| AVS 59th Annual International Symposium and Exhibition | |
| Advanced Surface Engineering | Monday Sessions |
| Session SE+NS-MoM |
| Session: | Nanostructured Thin Films and Coatings I: Interface Aspects |
| Presenter: | M. Rebelo de Figueiredo, University of California Berkeley |
| Authors: | M. Rebelo de Figueiredo, University of California Berkeley M. Tkadletz, Materials Center Leoben, Austria M. Schlögl, Montanuniversität Leoben, Austria R. Hollerweger, Montanuniversität Leoben, Austria P.H. Mayrhofer, Montanuniversität Leoben, Austria C. Mitterer, Montanuniversität Leoben, Austria P. Hosemann, University of California Berkeley |
| Correspondent: | Click to Email |
In the past decades, measurement techniques to probe the mechanical properties of hard coatings have been evolved dramatically and nowadays a wide variety of methods and devices are available. Within the field of evaluating the hardness of coating materials, nanoindentation has been established as a standard method utilizing the Oliver and Pharr approach. The measurements are commonly performed at room temperature. Industrial applications like metal cutting, however, demand resistance to wear also at temperature levels of up to 1000°C, which can easily be reached in the contact zone between a coated tool and the machined part. Therefore, knowledge about the mechanical properties of hard coatings at elevated temperatures is of vital importance. Nanoindentation devices allowing to go to temperatures as high as 750°C became available in recent years. While it appears simple to install heating devices in a nanoindenter, the minimization of the thermal drift, tip durability, and environmental control are a particular challenge to perform measurements at these temperatures. Therefore, significant efforts in monitoring all effects of a measurement performed at these conditions need to be spent in order to gain valid indentation data.
Within the present work, a series of different hard coatings were analyzed, utilizing nanoindentation experiments up to 750°C. The coatings evaluated cover selected samples representing the state-of-the-art employed in cutting operations like Al2O3 and TiAlN as well as newly developed coating materials like TiAlTaN. Possibilities and experimental limitations of high-temperature nanoindentation are critically discussed. A sound knowledge of the dependence of hardness on microstructural changes occurring at elevated temperatures provides the basis for the further development of coating materials and design.