Method for improving surface properties of stainless steels for bipolar plates of polymer electrolyte membrane fuel cells

摘要

Disclosed is a method for improving surface properties of the stainless steels for bipolar plate of polymer electrolyte membrane fuel cell having low interfacial contact resistance and excellent corrosion resistance. The method for improving surface properties of the stainless steels according to one exemplary embodiment of the present invention includes: pickling a stainless steel with an aqueous sulfuric acid solution, the stainless steel comprising, by weight: C: 0.02% or less, N: 0.02% or less, Si: 0.4% or less, Mn: 0.2% or less, P: 0.04% or less, S: 0.02% or less, Cr: 25-32%, Mo: 0.1 to 5%, Cu: 0.1 to 2%, Ti: 0.5% or less, Nb: 0.5% or less, and the balance of Fe and other inevitable elements, and then washing the stainless steel with water, and then immersing the stainless steel in a mixture solution of nitric acid and hydrofluoric acid to form a passivation layer.