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Composition, microstructure and mechanical properties of boron containing multilayer coatings for hot forming tools

: Paschke, H.; Stueber, M.; Ziebert, C.; Bistron, M.; Mayrhofer, P.


Surface and coatings technology 205 (2011), Suppl.2, pp.S24-S28
ISSN: 0257-8972
Journal Article
Fraunhofer IST ()
nanostructure; PECVD; boron based coating; wear/abrasion-resistant coatings; multilayer coating

The tribological conditions of hot forming processes are much different from those at room temperature. Thus classical wear-resistant coating like CrN, CrAlN, TiAlN in most cases are not sufficient for hot forming tools in industrial applications.Additionally the use of lubricants is limited, thermal shock conditions and the increase of sticking work piece material are leading to severe wear.This paper presents examples for ternary boron based Ti-B-N gradient coatings in specific multilayer designs obtained through plasma enhanced chemical vapor deposition. After a thorough characterization of the chemical composition by Auger electron spectroscopy, the microstructure by X-ray diffraction and the mechanical properties by microindentation and small-angle cross section nanoindentation, the coatings were applied onto hot forming tools made from DIN 1.2367 tool steel. The coated tools were tested in hot forging of AISI 1043 raw parts in an automatic press and have been comp ared in terms of adhesion and wear resistance. In this study an optimum design has been found which significantly reduces sticking of work piece material and wear. This allows an efficient production without interruptions for a reworking of the tools and enables to increase the process reliability paired with a longer tool life.