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T. Glechner, C. Tomastik, E. Badisch, P. Polcik, H. Riedl:
"Influence of WC/C target composition and bias potential on the structure-mechanical properties of non-reactively sputtered WC coatings";
Surface & Coatings Technology, 432 (2022), 128036; 1 - 8.

Physical vapor deposited WC based coatings strongly vary in their microstructure ranging from multi-phased columnar-crystalline up to nanocomposite coatings in relation to the usage of reactive or non-reactive carbon sources. Within this study, we investigated in detail the influence of additional carbon implemented into WC based target mmaterials as well as bias potential on the structure-mechanical properties of non-reactively sputtered WC coatings. Providing additional graphitic carbon within WC targets promotes the formation of nanocrystalline morphologies. Increasing bias potentials dominate the transition from a nanocrystalline to a columnar-crystalline morphology obtaining also a mixed state in between. The change in morphology is accompanied by a large modification in mechanical properties with hardness values ranging from 27 to 39 GPa, respectively. In addition, high adatom mobility - caused by bias potentials up to −200 V - predominates the phase formation of crystalline WC coatings changing from face-centered cubic (fcc)-WCx to competing W2C based structures. The W-C phase formation is furthermore examined using DFT calculations.

http://dx.doi.org/10.1016/j.surfcoat.2021.128036

https://publik.tuwien.ac.at/files/publik_304056.pdf