Evaluation of corrosion behavior of an amorphous Ni₆₀Nb₄₀-alloy with its crystalline form in stimulated PEMFC conditions

Ni60Nb40 amorphous ribbon was prepared by melt spinning method and its corrosion property compared with its crystalline counter part i.e., Ni60Nb40 crystalline plate were prepared by copper mold suction casting technique. The amorphicity of these alloys were characterized by XRD technique. The corrosion properties of these alloys were also tested by electrochemical potentiodynamic polarization technique as well as chemical immersion test in 1 M H2SO4 (80 degrees C) with air and H-2 bubbling to simulate cathodic and anodic conditions of Polymer Exchange Membrane Fuel Cell (PEMFC), respectively. The corrosion resistance property of amorphous alloy was found to be more than one order higher than that of its counterpart. The stability and occurrence of pitting during corrosion were monitored by cyclic polarization technique. The changes in surface morphologies of alloys before and after corrosion were characterized by EPMA. The change in cationic concentrations and passive layer thickness on the surfaces during corrosion were measured by using XPS technique. [GRAPHICS] . Potentiodynamic polarization curves of amorphous and crystalline Ni-60-Nb-40- alloys recorded in 1M H2SO4 + 2ppm F- in air bubbled conditions.