FeS solid lubrication duplex layer was prepared on the surface of 45 steel by ion nitrocarburizing and ion sulphurizing process. The sulphide grains in micron and nano scale and holes distributing equably on the duplex layer. The duplex layer is composed of FeS, FeS2 and Fe3N. Under liquid paraffin oil with 0.2wt%n-Fe3O4 lubricating, the synergistic effect between n-Fe3O4 and the duplex layer is produced, and the chemical reaction films including sulphide, sulphate and nitride is formed, which makes the friction factor of the duplex layer keep being the lowest and about 0.075, and the volume loss is reduced by 91% than that of the plain surface, and reduced by 89% and 21% than that of the sulphurized surface and the nitrocarburized surface, respectively.
The composition of FeS solid lubrication duplex layer on 45 steel surface was studied by using SEM, EDS, AES and XPS. The results show that the sulphurized surface layer of FeS solid lubrication duplex is composed of the sulphide aggradation layer deposited on the nitrocarburized sub-surface layer and the sulphide diffusion layer formed by some S element infiltrating the nitrocarburized surface. The sulphide aggradation layer is mainly composed of FeS and FeS2, the key composition of the sulphide diffusion layer is FeS, and Fe(2/3/4)N is the key composition of the nitrocarburized sub-surface layer. The result of friction reduction and wear resistance test combined with the composition of FeS solid lubrication duplex layer explains that the friction coefficient and wear volume of the duplex layer are lower than those of the plain surface, which attribute to the relatively softer sulphurized surface layer provided self-lubricating property while the harder nitrocarburized sub-surface layer provided sufficient load bearing capacity in view of resistance to plastic deformation, so that spallation failure of the sulphurized surface layer can be effectively avoided, and they exert excellent friction reduction and wear resistance functions in different moments during rubbing process respectively.
FeS solid lubrication duplex layer was prepared on the surface of 45 steel by ion nitrocarburizing-ion sulphurizing process. The sulphide grains and holes all in micron and nano scale and distributing equably in the sulphide surface layer with 10 μm thickness of the duplex layer. The duplex layer is composed of FeS, FeS2 and Fe3N. Under liquid paraffin oil with 0.1wt% n-Al2O3 lubrication, the synergistic effect between n-Al2O3 and the duplex layer is produced, and the chemical reaction films including sulphide, sulphate and nitride is formed, which makes the friction factor of the duplex layer keep being the lowest and about 0.07, and the volume loss is reduced by 97% than that of the plain surface(rubbing for 10 min), and reduced by 92% and 21% than that of the sulphurized surface and the nitrocarburized surface, respectively.
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