The increasing demand for precision components of high-strength aluminum alloys with excellent surface quality is a challenge for the metal working industry. Especially in extrusion processes, where huge amounts of Aluminum are directly formed to long products without further surface finishing, extrusion tools are needed, that yield constant product qualities over long production times. Unfortunately, Aluminium tends to undesired strong adhesion to most tool surfaces, especially under high pressure and temperature – which are necessary to achieve high degrees of deformation.
In close cooperation WEFA Inotec GmbH and Fraunhofer IWM have developed an extrusion sliding test rig for the characterization of wear protection coatings for extrusion dies. The experimental results from the extrusion tests provide data of friction forces and give insight to the interaction of work piece and tool coating. These results are complemented by state-of-the-art atomistic simulation of coating/work piece interfaces.
Besides commercially available Al2O3-based coatings, variations of TiAl(X)N coatings (X = Boron, Chromium or Tungsten) were provided by Fraunhofer IST. The experimental results of these coatings are compared in terms of high-temperature wear behavior and post-experimental microstructure analysis.
Besides the theoretical description of the influence of atom-doping on the interface behavior, the experimentally accessed wear behaviors of the new coatings are described in this work. The authors present the limits and the prospects of these coating systems in the field of aluminum extrusion.