Carbon nitride based hard multilayer films prepared by closed field unbalanced magnetron sputtering

Research output: Journal Publications and Reviews (RGC: 21, 22, 62)21_Publication in refereed journalpeer-review

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Original languageEnglish
Pages (from-to)15-25
Journal / PublicationSurface Engineering
Issue number1
Publication statusPublished - Feb 2006


Single layer a-CNx films as well as CN/HN multilayer films were deposited onto Si (100) and M42 high speed steel substrates by closed field unbalanced magnetron sputtering. In CNx/TiN multilayers, different bilayer (CNx+TiN layer) thickness could be attained in two ways: by changing the substrate rotation speed (1·3-20 rev min-1) and by varying the C target current only with substrate rotation speed fixed at 4 rev min-1 during the deposition process. The films were characterised by employing atomic force microscopy (AFM), nano/microindentation measurements, X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), pin on disc wear test, scratch tester and Rockwell C tester. The XPS results of CNx films suggest the formation of a major fraction of N-C sp2 bonds and a few N-C sp3 bonds. The nanohardness of CNx film about 11·7-20·8 GPa depends on the N/C ratio. In CNx/TiN multilayers, TIN, TiO2, TiC, C - N and C=N chemical and bonding states exist, The mechanical and tribological properties are influenced by different bilayer periods (about 10-1 nm). The root mean square (RMS) surface roughness measured by AFM was between 0·7 and 1·9 nm. High microhardness (∼50 GPa) of the multilayered structure depends on the bilayer thickness. The internal compressive stress is associated with the hardness of the multilayer which falls to about 3·3-7·7 GPa. The pin on disc tests under dry condition show a low friction coefficient between 0·11 and 0·15. Rockwell C and scratch tests show excellent adhesion results for the coating prepared at C target current of 0·5 A. © 2006 Institute of Materials, Minerals and Mining.

Research Area(s)

  • Amorphous carbon films, Bonding structure, Magnetron sputtering, Multilayer, Raman spectroscopy