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Durable Protective Overcoat for High Density Magnetic Storage

Ultrathin carbon with interspersed graphene/fullerene-like nanostructures

Nature, Scientific Reports has published an article written by Neeraj Dwivedi, Nalam Satyanarayana, Department of Electrical and Computer Engineering, National University of Singapore, 117583 Singapore, Reuben J. Yeo, Hai Xu, Kian Ping Loh, Graphene Research Centre and Department of Chemistry, National University of Singapore, 117543 Singapore, Sudhiranjan Tripathy, Institute of Materials Research and Engineering (IMRE), A*STAR (Agency for Science, Technology, and Research), 3 Research Link, 117602 Singapore , and Charanjit S. Bhatia, Department of Electrical and Computer Engineering, National University of Singapore, 117583 Singapore.

Schematic representation of the substrate and fabrication
process of FCVA deposited carbon in sample S-3.

Current commercial hard disk media with magnetic layers, commercial COC
and lubricant, (b) Ar+ ion etching of commercial media to remove the commercial
COC and lube, c) commercial media after removal of commercial COC and lubricant,
(d) 1st level carbon modification of etched commercial media at C+ ion energy of 350 eV using FCVA and (e) 2nd level carbon modification of media at C+ ion energy of 90 eV using FCVA.

GRAPHENE_srep11607-f1


Samples (a) S-2 and (b) S-3. Figure (c) is the zoomed-in version of certain portion of sample S-3,
which is indicated by red color rectangle in (b).

GRAPHENE_srep11607-f2

 

Abstract: “One of the key issues for future hard disk drive technology is to design and develop ultrathin (<2 nm) overcoats with excellent wear- and corrosion protection and high thermal stability. Forming carbon overcoats (COCs) having interspersed nanostructures by the filtered cathodic vacuum arc (FCVA) process can be an effective approach to achieve the desired target. In this work, by employing a novel bi-level surface modification approach using FCVA, the formation of a high sp3 bonded ultrathin (~1.7 nm) amorphous carbon overcoat with interspersed graphene/fullerene-like nanostructures, grown on magnetic hard disk media, is reported. The in-depth spectroscopic and microscopic analyses by high resolution transmission electron microscopy, scanning tunneling microscopy, time-of-flight secondary ion mass spectrometry, and Raman spectroscopy support the observed findings. Despite a reduction of ~37 % in COC thickness, the FCVA-processed thinner COC (~1.7 nm) shows promising functional performance in terms of lower coefficient of friction (~0.25), higher wear resistance, lower surface energy, excellent hydrophobicity and similar/better oxidation corrosion resistance than current commercial COCs of thickness ~2.7 nm. The surface and tribological properties of FCVA-deposited COC was further improved after deposition of lubricant layer.”

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