Speaker
Description
Thin-film materials research is a highly interdisciplinary field of considerable importance for numerous technological applications. In addition to their chemical composition and electrical, optical, and mechanical properties, a thorough understanding of their structure and morphology is essential for fully exploiting their potential and optimizing fabrication processes. This short lecture provides an overview of the characteristic aspects of laboratory X-ray structural analysis of hard coatings.
Hard layers and coatings are widely used in industry to improve the mechanical and tribological properties of carrier material, for example in manufacturing tools, or as protective barriers against corrosion and oxidation at high temperatures. Recent research showed that boron-based nanostructured hard coatings exhibit very promising thermal and mechanical properties. Our recent research focused on transition metal borides (TMB$_{x}$) hard coatings deposited by DC magnetron sputtering and also by its novel development High Power Impulse Magnetron Sputtering. Selected examples include material systems: V-TM-B$_{x}$, Zr-Ta-Si-B$_{x}$, TiB$_{x}$/TaB$_{x}$ and ZrB$_{x}$/TaB$_{x}$ superlattices. Multilayer architecture is one of possible approaches to improve hardness and fracture toughness simultaneously.
The several examples of X-ray structural analysis of transition-metal boride around um thick coatings prepared by various sputtering deposition techniques demonstrate the development of pronounced uniaxial texture depending on deposition geometry. The phase composition and phase transformations are also strongly influenced by the deposition conditions and subsequent thermal treatment.
In general, the limited thickness of thin films and coatings, typically in the range of a few nanometers to several micrometers, influences the measured diffraction intensities through the product of the X-ray attenuation coefficient and the film thickness. Because the X-ray penetration depth generally exceeds the coatings thickness, grazing-incidence X-ray scattering techniques are commonly used to restrict the probed volume to the thin coating itself, thereby minimizing the contribution from the substrate.
Although texture characterization and grazing-incidence X-ray scattering techniques are routinely performed at synchrotron facilities, basic structural characterization can, to a considerable extent, also be carried out using standard laboratory-based X-ray instrumentation.
Acknowledgements
The authors gratefully acknowledge the support by the Slovak Research and Development Agency (Grant No. APVV-24-0038) and support under the Operational Program Integrated Infrastructure for the project: Advancing University Capacity and Competence in Research, Development and Innovation (ACCORD ITMS2014+:313021X329), co-financed by the European Regional Development Fund.
