The Effects of Testing Conditions on Corrosion Behaviours of SS316L for Bipolar Plate of PEMFC

Abstract

Corrosion of stainless steel bipolar plate (BPP) remains a big challenge while it has been considered to be one of the most appropriate candidates for proton exchange membrane fuel cell (PEMFC) in automotive application. This work aims to study comprehensively the effects of temperature, pH, bubbled gas and potential on corrosion behaviours of SS316L. Moreover, SEM and EDX are performed to reveal the evolutions of surface morphology, microstructure and chemical composition of SS316L under different testing conditions. The results indicate that temperature, pH and potential have significant influences on corrosion potential (E corr. ), corrosion current density (I corr. ) and passive current density (I p ) of SS316L. In addition, interactions between different testing conditions on corrosion resistance are strong. The main corrosion mechanism of SS316L would be shifted from pitting to intergranular or uniform corrosion as pH decreases from 3 ∼ 5 to 0.3 ∼ 1. Accelerated testing solutions with pH in the range of 0.3 ∼ 1 may be suitable to evaluate corrosion resistance of materials for BPP at lower potential. However, simulated testing conditions with pH in the range of 3 ∼ 5 is more appropriate when higher potentials of 1.0 ∼ 1.4 V (vs Ag/AgCl) need to be considered.