The Study On The Microstructure And Properties Of Vacuum Fusion Sintering Nickel-base Alloy Coating With Rare Earth Joined

The Ni-base self-fluxing alloy coating was obtained by the technique of vacuum fusion sintering on the 45 steel. In virtue of X-ray diffraction, SEM and EDX, the microstructure and phase-structure of coating were investigated. This paper also studies the active mechanism of rare earth elements on chemical component, microstructure and properties of vacuum fusion sintering Ni-base alloy coating in the way of examining and evaluating in hardness, wear resistance, corrosion resistance and oxidation resistance of such alloy. The database of basis parameters is established in this paper. The results show that with the addition of rare earth elements (Ce, La, Y) , the distribution of chemical elements, microstructure and properties of vacuum fusion sintering Ni-base self-fluxing alloy coating changes remarkably. Such kind of change can be described as the followings. Firstly the microstructure of coating is composed of Ni-base solid solution and a lot of massive, globular and needle harden-phases CrB, Ni3B, Cr7C3, Cr23C6, Cr3Ni5Si2 in the solid solution. Secondly the metallurgical bonding between the matrix and coating has been realized. Thirdly the NiCrBSiRE coating containing rare earth element make needle microstructure vanished, lamellar and globular phase deposited, and precipitate new phases-NiB and Ni2B. Fourthly rare earth elements change the distribution of Cr, Ni and B among the coating and make the content of Cr, Ni and B in Ni-base solid solution and some harden-phases rises. Fifthly rare earth elements also hinder the diffusion of Fe atom from matrix to coating and hold back the dilution of Fe, ensuring the chemical composition of the coating. Sixthly the hardness of coating surface and the micro-hardness of Ni-base solid solution and some harden-phases have been largely increased. Seventhly the micro-hardness of transition area between the matrix and coating changes more mildly and the peak value of hardness appearing in the coating side 0.5 mm~0.7mm to transition area is much higher than the coating without RE. Eighthly the wear resistance, corrosion resistance and oxidation resistance of coating are enhanced. Ninthly the corrosion resistance of coating is better in NaOH, NaCl and H2SO4 solution and worse in HC1 and worst in HNO3. Lastly in contrast with different RE element and different addition content, the properties of coating with 0.3% compound rare earth is most excellent. The database using Fox to establish makes the memory and citation of a great lot data convenient and shortcutting.