scholarly journals Effects of Functionalization in Different Conditions and Ball Milling on the Dispersion and Thermal and Electrical Conductivity of MWCNTs in Aqueous Solution

Nanomaterials ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 1323
Author(s):  
Baasandulam Tserengombo ◽  
Hyomin Jeong ◽  
Erdenechimeg Dolgor ◽  
Antonio Delgado ◽  
Sedong Kim
Keyword(s):  
Thermal Conductivity ◽  
Electrical Conductivity ◽  
Sodium Hydroxide ◽  
Ball Milling ◽  
Alkaline Treatment ◽  
Milling Process ◽  
Potassium Persulfate ◽  
Dispersion Characteristics ◽  
Multiwalled Carbon ◽  
Structural Investigations

In this work, the effects of a functionalization method involving different conditions and milling processes on the dispersion and thermal and electrical conductivity of multiwalled carbon nanotubes were studied. The surfaces of MWCNTs were modified using a mixture of sulfuric and nitric acid as an acid treatment and potassium persulfate and sodium hydroxide as an alkaline treatment to achieve more hydrophilic MWCNTs. The morphological and structural investigations were carried out using transmission electron microscopy and Fourier transform infrared spectroscopy. Furthermore, the dispersion characteristics and thermal and electrical conductivity of the as-prepared water-based nanofluids were measured. As a result, the dispersion characteristics revealed that the best dispersion and stability results were obtained for alkaline-treated MWCNTs using potassium persulfate and sodium hydroxide. The thermophysical study using a thermal conductivity analyzer exhibited that the thermal conductivity of the pristine MWCNT nanofluid (0.1 wt%) was enhanced from 603.5 to 610.4 mW/m·K and the electrical conductivity of the raw MWCNT nanofluid was increased from 16.2 to 125.8 μS/cm at 25 °C after alkaline treatment and milling processes, which were performed using planetary ball milling. Regarding the overall results, the milling process and mild alkaline oxidation process are more environmentally friendly, effective, and convenient for the functionalization of CNTs, without requiring any organic solvents or strong acids.

Synthesis and Thermoelectric Properties of WO3/Cu2SnSe3 Composites

2018 ◽  
Vol 913 ◽  
pp. 811-817 ◽  
Author(s):  
Di Wu ◽  
Ji Ai Ning ◽  
De Gang Zhao ◽  
Xue Zhen Wang ◽  
Na Liu
Keyword(s):  
Thermal Conductivity ◽  
Electrical Conductivity ◽  
Electrical Properties ◽  
Grain Boundary ◽  
Figure Of Merit ◽  
Milling Process ◽  
Thermoelectric Figure Of Merit ◽  
Thermoelectric Figure ◽  
Plasma Sintering ◽  
Spark Plasma

In this study, nanometer WO3 powder was uniformly dispersed into the Cu2SnSe3 powder by ball milling process, and the WO3/Cu2SnSe3 thermoelectric composite was prepared by spark plasma sintering (SPS). The results showed that the nano-WO3 particles were mainly distributed in the grain boundary of Cu2SnSe3 matrix, and the grain growth of Cu2SnSe3 was inhibited. The addition of nano-WO3 could enhance the electrical conductivity of Cu2SnSe3, and while the Seebeck coefficient increased slightly for the 0.4% WO3/Cu2SnSe3 composite. The thermal conductivity was not decreased until the content of WO3 exceeded 1.6%. The highest thermoelectric figure of merit ZT of 0.177 was achieved at 700 K for 0.4% WO3/Cu2SnSe3 composite. The enhancement of ZT value of WO3/Cu2SnSe3 thermoelectric material was mainly attributed to the improvement of the electrical properties.

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.

Water Based Multiwalled Carbon Nanotube Nanofluids With Optimized Thermal Conductivity

2009 ◽  
Author(s):  
Li Fei Chen ◽  
Huaqing Xie ◽  
Wei Yu ◽  
Yang Li
Keyword(s):  
Thermal Conductivity ◽  
Ball Milling ◽  
Volume Fraction ◽  
Free Water ◽  
Strong Acid ◽  
Multiwalled Carbon ◽  
Conductivity Enhancement ◽  
Water Based ◽  
Multi Walled Carbon Nanotubes ◽  
Walled Carbon Nanotubes

We report a method to prepare surfactant-free water based nanofluids containing multi-walled carbon nanotubes (CNTs). The as prepared CNTs with hard dispersibility, after being cut by mechanical ball-milling approach following strong acid treatment, can be directly dispersed into water. The thermal conductivity of the nanofluids is optimized by controlling the CNT length and straightness. It is realized by changed the ball-milling times. The thermal conductivity enhancement of water based CNT nanofluids with volume fraction of 1% attains 29.5% by controlling the CNT length and straightness when the temperature is 63.9°C.

