The Effect of Tin Addition on the Corrosion Behaviour of Sintered Stainless Steel in H sub 2 SO sub 4

The influence of Sn addition on the corrosion behaviour of hot-pressed sintered stainless steel of type 316 in H sub 2 SO sub 4 solutions was investigated. The samples were investigated by SEM observation, open circuit potential during an immersion test and potentiodynamic polarization. It was found that Sn additions of 0.5-3 wt.% enhance the densification processes and as a result the amount of the interconnected open pores was decreased. The corrosion resistance of hot-pressed sintered stainless steel was substantially improved by the Sn addition. The weight loss of the samples containing Sn is negligible after 200 h of immersion compared to corrosion. The potentiodynamic measurements indicate that as a result of the Sn addition, the critical current density and the passivation current density were decreased, as compared to the hot-pressed stainless steel. The cathodic polarization curves indicate surface poisoning, causing higher over-potential for the hydrogen evolution. 11 ref.--AA