Titel Werkzeugbeschichtungsentwicklung und tribologische Untersuchungen bis 300°C für die Umformung von Aluminiumlegierungen (Tool coating developments and tribological investigations up to 300°C for forming of aluminum alloys)
Autor Martin Keunecke, Klaus Bewilogua, Tom O`Donnell, Tim Abraham, Günter Bräuer, Tobias Hertrampf
Infos zum Autor Dr.-Ing. Martin Keunecke (Tel. 0531 2155 652; E-Mail: martin.keunecke@ist.fraunhofer.de),

Dr. Klaus Bewilogua; Tom O`Donnell; Tim Abraham; Prof. Dr. Günter Bräuer
Fraunhofer-Institut für Schicht- und Oberflächentechnik IST, Bienroder Weg 54 E, 38108 Braunschweig, Germany

Dipl.-Ing. Tobias Hertrampf
alutec metal innovations GmbH & Co. KG, Ferdinand-von-Steinbeis-Ring 40, 75447 Sternenfels, Germany
Inhalt Zusammenfassung
Modifizierte TiAlN-Beschichtungen und DLC-Beschichtungen wurden hergestellt und charakterisiert. Die Modifikationen zeigten in Tribometertests gegen Aluminium bei 100°C und 300°C eine Verbesserung gegenüber TiAlN-Beschichtungen. Bei dem hier betrachteten Belastungsprofil scheinen DLC-Beschichtungen aber Hartstoffschichten hinsichtlich der Adhäsionsneigung gegenüber Aluminium überlegen zu sein.

Due to their outstanding weight and strength combination, aluminum alloys are particularly suitable for the production of weight-optimized components in several applications especially for example in the automotive, aerospace and general mechanical engineering industries. Particularly in forming processes, the strong adhesion tendency of aluminum alloys affects the surface quality of produced parts, the production process stability, the targeted tolerances and often leads to a premature end of tool life. Beside this, abrasive tool wear could occur. Currently a significant amount of lubrication is often required for an efficient aluminum forming. Due to production and post-cleaning costs, health, sustainability and environmental purposes, a strong demand for the reduction or replacement of lubricants exists. However, this means increasing demands to tools and their surfaces. A further challenge represents the forming of aluminum alloys at elevated temperatures, e.g. in reverse extrusion or extrusion moulding applications due to a higher adhesion tendency of aluminum. A valid solution approach are adapted wear resistant tool coatings. There exists a broad range of well-established tool coatings, like nitrides, oxides, borides or carbon based coatings (e.g. DLC, diamond-like carbon). Such coatings have to be adapted to the special tribological requirements against aluminum alloys. In particular, DLC (a-C:H) show a high tribological potential. Development results of different tribological nitride, boride and DLC coatings produced by PVD and PECVD technologies for tribological contact with aluminum will be presented. The coatings were analyzed due to their hardness, abrasive wear properties and morphology. The main goal of investigation was the assessment of the tribological behaviour and coefficient of friction devolution of these coatings against aluminum. This was performed by pin-on-disk and oszillating tribological tests against aluminum alloys specimens (EN-AW-1098 (Alu99.98%) and EN-AW Al6060 (AlMgSi 0.5)). Also, in order to assess the temperature dependence, tribological tests were carried out up to 300°C. The wear and adhesions were determined and investigated. Subsequent selected coatings were deposited onto forming tools and applied in reverse extrusion production tests. After application tests, the tool wear was analyzed and correlated with measured coating properties and tribological tests results. It could be demonstrated that adapted DLC coatings lead to a significant raise in productivity with the potential for reduction of lubricants. In this presentation, developments and test results will be introduced, discussed and ways for further improvement derived.
Datum 2017