Development of a new aluminizing method for molten carbonate fuel cell wet seals

A new aluminization method for molten carbonate fuel cell bipolar plate wet seals is described in this paper based on the application of the electrospark deposition (ESD) process. The molten carbonate corrosion behavior of single Al, FeAl, and a dual (FeAl/Al) diffusion coating applied onto a AISI 316L steel sheet of 0.5 mm thickness is examined. FeAl-containing coatings show low-rate corrosion after exposure to a (Li + K) carbonate melt at 650 degrees C for 1000 h, whereas the single Al coating suffers excessive corrosion. Coatings degradation modes involve interdiffusion phenomena and transient formation of nodule iron-oxides. The dual (FeAl/Al) coating exhibits the best corrosion resistance due to its higher Al surface content. Characteristics of the ESD coatings in terms of thickness, uniformity, and composition are also reported.