Abstract:In order to reduce the friction coefficient of Ni-base alloy coating and further improve its wear resistance, Ni-base alloy composite coatings modified by both graphite and TiC particles were prepared by plasma spray technology on the surface of 45 carbon steel. The results show that friction coefficient of the composite coating is 47.45% lower than that of the Ni-base alloy coating, and the wear mass loss is reduced by 59.1%. Slip lines and severe adhesive plastic deformation are observed on the worn surface of the Ni-base alloy coating, indicating that the wear mechanisms of the Ni-base alloy coating are multi-plastic deformation wear and adhesive wear. A soft transferred layer abundant in graphite and ferric oxide is developed on the worn surface of the composite coating, which reduces the friction coefficient and wear loss in a great deal. The main wear mechanism of the composite coating is fatigue delamination of the transferred layer.

Key words: Ni-base alloy; plasma spraying; composite coating; graphite; TiC; tribology