**4. Conclusions**


**Author Contributions:** Conceptualization, K.P., P.H. and M.T.; formal analysis, K.P., A.S., P.H.; investigation, K.P. ´ and P.H.; methodology, K.P. and P.H.; writing–original draft, K.P., A.S.; writing–review and editing, K.P., A. ´ S., P.H. ´ and M.T. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research was supported by the Polish Ministry of Science and Higher Education (Poland), grant number 16.16.110.663 (AGH University of Science and Technology).

**Acknowledgments:** The authors are grateful to Krzysztof Wieczerzak and Piotr Bała (AGH University of Science and Technology in Krakow-Academic Centre for Materials and Nanotechnology, Poland) for the hardness analysis. Appreciation is also expressed to A.S. Wronski (University of Bradford, UK) for editing the manuscript.

**Conflicts of Interest:** The authors declare no conflict of interest.
