Servicio de Información Comunitario sobre Investigación y Desarrollo - CORDIS

Development of Chromium+Carbon nanodispersion coating with extremely low wear and low friction under dry conditions

The developed Chromium+Carbon nanodispersion coating (Cr+C-ND) is a coating for protecting metallic surfaces from wear and to reduce the friction force under tribological loading. It is a nanostructured amorphous coating consisting of 80-95% carbon and 5-20% chromium. The nanostructure is based on nanometer-sized Cr and CrC inclusions in a mainly diamond-bonded amorphous carbon matrix. The overall coating hardness is high (30 GPa) resulting in good wear resistance. Compared to pure carbon films, the Cr+C-ND showes lower friction coefficients (0.08) under dry conditions in contact to steel.

The wear resistance in slightly lower compared to carbon films but the wear of counter part is significantly reduced. Both the crack resistance (fracture toughness) and the oxidation resistance of the Cr+C-ND are improved compared to carbon films. For these reasons the Cr+C-ND is predestined for tribological application under dry-running and mixed-lubrication conditions with emergeny-running conditions.

The coating can be deposited by vacuum-arc discharge in dedicated PVD coating machines. There was developed a pulsed arc technique allowing for high-rate deposition of good-quality Cr+C-ND in the thickness range 100 nm - 10 µm. The films can be deposited on complex three-dimensional metal substrates as steel components and tools. The nanostructuring is obtained by co-deposition from a graphite and a chromium arc source with highly activated plasmas. The films have high potential for low-wear and low-friction application e.g. on components in automotive industry. The special benefit of the coatings is the extremely low friction and wear under dry and mixed lubrication conditions.

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Fraunhofer Institute Material and Beam Technology
Fraunhofer IWS, Winterbergstrasse 28
01277 Dresden
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