Effect Of Rare Earth On Microstructure And Properties Of Ni60 Self-fluxing Coating

The Ni60 self-fluxing alloy coatings and Ni60 + RE self-fluxing alloy coatings were obtained by the high frequency induction remelting and the vacuum fusion sintering on the surface of 45 steel. The microstructure and phase structure of the coatings, composition distribution and structure characteristic of interface between coating and substrate were studied using XRD, SEM and EDX. And through measuring and analysis to the coating microhardness and the corrosion-resisting, the affecting mechanisms of RE on the composition, structure and properties of coatings were discussed.The results showed that:1. The binding between Ni60 alloys coatings and substrate metal (45steel) forms good metallurgy union; The RE added in Ni60 alloy coating makes the external apparent quality of the coatings be improved greatly and its morphology is more even and compact.2. The structures of Ni60+RE alloys coatings obtained by both high frequency induction remelting and vacuum fusion sintering have significantly changed compared with that of pure Ni60 coating, that is, the structure of the latter is mainly composed by Ni-base solid solution and a lot of compounds such as CrB,NiB,Cr7C3,Fe3C;However, besides above phase constitutions, the Ni60+RE alloys coating obtained by high frequency induction remelting includes some new phase such as Ni2B;the Ni60+RE alloys coating obtained by vacuum fusion sintering includes not only Ni2B but also small amount of Ni3B;3. The RE added in Ni60 alloy coating changes the element distribution of Cr, Ni and B, which makes the element distribution of Cr, Ni and B in the interface between coatings and substrate, middle and upper parts of the coating have been changed;4. Compared with the pure Ni60 alloy coating, the surface microhardness of Ni60+RE alloys coatings have been increased, and the microhardness of interface between coatings and substrate also greatly enhanced;5. Compared with the corrosion resistance of pure Ni60 coating, the Ni60+ 0.3%CeO2 coating made by induction remelting shows the worse corrosion resistance; The corrosion resistance of Ni60+RE coatings prepared by the vacuum fusion sintering have been increased in different degrees;6. Contrasting to the effects of three different rare earth elements, the modification results of 0.3%RE (0.15%CeO2+0.15%La2O3) is most obvious.