Evaluation of the acoustic performances of metal powder based materials

Electrodes in Molten Carbonate Fuel Cells (MCFC) are constituted by porous metal mixtures. Metals employed are nickel for the cathodic electrode and nickel-chrome for the anodic one. Plates are built from the metal powders treated by tape casting and sintering processes. Material characteristics such as porosity and density may be properly designed by varying powder particle size, organic binder composition and sintering conditions. These materials may be potentially valuable as acoustic absorbers and their acoustical properties may be adjusted by changing the material’s characteristics. Generally materials for MCFC require no impurities and their cost is a critical issue; in acoustical applications, purity requirements are not necessary and scrap samples may be used, contributing strongly to cut costs. This paper deals with an investigation on a typical MCFC material to verify their suitability for noise insulation and absorption. For this purpose, a measurement campaign by Kundt tube on MCFC electrodes was carried out by varying the plate porosity, width, mixture content and purity; optimal configuration has been found in terms of maximum absorption frequency. Results suggested that, for acoustical application, some metal powder maybe substituted by a polymer powder in order to further reduce costs and further improve absorption. Manufacturing procedures are actually under study.