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DS: Fachverband Dünne Schichten

DS 16: Layer Properties: Electrical, Optical, and Mechanical

DS 16.12: Talk

Tuesday, March 8, 2016, 12:30–12:45, H11

High-temperature micro-mechanical testing of a thin-film CrN tooling system — •James P Best¹, Johannes Zechner², Jeffrey M Wheeler³, Juri Wehrs¹, Marcus Morstein⁴, and Johann Michler¹ — ¹EMPA, Thun, Switzerland — ²KAI GmbH, Villach, Austria — ³ETH, Zürich, Switzerland — ⁴PLATIT AG, Selzach, Switzerland

Forging and cutting tools for high-temperature applications are often protected using hard nanostructured ceramic coatings. While a moderate amount of knowledge exists for material properties at room temperatures, significantly less is known about the system constituents at the elevated temperatures generated during service.

In this work, we present results on both the hard ceramic coating and the nitrided steel substrate using in situ micro-mechanical measurements at temperatures to 500 °C. FIB milled micro-pillars of plasma-nitrided tool steel were first investigated using in situ compression experiments. It was found that elevated temperature led to significant and reversible softening of the nitrided steel and transition from slip-based to more ductile plastic flow.

The fracture toughness behavior was then investigated using various micro-geometries and notching parameters. Toughness measurements at high temperatures highlighted the profound effect of the notching ion during small-scale fracture measurements. It was found that gallium ion implantation led to significant toughening of CrN, based on gallium dosage experiments and alternative notching using both xenon and helium sources.