the study are: charcoal and Pyrex, both of them are different in nature and have not been investigated thoroughly or even compared fairly in terms of their effect on polymer matrix. Further, they can be considered as a cheap filler, charcoal can be obtained from a simple pyrolysis process of plants (charcoal) and Pyrex waste can be collected easily. Both types are added to the selected matrix with volume percent ranged from 10 to 60 with increments of 10. To ensure a fair comparison, the particle size is fixed (is about 1.7 micrometer). The results showed that the epoxy thermal conductivity has enhanced by about two orders of magnitudes over the studied range of filler. In terms of mechanical properties, the charcoal improves the tensile strength about 84% at 60% volume fraction while the Pyrex effect is about 40% at the same filler level. On the contrast, the results of compressive strength do not show an appreciable improvement overall. It decreases by about 12% at 60% volume fraction of charcoal while increases about the same percent with Pyrex at the same filler level.

Thermal Conductivity of Metal-Oxide Nanofluids: Particle Size Dependence and Effect of Laser Irradiation

2006 ◽  
Vol 129 (3) ◽  
pp. 298-307 ◽  
Author(s):  
Sang Hyun Kim ◽  
Sun Rock Choi ◽  
Dongsik Kim
Keyword(s):  
Thermal Conductivity ◽  
Particle Size ◽  
Effective Thermal Conductivity ◽  
Laser Irradiation ◽  
Volume Fraction ◽  
Suspended Particle ◽  
Titanium Dioxide Nanoparticles ◽  
Size Change ◽  
Conductivity Enhancement ◽  
Wide Range

The thermal conductivity of water- and ethylene glycol-based nanofluids containing alumina, zinc-oxide, and titanium-dioxide nanoparticles is measured using the transient hot-wire method. Measurements are performed by varying the particle size and volume fraction, providing a set of consistent experimental data over a wide range of colloidal conditions. Emphasis is placed on the effect of the suspended particle size on the effective thermal conductivity. Also, the effect of laser-pulse irradiation, i.e., the particle size change by laser ablation, is examined for ZnO nanofluids. The results show that the thermal-conductivity enhancement ratio relative to the base fluid increases linearly with decreasing the particle size but no existing empirical or theoretical correlation can explain the behavior. It is also demonstrated that high-power laser irradiation can lead to substantial enhancement in the effective thermal conductivity although only a small fraction of the particles are fragmented.

Liquid Layering and the Enhanced Thermal Conductivity of Ar-Cu Nanofluids: A Molecular Dynamics Study

2016 ◽  
Author(s):  
Jithu Paul ◽  
A. K. Madhu ◽  
U. B. Jayadeep ◽  
C. B. Sobhan
Keyword(s):  
Thermal Conductivity ◽  
Molecular Dynamics ◽  
Particle Size ◽  
Molecular Dynamics Simulations ◽  
Volume Fraction ◽  
Strong Dependence ◽  
Particle Sizes ◽  
Dynamics Simulations ◽  
Enhanced Thermal Conductivity ◽  
Liquid Layering

Nanofluids — colloidal suspensions of nanoparticles in base fluids — are known to possess superior thermal properties compared to the base fluids. Various theoretical models have been suggested to explain the often anomalous enhancement of these properties. Liquid layering around the nanoparticle is one of such reasons. The effect of the particle size on the extent of liquid layering around the nanoparticle has been investigated in the present study. Classical molecular dynamics simulations have been performed in the investigation, considering the case of a copper nanoparticle suspended in liquid argon. The results show a strong dependence of thickness of the liquid layer on the particle size, below a particle diameter of 4nm. To establish the role of liquid layering in the enhancement of thermal conductivity, simulations have been performed at constant volume fraction for different particle sizes using Green Kubo formalism. The thermal conductivity results show 100% enhancement at 3.34% volume fraction for particle size of 2nm. The results establish the dominant role played by liquid layering in the enhanced thermal conductivity of nanofluids at the low particle sizes used. Contrary to the previous findings, the molecular dynamics simulations also predict a strong dependence of the liquid layer thickness on the particle size in the case of small particles.

scholarly journals Improved Heat Transfer in Guar Gel Composites Reinforced with Randomly Distributed Glass Microspheres

