Abstract
Three methods of measuring corrosion rate, two polarization resistance methods and an electric resistance method, were discussed in this chapter. At first, the principle of the d. c. and a. c. polarization resistance methods based on the Stern-Geary equation for instantaneous rates of corrosion was described and the error of the methods was briefly discussed. Two measuring technique based on the polarization resistance, the PAIR method and the Marsh method, were described, respectively, and the characteristic feature of the instruments available on the market was outlined and probe materials applicable to the instruments were described for user's convenience. The polarization resistance meter using a rectangular wave technique was also illustrated. The equipment for measuring corrosion by the electric resistance technique and available probe materials were described. Some new types of electrochemical corrosion measurements and the mesuring instruments were also introduced.
