Modifikationen amorpher Kohlenstoffschichten zur Anpassung der Reibungsbedingungen und zur Erhöhung des Verschleißschutzes

Description

Amorphous carbon coatings combine low friction in dry contact against steel with high wear resistance. Their property profile is closely linked to the chemical-structural composition and can be controlled by the process conditions during coating deposition. This thesis contributes to the targeted modification of tribological conditions by means of amorphous carbon coatings with regard to their application as tool coatings in sheet bulk metal forming processes. The coatings are intended to allow local adjustment of the friction conditions in order to control the material flow during forming. In this way, component quality can be improved, and process forces can be reduced. In addition, approaches for increasing wear resistance through multilayer coating architectures and for integrating a sensory function for wear detection are being considered.

The investigations show that the characteristic tribological behavior of amorphous carbon coatings can be locally restricted with masking techniques. However, the load-carrying capacity of locally coated surfaces is at least in part limited. High wear and fatigue resistance is achieved by multilayer coating architectures of hydrogen-containing and tungsten- or silica-doped amorphous carbon coatings. Monitoring the electrical resistance of a sensory carbon-based multilayer coating enables the detection of coating wear. These findings will facilitate an extended and individually determinable service life of coated tools for sheet bulk metal forming in the future.