Abstract
As an important high-power impulse magnetron sputtering (HIPIMS) parameter, charge voltage has a significant influence on the microstructure and properties of hard coatings. In this work, the Mo–Cu–V–N coatings were prepared at various charge voltages using HIPIMS technique to study their mechanical and tribological properties. The microstructure was analyzed by scanning electron microscope (SEM), X-ray diffraction (XRD), and transmission electron microscopy (TEM). The mechanical and tribological properties were investigated by nano-indentation and ball-on-disc tribometer. The results revealed that all the coatings showed a solid-solution phase of B1-MoVN, the V atoms dissolved into face-centered cubic (FCC) B1-MoN lattice by partial substitution of Mo, and formed a solid-solution phase. Even at a high Cu content (~8.8 at. %), the Cu atoms existed as an amorphous phase. When the charge voltage increased, more energy was put into discharge, and the microstructure changed from coarse structure into dense columnar structure, resulting in the highest hardness of 28.2 GPa at 700 V. An excellent wear performance with low friction coefficient of 0.32 and wear rate of 6.3 × 10−17 m3/N·m was achieved at 750 V, and the wear mechanism was dominated by mild abrasive and tribo-oxidation wear.
Highlights
In recent years, high-temperature self-lubricating coatings have been widely investigated in tribological applications due to the formation of transition metal oxides (e.g., WO3, MoO3, V2O5) [1,2,3,4]
In this work, the Mo–Cu–V–N coatings were prepared by high-power impulse magnetron sputtering (HIPIMS) technique at various charge voltages, and the influence of charge voltage on microstructure and properties of Mo–Cu–V–N coatings was studied in detail
The N/(Mo + V) atomic ratios decreased from 1.05 at 650 V to 0.91 at 700 V, and varied in a small range of 0.86 to 0.95 at higher charge voltages. It implied that the Mo–Cu–V–N coatings were sub-stoichiometric N at higher charge voltages above 700 V
Summary
High-temperature self-lubricating coatings have been widely investigated in tribological applications due to the formation of transition metal oxides (e.g., WO3, MoO3, V2O5) [1,2,3,4]. These lubricious oxides with weak bonding plane could form a series of sub-stoichiometric compounds that were referred to as Magnéli phases [5], which exhibited excellent lubricating effect due to low shear strength [6]. In this work, the Mo–Cu–V–N coatings were prepared by HIPIMS technique at various charge voltages, and the influence of charge voltage on microstructure and properties of Mo–Cu–V–N coatings was studied in detail
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