scholarly journals Microstructures and Properties of Cu-rGO Composites Prepared by Microwave Sintering

Materials ◽  
2021 ◽  
Vol 14 (17) ◽  
pp. 4899
Author(s):  
Xuebin Chen ◽  
Lei Zhao ◽  
Liwu Jiang ◽  
Haizhou Wang
Keyword(s):  
Thermal Conductivity ◽  
Electrical Conductivity ◽  
Graphene Oxide ◽  
Ball Milling ◽  
Composite Powder ◽  
Microwave Sintering ◽  
Pure Copper ◽  
Argon Atmosphere ◽  
Copper Particles ◽  
Scanning Electron

This study investigated the effects of microwave sintering on the microstructures and properties of copper-rGO composites. Graphene oxide was coated onto copper particles by wet ball milling, and copper-rGO composites were formed upon microwave sintering in an argon atmosphere. Scanning electron microscopy was then used to observe the mixing in the ball-milled composite powder, and the morphology of the bulk composite after microwave sintering. Raman spectra revealed how graphene oxide changed with ball milling and with microwave sintering. The microhardness, electrical conductivity, and thermal conductivity of the composite were also measured. The results showed that graphene oxide and copper particles were well combined and uniformly distributed after wet ball milling. The overall microhardness of microwave-sintered samples was 81.1 HV, which was 14.2% greater than that of pure copper (71 HV). After microwave sintering, the microhardness of the samples in areas showing copper oxide precipitates with eutectic structures was 89.5 HV, whereas the microhardness of the precipitate-free areas was 70.6 HV. The electrical conductivity of the samples was 87.10 IACS%, and their thermal conductivity was 391.62 W·m−1·K−1.

Experimental Investigation on Thermal Conduction of Carbon Nanotubes Reinforced Copper Matrix Composites

2014 ◽  
Vol 564 ◽  
pp. 455-460
Author(s):  
Faiz Ahmad ◽  
Muhammad Aslam ◽  
M. Rafi Raza ◽  
Ali S. Muhsan ◽  
M.irfan Shirazi
Keyword(s):  
Thermal Conductivity ◽  
Carbon Nanotubes ◽  
Sintered Density ◽  
Pure Copper ◽  
Copper Particle ◽  
Copper Matrix ◽  
Powder Metallurgy Method ◽  
Matrix Composites ◽  
Electron Microscopic ◽  
Scanning Electron

The performance of the micro-chip is affected by overheating and hence reduces the efficiency of electronic devices. The development of high thermal conductivity material can solve problems associated with dissipation of heat from the micro-chips. Thermal conductivity for carbon nanotubes (CNTs) are in the ranges of 1200-3000 W/moK which considered as the best candidate material for heat sink applications. This research investigates the fabrication of CNTs reinforced copper composites using powder metallurgy method. Copper powder and CNTs were ball milled to prepare mixtures and compacted at 600 MPa to fabricate test samples. The compacted test samples were sintered in argon atmosphere at 850oC. Sintered density of CNTs/Cu composites was measured and compared with theoretical density. Density data showed that 98% sintered density was achieved. Optical and scanning electron microscopic (SEM) examination of sintered compacts showed good grain growth, however porosity was also noted in sintered samples. Field emission scanning electron microscopy (FESEM) showed well dispersion of CNTs in copper matrix and interfacial bonding between copper particle and CNTs. In this experiment, the addition of 2 % vol. CNTs in copper matrix showed 9% increase in thermal conductivity approximately compared to thesintered pure copper.

Structural Evaluation of Ti-22.2Si-11.1B Powders Milled with PCA Addition

2008 ◽  
Vol 591-593 ◽  
pp. 147-153
Author(s):  
Gilbert Silva ◽  
Erika Coaglia Trindade Ramos ◽  
N.S. da Silva ◽  
Alfeu Saraiva Ramos
Keyword(s):  
Electron Microscopy ◽  
Ball Milling ◽  
Ball Mill ◽  
Milling Process ◽  
Argon Atmosphere ◽  
X Ray Diffraction ◽  
X Ray ◽  
Structural Evaluation ◽  
Equilibrium Structures ◽  
Scanning Electron

A large amount of the Ti6Si2B compound can be formed by mechanical alloying and subsequent heat treatment from the elemental Ti-22.2at%Si-11.1at%B powder mixture, but the yield powder after ball milling is reduced due to an excessive agglomeration of ductile particles on the balls and vial surfaces. This work reports on the structural evaluation of Ti-22.2at%Si-11.1at%B powders milled with PCA addition, varying its amount between 1 and 2 wt-%. The milling process was carried out in a planetary ball mill under argon atmosphere, and the milled powders were then heated at 1200oC for 1h under Ar atmosphere in order to obtain equilibrium structures. Samples were characterized by X-ray diffraction, scanning electron microscopy, and thermal analysis. Results revealed that the PCA addition reduced the excessive agglomeration during the ball milling of Ti-22.2at-%Si-11.1at-%B powders. After heating at 1200oC for 1h, the Ti5Si3, Ti3O and/or Ti2C phases were preferentially formed in Ti-22.2at%Si-11.1at%B powders milled with PCA addition, and the Ti6Si2B formation was inhibited.

