scholarly journals Preparation of W-Plated Diamond and Improvement of Thermal Conductivity of Diamond-WC-Cu Composite

Metals ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 437
Author(s):  
Xulei Wang ◽  
Xinbo He ◽  
Zhiyang Xu ◽  
Xuanhui Qu
Keyword(s):  
Thermal Conductivity ◽  
Theoretical Prediction ◽  
Volume Fraction ◽  
Tungsten Coating ◽  
Pressure Infiltration ◽  
Average Value ◽  
Interface Thermal Resistance ◽  
Composite Forming ◽  
Dem Model ◽  
Sintering Method

The tungsten (W)-plated diamond process was explored and optimized. A dense and uniform tungsten coating with a thickness of 900 nm was successfully prepared by the powder covering sintering method. The Diamond-WC-Cu composite with high density and high thermal conductivity were successfully prepared by cyclic vacuum pressure infiltration. The microstructure and composition of the W-plated diamond particles were analyzed. The effect of tungsten coating on the microstructure and thermal conductivity of the Diamond-WC-Cu composite was investigated. After calculation, the interface thermal resistance of the composite forming the tungsten carbide transition layer is 2.11 × 10−8 m2∙K∙W−1. The thermal conductivity average value of the Diamond-WC-Cu composite with a diamond volume fraction of 60% reaches 874 W∙m−1∙K−1, which is close to the theoretical prediction value of Hasselman-Johnson (H-J) model and differential effective medium (DEM) model. Moreover, the Maxwell-Eucken (M-E) model, H-J model, and DEM model were used to evaluate the thermal conductivity of the Diamond-WC-Cu composite.

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.

Properties of New TiC/TiB2/Fe-Al Cermet Alloy

2010 ◽  
Vol 638-642 ◽  
pp. 2138-2141 ◽  
Author(s):  
Hiroyuki Nakayama ◽  
Shuji Tada ◽  
Masashi Mikami ◽  
Kimihiro Ozaki ◽  
Keizo Kobayashi
Keyword(s):  
Thermal Conductivity ◽  
Intermetallic Compound ◽  
Mechanical Milling ◽  
Volume Fraction ◽  
Pulsed Current ◽  
Sintered Compact ◽  
High Relative Density ◽  
Sintering Method ◽  
Sintered Materials ◽  
Cermet Alloy

Effect of TiB2 substitution on thermal conductivity and hardness in TiC / Fe-Al cermets was investigated. The (70-x)TiC / xTiB2 / 26Fe-4Al mass % cermets were fabricated by mechanical milling and subsequent pulsed current sintering method. The high relative density compacts was formed by sintering at 1423 K under 25 MPa for 60 s. The sintered materials were mainly composed of TiC, TiB2 and Fe-Al intermetallic compound. In addition, small amounts of Fe2B surrounding TiB2 were formed. The thermal conductivity of the sintered compact lineally increased with increasing TiB2 volume fraction. However, the hardness of the sintered compacts of x = 20 – 40 were higher than that of x = 0. Therefore, the substitution of TiC to TiB2 in the TiC / Fe-Al based cermet is effective to improve the thermal conductivity without the degradation of hardness.

Diamond-Based Metal Matrix Composites for Thermal Management Made by Liquid Metal Infiltration — Potential and Limits

2008 ◽  
Vol 59 ◽  
pp. 111-115 ◽  
Author(s):  
Ludger Weber ◽  
Reza Tavangar
Keyword(s):  
Thermal Conductivity ◽  
Metal Matrix Composites ◽  
Metal Matrix ◽  
Room Temperature ◽  
Volume Fraction ◽  
Coefficient Of Thermal Expansion ◽  
Diamond Powder ◽  
Matrix Composites ◽  
Pressure Infiltration ◽  
The One

