Surface Treatments of Stainless Steel by Electroless Silver Coatings as a Bipolar Plate for Proton Exchange Membrane Fuel Cells

Abstract

The objective of this study is to examine the effect of heat treatment at various temperatures on the corrosion behavior of electroless silvercoated SS 304 in a simulated proton exchange membrane (PEM) fuel cell environment. The corrosion properties of this material were studied using a potentiodynamic polarization technique. Xray diffraction (XRD) patterns, polarization curves, and scanning electron microscopy (SEM) of coated and heattreated specimens obtained in various heating temperatures were also utilized. It was found that the corrosion potential of the coated and heattreated specimens shift toward a noble potential, and a significant decrease in corrosion current density was also observed. The corrosion current density decreased by a factor of about 1/500 for the heattreated sample of 600 آ°C compared to the substrate. The heattreated specimens displayed greater corrosion resistance than unheated and bare ones. According to the polarization studies and SEM images, the heattreated specimen at 600 آ°C shows excellent corrosion resistance with a homogeneous dense surface morphology. These results demonstrated the coatings were suited for fuel cell applications in the proton exchange membrane fuel cell (PEMFC) environment.