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MM: Fachverband Metall- und Materialphysik

MM 15: Poster Session

MM 15.74: Poster

Montag, 11. März 2013, 18:00–20:00, Poster E

TEM study of annealed γ-Al₂O₃-coatings for cutting tools and of γ-Al₂O₃-coated cutting tools after the use in cutting tests — •Merlin G.J. Müller¹, Joachim Mayer¹, Susanne E. Cordes², Kirsten Bobzin³, Nazlim Bagcivan³, Mara Ewering³, and Ricardo H. Brugnara³ — ¹Central Facility for Electron Microscopy, Aachen, Germany — ²Laboratory for Machine Tools and Production Engineering, Aachen, Germany — ³Surface Engineering Institute, Aachen, Germany

Among the transition aluminas, the γ-Al₂O₃-phase has a high potential for the use as hard coating in many technological applications, because it exhibits excellent properties e.g. high hot hardness and high thermal stability. It can also be deposited by means of physical vapor deposition at lower temperatures (below 700 ^∘C) than the stable α-Al₂O₃ phase, deposited by means of chemical vapor deposition (about 1000 ^∘C). Thus, even temperature sensitive materials can be coated and the resulting alumina layer is rather fine-grained which should lead to better mechanical properties. The phase transformation of the metastable γ-Al₂O₃-phase into the stable α-Al₂O₃-phase at high temperatures can cause cracks or even the delamination of the coating. To investigate the phase stability of γ-Al₂O₃-coatings, the structure of annealed samples and of samples after the use in cutting tests were characterized by Transmission Electron Microscopic-methods. The γ-Al₂O₃-coatings were deposited by means of Magnetron Sputter Ion Plating on cutting inserts with a (Ti,Al)N-interlayer or directly onto Si-wafers.