The effect of sintering temperature on the mechanical properties of a Cu/CNT nanocomposite prepared via a powder metallurgy method (original) (raw)
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In this research work, copper and CNTs have been processed using high energy milling in different milling times (5, 10 and 15 hours). FESEM and XRD have been used to characterize the milled powders. The FESEM micrographs of the milled powders indicated that the morphology of powders changed from spherical shape to flake as milling time increased. The effect of sintering temperature as well as CNTs content on the properties of Cu-CNTs nanocomposite has been investigated. The optimum sintering temperature to produce Cu-CNTs nanocomposites is determined to be 900 oC. The microstructure and phase analysis of Cu-CNTs nanocomposites were studied by field emission scanning electron microscopy and X-ray diffraction. Mechanical properties of nanocomposite samples at various sintering temperatures were investigated. Cu-CNTs nanocomposite with 4 vol.% CNTs fabricated by powder metallurgy method indicated the highest value of the micro-hardness and bending strength as compared to pure copper.
Sintering and Dimensional Analysis of Cu/CNTs via a Powder Metallurgy Route
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Recently, carbon nanotubes (CNTs) reinforced metal matrix composites (MMCs) have attracted an increasing interest, due to their promising properties such as high Young’s modulus and tensile strength. CNTs are considered to be an attractive reinforcement material for lightweight and high-strength metallic matrix composites. When powder metallurgy (PM) is used to form these MMCs (such as Cu/CNTs composites), the sintering parameters are crucial in obtaining good final parts. This work attempts to investigate the effect of sintering parameters on physical properties in these MMCs. The process comprised of mixing of Cu powder with CNTs, compacting of the powder mixture to form green parts and sintering using a quartz tube furnace under argon atmosphere. In this study, four trials of heating rate were performed and evaluated before sintering process was conducted. Finally, the green body was initially heated isothermally at 100°C for 1 hour with heating rate of 1.0 °C/min and sintered at...
Sintering behaviour of Copper/carbon nanotube composites and their characterization
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The potential usage of Copper (Cu) is very limited, where combined mechanical and thermal properties are desirable, which can be overcome by using carbon nanotube (CNT) as a reinforcement. An attempt was made to synthesize Cu/CNT composites by varying CNT diameter and its concentration through a molecular level mixing technique followed by uniaxial compaction and conventional sintering. The sintering behaviour of Cu and Cu/CNT composites was studied to understand the influence of different parameters. The sintering duration of Copper was decreased with an increase of CNT diameter. The maximum enhancement of properties was achieved at 0.25 wt.% CNT irrespective of its diameter, where the thermal conductivity and hardness were obtained as 328 W/mK at 20-40 nm diameter CNT composites and 81.2 ± 2.9 VHN at 40-60 nm diameter CNT composites, respectively. The conventional method of synthesize can generate the desired characteristics of composites at par with high end techniques, such as SPS.
Microstructures and tensile behavior of carbon nanotube reinforced Cu matrix nanocomposites
Materials Science and Engineering: A, 2006
Carbon nanotubes (CNTs) have been considered as an ideal reinforcement to improve the mechanical performance of monolithic materials. However, the CNT/metal nanocomposites have shown lower strength than expected. In this study, the CNT reinforced Cu matrix nanocomposites were fabricated by spark plasma sintering (SPS) of high energy ball-milled nano-sized Cu powders with multi-wall CNTs, and followed by cold rolling process. The microstructure of CNT/Cu nanocomposites consists of two regions including CNT/Cu composite region, where most CNTs are distributed, and CNT free Cu matrix region. The stress-strain curves of CNT/Cu nanocomposites show a two-step yielding behavior, which is caused from the microstructural characteristics consisting of two regions and the load transfer between these regions. The CNT/Cu nanocomposites show a tensile strength of 281 MPa, which is approximately 1.6 times higher than that of monolithic Cu. It is confirmed that the key issue to enhance the strength of CNT/metal nanocomposite is homogeneous distribution of CNTs.
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In this research, copper (Cu)-carbon nanotubes (CNTs) nanocomposites were synthesized with different weight percentages of CNTs by double pressing double sintering (DPDS) method as well as conventional sintering method. A planetary ball mill was used to disperse CNTs in Cu matrix. The milled powders were first cold pressed to 450 MPa in a uniaxial stainless-steel die with cylindrical compacts (diameter: 12 mm and height: 5 mm). The effect of CNTs content and the DPDS method on the properties of the nanocomposites were investigated. The microstructure and phase analysis of Cu-CNTs nanocomposite samples were studied by FESEM and X-Ray Diffraction. The electrical conductivity of nanocomposites was measured and compared to both sintering methods. Mechanical properties of Cu-CNTs nanocomposites were characterized using bending strength and micro-hardness measurements. Enhancements of about 32 % in bending strength, 31.6 % in hardness and 19.5 % in electrical conductivity of Cu-1wt. % CNTs nanocomposite synthesized by DPDS method were observed as compared to Cu-1wt. % CNTs nanocomposites fabricated under the similar condition by a conventional sintering process.
