Anodic polarization of tungsten in neutral and alkaline solutions under conditions of anode film growth

Abstract Anodic polarization of W has been studied in neutral (Na 2 SO 4 , NaCl) and alkaline solutions (ammonium borate, Na 2 CO 3 , Na 3 PO 4 , and NaOH) by the galvanostatic method under conditions which lead to anode film growth. The rate of oxide growth has been calculated as a function of current density, nature and concentration of electrolyte. Film growth to potentials above 100 V is achieved in alkaline solutions, provided the solution is dilute and the current density is high. The applicability of the high field ionic conduction has been verified from the dependence of both reciprocal capacity and potential on the logarithm of current density. Data are recorded for the coulometric increase of oxide thickness. The constants of the exponential law, and the electric field.