Dr. Nina Schalk

Montanuniversität Leoben, Austria
Nina Schalk has been working on the synthesis and characterization of thin filmssince 15 yearsand is head of the research group “Advanced Surface Engineering” at the Department of Materials Science at Montanuniversität Leoben, Austria. In 2022 she was promoted to the rank of an Associate Professor in Surface Engineering. Nina Schalk has published more than 70 articles in internationally peer-reviewed journals (h-index 22, Scopus). She is member of the editorial board of the journal Surface & Coatings Technology, the ICMCTF long range planning committee and member of the executive committee of the Advanced Surface Engineering Division of the AVS.

Talk title: Unprecedented insights into microstructure-property relations of Ti(Al)SiN coatings by combinatorially applied advanced characterization methods 
Coating systems used to protect cutting tools are becoming increasingly complex, which necessitates the combination of several advanced characterization methods to establish synthesis - structure - property relationships. Here, TiSiN was chosen as model system to demonstrate the necessary insight into the coating structure on the nanoscale. Literature on the formed phases in TiSiN is controversial; while there are reports on the formation of a single-phase TiSiN solid solution, the majority of publications reports the formation of a nanocomposite structure. However, the phase composition of the nanocomposite is equally controversial. Commonly, the formation of Si-free TiN nanocrystals, accompanied by either a crystalline or an amorphous Si-containing phase is reported, but there are also works suggesting the formation of a TiSiN solid solution instead of the Si-free phase. To illuminate the formation of a nanocomposite structure versus a TiSiN solid solution, a series of TiSiN model coatings was synthesized. By the combination of (high temperature) X-ray diffraction, transmission electron microscopy, atom probe tomography and Doppler broadening spectroscopy of the positron annihilation lines as well as annealing treatments and differential scanning calorimetry, the structure of these model coatings was investigated in detail. In addition, the experimental studies were complemented by density functional theory calculations, shining light on the effect of the Si content, defects and the deposition atmosphere on the formed phase(s). The combination of these experimental and simulation methods allows to gain a novel and previously not accessible insight into the complex correlation of deposition conditions and structure of TiSiN coatings, providing answers to open questions under debate for almost three decades, i.e. nanocomposite versus solid solution formation in TiSiN coatings. The presented approach enables the establishment of a solid basis for the development of coatings with outstanding properties.