Preparation And Investigation Of Tribological Properties Of Sulfide Layers On The Surface Of Different Laser Cladding Coatings

Laser cladding can improve the wear reduction and corrosion resistance of the materials,the coatings prepared by laser cladding can obtian high hardness.However,such coatings are easy to excessive wear of mating plate.In order to provide optimum wear protection for easily worn components,it is necessary to adopt a solid lubricant coating to reduction friction.The composite layer prepared by laser cladding and sulfurizing can improve wear reduction obviously.In this paper,the sulfrizing layer was prepared on the different laser claddings by low temperature ion sulphurizing technology.The surface morphologies,phase structures and wear resistance at the composite treated layers were analyzed by SEM,XRD,AES,AFM and bench test instrument.The effects of powder materials and the parameters on the forming quality of cladding coatings were systematically studied,the different laser cladding coatings with good formlity were achieved by adjusting scanning speed under the condition of 3.3kW and the overlapping rate is 30%.The sulfide layers with a bit thickness were were achieved on different laser cladding coatings by measures of designing tooling,using auxiliary sulfurizing workpiece and controlling parameters.The characterization results of surface morphologies show that the surface of the composite layer is loose and porous,and the average diameter of sulfate particles is about 80nm-150nm.Sulfide layer and cladding layer is chemically integrated in a sawtooth staggered way.The thickness of composite layer on Fe based laser cladding coatings is about 4-5um,while the composite layer on N i and Co based laser cladding coatings is about2-4um.The different composite modified layer compose of martix phase from cladding layer and solide solution.CXCry is the mainly strengthen phase in the composite layers.The Fe-based laser coatings mainly compose of?Fe,Cr?,Cr-Fe-C,Cr₂₃C₆,Fe_x C_y and so on;The Ni-based laser coatings mainly compose of Fe-Ni,Cr-Ni-Fe-C?Cr₂₃C₆?WC and so on;The Co-based laser coatings mainly compos of Fe-Co-C,Cr₇C₃,WC and so on.FeS is the mainly lubricated phase in Fe based composite midified layers,while the FeS,WS₂ are both mainly lubricated phase in N i and Co based composite midified layers,which teseed by XRD and XPS.A ball-on-disc wear tester was adopted to evaluate the tribological properties of different composite layer.Results indicate that high performance co mpound modified layer which has better anti-friction,wear resistance and anti-scuffing properties,will make wear mechanism changed to mild abrasion from severe adhesive and abrasive wear.The friction coefficient reduced to 1/2 at least.In addition,sulfurizing treatment could reduce the effect of load on friction coefficient.Under medium and low load,the friction-reducing,wear resistance and anti-scuffing performances of cladding layer can be significantly presented,while with the increase of speed and load,the superiority of sulfide layer's lubrication performance will definitely decreasing.The ability of different composite layers is different because of the differerces between the laser cladding coatings.It can be ranked by the order of Co base d composite layer-Ni Co based composite layer-Fe based composite layer according to the extend of anti-scuffing and tribological properties.Based on the above analysis,the influence of differern coatings on composite layers mainly focus on the preparatio n and the exertion of potion on anti-scuffing.The elements of sulfide mainly come from laser cladding coatings and the auxiliary work piece,so the thickness and other characteries of sulfide layers are different on different coatings.The differences of properties on nti-scuffing and tribological properties with different coatings mainly determined in the hardness and microstructure of substrate respectively.