Evaluation of Electrical Breakdown of Anodic Films on Titanium in Phosphate-base Solutions

Titanium is a highly reactive metal so that a thin layer of oxide forms on its surface whenever exposed to the air or other environments containing oxygen. This layer increases the corrosion resistance of titanium. The oxide film is electrochemically formed through anodizing. In this study, anodizing of titanium was performed in phosphate-base solutions such as H3Po4, NaH2Po4, and Na2Hpo4 at 9.75Ma/cm2 and 35ºC under galvanostatic conditions. The Potential-Time curves in the above solutions show that the anodic films formed on titanium are compact and their thickness depends on the solution type and concentration. The SEM and XRD techniques show that these layers are amorphous. In this paper, the effect of electrolyte concentration, composition and resistivity on breakdown voltage have been discussed in terms of Ikonopisov electron avalanche breakdown model. This model shows that the major factor contributing to the decrease in breakdown voltage is the increased electrolyte concentration leading to increased primary electronic current.