1994 Volume 43 Issue 8 Pages 433-440
The photoelectrochemical behavior of Cu coated with TiO2 by sol-gel method was studied, aiming at the cathodic protection of Cu by the TiO2 coating under illumination. It was found that the heat treatment in the coating process played a crucial role in determining the photo-effect of TiO2 coating on the Cu substrate, Heat treatment at temperatures above 400°C was found to be essential to cause the potential of the TiO2 coated Cu specimen to shift toward less noble direction under illumination, The optimum heat treatment temperature for catholic protection was found to lie in the temperature range between 600°C and 700°C, in which the specimen exhibited the least noble photopotential. The increase in coating thickness more than 0.1μm seemed to have little influence on the photopotential in deaerated solutions. Under the appropriate heat treatment conditions, the results demonstrated an effective catholic protection for Cu by the TiO2 coating over the tested solution pH range from 4 to 12, because the photopotentials were in the immunity domain in the E-pH diagram of Cu.