Microstructure and mechanical properties of multilayer TiB2/C and co-sputtered TiB2-C coatings for cutting tools
β 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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β¦ 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.
π SIMILAR VOLUMES
Thermal decomposition of AlN-SiC(-TiB 2 ) systems during densification was analyzed, and effects of B, B 4 C and C on the densification behavior of the systems were studied. SiO 2 impurity in the powder mixture was nearly completely removed by carbothermal reaction at 1500 β’ C in vacuum, while Al 2