Tribological behavior of a Ni-WS2 composite coating across wide temperature ranges

• Published in: Rare metals 2019-11, Vol.38 (11), p.1078-1085
• Main Authors: Cui, Shuai, Li, Wen-Sheng, He, Ling, Feng, Li, An, Guo-Sheng, Hu, Wei, Hu, Chun-Xia
• Format: Article
• Language: English
• Subjects: Biomaterials; Cathodic polarization; Chemistry and Materials Science; Coefficient of friction; Electroplating; Energy; Friction; Friction reduction; Low carbon steels; Lubrication; Materials Engineering; Materials Science; Metallic Materials; Nanoscale Science and Technology; Nickel coatings; Physical Chemistry; Scanning electron microscopy; Substrates; Tribology; Wear mechanisms; X-ray diffraction
• ISSN: 1001-0521; 1867-7185
• DOI: 10.1007/s12598-018-1152-5

In order to reduce the friction coefficient of a pure nickel coating and extend the lifetime of metal parts under extreme friction conditions, a series of Ni-based WS 2 -composite solid lubrication coating containing different WS 2 concentrations were prepared on a 45# mild carbon steel substrate by electroplating. The cyclic voltammetry method was used to investigate the electroplating regulation of the Ni-WS 2 composite coatings. X-ray diffraction (XRD) and scanning electron microscopy (SEM) were used to analyze the microstructures and wear surfaces of the composite coatings, the tribological properties and wear mechanisms of the composite coatings with different WS 2 concentrations. The results show that the addition of WS 2 can promote the cathode polarization of the electroplating process, and the polarization degree goes up with the increase in WS 2 concentrations. The friction coefficient of Ni-composite coatings significantly decreases by the addition of WS 2 particles. The lowest friction coefficient at room temperature is obtained at a value around 0.01–0.03 from the coating deposited in the electrolyte solution with a 30 g·L −1 WS 2 concentration. The friction coefficient of the Ni-WS 2 composite coating remains in 0.01–0.03 with the increase in temperature from room temperature to 300 °C. When the temperature goes up to 500 °C, the friction coefficient manifests a continuous increase to 0.12, because WS 2 is gradually oxidized into WO 3 and therefore loses its lubrication ability.