Investigation On Erosion-corrosion Behaviours Of Sputter-deposited Cr₂O₃ Coating Prepared By Double Cathode Plasma Technique

In this paper,a Cr₂O₃ coating is fabricated onto a 316 L substrate using a double cothode plasma technique,the microstructure of the coating was characterized by X-ray photoelectron spectroscopy（XRD）and scanning electron microscopy（SEM）;the mechanical properties were measured by scratch test,nanoindentation test and friction and wear test;the corrosion resistance and erosion–corrosion resistance of the coating were analysed by OCP–t curve,current response at a potential of +0.2V polarization curve and electrochemical impedance spectroscopy（EIS）.The result of the above test are as follow:（1）The prepared Cr₂O₃ coating are uniform and compact,the crystal shape is columnar with the（110）preferred orientation;the scratch test indicates that the critical load value of the coating is 77.55 N,which proves that the coating can meet the working of the requirement;nanoindentation test revealed that the hardness and elastic modulus values as 29.2Gpa and 272.8Gpa;the friction and wear test revealed that friction coefficient of the coating stable at 0.45,which proves that the coating has better anti-friction quality.（2）In the liquid flow（3.5wt.%Na Cl solution）and liquid–solid slurry flow（3.5wt.%Na Cl+10wt.% quartz sand flow）condition,the curves of open circuit potential and current curve versus time are shown the passive film of coating has high stability and repair speed,the erosive-corrosive resistance better than 316 L stainless steel;the result of polarization curve and electrochemical impedance spectroscopy（EIS）revealed that the coating has lower corrosion current density and a wider passivation zone and proved that the Cr₂O₃ coating has lower corrosion rate and higher stability.In the measurement of interaction,316 L stainless steel is more susceptible to interaction because of the fragility of the passive film,the weight loss of Cr₂O₃ coating under various factors is lower than 316 L stainless steel in same experimental situation,especially the influence of interaction is obviously reduced.It is proved that the Cr₂O₃ coating has better erosive-corrosive resistance.The strong erosion resistance of Cr₂O₃ coatings easy to be seen on the SEM images of surface topography,corrosive pitting of 316 L stainless steel occurred in two kinds ofcorrosion medium,Cr₂O₃ coating only occurred a bit corrosion pitting and the furrows by the impact of solid phased particles in two phase flow after 20 h.In summary,Cr₂O₃ coating could applied to the erosive-corrosive situation because better erosive-corrosive resistance and high hardness.