Diamond-based metal matrix composites have been made based on pure Al and eutectic Ag-3Si alloy by gas pressure infiltration into diamond powder beds with the aim to maximize thermal conductivity and to explore the range of coefficient of thermal expansion (CTE) that can be covered. The resulting composites covered roughly the range between 60 and 75 vol-% of diamond content. For the Al-based composites a maximum thermal conductivity at room temperature of 7.6 W/cmK is found while for the Ag-3Si based composites an unprecedented value of 9.7 W/cmK was achieved. The CTE at room temperature varied as a function of the diamond volume fraction between 3.3 and 7.0 ppm/K and 3.1 and 5.7 ppm/K for the Al-based and the Ag-3Si-based composites, respectively. The CTE was further found to vary quite significantly with temperature for the Al-based composites while the variation with temperature was less pronounced for the Ag-3Si-based composites. The results are compared with prediction by analytical modeling using the differential effective medium scheme for thermal conductivity and the Schapery bounds for the CTE. For the thermal conductivity good agreement is found while for the CTE a transition of the experimental data from Schapery’s upper to Schapery’s lower bound is observed as volume fraction increases. While the thermophysical properties are quite satisfactory, there is a trade-off to be made in these materials between high thermal conductivity and low CTE on the one side and surface quality and machinability on the other.

Alumina/Aluminum Composite Fabricated by Freeze and Dry Process with Water-Soluble Polymer Slurry

2005 ◽  
Vol 486-487 ◽  
pp. 329-332
Author(s):  
M. Nakata ◽  
Katsuaki Suganuma
Keyword(s):  
Thermal Conductivity ◽  
Volume Fraction ◽  
Coefficient Of Thermal Expansion ◽  
Porous Ceramics ◽  
Water Soluble ◽  
Aluminum Composite ◽  
Water Soluble Polymer ◽  
Pressure Infiltration ◽  
Dry Process ◽  
Polymer Slurry

To clarify the effects of parameters of porous ceramics form on the characteristics of composites fabricated by high-pressure infiltration, Alumina forms with different porosity (15~70vol %) and pore morphology were fabricated by Freeze and Dry Process and Partial Sintering Process. Alumina/aluminum composites were made by the squeeze casting. The composites contained the different volume fraction of aluminum depending on the initial porosity of the ceramics form. The coefficient of thermal expansion (CTE) and thermal conductivity of composites were measured. The results indicated clearly that variation of the structure of porous ceramics form fairly affected CTE but the effects on thermal conductivity were small.

Interface Thermal Resistance and Length Effect on Thermal Conductivitiy of SWNT Bundles

2012 ◽  
Author(s):  
Kasim Toprak ◽  
Yildiz Bayazitoglu
Keyword(s):  
Thermal Conductivity ◽  
Thermal Resistance ◽  
Effective Thermal Conductivity ◽  
Volume Fraction ◽  
Water Medium ◽  
Interface Thermal Resistance ◽  
Contact Points ◽  
Length Fraction ◽  
Vertically Aligned ◽  
Packing System

Using different calculations and measurement methods, the results for the thermal conductivity in a single wall carbon nanotube (SWNT) are compared. Then, the interface thermal resistance effects on the effective thermal conductivity of multiple SWNTs in a hexagonal packing system submerged in oil, air, and water are studied. The results show that as the interface thermal resistance increases, the effective thermal conductivity decreases. Moreover, length, length fraction, and volume fraction effects on the thermal conductivity of the system submerged in a water medium are approximated by including the interface thermal resistances of the nanotube-matrix and nanotube-nanotube. The systems’ length ranged between 500–3000 nm. The created models contain either vertically aligned or non-straight nanotubes. Non-straight nanotubes systems make one or two contact points with other nanotubes. These contact points’ location vary based on the length ratio known as the length fraction. It is found that the effective thermal conductivity of the SWNT bundle has the highest value when they are uniformly aligned and dispersed without contact. As the density and length of the SWNTs increase, the effective thermal conductivity of the bundle system also increases.

A Study of Some Mechanical and Physical Properties for Palm Fiber/Polyester Composite

2020 ◽  
Vol 38 (3B) ◽  
pp. 104-114
Author(s):  
Samah M. Hussein
Keyword(s):  
Mechanical Properties ◽  
Thermal Conductivity ◽  
Dielectric Constant ◽  
Date Palm ◽  
Volume Fraction ◽  
Unsaturated Polyester ◽  
Dielectric Strength ◽  
Palm Fiber ◽  
Mechanical And Physical Properties ◽  
Polyester Composite

This research has been done by reinforcing the matrix (unsaturated polyester) resin with natural material (date palm fiber (DPF)). The fibers were exposure to alkali treatment before reinforcement. The samples have been prepared by using hand lay-up technique with fiber volume fraction of (10%, 20% and 30%). After preparation of the mechanical and physical properties have been studied such as, compression, flexural, impact strength, thermal conductivity, Dielectric constant and dielectric strength. The polyester composite reinforced with date palm fiber at volume fraction (10% and 20%) has good mechanical properties rather than pure unsaturated polyester material, while the composite reinforced with 30% Vf present poor mechanical properties. Thermal conductivity results indicated insulator composite behavior. The effect of present fiber polar group induces of decreasing in dielectric strength, and increasing dielectric constant. The reinforcement composite 20% Vf showed the best results in mechanical, thermal and electrical properties.