AN OVERVIEW OF PROCESSING AND PROPERTIES OF CU/CNT NANO COMPOSITES
Elseviers, 2017
Carbon nanotubes (CNTs) are known for their extraordinary mechanical, electrical and thermal properties. These properties make them ideal reinforcements in the metal matrix. Particularly, the combination of Cu/CNT is interesting in view of excellent thermal, electrical and physical properties of copper. In this overview, the reports on Cu/CNT composites are critically analyzed with respect to the process techniques, mechanical and tribological properties. Powder metallurgy coupled with spark plasma sintering is found to be a most widely used process to fabricate Cu/CNT composites. Comparatively, a small amount of CNTs is sufficient to improve the properties of composites as against the conventional micron size particle reinforced composites. The strength, wear resistance and corrosion resistance of the composites increase significantly with an increase of volume fraction of CNTs. The density and thermal conductivity reduce with an increase of CNTs. There exists a critical volume fraction above that both the mechanical properties and the thermal conductivity are drastically reduced due to the problems of CNTs agglomeration and the increase of process related defects such as porosity, delamination and so on. Fracture surface features of Cu/CNT composites show that the fracture mode transits from ductile to brittle fracture with an addition of CNTs.
Effect of CNTs dispersion on the thermal and mechanical properties of Cu/CNTs nanocomposites
Modified technique of metal injection molding (MIM) was used to fabricate multiwalled carbon nanotube (CNT) reinforced Cu nanocomposites. The effect of adding different amount of CNTs (0-10 vol.%) on the thermal and mechanical behaviour of the fabricated nanocomposites is presented. Scanning electron microscope analysis revealed homogenous dispersion of CNTs in Cu matrices at different CNTs contents. The experimentally measured thermal conductivities of Cu/CNTs nanocomposites showed extraordinary increase (76% higher than pure sintered Cu) with addition of 10 vol.% CNTs. As compared to the pure sintered Cu, increase in modulus of elasticity (Young’s modulus) of Cu/CNTs nanocomposites sintered at 1050qC for 2.5 h was measured to be 48%. However, in case of 7.5 vol.% CNTs, Young’s modulus was increased significantly about 51% compared to that of pure sintered Cu.
Carbon nanotubes (CNTs) with its exceptional thermal and mechanical properties hold the promise of delivering high performance nanocomposite materials. To utilize CNTs as effective reinforcement in metal nanocomposites, appropriate dispersion and robust interfacial adhesion between individual CNT and metal matrix have to be certain. This work presents a novel combined technique of nanoscale dispersion (NSD) of functionalized multiwalled carbon nanotubes (MWCNTs) in copper (Cu) matrix composite followed by powder injection molding (PIM). MWCNTs contents were varied from 0 to 10 volume fraction. Evidences on the existence of functional groups and microstructural analysis of the fabricated nanocomposites were determined using TEM, EDX, FESEM and FTIR. Thermal conductivity and elasticity measurements were also performed. The results showed that the impurities of the pristine MWCNTs such as Fe, Ni catalyst, and the amorphous carbon have been significantly removed after sonication process. FESEM and TEM observations showed high stability of MWCNTs at elevated temperatures and uniform dispersion of MWCNTs in Cu matrix at different volume fractions and sintering temperatures (950, 1000 and 1050 C). The experimentally measured thermal conductivities of Cu/MWCNTs nanocomposites showed remarkable increase (11.25% higher than pure sintered Cu) with addition of 1 vol.% MWCNTs, while the modulus of elasticity (Young’s modulus) of Cu/MWCNTs nanocomposites sintered at 1050 C for 2 h was increased proportionally to the increment in MWCNTs contents.
Acta Physica Polonica A, 2019
In this study the effect of carbon nanotube content on the wear behaviours of Cu-carbon nanotube composites produced by powder metallurgy method was investigated. In the scope of the study five different amounts of carbon nanotube (0.5%, 1.0%, 1.5%, 2.0%, 2.5%) were added into pure Cu powders and mechanically milled for 360 min. The mechanically milled Cu-carbon nanotube powders were cold pressed under 600 MPa load and sintered in atmosphere-controlled furnace at 1000 • C for 1 h. Microstructure examinations, hardness measurements, and wear tests were carried out. In this study, the hardness values were found to have increased with increasing carbon nanotube content up to 1.5%. Then it decreased with increasing carbon nanotube content. Wear test results were compatible with hardness results. The lowest weight losses were measured with 1.5% carbon nanotube content.