Mechanical and thermal properties of multiwalled carbon-nanotube-reinforced Al2O3 nanocomposites

Guo, Christine; X, Luo; Shah, W.A.; Li, J.K.; Bin, Huang; Umer, Malik Adeel; Yang, Yao

doi:10.1016/j.ceramint.2020.04.039

Cited by 26 publications

(2 citation statements)

References 53 publications

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“…An increase in CNT concentration in ZC2 saw the sintering and lubricating characteristics of CNTs overtake the density inhibiting effects, and relative density of the sample was comparable to monolithic ZTA. This is in agreement with previous reports, where CNT–alumina/CNT–zirconia composites were found to have comparable 30–32 or better 17,33 density. Apparent porosity of ZC2 (1.21%), while less than ZC1, was still 28.7% more than that of monolithic sample Z (.94%).…”

Section: Resultssupporting

confidence: 94%

Little amounts of carbon nanotubes as anti‐wear reinforcement for alumina in dry sliding

Goswami

Ghosh

et al. 2022

Int J Applied Ceramic Tech

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Carbon nanotubes (CNTs) are a leading choice for reinforcing oxide and nitride ceramics, but investigations into the tribological performance of CNT-ceramic composites remain inconclusive. Here, we show that reinforcement with only .1 wt% multi-walled CNTs improves the antifriction and anti-wear performance of zirconia-toughened alumina by up to 23% and 51%, respectively. Dry sliding tests under normal loads of 40-60 N for a sliding distance of 1000 m reveal a loaddependent transition in the lubrication mechanism-CNTs retain their tubular morphology at low loads and reduce friction via a sliding-rolling response, whereas high sliding loads trigger the formation of a uniform, thin lubricating film by the repeated crushing and smearing of exfoliated nanotubes. Raman spectra analyses confirmed that the carbon-rich tribo-film possesses a graphitic structure. Well-dispersed CNTs prevent wear loss by mechanisms, such as crack bridging and grain anchoring. The present work opens up new frontiers for the application of CNT-alumina tribo-ceramics in anti-wear, unlubricated, and high contact stress applications, such as in the manufacturing and mining industries.

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Section: Resultssupporting

confidence: 94%

Little amounts of carbon nanotubes as anti‐wear reinforcement for alumina in dry sliding

Goswami

Ghosh

et al. 2022

Int J Applied Ceramic Tech

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“…Out of all available metal oxides, Al 2 O 3 was chosen for three reasons. First, reinforcing Al 2 O 3 with CNTs is widely documented in the literature, with contribution spanning mechanical, − thermal, − and electrical ,− properties. Ahmad et al reported 94% increase in fracture toughness of Al 2 O 3 with 4 vol % of MWCNTs, Kumari et al reported 150% increase in its thermal conductivity with 19.1 wt % of MWCNTs, and Ahmad et al.…”

Section: Introductionmentioning

confidence: 99%

Alumina Thin-Film Deposition on Rough Topographies Comprising Vertically Aligned Carbon Nanotubes: Implications for Membranes, Sensors, and Electrodes

Rovinsky

Barick

Lieberman

et al. 2020

ACS Appl. Nano Mater.

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In this article, the limits of thin-film deposition on very rough topographies are demonstrated by depositing alumina on vertically aligned carbon nanotubes (VACNTs). Vapor deposition techniques are the enabling platforms of the thin-film industry, offering high material versatility and good coverage ability on relatively flat surfaces, leading to frequent use in a large array of applications, especially nanoscale electronic devices such as sensors and electrodes. However, when surface topography exhibits high roughness, even depositions that are not limited to line-of-sight show only partial coverage, significantly hindering performances. Our manufacturing process of VACNT/Al2O3 nanocomposites has three vaporous steps: CNT growth by chemical vapor deposition (CVD), functionalization via controlled thermal oxidation, and atomic layer deposition (ALD) of alumina. The same limited accessibility hinders each of these three steps. Morphological analyses show different CNT heights throughout the sample, with shorter CNTs in the middle, having less access to gases. As height differences between the center and peripheries escalate, sample centers may collapse under the tension. The limited accessibility of the center is manifested also in inhomogeneous oxygen contents, between sample centers and peripheries. Finally, a sharp transition in deposition quality occurs during the deposition process of Al2O3, from homogeneous to inconsistent, which is also linked to the accessibility differences between. Adjusting process parameters, we have successfully coated 1.8 mm-tall VACNT arrays with a homogeneous thin (few nm) Al2O3 layer and were able to increase the depth at which, thick (few dozens of nm) Al2O3 coating is uniform from 20 to 350 μm. However, when VACNTs were functionalized, the penetration depth was found to correlate negatively with center oxygen content. These results, indicating diffusion as a rate-setting step in complex topography coatings, can significantly improve deposition quality and enhance the performance of thin-film applications such as membranes, sensors, and electrodes for energy harvesting and storage.

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Microstructure, mechanical, and thermal properties of graphene and carbon nanotube-reinforced Al2O3 nanocomposites

Shah

Yang

2021

J Mater Sci: Mater Electron

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Mechanical and thermal properties of multiwalled carbon-nanotube-reinforced Al2O3 nanocomposites

Cited by 26 publications

References 53 publications

Little amounts of carbon nanotubes as anti‐wear reinforcement for alumina in dry sliding

Little amounts of carbon nanotubes as anti‐wear reinforcement for alumina in dry sliding

Alumina Thin-Film Deposition on Rough Topographies Comprising Vertically Aligned Carbon Nanotubes: Implications for Membranes, Sensors, and Electrodes

Microstructure, mechanical, and thermal properties of graphene and carbon nanotube-reinforced Al2O3 nanocomposites

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