USE OF NANOFLUIDS BASED ON CARBON NANOPARTICLES TO DISPLACE OIL FROM THE POROUS MEDIUM MODEL

2020 ◽  
Vol 6 (4) ◽  
pp. 141-157
Author(s):  
Yuri V. Pakharukov ◽  
Farid K. Shabiev ◽  
Ruslan F. Safargaliev ◽  
Boris S. Yezdin ◽  
Valery V. Kalyada
Keyword(s):  
Electron Microscopy ◽  
Thermal Conductivity ◽  
Electrical Conductivity ◽  
Scanning Electron Microscopy ◽  
Porous Medium ◽  
Synergistic Effect ◽  
Transition Region ◽  
Dimensional Structure ◽  
Hybrid Nanofluids ◽  
Scanning Electron

Graphene, due to its two-dimensional structure, has some unique properties. For example, the thermal conductivity and electrical conductivity of graphene are an order of magnitude higher than the thermal conductivity and electrical conductivity of copper. For this reason, graphene-based nanofluids are now used in many industries. Due to the effect of self-organization of graphene nanoparticles with hydrocarbon molecules, the use of graphene has become possible in the oil industry. Graphene-based nanofluids are used as a displacement fluid to increase the oil recovery coefficient. The displacing ability of graphene-based nanofluids is concentration dependent. An increase in the concentration of nanoparticles entails an increase in viscosity, which negatively affects the performance characteristics of the nanofluid. This problem is partially solved due to the synergistic effect, hybrid nanofluids consisting of nanoparticles of graphene and metals or carbides enhance the displacing ability. Using atomic force microscopy, scanning electron microscopy and molecular modelling methods, this work has studied the formation of supramolecular structures that form a transition region at the oil-nanofluid interface with low surface tension as a result of a synergistic effect in the interaction of graphene planar nanoparticles and silicon carbide nanoparticles covered with graphene layers (Core-shell). The model experiments on a Hele-Shaw cell have shown that in a porous medium, such hybrid nanofluids have a high displacement ability of residual oil. At the same time, the oil — nanofluid interface remains stable, without the formation of viscous fingers. During the study by scanning electron microscopy, a transition region was observed, in the structuring of which the nanoparticles were directly involved. The displacement efficiency of a hybrid nonofluid depends on the concentration of nanoparticles and their interaction.

scholarly journals Graphene oxide-loaded shortening as an environmentally friendly heat transfer fluid with high thermal conductivity

2017 ◽  
Vol 21 (5) ◽  
pp. 2247-2254
Author(s):  
Thammasit Vongsetskul ◽  
Peeranut Prakulpawong ◽  
Panmanas Sirisomboon ◽  
Jonggol Tantirungrotechai ◽  
Chanasuk Surasit ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Electron Microscopy ◽  
Thermal Conductivity ◽  
Graphene Oxide ◽  
Environmentally Friendly ◽  
High Thermal Conductivity ◽  
Chemical Degradation ◽  
Heat Transfer Fluid ◽  
Increasing Temperature ◽  
Scanning Electron

Graphene oxide-loaded shortening (GOS), an environmentally friendly heat transfer fluid with high thermal conductivity, was successfully prepared by mixing graphene oxide (GO) with a shortening. Scanning electron microscopy revealed that GO particles, prepared by the modified Hummer?s method, dispersed well in the shortening. In addition, the latent heat of GOS decreased while their viscosity and thermal conductivity increased with increasing the amount of loaded GO. The thermal conductivity of the GOS with 4% GO was higher than that of pure shortening of ca. three times, from 0.1751 to 0.6022 W/mK, and increased with increasing temperature. The GOS started to be degraded at ca. 360?C. After being heated and cooled at 100?C for 100 cycles, its viscosity slightly decreased and no chemical degradation was observed. Therefore, the prepared GOS is potentially used as environmentally friendly heat transfer fluid at high temperature.

Flexible electrothermal polymer film based on reduced graphene oxide–water polyurethane

2020 ◽  
Vol 34 (25) ◽  
pp. 2050265 ◽  
Author(s):  
Ke Wang ◽  
Zhimin Zhou ◽  
Yuehui Wang
Keyword(s):  
Thermal Conductivity ◽  
Electrical Conductivity ◽  
Graphene Oxide ◽  
Composite Film ◽  
Reduced Graphene Oxide ◽  
Rapid Heating ◽  
Tape Casting ◽  
Composite Films ◽  
Low Input ◽  
Reduced Graphene

In this paper, waterborne polyurethane (WPU) conductive films incorporated with reduced graphene oxide (RGO) as conductive fillers were prepared by solution blending and tape casting method. The electrical conductivity, thermal conductivity and microstructures of the composite films were systematically investigated. The experimental results demonstrate that the electrical conductivity and thermal conductivity of the RGO–WPU composite films first increased then decreased with the increase of the RGO content. The resistivity of composite film with 7% RGO reaches to the smallest that is about [Formula: see text], and the thermal conductivity of the composite film with 7% graphene was about 0.29 W.m.K[Formula: see text], which an increase of 70% compared with pure WPU. The electrical conductivity of the composite film decreased with the increase of the original concentration of WPU solution and thickness of the composite film. As film heater, the composite film displayed effective and rapid heating at low input voltages owing to the good conductivity. With an input voltage was in the range of 10–24 V, the film took less than 30s to reach a steady-state temperature, demonstrating the fast response of the composite film heater and suitable for applications in the field of the fast temperature switching with low input voltages as flexible electrothermal heater.

