Patent Number: 7,785,425

Title: Method for passivating stainless steel product and method for producing stainless steel separator for fuel cell

Abstract: By a press-formed starting member (11) being immersed in a process liquid (12) at 40 to 60.degree. C. and of pH 9 to 12, a passive film (26) is formed at the surface of the press-formed starting member. There is no solving out of metal ions from the press-formed starting member, and the passivation treatment can be carried out by just immersion in a single solution, so that costs including waste processing can be reduced. In another aspect, degreasing, cleaning and passivation treatment are carried out by spraying the press-formed starting member. By the use of spraying, the degreasing, cleaning and passivation treatment can be made rapid, and the amounts of process liquid needed for degreasing, cleaning and passivation treatment can be reduced.

Inventors: Ishigami; Osamu (Sayama, JP), Kondo; Tetsuya (Sayama, JP), Ogawa; Yoshimitsu (Sayama, JP)

Assignee: Honda Motor Co., Ltd.

International Classification: C23C 22/62 (20060101); C23C 22/00 (20060101)

Expiration Date: 8/31/12018