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.

scholarly journals Comparative Characterization of Multiscale Carbon Fiber Composite with Long and Short MWCNTs at Higher Weight Fractions

2012 ◽  
Vol 2012 ◽  
pp. 1-9 ◽  
Author(s):  
Michael Zimmer ◽  
Qunfeng Cheng ◽  
Shu Li ◽  
James Brooks ◽  
Richard Liang ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Carbon Nanotubes ◽  
Electrical Conductivity ◽  
Carbon Fiber ◽  
Fiber Composite ◽  
Carbon Fiber Composite ◽  
Multiwalled Carbon ◽  
The Matrix ◽  
Carbon Fiber Reinforced Composites ◽  
Multi Walled Carbon Nanotubes

There are documented advantages to using carbon nanotubes (CNTs) in composites for various property enhancements. However, to date, only limited studies have been conducted on using of longer CNTs over 1 mm in length. This study used long multiwalled carbon nanotubes (LMWCNTs) and their longer extended networks to test multiple properties in thermal conductivity, electrical conductivity, mechanical strength, and modulus and then compared these properties to those of shorter multi-walled carbon nanotubes (SMWCNTs). For carbon fiber-reinforced composites, the longer graphite paths from LMWCNTs in the matrix were expected to improve all properties. The longer networks were expected to allow for more undisturbed phonon transportation to improve thermal conductivity. This in turn relates to improved electrical conductivity and better mechanical properties. However, results have shown that the LMWCNTs do not improve or decrease thermal conductivity, whereas the shorter MWCNTs provide mixed results. LMWCNTs did show improvements in electrical, mechanical, and physical properties, but compared to shorter MWCNTs, the results in other certain properties varied. This perplexing outcome resides in the functioning of the networks made by both the LMWCNTs and shorter MWCNTs.

Low Thermal Conductivity of Bulk Amorphous Si1−xGe x Containing Nano-Sized Crystalline Particles Synthesized by Ball-Milling Process

2018 ◽  
Vol 47 (6) ◽  
pp. 3260-3266 ◽  
Author(s):  
Omprakash Muthusamy ◽  
Shunsuke Nishino ◽  
Swapnil Ghodke ◽  
Manabu Inukai ◽  
Robert Sobota ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Ball Milling ◽  
Milling Process ◽  
Low Thermal Conductivity ◽  
Ball Milling Process

Electro-Mechanical and Thermal Properties of Multiwalled Carbon Nanotube Reinforced Alumina Composites

2008 ◽  
Vol 368-372 ◽  
pp. 701-703 ◽  
Author(s):  
Kaleem Ahmad ◽  
Wei Pan ◽  
Chun Lei Wan
Keyword(s):  
Mechanical Properties ◽  
Thermal Conductivity ◽  
Electrical Conductivity ◽  
Thermal Properties ◽  
Carbon Nanotube ◽  
Mechanical And Thermal Properties ◽  
Multiwalled Carbon ◽  
Plasma Sintering ◽  
Spark Plasma ◽  
Alumina Composites

Multi-walled carbon nanotube (MWNT) reinforced alumina composites with different MWNT contents (5 and 10 vol %) were fabricated by spark plasma sintering. The room temperature dc electrical conductivity, thermal conductivity, and mechanical properties were investigated. Results showed that the electrical conductivity has improved around twelve orders of magnitude by addition of 5 vol% of MWNT. The fracture toughness changed from 3.2 to 4.4 MPa m1/2 with 39% improvement over monolithic Al2O3. The thermal conductivity decreased with increase of MWNT contents. The low values of thermal conductivity suggest that interfacial thermal barrier play an important role in determining these properties. MWNT can be used to improve concurrently electrical, mechanical properties of Al2O3 but with lower values of thermal properties.

