| As the two main failure models,friction and wear result in huge economic loss.Nickel-iron alloy coating has excellent property;however,hardness,wear resistance and corrosion-resistance still need to be improved to satisfy the need for rapid development in the modern industry.This paper mainly adopts composite electroplating to prepare the iron-nickel graphene composite coating on the 45#steel substrate,and the surface morphology,composition and structure of composite coating have been characterized by SEM,EDS,XRD and Raman spectrum.The process parameters have been optimized using orthogonal experiment and single factor experiment.The effects of different process parameters and heat treatment on the hardness,wear-resistant and corrosion-resistant have been investigated.The results have indicated that:(1)The optimal technological conditions for the preparation of Fe-Ni-graphene composite coating were as follows:graphene concentration 1g/L,current density5A/dm~2,temperature 50°C,time 90 min,stirring speed 300 r/min.The microhardness of the composite coating of iron-nickel graphene is 1158.67 HV under optimal conditions,which is 101.22%and 262.56%higher than that of the iron-nickel alloy coating and the 45th steel substrate respectively.The average friction coefficient of the composite coating is 0.2236.Compared with the iron-nickel alloy coating and the45 steel base,the reduction was 49.16%and 66.60%,respectively.By Raman spectroscopy analysis,graphene nanosheets were confirmed in the iron-nickel graphene composite coating;the diffraction peak of the(111)plane iron-nickel alloy was the strongest,and the average grain size of the iron-nickel alloy coating and the iron-nickel graphene composite coating are 54.71nm and 14.98nm,respectively,indicating that the addition of graphene refines the grains,which results in improved mechanical properties.(2)With the increase of the graphene concentration,the surface roughness and microhardness of the composite coating are first increased and then decreased,and the friction coefficient and the wear rate are also decreased first,then increased and then decreased.With the increase of current density,the surface roughness and microhardness of the composite coatings both increased first and then decreased,and the friction coefficient and wear rate showed a tendency of decreasing first and then increasing.With the increase of bath temperature,the surface roughness and microhardness of the composite coating both increased first and then decreased,and both the friction coefficient and the wear rate decreased first and then increased.With the increase of the stirring speed,the roughness and microhardness of the composite coating both increased first and then decreased,and the friction coefficient and wear rate showed a trend of decreasing first and then increasing.The incorporation of graphene into the iron-nickel alloy matrix improves the micro-hardness of the composite coating,and it also acts as a lubricant,thereby increasing the wear resistance of the composite coating.(3)The composite coating with 1 g/L graphene and current density of 5 A/dm~2has the best corrosion resistance and the corrosion rating is 5,which is higher than that of the iron-nickel alloy coating,and the composite coating after corrosion The hardness is 707.94 HV,which is 32.42%lower than that before corrosion,and the microhardness of the iron-nickel alloy after corrosion is reduced by 64.89%.The graphene nanoparticles are embedded in an iron-nickel matrix,and can form a stable physical barrier layer between the metal matrix and the active medium,and play an important role in protecting the iron-nickel alloy matrix.The graphene also can passivate the plating metal.The role is to further improve the corrosion resistance of the composite coating.(4)With the increase of the heat treatment temperature,the microhardness of the composite coating tends to decrease.When the temperature reaches 600°C,the microhardness decreases to 307.07 HV after 2 h of heat treatment,which is 69.98%lower than that without heat treatment.With the increase of heat treatment time,the microhardness of the composite coating tends to decrease.When the composite coating was heat-treated at 400°C for 300 minutes,the microhardness decreased to397.71 HV,which was a drop of 60.76%when compared with no heat treatment.The average grain size of Fe-Ni alloy before and after heat treatment was 14.98 nm and46.66 nm,respectively.The heat treatment made the grain size of the composite coating increase,and the mechanical properties decreased. |
PDF Full Text Request