Study On Friction And Wear Properties Of Fe(WC)/Ni(WC)Composite Coatings Prepared By Twin-wire Arc Spraying

In the present study,the twin-wire arc spraying(TWAS)equipment(Thermion,USA)and two different types of cored wires(Oerlikon metco,Switzerland)were choosed to prepare a metal-based ceramic Fe(WC)/Ni(WC)composite coatings on the surface of 316L stainless steel substrate successfully.The microstructure,phase composition,microhardness and thermostability of the coating were investigated and determined by the scanning electron microscope(SEM)equipped with energy-dispersive X-ray spectroscopy(EDS),X-ray diffraction(XRD)patterns,vickers microhardness tester(ARTCAM-130SSI-BW)and thermal gravimetry(TG)and differential scanning calorimeter(DSC)thermal analyzer(SETRAM Syesysl6),respectively.In addition,electrochemical workstation(RST5000),white light interferometer(Contour GT,USA)and ball-on-disc multifunctional friction tester(UMT TriboLab,USA)and other equipments was used to study the electrochemical corrosion resistance of the coating at different corrosion medias and different solution concentrations.And the friction and wear properties and wear mechanisms of the coating were tested under different temperatures and loads.The results show that.(1)The combination of coating and substrate is mechanically combined,the coating exhibits a good adhesion with substrate.The microstructure of the coating shows a typical lamellar structural characteristic and has a dense microstructure,different elements in the coating evenly distributed,no element enrichment phenomenon.The porosity of the coating is 5.74%.And the phase analysis shows that the coating is mainly composed of bonding phases Fe3Ni2 and(Fe,Ni)consist of Fe-Ni and C-W composed of binary eutectic reinforced phases WC and W2C,the reinforced phases are evenly surrounded by bonding phases,which plays a dispersion enhancement in the coating,and which is conducive to improve the wear resistance of the coating.The average microhardness of the coating is 714HV0.1,the high hardness of the coating is conducive to the wear resistance of the coating.(2)The coating shows a good corrosion resistance in different concentrations of H2SO4 and HNO3 solutions,the order of magnitude is 10-4(A·cm-2)of self-corrosion current density,which indicates that the corrosion rate of the coating is lower.With the increase of solution concentration,the corrosion rate of the coating increases gradually,but the increase rate of the corrosion rate in the concentrated H2SO4 decreases,which shows that the corrosion resistance of the coating in the concentrated H2SO4 is better than that of the dilute H2SO4.At the same time,the corrosion tendency and corrosion rate of the coating in the H2SO4 solution are lower than the corrosion tendency and corrosion rate in the HNO3 solution.That is,the corrosion resistance of the coating in H2SO4 solution is better than that in the HNO3 solution.(3)The coating shows different friction and wear properties and wear mechanisms under different friction parameters.When the load and sliding speed are constant,the friction coefficient and wear rate of the coating increase with the increase of temperature,while at high temperature 550?,the friction coefficient of the coating decreases due to the thermal softening and high temperature oxidation.However,the coating exhibits a negative increase in wear loss due to the adhesion of abrasive debris and transfer of grinding ball material.At lower temperatures(below 350?),the wear mechanisms of the coating is mainly plastic deformation peeling wear,slight fatigue wear and abrasive wear.At high temperatures(above 350?),the wear mechanisms of the coating transforme into a combination of plastic deformation,abrasive wear,slight adhesion wear and oxidation wear.When the coating is under lower loads(bolow 30N)and with the increase of load,the friction coefficient decreases and the wear rate increases of the coating.However,the friction coefficient and wear rate decreases a little under high load(above 30N).The wear mechanisms of the coating under different loads are the main plastic deformation,slight fatigue wear and abrasive wear,and with the increase of the load,the plastic deformation and abrasive wear increase,and at higher loads,a slight oxidation wear occurs due to the effect of friction temperature rises.