Formation of self-organized pores on type 316 stainless steel in organic solvents

The present work reports the formation of self-organized pores on type 316 stainless steel by the electrochemical treatment in organic solvents. The electrochemical treatment consists of a potential ramp from 0 V to desired applied potentials and subsequent potentiostatic polarization at the desired applied potentials. Pores are formed on stainless steel surface in various organic solvents when they contain perchloric acid. In ethylene glycol electrolyte containing 10 vol.% perchloric acid pores with the average diameter of 150 nm and the average depth of 10 nm are formed already after the potential ramp to 40 V. The diameter and depth of pores drastically increase in the early stage of the treatment and then becomes slightly smaller. The applied potential also affects the porous morphology, that is, the diameter and depth linearly increase with increasing applied potential. Water into the organic solvent can drastically enhance the growth rate of pores.