Research On Microstructure And Properties Of FeMnCrNi Composite Coating By High Velocity Arc Spraying

As a widely used surface engineering technology,high-velocity arc spraying technology mainly uses electric arc as a high-temperature heat source to quickly melt the material to a molten state,and use compressed air to atomize it into micro-melting droplets.Spray to the surface of the substrate,deposit and solidify into a coating.It has the advantages of simple equipment and easy operation,low use cost,high energy efficiency,good safety,and high coating quality.The high-velocity arc spraying technology is applied to the agricultural machinery industry,and high-performance,low-cost coatings are prepared on the soil-contacting parts of traditional agricultural machinery,which can effectively reduce the failure frequency of the parts,improve work efficiency,and extend the service life.Therefore,this article aims at the problem of poor performance of related soil-contacting parts,combined with the advantages and characteristics of high-velocity arc spraying technology,based on the existing material system,designs and develops coating materials with high hardness,wear resistance and corrosion resistance.,In order to extend the service time of the soil-touching parts of agricultural machinery and reduce resource consumption.The main research contents of this paper are as follows:（1）Coating scheme design and wire preparation:according to the requirements of the application object for the coating performance,it is determined that the Fe-based alloy coating is mainly used,with Mn,Cr,and Ni elements.At the same time,for better coating performance,respectively Adding Cr₃C₂ and Al₂O₃-B₄C ceramic particles to the wire,finally designed three coating schemes,and prepared the corresponding powder core wire.（2）Orthogonal test optimization:for three kinds of coatings,spraying voltage,spraying current and spraying distance are used as test factors,porosity and microhardness are test indicators,according to the orthogonal test of three factors and three levels L9（3³）carry out optimization test on the coating;through visual analysis and analysis of variance to study the influence law of factor level,compare the comprehensive performance of each coating to obtain the optimal process parameters;prepare the coating again according to the optimal process parameter combination,and conduct test verification.The results show that the order of factors affecting the overall performance of Fe Mn Cr Ni coating is:spraying voltage>spraying current>spraying distance;the order of factors affecting the overall performance of Fe Mn Cr Ni/Cr₃C₂ coating is:spraying distance>spraying voltage>spraying current;Fe Mn Cr Ni/Al₂O₃-B₄C coating The sequence of factors affecting the comprehensive performance of the layer is:spraying voltage>spraying distance>spraying current.（3）Research on the structure and mechanical properties:the coatings were prepared under the optimal process parameters of the orthogonal experiment,and the coatings were prepared by scanning electron microscope,energy spectrometer,X-ray diffractometer,and laser confocal microscope.Morphology analysis,element analysis,phase analysis;the microhardness and bonding strength of the coating were experimentally studied by using a microhardness tester and an electronic universal testing machine.The results show that the coating is a typical layered stack structure;the coating and the substrate are mainly mechanically combined.The coating thickness is 400～600μm;surface roughness:Fe Mn Cr Ni/Al₂O₃-B₄C coating>Fe Mn Cr Ni/Cr₃C₂ coating>Fe Mn Cr Ni coating;porosity:Fe Mn Cr Ni/Al₂O₃-B₄C coating>Fe Mn Cr Ni/Cr₃C₂ coating>Fe Mn Cr Ni coating;microhardness:Fe Mn Cr Ni/Al₂O₃-B₄C coating>Fe Mn Cr Ni/Cr₃C₂ coating>Fe Mn Cr Ni coating;bonding strength:Fe Mn Cr Ni coating>Fe Mn Cr Ni/Cr₃C₂ coating>Fe Mn Cr Ni/Al₂O₃-B₄C coating.（4）Research on electrochemical corrosion and friction and wear performance:conduct electrochemical corrosion and friction and wear performance tests on the coatings prepared with the optimal process parameters,and use scanning electron microscope,energy spectrometer,and laser confocal microscope to test the performance of the coating.The surface morphology,cross-section morphology and element changes were analyzed.The results show that the corrosion potential:Fe Mn Cr Ni coating>Fe Mn Cr Ni/Cr₃C₂coating>Fe Mn Cr Ni/Al₂O₃-B₄C coating;corrosion current density:Fe Mn Cr Ni/Cr₃C₂coating>Fe Mn Cr Ni/Al₂O₃-B₄C coating>Fe Mn Cr Ni coating;charge transfer resistance:Fe Mn Cr Ni coating>Fe Mn Cr Ni/Al₂O₃-B₄C coating>Fe Mn Cr Ni/Cr₃C₂ coating;the order of strength of corrosion resistance:Fe Mn Cr Ni coating>Fe Mn Cr Ni/Al₂O₃-B₄C coating>Fe Mn Cr Ni/Cr₃C₂ coating.For Q235 steel and the three kinds of coatings,with the increase of load and reciprocating speed,the friction coefficient shows a downward trend.The influence of reciprocating speed is greater than that of load,and the friction coefficient of Fe Mn Cr Ni/Al₂O₃-B₄C coating is the lowest;while the width of the wear scar On the upward trend,Fe Mn Cr Ni coating and Fe Mn Cr Ni/Cr₃C₂ coating are more affected by load,Q235 steel and Fe Mn Cr Ni/Al₂O₃-B₄C coating are more affected by reciprocating speed,and Fe Mn Cr Ni/Cr₃C₂ coating has the smallest wear scar width.Main wear forms:Q235 steel is abrasive wear and adhesive wear,Fe Mn Cr Ni coating is abrasive wear and adhesive wear,Fe Mn Cr Ni/Cr₃C₂ coating is surface fatigue wear and abrasive wear;Fe Mn Cr Ni/Al₂O₃-B₄C coating is surface fatigue wear.