Fabrication of a Porous Ni-Based Metal with a Multi-pore Structure by a Screen Printing Process

Abstract

Porous metals are commonly considered as having relatively excellent characteristics, such as a large surface area, light, lower heat capacity levels, high toughness, and good permeability. Ni alloys have high corrosion resistance, good heat resistance and chemical stability for high-temperature applications. In this study, porous Ni-based metals for hydrogen reformer catalyst support are developed with Ni alloys, in this case Ni–Cr powder (28 μm), NiO powder (2 μm), and a fine Ni powder (< 1 μm). Ni–Cr powders are spread onto Al2O3 substrate by a printing process. Ni-based foam is then placed on the printed powder and a loading plate. These are sintered at 1200 °C under a high vacuum condition. The NiO powder and the fine Ni powder slurry are then screen-printed sequentially on the double structure (NiCr-coated Ni foam). In this study, the fine Ni powder is printed one, three, and five passes. The porous Ni alloys, which have double-pore structure, triple-pore structure and quadruple-pore structure, are fabricated by screen printing processes. With increased stacking of the pore structure, the porosity decreased from 86 to 82%, and the pore sizes decreased from 6.25 to 0.3 μm. The porosity and pore size of the multi-pore structure can be controlled by the size of powder and screen printing process.