Preparation Of Nickel-Based Coating And Carbon-Based Film Composite Protective System And Its Corrosion And Wear Properties

As a solid lubrication materials with high hardness,low friction and high abrasion resistance,diamond like carbon-based films has aroused great repercussions in the field of surface materials during recent years.However,hardness and toughness of the carbon-based film are difficult to balance.How to integrate diamond-like carbon film with high hardness,toughness and low friction is still a technical problem in this field.In this paper,the composite protection system of nickel-based coating(Ni60C)/DLC Film(a-C,a-C:H and a-C:Cr)was prepared on the surface of 316L stainless steel substrate by spray welding and physical vapor deposition technology,and compared with three kinds of DLC films prepared directly on the surface of 316L stainless steel,The mechanical properties and tribological properties of the two protective systems were evaluated.The conclusions show that:(1)Ni60C coating can significantly improve the film-base binding strength of DLC film.The reason for the phenomenon due to compared with 316L stainless steel,Ni60C coating has higher hardness and yield strength,and its thermal expansion coefficient is less than that of stainless steel,which makes the DLC film has smaller internal stress and bearing capacity.(2)In the three simulated conditions,DLC films of the composite protection system show better wear resistance performance than monolayer films,which is mainly due to the Ni60C coating as the middle layer,which effectively inhibits the graphite process of the film in the process of friction,reduces the probability of large area shedding and failure of the film due to friction contact stress during the friction process of the film,and improves the wear resistance of the film.(3)In the atmospheric environment,the wear rate of a-C:H films is the lowest in both protect systems,and the wear rate of a-C:Cr films is the highest.This is mainly due to the process of friction,the wear process of a-C:H film is mainly dominated by the transfer film.The resulting of transfer film will block the direct contact of the friction interface;wear mechanism of a-C:Cr film is mainly based on abrasive wear,abrasive particles with friction to form some furrows,which increasing the film wear rate.(4)In 5wt.%sulfuric acid solution,the corrosion wear rates of a-c:H film and a-C:Cr film of the two systems is lower than others,and the corrosion and wear rate of a-C film is the highest.Which is due to the formation of passivation membranes on the surface of the a-c:H film,which blocks the infiltration of corrosive fluids,and the equal Cr_x C_y in the a-C:Cr film can clog the corrosion channel and reduce the corrosion and wear rate of the film.(5)In 5wt.%sodium hydroxide solution,the corrosion wear rates of a-c:H film and a-C film of the two systems is lower,on the contrary,a-C:Cr film shows the highest corrosion and wear rates.This was mainly attributed to the poor corrosion resistance of a-c:Cr films in 5wt.%sodium hydroxide solution.