METHOD OF SURFACE TREATMENT FOR STAINLESS STEEL PRODUCT FOR FUEL CELL

摘要

A method for treating the surface of a stainless steel product for a fuel cell containing, in wt %, 0.15 % or less of C, 17 to 36 % of Cr, 0.005 to 3.5 % of B, which comprises the first step of forming in advance a passive film with an oxidizing acid on the surface of the stainless steel product, the second step of allowing an aqueous acid solution to corrode the passive film, to thereby project one or more of a M23C6 type carbide, a M23(C,B)6 type borocarbide and M2B type boride, which are inclusions having good electroconductivity, the third step of forming a passive coating film with an oxidizing acid on the surface of the steel product except that of the inclusion above projected, and the forth step of washing with water and drying. The method of treatment allows, without the use of a method requiring a high cost such as gold plating, the improvement in the contact resistance of the stainless steel product for a fuel cell, which results in the retention of excellent characteristics of a stainless steel product over a long period of time.