2021 ◽  
Author(s):  
Ruifeng CAO ◽  
Taotao WANG ◽  
Yuxuan ZHANG ◽  
Hui WANG
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Particle Size ◽  
Composite Materials ◽  
Effective Thermal Conductivity ◽  
Volume Fraction ◽  
Particle Volume Fraction ◽  
Glass Microspheres ◽  
Particle Volume ◽  
Number Of Particles

Improved heat transfer in composites consisting of guar gel matrix and randomly distributed glass microspheres is extensively studied to predict the effective thermal conductivity of composites using the finite element method. In the study, the proper and probabilistic three-dimensional random distribution of microspheres in the continuous matrix is automatically generated by a simple and efficient random sequential adsorption algorithm which is developed by considering the correlation of three factors including particle size, number of particles, and particle volume fraction controlling the geometric configuration of random packing. Then the dependences of the effective thermal conductivity of composite materials on some important factors are investigated numerically, including the particle volume fraction, the particle spatial distribution, the number of particles, the nonuniformity of particle size, the particle dispersion morphology and the thermal conductivity contrast between particle and matrix. The related numerical results are compared with theoretical predictions and available experimental results to assess the validity of the numerical model. These results can provide good guidance for the design of advanced microsphere reinforced composite materials.

Stability of Zinc Oxide Nanofluids Prepared with Aggregated Nanocrystalline Powders

2008 ◽  
Vol 8 (12) ◽  
pp. 6361-6366
Author(s):  
J. P. Leonard ◽  
S. J. Chung ◽  
I. Nettleship ◽  
Y. Soong ◽  
D. V. Martello ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Particle Size ◽  
Zinc Oxide ◽  
Brownian Motion ◽  
Preparation Method ◽  
Volume Fraction ◽  
High Volume ◽  
Nanocrystalline Powders ◽  
Zno Powder ◽  
20 Nm

Aqueous zinc oxide (ZnO) suspensions were prepared using a two-step preparation method in which an aggregated nanocrystalline ZnO powder was dispersed in water using a polyelectrolyte. The fluid showed anomalously high thermal conductivity when compared with the Maxwell and Hamilton-Crosser predictions. However, analysis of the particle size distribution showed that the fluid contained aggregated 20 nm crystallites of ZnO with a high volume fraction of particles larger than 100 nm. Sedimentation experiments revealed that particles settled out of the stationary fluid over times ranging from 0.1 hours to well over 10,000 hours. The size of the particles remaining in suspension agreed well with predictions made using Stoke's law, suggesting flocculation was not occurring in the fluids. Finally, a new concept of nanofluid stability is introduced based on the height of the fluid, sedimentation, Brownian motion and the kinetic energy of the particles.

Research of Thermal Conductivity and Tensile Strength of Carbon Black-Filled Nature Rubber

2009 ◽  
Vol 87-88 ◽  
pp. 200-205 ◽  
Author(s):  
Yan He ◽  
Zhong Yin ◽  
Lian Xiang Ma ◽  
Jun Ping Song
Keyword(s):  
Thermal Conductivity ◽  
Particle Size ◽  
Tensile Strength ◽  
Carbon Black ◽  
Volume Fraction ◽  
Carbon Black Particle ◽  
Black Particle ◽  
The Difference ◽  
Thermal Conductivities

Through measuring the thermal conductivities and tensile strength of nature rubbers filled with carbon black and comparing with each other, it is shown that the difference of carbon black particle size and the structure affects on the thermal conductivity and tensile strength of nature rubber. Thermal conductivities of carbon black-filled nature rubber are enhanced with the increase of volume fraction of filler; tensile strength of composite increases first and then decreases with the increase of carbon black volume fraction.

Computational Design and Development of Alumina-Nickel Droplet Composites

2016 ◽  
Author(s):  
S. Sohail Akhtar ◽  
A. F. M. Arif ◽  
M. U. Siddiqui ◽  
Kabeer Raza ◽  
L. Taiwo Kareem ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Particle Size ◽  
Thermal Expansion ◽  
Thermal Expansion Coefficient ◽  
Expansion Coefficient ◽  
Volume Fraction ◽  
Matrix Material ◽  
Microstructural Analysis ◽  
Computational Design ◽  
Minimum Size