Improvement of Electrical Conductivity of Polyurethane/Polypyrrole Blends by Graphene

2020 ◽  
Vol 831 ◽  
pp. 122-126
Author(s):  
Pafun Janpoung ◽  
Prasit Pattananuwat ◽  
Pranut Potiyaraj
Keyword(s):  
Thermal Stability ◽  
Electrical Conductivity ◽  
Fourier Transform ◽  
Graphene Oxide ◽  
Controlled Synthesis ◽  
Sem Images ◽  
Thermogravimetric Analyzer ◽  
Solution Blending ◽  
Blending Process ◽  
Scanning Electron

Polyurethane (TPU)/polypyrrole (PPy) blends were successfully prepared by the solution blending process with different contents of reduce graphene oxide (rGO). The controlled synthesis of PPy/rGO composites was reported by varying graphene contents of 10, 20, 30 and 40% w/v. Fourier transform infrared (FTIR) and Scanning electron microscope (SEM) were used to characterize their structures and morphologies. The SEM images show the growing of PPy along the surface of graphene. FTIR illustrated that the PPy/rGO composites were in the doped state. The electrical conductivity of PPy/rGO composites with the concentration of graphene at 40% was about 30 times higher than that of pure PPy. Thermogravimetric analyzer (TGA) thermograms indicated that the PPy/rGO composites have better thermal stability than pure PPy.

Microwave sintering and properties of AlN/TiB2 composites

2003 ◽  
Vol 18 (1) ◽  
pp. 66-76 ◽  
Author(s):  
Geng-fu Xu ◽  
Yuval Carmel ◽  
Tayo Olorunyolemi ◽  
Isabel K. Lloyd ◽  
Otto C. Wilson
Keyword(s):  
Thermal Conductivity ◽  
Dielectric Loss ◽  
Microwave Sintering ◽  
Nitrogen Atmosphere ◽  
Argon Atmosphere ◽  
High Thermal Conductivity ◽  
Theoretical Density ◽  
Promising Material ◽  
Densification Behavior ◽  
Structural Applications

The effect of TiB2 on the densification behavior and properties of microwave-sintered AlN/TiB2 ceramic was investigated. The densification of the composite was significantly retarded in nitrogen atmosphere due to strong nitridation of TiB2 compared to sintering in argon atmosphere. The densities of the AlN/TiB2 composites containing different amounts of TiB2 all reached 99% of the theoretical density during 2 h of sintering at 1850 and 1900 °C. Microstructure analysis revealed that the TiB2 particles were dispersed in the AlN matrix while AlN grains retained its contiguity. This microstructure led to a composite with superior properties; thermal conductivity as high as 149 W/(m K) was achieved. The microwave sintered composites are harder and tougher than pure AlN. Microwave-sintered AlN/TiB2 composite is a promising material for structural applications in which high thermal conductivity and controlled dielectric loss are important.

Effect of the Ball Milling on the Microstructure and Mechanical Properties of AlN/Cu Composite

2015 ◽  
Vol 816 ◽  
pp. 15-20
Author(s):  
Qian Yu ◽  
Mei Hui Song ◽  
Yan Li ◽  
Xiao Chen Zhang
Keyword(s):  
Thermal Conductivity ◽  
Electrical Conductivity ◽  
Particle Size ◽  
Particle Size Distribution ◽  
Size Distribution ◽  
Ball Milling ◽  
Bending Strength ◽  
Rotation Speed ◽  
Mixing Time ◽  
Composite Powders

AlN/Cu composite powder was prepared by ball milling method. Laser particle size analyzer, X-ray diffraction and scanning electron microscopy analysis were performed to study AlN/Cu composite powders. The effects of rotation speed, mixing time, and ball to powder weight ratio (BPR) on the particle size distribution, composition, and morphology were investigated. Results showed that the best ball milling parameters were the rotation speed of 200r/min, mixing time of 6 hours and BPR 10:1. In this best condition, AlN/Cu composite powders would be obtained with optimum particle size distribution and morphology. Then composite powders were pressed at 500MPa and sintered at 1000°C in N2atmosphere. Finally, the composite with an AlN content of 33wt% showed the bending strength of 370MPa, Vikers hardness HV154, thermal conductivity of 182.7W/m°C and electrical conductivity of 3.08MS/m. However, the composite with an AlN content of 25wt% showed the bending strength of 329MPa, Vikers hardness HV122, thermal conductivity of 195W/m°C and electrical conductivity of 6.54MS/m.

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