抄録
It has been about 10 years since the titanium electrode plated with platinum appeared in electrochemical industry, and it has been evaluated as an excellent insoluble electrode. It is said that more than dozens of patents on the manufacturing method of this electrode have been published. However, the electrode having very high corrosion resistance has never been manufactured.
The activation energy for the interface reaction between titanium and the acid was calculated from the measured rate of dissolution of titanium in hydrofluoric acid, and the mechanism of dissolution of titanium was estimated as an essential factor in plating platinum on titanium in aqueous solution.
The following results were obtained.
1) The change in activation energy of titanium in hydrofluoric acid with the concentration of acid was as follows:
Concentration Activation energy 2% 9.5Kcal.mol-1
1% 9.7Kcal.mol-1
0.5% 9.3Kcal.mol-1
2) The change of energy, when the solution was being stirred, was as follows:
Concentration Activation energy
2% 9.7Kcal.mol-1
1% 9.6Kcal.mol-1
0.5% 9.4Kcal.mol-1
3) Almost the same values of activation energy were obtained between the solution with and without stirring, even though the reaction rate was not determined owing to the diffusion by stirring. Therefore, it was concluded that the reaction rate is not determined by the diffusion process.
