Research On Preparation And Tribological Properties Of Nickel-based Composite Coating Containing Graphene

In this paper, we discussed the preparation methods of graphene and its nickel based composite coating, its tribological properties were also studied.We used redox method to prepare graphene. SEM and TEM were used to observe morphologies of graphene, XRD, Raman spectra, FT-IR and XPS were used to analyze the phase and composition. Then we compared the influence of different reducing agents on the quality of graphene.Using double pulse electrodeposition method to prepare the graphene/nickel based composite coatings with different graphene addition, under different plating temperature and different plating time on 45# steel surface. Micro hardness tester and surfagauge were used to evaluate the mechanical properties of composite coating, optical metallographic microscope and SEM were used to observe cross sectional and surface morphologies, XRD, EDS and XPS were used to analyze phase and composition. Then we tested its tribological properties by pin on disk friction machine under dry friction condition by using Si3N4 ball, and used SEM, EDS and Raman spectra to observe morphologies and analyze composition of wear track. Meanwhile, we prepared diamond and CNT nickel based composite coatings by using the same method and compared them with graphene nickel based composite coating.The results show that, graphite oxide was prepared by improved hummers method, 80% hydrazine hydrate, trihydrate sodium acetate and sodium oxalate were used as reducing agents respectively to reduce graphite oxide. Using Hydrazine hydrate can obtain better quality of graphene.The average thickness of graphene/nickel based composite coating is about 85±5μm, and it increases gradually with the increase of addition amount of graphene. The content of graphene in the composite coating increases with the increase of graphene in the plating solution. Graphene can reduce the average grain size of composite coating. The hardness also increases.The friction coefficient of graphene/nickel based composite coating decreases with the increase of addition amount of graphene. When the content of graphene is more than 0.3g/L, the friction coefficient is less than pure nickel, about 0.6. Compared with pure nickel coating, the wear rate decreases about 10%, revealing that graphene can reduce the friction coefficient and wear rate concurrently. When changing plating temperature, the surface of composite coating becomes uniform with the rise of temperature. Besides, the wear track begins to appear oxidation and peel off. XRD and Raman spectrum both show the strongest peak at 60 ℃. Friction and wear test shows the lowest friction coefficient of composite coating at 60 ℃ and 6h.