J.M. Gonzalez-Carmona, C. Ortega-Portila, G.C. Mondragon-Rodriguez, Center for Engineering and Industrial Development (CIDESI), Santiago de Querétaro, Mexico
Titanium aluminum oxynitride (TiAlON) and niobium-doped titanium aluminum oxynitride (TiAlNbON) coatings were deposited on AISI D2 steel substrates by the reactive cathodic arc technique. Structural characterization was obtained through X-ray diffraction (XRD). The findings for TiAlON revealed crystallographic orientations akin to titanium aluminum nitride (TiAlN). In the case of TiAlNbON, the separation of the titanium aluminum oxides phase (Al₂TiO₅) was identified, rendering it a polycrystalline and polyphase coating. This was confirmed through transmission electron microscopy (TEM) analyses. The surface morphology revealed macroparticles or "droplets," characteristic of cathodic arc films, contributing to an approximate 50% increase in substrate roughness. A nanohardness value of 12.85 ± 2.85 GPa was obtained for the coatings, indicating an increase in the elastic modulus and resistance to plastic deformation, particularly for TiAlNbON. This led to an enhancement in adhesion for the Nb-doped coating by up to 80%. The tribological analysis, conducted via pin-on-disk at temperatures of 25 °C, 500 °C, 700 °C, and 900 °C, revealed that when the combination of oxidation and tribo-oxidation influences the wear process, the ability of Nb to modify the diffusion of oxygen and stabilize the oxides contributes to a reduction in wear. This transition occurs from abrasion mechanisms at low temperatures to combined abrasion-adhesion mechanisms at high temperatures.