Ti(Al)SiN protective hard coatings are promising candidates for the metal cutting industry, due to their favorable properties such as a high hardness and good oxidation resistance. Within the scope of this work, the microstructure of cathodic arc evaporated TiN, Ti 84Si 16N, Ti 81Al 3Si 16N and Ti 70Al 14Si 16N was correlated with their mechanical properties. X-ray diffraction (XRD) as well as scanning electron microscopy investigations of the cross-sections revealed a pronounced grain refinement for Ti(Al)SiN compared to TiN. The texture of the coatings was analyzed by XRD pole-figures, showing a change in the preferred orientation in growth direction from (111) for TiN to (200) for Ti(Al)SiN. Hardness values were found to strongly increase from 29 GPa to 40 GPa upon Si addition, but remained constant for further alloying with Al. Micromechanical bending tests allowed to gain a detailed insight into the fracture properties of the investigated coatings and revealed an enhanced fracture stress and fracture toughness (K IC) for Ti(Al)SiN compared to TiN. Hereby, the K IC value of 2.4 ± 0.3 MPa m 1/2 for TiN could be increased to a maximum of 3.3 ± 0.2 MPa m 1/2 for Ti 70Al 14Si 16N. The present findings provide a systematic overview of the microstructure and mechanical properties of arc evaporated Ti(Al,Si)N coatings, thus allowing to select the most suitable coatings for different applications in the cutting industry.
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The authors would like to thank Bernhard Sartory (Materials Center Leoben Forschung GmbH) for the SEM investigations of the cross-sections and Marianne Penoy, MSc. (CERATIZIT Luxembourg s.àr.l.) for the GDOES measurements. The financial support by the Austrian Federal Ministry for Digital and Economic Affairs and the National Foundation for Research, Technology and Development is gratefully acknowledged.
© 2021 The Author(s)