Coil spring for a fuel cell

Abstract

A coil spring for fuel cells, used for a fuel cell or a cartridge for the fuel cell, comprising an austenite type stainless steel without any nickel layer formed on the surface thereof, and having a cationic index I of not more than 60 as expressed by the following formula (1), I=A+2B+3C  (1) wherein A, B and C represent, respectively, a concentration (ppb) of monovalent metal ions, a concentration (ppb) of metal ions which are neither monovalent nor trivalent, and a concentration (ppb) of trivalent metal ions per the coil spring in a methanol solution of when the coil spring is dipped in the methanol solution (containing 1% of water+4000 ppm of formic acid) and preserved therein at 60° C. for one week. Even when brought into contact with the content solution exhibiting acidity of the fuel cell, the coil spring reliably suppresses the elution of metal ions thereof.

Dependencies are inferred from the claim text.