Tribocorrosion Properties Of Typical PVD Nitride Coatings In Seawater Environment

The marine environment is one of the complex tribocorrosion system in the nature.The process of development and utilization of marine resources become more and more frequently.There are lots of corrosive chlorine ion in seawater,which makes the key frictional pairs and components lived in deep seawater more week,not only affected by the friction and wear,but also the serious electrochemical corrosion.The kind of interaction tends to accelerate the destruction of the materials,which could result in a lot of marine accidents and severe economic lost.Physical vapor deposition technology?multi arc ion plating?is one of the most widely used means to improve wear resistance and corrosion resistant metal materials performance.To research the tribocorrosion behavior of nitride coatingsinartificialseawaterenvironment.Thispaperdepositedthethree coatings?TiN,TiAlN and CrAlN?on the surface of 316 steel by multi arc ion plating system.Si₃N₄ balls worked as the grinding device in a triboelectrochemical cell using a ball-on-disk tribometer,integrated with a potentiostat for the electrochemical test in artificial seawater.The surface of three coatings performance of properties was tested by were modified by XRD,nanoindentation and scratch,electrochemical workstation,membrane adhesion,abrasion under different fixed potential,and cross profiles of wear track under varing fixed potential were prepared.The morphologies were analyzed by the SEM.Through the research,the following conclusions are obtained:?1?The open circuit potential of TiN coating declined slowly with the sliding time in artificial seawater environment.The average friction coefficient at different constant potential-1 V,-0.5 V,-0.25 V,OCP,0 V,0.25 V and 0.5 V were 0.392,0.416,0.394,0.324,0.348,0.404,0.415.TiN coating wear volume and wear rate increased with the increase of potential.The coating wore out under 0.25 V.At-1 V,-0.5 V,OCP,0.25 V,with the increase of load potential,the corrosion accelerated wear volume of TiN coating was gradually increased.The proportion of the total losses were 0%,41.78%,61.77%,63.72%,75.61%.At 0 V,the wear accelerated corrosion volume of TiN coating produced,which accounted for t 6.1%of the total loss.The mainly tribocorrosion mechanism of TiN coating in artificial seawater environment was abrasive wear and fatigue pitting.?2?The open circuit potential of TiAlN coating declined slowly with the sliding time in artificial seawater environment.The average friction coefficient at different constant pot-ential-1 V,-0.5 V,-0.25 V,OCP,0 V,0.25 V and 0.5 V were 0.53,0.51,0.50,0.48,0.49,0.50,0.45.The friction coefficient of TiAlN coatings in water environment was lower because of the compound particles of TiO₂ as the lubricant on the surface mixed with the artificial seawater.Under cathodic polarization potential of 0.25 V,the sliding surface began to produce the wear accelerated corrosion volume.With the increase of polarization potential,the corrosion effect became more obvious.The mainly tribocorrosion mechanism of TiAlN coating in artificial seawater environment was plastic deformation and fatigue pitting.?3?The open circuit potential of CrAlN coating rised about 0.062 V slowly,which accounted for about 28%of the initial potential.It was found that the polarization curve of anodic area existed obvious passivated zone,which restrained further corrosion of coating during the sliding contact.The coefficient of friction decreased significantly at the anodic potential.The total loss at the anodic potential of 0.5 V could be as large as 2.99 times of that at the cathodic potential of-1 V.At-1 V,-0.5 V,-0.25 V and OCP,the corrosion accelerated wear volume of CrAlN coating was gradually increased.The proportion of the total losses were 0%,12.36%,37.26%,60.58%.At 0 V,the wear accelerated corrosion volume was generated,which accounted for about 13.71%of the total loss.While the corrosion accelerated wear volume accounted for 47.71%.The mainly tribocorrosion mechanism of CrAlN coating in artificial seawater environment was abrasive wear,plastic deformation and fatigue pitting.