Mechanical and tribological characterization of nanostructured HfB2 films deposited from compound target

Abstract

Fabrication and development of HfB2-based nanostructured coatings was investigated. All films were deposited on stainless-steel substrates by RF magnetron sputtering from stochiometric HfB2 target in argon atmosphere. The aim of this work is to evaluate the effects of the bias potential on the microstructure, mechanical and tribological properties. These parameters strongly depend on the experimental conditions. X-ray diffraction analysis indicated the difference in microstructure: from dense hexagonal structure with (0001) preferred orientation of nanocrystallites to quasi-amorphous with blurred HfB2 phase peaks. All coatings were measured using nanoindentation (using Berkovich tip), tribology (ball-on-disk) and nano-scratch (friction). Coatings with a thickness of 1–2 µm had a significant dependence of properties on the microstructure: hardness drastically increased from 8 to 45 GPa, H/E ratio and elastic recovery changed respectively: 0.04–0.15 and 0.26–0.72.