A COMBINATION OF POINT DEFECTS AND NANOSIZED GRAINS TO MINIMIZE LATTICE THERMAL CONDUCTIVITY OF Sn AND Se CO-DOPED CoSb3 VIA MIXED BALL MILLING AND SPARK PLASMA SINTERING

2021 ◽  
pp. 2150089
Author(s):  
THAMMANOON KAPANYA ◽  
BINBIN JIANG ◽  
JIAQING HE ◽  
YANG QIU ◽  
CHANCHANA THANACHAYANONT ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Electrical Conductivity ◽  
Seebeck Coefficient ◽  
Ball Milling ◽  
Point Defects ◽  
Power Factor ◽  
Lattice Thermal Conductivity ◽  
Plasma Sintering ◽  
Spark Plasma ◽  
Co Doped

The efficient strategies to minimize thermal conductivity in skutterudite materials are creating point defects along with nanosized grains. In this report, Sn and Se co-doped CoSb3 materials were synthesized through mixed-ball milling and spark plasma sintering techniques to utilize this strategy. Their phases, microstructure and thermoelectric properties were investigated under the content variation of Sn and Se in CoSb3 samples. The experimental results revealed that the Sn and Se were substituted at Sb sites in CoSb3 crystal structure and grain sizes were restricted to a hundred nanometer. The lattice thermal conductivity was reduced to 2.4[Formula: see text]W/mK at 298K. Interestingly, increasing Sn and Se doped content could further minimize the lattice thermal conductivity. The lowest value at room temperature is 1.79[Formula: see text]W/mK for CoSb[Formula: see text]Sn[Formula: see text]Se[Formula: see text] which was dramatically lower than pure CoSb3. Moreover, the increment of Sn and Se content also increased the electrical conductivity of doped samples, while the negative Seebeck coefficient sign tended to decrease. As expected, low electrical conductivity and substantial reduction in the Seebeck coefficient of doped samples at high measurement temperature, resulting in low power factor and low ZT values. It was clearly seen that the highest power factor of 880[Formula: see text][Formula: see text]W/mK2 was found at 516[Formula: see text]K in CoSb[Formula: see text]Sn[Formula: see text]Se[Formula: see text]. Furthermore, it also dominated the highest ZT value of 0.29 at 565 K, compared to the other Sn and Se co-doped samples. From these results, ball milling under dry conditions followed by wet conditions not only allowed a longer milling process but also generated a small fraction of pore which was a part of the reduction in thermal conductivity. Especially, the advantage of the existence of Sn and Se point defects and nanosized grains from this work will be escalated when it was applied to prepare materials that have high power factor values.

Grain size-induced enhancement of thermoelectric performance of Cu3Sb1−xInxSe4 materials

2021 ◽  
pp. 2151026
Author(s):  
Lin Bo ◽  
Wen-Ying Wang ◽  
Yong-Peng Wang ◽  
Lei Wang ◽  
Fu-Jin Li ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Electrical Conductivity ◽  
Grain Size ◽  
Ball Milling ◽  
Temperature Region ◽  
Hot Pressing ◽  
Room Temperature ◽  
Powder Processing ◽  
Thermoelectric Performance ◽  
In Doping

The ternary Cu3SbSe4 thermoelectric material with diamond-like structure exhibits good thermoelectric performance in the middle temperature region. In this study, the Cu3Sb[Formula: see text]In[Formula: see text]Se4 ([Formula: see text]= 0–0.03) materials were fabricated by melting-annealing-ball milling-hot pressing process. The influences of In-doping and grain size on the microstructure and thermoelectric properties of Cu3Sb[Formula: see text]In[Formula: see text]Se4 were evaluated. It is found that the electricity conduction at room temperature for Cu3Sb[Formula: see text]In[Formula: see text]Se4 sample was significantly increased to 6.1 × 103Sm[Formula: see text] due to the In-doping. Additionally, during the powder processing, a relatively low thermal conductivity for the refinement Cu3Sb[Formula: see text]In[Formula: see text]Se4-BM-72H sample was obtained. Benefiting from the enhanced electrical conductivity and the decreased thermal conductivity, the maximum zT value of 0.75 was achieved for Cu3Sb[Formula: see text]In[Formula: see text]Se4-BM-36H at 650 K.

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