Phase composition and tribomechanical properties of Ti-B-C nanocomposite coatings prepared by magnetron sputtering

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URI: https://hdl.handle.net/11556/4543
ISSN: 0022-3727
DOI: 10.1088/0022-3727/45/37/375401
Publication date
2012-09-19
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Abstract
Protective nanocomposite coatings based on hard ceramic phases (TiC, TiB 2) combined with amorphous carbon (a-C) are of interest because of their adequate balance between mechanical and tribological performances. In this work, TiBC nanocomposite coatings were prepared by co-sputtering of graphite and TiB 2 targets. Varying the discharge power ratio applied to the graphite and TiB 2 targets from 0 to 2, the a-C content in the coatings could be tuned from 0 to 60%, as observed by means of Raman and x-ray photoelectron spectroscopy (XPS). The microstructural characterization demonstrated a progressive decrease in crystallinity from an initial nanocrystalline (nc) TiB 2-like structure to a distorted TiB xC y ternary compound with increasing C concentration. X-ray absorption near-edge structure measurements on the B K-edge helped to determine a hexagonal arrangement around the B atoms in the ternary TiB xC y phase. A fitting analysis of the C 1s XPS peak allowed us to evaluate the relative amount of a-C and TiB xC y components. A drastic change in hardness (from 52 to 13GPa) and friction coefficient values (from 0.8 to 0.2) is noticed when moving from nc-TiB 2 to TiBC/a-C nanocomposites. The fraction of a-C necessary to decrease the friction below 0.2 was found to be 45%. Raman observation of the wear tracks determined the presence of disordered sp 2-bonded carbon phase associated with the diminution of the friction level.
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Electronic, Optical and Magnetic Materials , Condensed Matter Physics , Acoustics and Ultrasonics , Surfaces, Coatings and Films
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journal article
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Sánchez-López , J C , Abad , M D , Justo , A , Gago , R , Endrino , J L , García-Luis , A & Brizuela , M 2012 , ' Phase composition and tribomechanical properties of Ti-B-C nanocomposite coatings prepared by magnetron sputtering ' , Journal Physics D: Applied Physics , vol. 45 , no. 37 , 375401 . https://doi.org/10.1088/0022-3727/45/37/375401