Methods of Calculation of Resistance to Polarization (Corrosion Rate) Using ASTM G 59

Wong, L L ; King, K J ; Martin, S I ; Rebak, R B

Lawrence Livermore National Laboratory

关键词: Corrosion;    Polarization;    36 Materials Science;    Electrolytes;   

DOI  :  10.2172/894779
RP-ID  :  UCRL-TR-218665
RP-ID  :  W-7405-ENG-48
RP-ID  :  894779

美国|英语

来源: UNT Digital Library

【 摘 要 】

The corrosion rate of a metal (alloy) can be measured using: (1) Immersion tests or weight loss such as in ASTM G 1 and G 31 or (2) Electrochemical techniques such as in ASTM G 59. In the polarization resistance (PR) or linear polarization method (G 59), the resistance to polarization (Rp) of a metal is measured in the electrolyte of interest in the vicinity of the corrosion potential (E{sub corr}). This polarization resistance can be mathematically converted into corrosion rates (CR). A plot of E vs. I in the vicinity of E{sub corr} is generated by increasing the potential at a fixed rate of 0.1667 mV/s and measuring the output current. The polarization resistance (Rp) is defined as the slope of a potential (E) (Y axis) vs. Current (I) (X axis) plot in the vicinity of the corrosion potential (E{sub corr}). When the potential is ramped and the current is measured, E is the independent variable and I is the dependent variable. In a proper mathematical plot, E should be represented in the X axis and I in the Y axis. However, in the conventions of the corrosion community, E is always plotted in the Y axis and I in the X axis. Therefore, how this plot of Delta E/Delta I is analyzed is a matter of current debate.