陽極防食における交流の影響 (第1報)

30%硫酸溶液中のSUS32鋼およびチタンの不働態化時間ならびに腐食速度に対する100c/s正弦波交流重畳の影響

抄録

An investigation has been made into the influence of an a. c. component in output current of a potentiostat using silicon controlled rectifiers on the corrosion behavior of anodically polarized metals. The anodic behavior of Type 316 stainless steel and commercial pure titanium immersed in N₂-saturated 30% sulfuric acid solutions at 25°C was studied with d. c. alone and with superimposition of different proportions of 100c/s sinusoidal a. c. to d. c.
The passivation time measured galvanostatically at various current densities for the polished surface of stainless steel and the etched surface of titanium was not appreciably affected by a. c. superimposition in which the proportion of a. c. did not exceed 150% of each level of the d. c. applied, and the passivation time for these metals at a fixed level of d. c. increased sharply with increase in percentage of superimposed a. c. at percentages above 1, 000%. However, in similar experiments for the polished titanium the a. c. superimposition in percentages up to 2, 000% had little influence on the passivation time. The corrosion rate measured potentiostatically in passive state for the polished surface of stainless steel and titanium was not affected by superimposed a.c. in percentages not exceeding 150%.
On the basis of these observations, it is assumed that the potentiostat using the SCR may be tolerated to contain the 100c/s a. c. component above 150% of d. c. component in its output current owing to the presence of condenser current caused by the impedance at the metal-solution interface.