Computational design for property management of composite materials offers a cost sensitive alternate approach in order to understand the mechanisms involved in the thermal and structural behavior of material under various combinations of inclusions and matrix material. The present study is concerned with analyzing the elasto-plastic and thermal behavior of Al2O3-Ni droplet composites using a mean field homogenization and effective medium approximation (EMA) using an in-house code. Our material design approach relies on a method for predicting potential optimum thermal and structural properties for Al2O3-Ni composites by considering the effect of inclusion orientation, volume, size, thermal interface resistance, percolation and porosity. The primary goal for designing such alumina-based composites is to have enhanced thermal conductivity for effective heat dissipation and spreading capabilities. At the same time, other functional properties like thermal expansion coefficient, elastic modulus, and electrical resistivity have to be maintained or enhanced. The optimum volume fraction was found to occur between 15 and 20 vol. %Ni while the average nickel particle size of 5 μm was found a minimum size that will enhance the thermal conductivity. The Young’s modulus was found decreasing as the volume fraction of nickel increases, which would result in enhanced fracture toughness. Electrical conductivity was found to be greatly affected by the percolation phenomenon in the designed range of volume fraction minimum particle size. As a validation, Al2O3 composites with 10% and 15% volume fraction Ni and droplet size of 18 μm are developed using spark Plasma Sintering process. Thermal conductivity and thermal expansion coefficient of the samples are measured to complement the computational design. Microstructural analysis of the sintered samples was also studied using optical microscope to study the morphology of the developed samples. It was found that the present computational design tool was accurate enough in predicting the desired properties of Al2O3-Ni composites.

Effective thermal conductivity of silicone/phosphor composites

2011 ◽  
Vol 45 (23) ◽  
pp. 2465-2473 ◽  
Author(s):  
Qin Zhang ◽  
Zhihua Pi ◽  
Mingxiang Chen ◽  
Xiaobing Luo ◽  
Ling Xu ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Particle Size ◽  
Effective Thermal Conductivity ◽  
Volume Fraction ◽  
Numerical Study ◽  
Element Model ◽  
Interfacial Thermal Resistance ◽  
Conductivity Measurements ◽  
The Monte Carlo Method ◽  
Random Particle

The effective thermal conductivity of silicone/phosphor composites is studied experimentally and numerically. Thermal conductivity measurements are conducted from 30°C to 150°C for the composites with phosphor volume fraction up to 40%. In the numerical study, a finite element model with empirical particle size distribution and random particle position is constructed using a probability density function and the Monte Carlo method, and the interfacial thermal resistance layer between phases also introduced in the model. The results indicate that when phosphor concentration is below 25 vol.%, the conductivity of the composite increases slightly with either phosphor volume fraction or temperature, and the Kapitza radius of the composite is 0.8 µm. When phosphor concentration is above 25 vol.%, the increase of conductivity correlates positively with phosphor volume fraction significantly but negatively with the temperature, and the Kapitza radius is 0.032 µm.

scholarly journals Finite Element Investigation of the Influence of SiC Particle Distribution on Diamond Cutting of SiCp/Al Composites

2020 ◽  
Vol 3 (4) ◽  
pp. 251-259
Author(s):  
Shijin Lu ◽  
Zengqiang Li ◽  
Junjie Zhang ◽  
Jianguo Zhang ◽  
Xiaohui Wang ◽  
...  
Keyword(s):  
Particle Size ◽  
Finite Element ◽  
Particle Distribution ◽  
Volume Fraction ◽  
Model Simulation ◽  
Orthogonal Cutting ◽  
Strong Impact ◽  
Particle Deformation ◽  
Metal Composites ◽  
Particulate Reinforced

AbstractCharacteristics of internal microstructures have a strong impact on the properties of particulate reinforced metal composites. In the present work, we perform finite element simulations to elucidate fundamental mechanisms involved in the ultra-precision orthogonal cutting of aluminum-based silicon carbide composites (SiCp/Al), with an emphasis on the influence of particle distribution characteristic. The SiCp/Al composite with a particle volume fraction of 25 vol% and a mean particle size of 10 μm consists of randomly distributed polygon-shaped SiC particles, the elastic deformation and brittle failure of which are described by the brittle cracking model. Simulation results reveal that in addition to metal matrix tearing, cutting-induced particle deformation in terms of dislodging, debonding, and cracking plays an important role in the microscopic deformation and correlated machining force variation and machined surface integrity. It is found that the standard deviation of particle size to the mean value has a strong influence on the machinability of microscopic particle–tool edge interactions and macroscopically observed machining results. The present work provides a guideline for the rational synthesis of particulate-reinforced metal composites with high machinability.

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