A mechanical exfoliation technique to produce exfoliated graphite-graphene nanoplatelet dispersion as a byproduct of aqueous graphite-based lubricant-assisted metal cutting is presented here. Low cutting speed oscillatory orthogonal metal cutting process has been carried out completely immersed in the lubricant containing graphite flakes. Reduction in the thickness of the graphite flakes from around 30 µm to graphite-graphene nanoplatelets with a size range of 1–15 nm is observed after machining. Characterization of the particles depicts low structural order and induced defects. Optimizing the parameters can tune this machining-induced exfoliation technique to produce high-quality defect and disorder free few-layer graphene sheets. © 2019 Society of Manufacturing Engineers (SME)

Sathyan Subbiah

Department of Mechanical Engineering

Additives

Defects

EXFOLIATION (MATERIALS SCIENCE)

Graphene

Graphite

Phase interfaces

Solid lubricants

Exfoliated graphite

Few-layer graphene

Graphene nanoplatelets

GRAPHITE LUBRICANTS

MECHANICAL EXFOLIATION

ORTHOGONAL METAL CUTTINGS

STRUCTURAL ORDERING

TOOL-CHIP INTERFACE

Metal cutting

IIT Madras is a public technical and research university located in Chennai, Tamil Nadu. Founded in 1959, it is recognised as an Institute of National Importance.

IIT Madras has been ranked as the top engineering institute in India for four years in a row by the National Institutional Ranking Framework of the MHRD

It currently offers undergraduate, postgraduate and research degrees across 16 disciplines in Engineering, Sciences, Humanities and Management. About 596 faculty belonging to science and engineering departments and centres of the Institute are engaged in teaching, research and industrial consultancy.

IIT Madras

Manufacturing Letters

We study morphological and structural changes in graphite flakes present in aqueous graphite-based lubricants when repeatedly subjected to extreme tribological interactions at the tool–chip interface in low speed, high depth of cut intermittent machining, a process involving combined high normal and shear stress. Orthogonal tube turning experiments are conducted on a specially fabricated mild steel workpiece completely submerged in an aqueous graphite solution. Surface profiler, electron microscopy and Raman spectroscopy studies on initial and sheared graphite flakes indicate crushing followed by layer sliding, rolling, edge curling, tearing and exfoliation of layers. Raman spectroscopy studies highlight formation of low amorphous carbon by structural disorder and edge defects formed while crushing and tearing with no new basal defects in the sheared graphite layers. Some regions of the flake thin down to highly disordered few-layer graphene with a thickness reduction from about 30 micrometres to about 1–2 nanometres with an I 2D /I G value of around 0.7. When reused back into the tribological region, these morphological changes can significantly influence the continued lubrication process by the generation of few-layer graphene. © 2019, Springer Science+Business Media, LLC, part of Springer Nature.

Tribology Letters

Structural and Morphological Transformations in Aqueous Graphite-Based Lubricant Subjected to Extreme Tribological Interactions of Low-Speed Intermittent Machining

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ACS Applied Materials & Interfaces

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Journal	Data powered by TypesetManufacturing Letters
Publisher	Data powered by TypesetElsevier Ltd
ISSN	22138463
Open Access	No