engleski

Surface modification of stainless steel-304 electrode. 2. An experimental comparative study of electrochemically, hydrothermally and chemically modified oxide films

Stainless steel-304 was modified electrochemically by potentiostatic and potentiodynamic methods (triangular and square-wave potential-time program) in 1 mol dm-3 NaOH solution, hydrothermally in 1 mol dm-3 NaOH at 200 oC, and chemically in 0.5 mol dm-3 K2Cr2O7 solution. Oxide films were characterized voltammetrically by the charge of Fe(OH)2/FeOOH surface electrochemical reaction. The stability of the oxide films was measured in 0.5 mol dm-3 H2SO4 by anodic potentiodynamic polarization and by open-circuit potential-time measurements. The hydrothermally grown oxide film was most stable. The most efficient oxide growth was achieved by the use of square-wave type of modification. The oxide modified by this procedure exhibited lower stability than the oxide grown by triangular potential-time program, which was much more stable due to uncompleted reduction of chromium oxide. The importance of careful control of experimental conditions, where a small change in surface treatment could lead to a significant change in corrosion behaviour, is pointed out.

Stainless steel-304; surface modification; oxide growth; passive oxide films

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