The Research On Tribocorrosion Properties Of CrN/CrAl(Si)N Multilayer Coating In Seawater

The components of construction machinery in marine environment are often subject to the interaction of corrosion and friction and wear,resulting in premature failure of materials,seriously affecting the normal operation of equipment,and endangering safety.Nitride coating is widely used in machinery,cutting tools,molds and other fields due to its excellent performance.Therefore,it is expected to provide excellent tribocorrosion protection for marine equipment parts.In this paper,the high flux CrAlN coating,the CrN/CrAlN multilayer coating and the CrN/CrAlSiN multilayer coating with different modulation ratio were prepared on 316 stainless steel by multi arc ion plating.Scanning electron microscope（SEM）,scanning probe microscope（SPM）and transmission electron microscope（TEM）were used to characterize the surface and cross-section morphology of the coating.The microstructure and element distribution of the coating were analyzed by X-ray diffraction（XRD）,glow discharge emission spectrometer（GDOES）and energy dispersive spectrometer（EDS）.The hardness,elastic modulus and adhesion of the coating were measured by nanoindentation and scratch instruments.The tribological behavior of the coating was studied by a reciprocating friction and wear tester,and the trobocorrosion properties of the coating in seawater environment were further tested by a system composed of a friction and wear tester and a three-electrode electrochemical workstation.The results are as follows:The effects ofAlcontent on microstructure,mechanical properties and tribological properties of high flux CrAlN coatings were investigated.With the increase ofAlcontent,the hardness,elastic modulus and adhesion of the coating first increase and then decrease.When theAlcontent is 19.27%,the maximum values are37.48 GPa,517.88 GPa and 20.15 N,respectively.The friction coefficient and wear amount of the coating in the atmosphere and sea water environment both decrease first and then increase,and the mechanical properties are the main factors affecting the wear resistance of the coating.Compared with the atmospheric environment,the friction coefficient and wear loss in the seawater environment are reduced by about50%,which is mainly due to the chemical reaction with the seawater medium and the formation of Ca CO₃,Mg CO₃ and other substances with lubricating effect.WhenAlcontent is 19.27%,CrAlN coating has the best wear resistance.The tribological properties of CrAlN monolayer and CrN/CrAlN multilayer coatings in atmospheric environment were studied,and the tribocorrosion behavior in seawater environment was further studied.Compared with the monolayer coating,the multi-layer coating structure is more compact,the mechanical properties are significantly improved,and the hardness is up to 37.65 GPa.Under dry friction condition,CrN/CrAlN multilayer coating has lower friction coefficient and wear loss,which are 0.53 and 0.0030 mm³,respectively.In seawater environment,the multilayer coating has high corrosion potential and low corrosion current density,which shows excellent corrosion resistance.With the increase of applied potential,the loss of coating increases gradually,and corrosion promotes wear.The trobocorrosion behavior of CrAlSiN monolayer and CrN/CrAlSiN multilayer coatings with different modulation ratios were studied.Under dry friction conditions,the friction coefficient and wear amount of the multilayer coating are lower than that of the monolayer.As the modulation ratio increases,it first increases and then decreases,and the minimum wear amount is 0.0031 mm³.In the seawater environment,the friction coefficient changes little,all around 0.28.The amount of material loss increases with the modulation ratio and decreases after increasing.When the modulation ratio is t _CrN=1 min,the material loss is the lowest.