Fretting Corrosion Behavior Of CuNi2Si Alloy In Acidic NaCl Solution

The catenary system is a key part to ensure the normal operation of the high-speed railway.Once its components fail,it will seriously affect the safety of passenger transport,and even bring catastrophic consequences.Due to the long-term environmental corrosion of catenary components in the service process,such as acid rain,high salinity,high humidity and other factors,as well as fatigue loads such as pantograph-catenary vibration and wind-induced vibration.The mating surface of fastening mating parts is easy to cause fretting corrosion damage,which leads to the failure of the parts.Therefore,study of the fretting corrosion characteristics of key components is of vital importance for ensuring the safe operation of catenary.In this thesis,the electrochemical corrosion behavior of CuNi2Si alloy,a common material for catenary clamps,in NaCl solution at different acidity（pH=3,4,5）was studied by using electrochemical workstation CHI660E.Meanwhile,The fretting corrosion characteristics were studied in two kinds of acidic（pH=3,5）NaCl solution and in NaCl solution at pH=3 under different applied potential by using self-made multi-functional fretting wear testing machine（MFC-01）.The fretting wear and corrosion interaction under different working conditions were quantitatively analyzed.The results show that:（1）With the increment of the pH value,the corrosion rate of CuNi2Si alloy decreased.The corrosion process was mainly controlled by the diffusion of dissolved oxygen and H⁺;the corrosion products were mainly Cu₂O.（2）In NaCl solution at two acidities（pH=3 and pH=5）,the coefficient of friction of CuNi2Si alloy decreased with the increase of load and the wear volume increased with the increase of load;Fretting accelerated the corrosion of CuNi2Si alloy;the wear mechanism was mainly corrosion wear,abrasive wear and plastic deformation;the material loss was more serious in NaCl solution at pH=5.（3）Under the condition of applied potential,the electrochemical state of contact surface had a significant effect on Fretting wear.The coefficient of friction in the anodic polarization region was less than those in the cathodic polarization region;the wear mechanism in the anodic polarization region was mainly corrosion wear,abrasive wear and plastic deformation,while the wear mechanism in the cathodic polarization region was mainly abrasive wear and plastic deformation;the material loss in the cathodic polarization region was more serious.（4）The interaction is"negative"in NaCl solution at pH=3 and pH=5;under the condition of applied potential,the cathodic polarization region is"positive"interaction,and the anodic polarization region is"negative"interaction;The loss of materials can be reduced under the appropriate applied potential(0V_SCE).