Properties Study On In-situ Synthesized Mo₂C-MoB(Ni₂Si)/Cu Composite Coating By Laser Cladding

Copper has the advantages of good ductility,high electrical conductivity,and strong thermal conductivity,but due to its low strength and poor wear resistance,its life expectancy will be greatly reduced under high-speed sliding electrical contact conditions.Therefore,it is a great challenge to ensure copper conductivity and thermal conductivity while improving its wear resistance under high-speed sliding electrical contact conditions.The preparation of a wear-resistant coating on the copper surface is an effective method.Laser cladding has the advantages of high efficiency,automatic operation,low pollution,cost saving,metallurgical bonding between coating and substrate,and high hardness and wear resistance of Mo₂C,MoB and Ni₂Si enhanced phases.This paper uses laser melting in situ synthesis to prepare Mo₂C-MoB/Cu and Mo₂C-Ni₂Si/Cu composite coatings on copper surface,which effectively improve the wear resistance of copper.In this paper,two kinds of Mo₂C-MoB/Cu and Mo₂C-Ni₂Si/Cu composite coatings were prepared by laser melting in-situ synthesis technique,and the physical and mechanical properties of the composite coatings were analyzed under different laser energy densities and different reinforcing phase contents.at an energy density of 21.67k J/cm² and reinforcing phase content of 15wt.%,excellent performance of Mo₂C-MoB/Cu composite coatings were successfully prepared.Mo₂C-MoB/Cu composite coating with a relative density of about 98.2%,microhardness of about 523 HV_0.2,and electrical conductivity of about 21%IACS was successfully prepared at an energy density of 26.67k J/cm² and an enhanced phase content of 17wt.%.The relative density was about 98.8%,the microhardness was about 439 HV_0.2,and the electrical conductivity was about16%IACS.The morphology,composition,and interfacial bonding of the phases in the Mo₂C-MoB/Cu composite coating and Mo₂C-Ni₂Si/Cu composite coating were analyzed by OM,XRD,SEM,and TEM,and it was found that the Mo₂C-MoB/Cu composite coating The Mo₂C and MoB phases are free of defects and impurities at the interface with the substrate and are uniformly distributed in the coating.The Mo₂C and Ni₂Si phases are free of defects and impurities at the bond with the substrate and are uniformly distributed in the coating.In the electric ablation performance experiments,both composite coatings showed obvious signs of electric ablation during the increase of current from 50 kA to 150 kA,and the electric ablation resistance of the Mo₂C-MoB/Cu composite coating was higher than that of the Mo₂C-Ni₂Si/Cu composite coating.In the frictional wear performance experiments,the wear mechanism was mainly abrasive wear when the current was not loaded.When the current was loaded,adhesive wear and arc corrosion wear were the main wear mechanisms.