42CrMo钢表面激光熔覆CuSn12Ni2涂层组织及摩擦性能研究OA

Marine and land wind power equipment often run for a long time under harsh conditions such as heavy and uneven loads,significantly lowering the viscosity and adhesion of lubricating oil and grease and resulting in the failure to form enough boundary films on the surface of the material,so the lubrication effect is not ideal.In this harsh environment,wind electric bearings are easy to fail due to wear or surface spalling,which shortens the service life of wind turbines and causes serious economic losses.Therefore,the work aims to improve the friction performance of(bearing steel simulation workpiece)42CrMo bearing steel,increase its ability to resist wear failure behavior and extend the service life of wind power bearings.CuSn12Ni2 copper alloy cladding layer was prepared on the surface of 42CrMo steel bearing by laser cladding coaxial powder.OM,SEM,EDS,XRD,laser spectral confocal microscopy,micro Vickers hardness tester,nano indentation tester and high speed friction and wear testing machine were used to study the porosity,microstructure and phase composition of the cladding layer,and evaluate the difference between the cladding layer and the substrate in the microhardness,friction coefficient,wear rate and weight loss.At P=2 800 W and V=40 mm/s,the compact defect-free CuSn12Ni2 copper alloy coating was prepared and the porosity was as low as 0.57%.The pore morphology of the CuSn12Ni2 copper alloy cladding layer was mainly regular sphere,which was a typical bubble type.This was closely related to the Marangoni effect,the energy density and the low melting boiling point of Sn during laser cladding.The microstructure was mainly composed of columnar crystals and fine dendrites,and the Cu/Sn elements were evenly distributed,mainly composed of Cu-Sn gold intermetallic compounds and α-Cu solid solution.Due to the existence of oxygen in the air and the friction heat generation,a copper alloy oxide film was formed on the friction surface during the friction process.In the process of non-lubricated or micro-lubricated friction,the oxide film acted as a solid lubricant to form a lubricating layer,prevent the direct contact between the cladding layer and the friction pair,reduce the friction coefficient of the contact surface,and make the wear rate and wear volume of the cladding layer low.By preparing CuSn12Ni2 copper alloy cladding layer,the friction performance of the substrate was greatly improved.The microhardness of the cladding layer and the substrate was 178.6HV0.2 and 243.1HV0.2,respectively.The average friction coefficient of the cladding layer(0.38)was lower than that of 42CrMo bearing steel(0.55).Compared with the substrate,the wear rate of the cladding layer was reduced by 58.33%,which was 22.419×10-4 mm3/(N·m)and 53.806×10-4 mm3/(N·m),respectively,and the mass loss of the cladding layer was only 3/8 of that of the substrate.The wear mechanism of 42CrMo substrate was composed of three-body abrasive wear and scratch wear,while the wear mechanism of the cladding layer was mainly oxidative wear,demonstrating excellent anti-friction performance.Therefore,the laser cladding CuSn12Ni2 coating on the surface of wind power bearings can effectively reduce wear and improve service life.