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Microstructure and mechanical properties of multilayer TiB2/C and co-sputtered TiB2-C coatings for cutting tools

✍ Scribed by M.A. Baker; R. Gilmore; C. Lenardi; P.N. Gibson; W. Gissler


Publisher
Elsevier Science
Year
1999
Tongue
English
Weight
108 KB
Volume
53
Category
Article
ISSN
0042-207X

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✦ Synopsis


The feasibility of reducing the friction coefficient of TiB -based coatings by the incorporation of carbon has been investigated for both multilayer and co-sputtered coatings. Characterisation was performed using pin-on-disk tribometry, nanoindentation, glancing angle X-ray diffractometry, X-ray photoelectron and Auger electron spectroscopy. The co-sputtered coatings were found to consist of two phases: a hexagonal TiB -type structure into which carbon is incorporated and a diamond-like carbon (DLC) phase. C is preferentially incorporated into the Ti(B,C) phase and the lubricating DLC phase only starts to form once saturation is reached. Consequently, a reduction in the friction is only found at total C concentrations higher than 50 at%. For the multilayers, there was an increase in the overall carbon content required to obtain a friction-reducing effect from about 10-50 at% as the TiB sublayer thickness was decreased from 100 to 1 nm. This was attributed to an increase in the relative proportion of carbon bonded with TiB in the interface regions. Coatings with a hardness of about 20-30 GPa and friction coefficients of (0.2 against a steel ball could be obtained at a suitable composition.


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