The studies on the anodic growth of film on tantalum were carried out at various current densities (2.5, 5.0, 10.0 and 15.0 mAcm-2) in presence of 0.1N solutions of acetic acid, succinic acid and picric acid (prepared in 1:1v/v of Ethanol + water) at four different temperatures (288.15, 298.15, 308.15 and 318.15K). The constants A and B of Guntherschulze and Betz empirical equation have been determined. The value of A varied with temperature but the value of B was found independent of temperature, which implies the non-dependence of Tafel slope on temperature. Dignam’s quadratic variation of field strength with ionic current density was examined critically. The zero field activation energy (f ), dimensionless quantity (C), zero field activation dipole (μ *), net activation energy W (E) and More function parameter (w*) of Dignam model were evaluated. The effects of temperature, current density and nature of electrolyte on various parameters of Dignam model have been discussed. An appreciable contribution of the quadratic term elucidates that single-barrier theories of ionic conduction do not explain the data satisfactorily.
