Microstructure and tribological property of Ni-MoS2 composite coatings prepared by ultrasonic and mechanical stirring electrodeposition

To optimize the deteriorated mechanical properties of the loose MoS2 coatings, ultrasonic oscillation was employed to change the deposition mode of MoS2 particles, hence their structure and mechanical properties. The electrodeposition of Ni-MoS2 self-lubricating composite coating was assisted by magnetic stirring (Mag-NM) or ultrasonic oscillation (US-NM), respectively. A comparison of coating structure, depositing mechanism, and friction performance was investigated by means of XRD and SEM. Moreover, the influence of MoS2 concentration on the coating morphology and the friction performance was explored. The results demonstrated that the Ni-MoS2 composite coatings have superior antifriction performance compared to pure Ni coating. Comparing to the porous structure of Mag-NM coatings, the US-NM coatings obtained compact structures with well-dispersive MoS2 particles. There is 80.4% hardness reduction occurred on the Mag-NM coatings, but only 8.8% reduction of the US-NM coatings. With the increase of MoS2 concentration, a clear and continuous wear trace was formed on the Mag-NM coatings. The protrusion grinding indicates the excellent wear resistance of the US-NM coatings.