Research On Ni-based Self-lubricating Composite Coating By Plasma Cladding And Its Tribological Properties

Friction and wear is one of the main failure modes of parts,so it is very important to improve the wear resistance of material surface.Plasma cladding technology has developed into a very mature surface modification technology,which can produce self-lubricating coatings with uniform structure and excellent comprehensive performance.In this paper,based on improving the anti-friction and wear resistance of the material surface,nickel-based materials with excellent wear resistance,corrosion resistance and wettability are selected as the binder phase.A nickel-based coating with ceramic phase Ti₃AlC₂as self-lubricating additive,a composite coating with MoS₂ and a composite self-lubricating coating modified with Ce O₂ were prepared on the surface of HT250 gray cast iron by plasma cladding technology.The analysis and comparison of the macroscopic forming quality,microstructure,microhardness and tribological properties of each cladding layer,as well as its wear mechanism were compared.In addition,the effects of changes in speed,load and lubrication conditions on the tribological properties of the cladding layer were also studied.The results showed that:In the system of Ni60A+Ti₃AlC₂,with the increase of Ti₃AlC₂ content,the friction coefficient of the Ni60A+Ti₃AlC₂ cladding layer decreases first and then increases.Among them,the friction coefficient of the Ni60A+10%Ti₃AlC₂ cladding layer is the smallest and 0.383,which is 29.6%lower than that of the Ni60A cladding layer.With the increase of Ti₃AlC₂content,the wear loss of the Ni60A+Ti₃AlC₂ cladding layer decreases first and then increases.Among them,the wear loss of the Ni60A+10%Ti₃AlC₂ cladding layer is the smallest and 1.9mg,which is 53.7%lower than that of Ni60A cladding layer.In the system of Ni60A+Ti₃AlC₂+MoS₂,with the increase of MoS₂ content,the friction coefficient first decreases and then increases.When the MoS₂ content is 5%,the friction coefficient is the smallest and 0.348.The friction coefficient is slightly lower than that of Ni60A+10%Ti₃AlC₂ cladding layer added with a single self-lubricant(the friction coefficient is 0.383).When 0.5%Ce O₂ is added,the wear resistance of the coating is improved,and the friction coefficient is only 0.330.The addition of Ce O₂ reduces the degree of adhesive wear and microscopic peeling wear.Under the condition of dry friction,within a certain speed range,the friction coefficient changes with the increase of speed.The overall trend is to first decrease and then increase,and the wear amount decreases first and then increases with the increase of speed.During dry friction,the friction coefficient of the cladding layer first decreases and then increases with the increase of the load,and the amount of wear increases with the increase of the load.Compared with dry friction,the friction coefficient of each cladding layer under oil lubrication conditions is significantly reduced,basically around 0.11?0.14,and the friction coefficient curve fluctuates very little and is almost straight.