Study On Wear Resistance And Corrosion Resistance Of Nitrogen-doped By Laser Grapheng-based Coating On 45 Steel

Iron and steel materials play an irreplaceable role in the marine,aerospace and chemical fields because of their excellent performance.However,when they are in corrosive and wear conditions,they are easily subject to corrosion and wear alone or in interaction.Graphene,a two-dimensional material with single atomic thickness,has weak interlayer interaction,electrical properties and good physical and chemical stability,which makes graphene show great potential as a lubricating additive and ultra-thin protective coating.However,the research on graphene in the field of metal protection is far from enough at present,and there are many problems in the preparation process.Therefore,how to quickly prepare graphene layers on metal materials to improve the wear resistance and corrosion resistance of steel has important practical significance for the application of materials.In this paper,45 steel is taken as the research object,graphene layers are rapidly prepared on steel through the interaction mechanism between laser and graphene,and the wear resistance,corrosion resistance and corrosion resistance are explored,aiming at improving different properties and expanding its application in different fields.The main results are as follows:(1)A method for preparing graphene layer on metal surface is proposed.Laser is selected as heat source,graphite as carbon source and nickel plating layer as catalytic layer.Graphene layer is rapidly prepared on the metal surface after nickel plating by laser irradiation with preset graphite,and the influence of laser process parameters on graphene formation is systematically studied.TEM and AFM tests show that the graphene prepared under the optimal laser parameters has few layers of graphene.XRD tests show that fcc lattice structure suitable for graphene growth grows on the surface of 45 steel substrate after nickel plating,and(002)crystal plane corresponding to graphene structure is also detected.XPS results show that under the protection of auxiliary gas,when laser interacts with carbon source,the harm caused by oxidation can be better avoided.(2)The properties of graphene coating prepared under the optimal laser parameters were analyzed.Graphene coating shows the highest microhardness and bonding strength,which is attributed to the stable interface bonding between coating and substrate under the action of laser.The friction and wear tests show that the average friction coefficient of graphene coating is the lowest,and the wear rate is lower.Electrochemical test shows that the corrosion rate of graphene coating is much lower than that of 45 steel,which is reduced by about 30 times.At the same time,it shows the highest charge transfer resistance and the lowest equivalent capacitance of electric double layer,which represents the smallest activated corrosion area of graphene coating.Finally,the corrosion and wear results of simulated working conditions under the impact of high-speed seawater and the wear of sand and mud show that the weight loss of graphene coating is only 2.96 mg/cm~2after 12 hours of testing,indicating that it has better protective performance for the substrate.(3)N-doped graphene coating(NG-coating)was successfully prepared on the substrate by mixing graphite powder and melamine powder.Friction test shows that the properties of NG-coating and G-coating are similar in the short term,but in the long term,G-coating is prone to oxidation,resulting in the failure of lubricating film,and NG-coating shows more stable wear resistance.In the corrosion test,the charge transfer resistance of NG-coating is the highest,which indicates that the conductivity of the substrate decreases after nitrogen doping,and even after soaking in corrosive medium for 24 h,it still maintains stable corrosion resistance.Corrosion test shows that the average weight loss of NG is 2.38 mg/cm~2,which shows better performance in actual working conditions.