Characterisation of a high-power impulse magnetron sputtered C/Mo/W wear resistant coating by transmission electron microscopy

Jo Sharp, Itzel Castillo Muller, Paranjayee Mandal, Ali Abbas, Magnus Nord, Alastair Doye, Arutiun Ehiasarian, Papken Hovsepian, Ian Maclaren, W. Mark Rainforth

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Abstract

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.
Original languageEnglish
Article number124853
Number of pages10
JournalSurface and Coatings Technology
Volume377
Early online date3 Aug 2019
DOIs
Publication statusPublished - 15 Nov 2019

Keywords

  • fluctuation electron microscopy
  • FEM
  • wear
  • coatings

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