Stainless steel bipolar plates

In this research, a specific surface modification technology was developed for stainless steel bipolar plates to obtain a corrosion-resistant oxide film. The surface roughness was measured, and an electron spectroscopy analysis (ESCA) was conducted to verify the chemical composition of the surface layer. From the binding energy of the ESCA spectrum, the amounts of chemical shift were used to identify the major chemical compositions. The thickness of the oxide film was analyzed by auger electron spectroscopy (AES). From the results of the ESCA and AES analyses, the effects of the surface modification on the integrity of the surface were evaluated. Uniform corrosion and localized corrosion tests were also conducted to investigate any improvement on the corrosion characteristics. A single cell was assembled for cell performance tests. The surface of the treated plates was bright and smooth. The ESCA and AES analyses showed that the treated plates had a much higher chrome content. The metallurgical structure was dense with substantially less defects. The chemical and electrochemical properties were more stable. The corrosion rates of the treated plates were also much improved, resulting in better electric conductivity, stable cell performance as well as longer cell life. (c) 2005 Elsevier B.V. All rights reserved.