Corrosion wear of high molybdenum and nitrogen stainless steel for biomedical applications

The corrosion-wear property of high molybdenum and nitrogen stainless steel (UNS no. S32050) was investigated and compared with that of Ti, Ti6Al4V, CoCrMo, and 316L stainless steel used conventionally for biomedical applications. The corrosion resistance and corrosion-wear resistance of S32050 were examined using electrochemical methods. The stability of the passive film in a corrosion-wear system was evaluated. The corrosion-resistance of S32050 is as good as Ti alloys, because its passive film was enhanced due to the synergistic effect of the large amount of Mo and N addition. Therefore, it is predicted that S32050 can minimize the toxic effects by the released ions. The wear loss of UHMWPE (ultrahigh molecular weight polyethylene) to S32050 was less than that to Ti6Al4V and 316L stainless steel, and similar to the CoCrMo. There were no scratches on the S32050 surface after the corrosion-wear test. S32050 had a low current density and high pitting potential under wear and had corrosion-wear properties superior to Ti6Al4V and similar to the CoCrMo in Hank's solution. S32050 with good corrosion-wear resistance could supplement the deficiencies of Ti alloys and CoCrMo. Thus, S32050 is considered to have the probability to be good metallic material for biomedical applications. (C) 2002 The Electrochemical Society.