Study of the boundary layer heat transfer of nanofluids over a stretching sheet: Passive control of nanoparticles at the surface

2015 ◽  
Vol 93 (7) ◽  
pp. 725-733 ◽  
Author(s):  
M. Ghalambaz ◽  
E. Izadpanahi ◽  
A. Noghrehabadi ◽  
A. Chamkha
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Boundary Layer ◽  
Nusselt Number ◽  
Heat Transfer Enhancement ◽  
Base Fluid ◽  
Stretching Sheet ◽  
Volume Fraction ◽  
Enhancement Ratio ◽  
Transfer Enhancement

The boundary layer heat and mass transfer of nanofluids over an isothermal stretching sheet is analyzed using a drift-flux model. The relative slip velocity between the nanoparticles and the base fluid is taken into account. The nanoparticles’ volume fractions at the surface of the sheet are considered to be adjusted passively. The thermal conductivity and the dynamic viscosity of the nanofluid are considered as functions of the local volume fraction of the nanoparticles. A non-dimensional parameter, heat transfer enhancement ratio, is introduced, which shows the alteration of the thermal convective coefficient of the nanofluid compared to the base fluid. The governing partial differential equations are reduced into a set of nonlinear ordinary differential equations using appropriate similarity transformations and then solved numerically using the fourth-order Runge–Kutta and Newton–Raphson methods along with the shooting technique. The effects of six non-dimensional parameters, namely, the Prandtl number of the base fluid Prbf, Lewis number Le, Brownian motion parameter Nb, thermophoresis parameter Nt, variable thermal conductivity parameter Nc and the variable viscosity parameter Nv, on the velocity, temperature, and concentration profiles as well as the reduced Nusselt number and the enhancement ratio are investigated. Finally, case studies for Al2O3 and Cu nanoparticles dispersed in water are performed. It is found that increases in the ambient values of the nanoparticles volume fraction cause decreases in both the dimensionless shear stress f″(0) and the reduced Nusselt number Nur. Furthermore, an augmentation of the ambient value of the volume fraction of nanoparticles results in an increase the heat transfer enhancement ratio hnf/hbf. Therefore, using nanoparticles produces heat transfer enhancement from the sheet.

Pool Boiling Characteristics of Metallic Nanofluids

2011 ◽  
Vol 133 (11) ◽  
Author(s):  
K. Hari Krishna ◽  
Harish Ganapathy ◽  
G. Sateesh ◽  
Sarit K. Das
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Boiling Heat Transfer ◽  
Volume Fraction ◽  
Pool Boiling ◽  
Heat Fluxes ◽  
Solid Particles ◽  
Heater Surface ◽  
Heat Transfer Characteristics ◽  
Transfer Characteristics

Nanofluids, solid-liquid suspensions with solid particles of size of the order of few nanometers, have created interest in many researchers because of their enhancement in thermal conductivity and convective heat transfer characteristics. Many studies have been done on the pool boiling characteristics of nanofluids, most of which have been with nanofluids containing oxide nanoparticles owing to the ease in their preparation. Deterioration in boiling heat transfer was observed in some studies. Metallic nanofluids having metal nanoparticles, which are known for their good heat transfer characteristics in bulk regime, reported drastic enhancement in thermal conductivity. The present paper investigates into the pool boiling characteristics of metallic nanofluids, in particular of Cu-H2O nanofluids, on flat copper heater surface. The results indicate that at comparatively low heat fluxes, there is deterioration in boiling heat transfer with very low particle volume fraction of 0.01%, and it increases with volume fraction and shows enhancement with 0.1%. However, the behavior is the other way around at high heat fluxes. The enhancement at low heat fluxes is due to the fact that the effect of formation of thin sorption layer of nanoparticles on heater surface, which causes deterioration by trapping the nucleation sites, is overshadowed by the increase in microlayer evaporation, which is due to enhancement in thermal conductivity. Same trend has been observed with variation in the surface roughness of the heater as well.

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