Abstract
We investigated the structure of the sintered porous metal for passive DMFC anode wick. This porous metal was made by space holder method and consists of large voids formed by space holder of the mean diameter 1000 µm (1000 µm SH) and the skeleton part with small voids formed by space holder of the mean diameter 180 µm (180 µm SH) and pores originated from the space among metal particles. The amount of penetrating fuel (10 mass% methanol solution) was proportional to the square root of immersion time. So, we connected the penetrating rate with the porous structure by “a bundle of capillaries" model based on Washburn equation by Bruil and Murata, et al. Penetrating rate became larger by the conditions below: (1) decreasing 1000 µm SH and increasing 180 µm SH to increase the skeleton part volume and its porosity, (2) increasing the fraction of smaller porosity of the skeleton part to increase its specific surface area, (3) coating metal surface with SiO2 to improve its wettability. But more than 75 vol% of 1000 µm SH was needed to release CO2 smoothly during generation. Additionally, 30 mass% methanol solution improved the generating performance without an effect of methanol crossover.
