Nitrogen alloyed MoSe2 coatings – Role of optimized morphology, structure and mechanical properties on diverse environment sliding performance

Transition metal dichalcogenide (TMD) coatings are gaining increasing interest among the scientific community as eco-friendly solutions for reducing friction, improving energy conservation, and lowering carbon footprints. N-alloyed MoSe₂ coatings (MoSeN), a subset of TMDs, remain largely underexplored, with no research on their frictional performance across various sliding environments. Herein, an in-depth analysis of DC-magnetron sputtered MoSeN coatings is presented, with N content varying from 0 to 42 at%. Investigation of composition, morphological features, crystal structure, mechanical strength and sliding performance are accessed. Our findings revealed that N additions resulted in increased compactness, amorphous structure and hardness of ∼4.6 GPa, and these improvements remained consistent despite compositional variations. The sliding competency was evaluated under six different conditions, revealing promising results in ambient-air and dry-N₂ atmospheres at room conditions and 100 °C. At 200 °C, the sliding performance in ambient-air was better than dry-N₂. Friction coefficient for N-alloyed coatings was relatively close, ranging between 0.03 and 0.06, except for a dry-N₂ environment at 200 °C. Nevertheless, wear rate showed slight variations, with higher values observed in dry-N₂ at 100 °C and 200 °C but remained within a specific range of 1–7 × 10⁻⁷ mm³/Nm for all other conditions. This study highlights the potential of MoSeN coatings to be scaled for industrial applications, offering a roadmap for reducing the inherent limitations of PVD sputtering.