Effect of Pulse Bias Voltage on Solid Lubrication Behavior of Magnetron Sputtered MoS₂ Coatings

The MoS₂ coatings, as a solid lubrication material for nuclear fusion reactor, were deposited by single-polarity pulse magnetron sputtering on substrate of iron-based alloy A286. The influence of the pulse bias voltage on the microstructures, interfacial adhesion and tribological properties of the coatings was investigated with X-ray diffraction, scanning electron microscopy, energy dispersive spectroscopy and mechanical probes. The results show that the pulse bias voltage had a major impact. For example, as the bias voltage increased from 300 to 800 V, the interfacial adhesion changed in a decrease-increase mode, accompanied by an increase-decrease variation in the grainsize; grown at 800 V, the MoS₂ coating had the lowest defect-density, highest compactness, weakest internal stress, and strongest interfacial adhesion, because of high-energy particles bombardment. The preferential island growth orientation and friction also depended on the pulse bias voltage; and the abrasive wear mechanism dominated.