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Characterisation of a High-Power Impulse Magnetron Sputtered C/Mo/W wear resistant coating by transmission electron microscopy

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posted on 24.01.2020, 09:53 by Jo Sharp, Itzel Castillo Müller, Paranjayee Mandal, Ali AbbasAli Abbas, Magnus Nord, Alastair Doye, Arutiun Ehiasarian, Papken Hovsepian, Ian MacLaren, W. Mark Rainforth
Thin films of C/Mo/W deposited using combined UBM/HIPIMS sputtering show 2–8 nm clusters of material richer in Mo and W than the matrix (found by EDS microanalysis), with structures that resemble graphitic onions with the metal atoms arranged regularly within them. EELS microanalysis showed the clusters to be rich in W and Mo. As the time averaged power used in the pulsed HIPIMS magnetron was increased, the clusters became more defined, larger, and arranged into layers with amorphous matrix between them. Films deposited with average HIPIMS powers of 4 kW and 6 kW also showed a periodic modulation of the cluster density within the finer layers giving secondary, wider stripes in TEM. By analysing the ratio between the finer and coarser layers, it was found that this meta-layering is related to the substrate rotation in the deposition chamber but in a non-straightforward way. Reasons for this are proposed. The detailed structure of the clusters remains unknown and is the subject of further work. Fluctuation electron microscopy results indicated the presence of crystal planes with the graphite interlayer spacing, crystal planes in hexagonal WC perpendicular to the basal plane, and some plane spacings found in Mo2C. Other peaks in the FEM results suggested symmetry-related starting points for future determination of the structure of the clusters.

Funding

Mercury Centre at the University of Sheffield ERDF under grant MERCURY – 904467

CONACyT and RobertoRocca Education Fellowship

EPSRC (EP/M009963/1, EP/K503903/1 & EP/R511705/1)

EPSRC CDT in Integrative Sensing and Measurement, Grant Number EP/L016753/1

History

School

  • Mechanical, Electrical and Manufacturing Engineering

Published in

Surface and Coatings Technology

Volume

377

Publisher

Elsevier

Version

VoR (Version of Record)

Rights holder

© The Authors

Publisher statement

This is an open access article under the CC BY license (http://creativecommons.org/licenses/BY/4.0/).

Acceptance date

02/08/2019

Publication date

2019-08-03

Copyright date

2019

ISSN

0257-8972

Language

en

Depositor

Dr Ali Abbas. Deposit date: 21 January 2020

Article number

124853

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