| 摘要 |
PROBLEM TO BE SOLVED: To measure corrosion speed highly precisely by measuring respective partial voltage values of constant currents among three electrodes, including a sample electrode and finding a partial voltage resistance value of the sample electrode based on an operation result excluding partial voltage value factors of solution resistance among the respective partial voltage values and a constant current value. SOLUTION: An AC constant current (i) is made to flow between a sample electrode 27 and a counter electrode 29 by an AC circuit 47. A voltometer 41 measures a sample- side partial voltage value Va between a collation electrode 28 and the sample electrode 27 and a voltometer 42 measures a fourth electrode side partial voltage value Vb between the collation electrode 28 and the fourth electrode 30. A ratio station 43 automatically sets a ratioαof solution resistance of the sample electrode side and the forth electrode side respectively based on the partial voltage values Va , Vb , and the partial pressure value Vb is multiplied by the ratioαso that the factor of the solution resistance partial voltage value is excluded. Secondly, a subtractor 44 subtracts the partial voltage value Vb×2 from the partial voltage value Va and a divider 45 divides Va -αVb by the AC constant current (i) fed from the constant current circuit 27, so that a partial electrode resistanceγ1 is found. With this constitution, highly precise corrosion speed can be measured.
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