Study On Microstructure Control And Tribocorrosion Properties Of Nitride/TiSiCN(Ag) Coupled Coatings

The titanium alloy is widely used in marine equipments for obvious performance advantages.People are forced to improve their overall performance due to extreme service environment in southen sea.In this paper,high temperature gas nitriding and multi-arc ion plating were used to get nitride Ti6Al4V and deposit TiSiCN?Ag?coating.Nitride/TiSiCN?Ag?duplex treatment coupled coatings with excellent comprehensive performance were obtained.The structure and composition,mechanical properties and tribocorrosion property of coatings were systematically investigated.The main findings are as follows:?1?After gas nitriding,the nitride layer on titanium alloy surface is divided into a surface nitrogen compound layer and a subsurface nitrogen diffusion layer.The nitride phase of titanium??-TiN,?-Ti₂N?is formed.The surface hardness is 25 GPa.The friction coefficient?0.2966?and the wear rate(4.732×10^-5 mm³/N·m)are significantly descreased compared to Ti6Al4V.?2?The nitride/TiSiCN duplex-treatment coupled coatings have maximum hardness value?33 GPa?and high loading capacity?88 N?,and the two kinds of surface modifications play the good mutual promotion role.The excellent tribocorrosion performance in artificial seawater is attributed to the change of wear mechanism?sliding to rolling?,the generation of graphitization,and the high hardness value of coatings.The increase in the total amount of wear is ascribed to corrosion determines the overall degree of synergy.?3?The TiSiCN?Ag?coating has a unique multi-arched layered structure.It has maximum hardness?37.8 GPa?,good ductility and fracture toughness(K_IC=2.12MPa·m^1/2).The TiSiCN?Ag?coating has excellent tribocorrosion performance due to the formation of a passive film which blocks the penetration of corrosive media into coating in seawater.4)Thenitride/TiSiCN?Ag?coupledcoatingsproducedistinct activation-passivation phenomenon at 0.1 V potential.Ag is clearly aggregated with large Ag particles in nitride/multi-arched layered coupled coatings which exhibits excellent tribocorrosion resistance due to the mechanical advantage of multi-arched structure and the lubricating property of Ag.