Tribological and mechanical properties of ZrxNy films obtained by HiPIMS in DOMS mode

Abstract

Maritime transportation represents one of the biggest industries worldwide. The functionality improvement of critical ship parts such as sea chest gratings could mean substantial impacts in fuel consumption reduction, larger lifetime span or reduction of non-indigenous sea species transportation. Since 2008, the ban imposed by the international maritime organization over polluting products, especially tributyltin, created the need to explore new sustainable and environmentally friendly alternatives. Multifunctional coatings have the potential to overcome this situation, creating highly tuneable materials able to combine properties according to the naval industry's needs. Zirconium nitride is known for its reliable mechanical and anti-corrosion properties, critical in a multifunctional coating used in the sea. In the present study, this material was obtained through high-power impulse magnetron sputtering technology in a reactive atmosphere (R-HiPIMS). SEM, EDS, AFM and XRD were used to assess the coatings. Also, the films’ mechanical properties and adhesion were assessed via nanoindentation and progressive load scratch tests, respectively. The pin-on-disk test was used to assess the coatings' tribological properties under dry and wet (3.5% wt. NaCl solution) conditions. The results demonstrate that the increase in hardness was directly influenced by the changes in the structure promoted by the nitrogen rise, from 16 GPa to 25 GPa, with a nitrogen increase in film composition from 47% to 54%. Besides, the tribological tests revealed the key role of an oxygen-rich tribolayer and surface roughness features (skewness and kurtosis) in keeping the film’s integrity. The ZrxNy films obtained by HiPIMS improved the mechanical and tribological properties compared to ZrN obtained by DCMS, opening new possibilities to be explored as a solution inside a multifunctional coating system.