Approximation of the Porosity and Flow Resistance of Porous Ceramic and Their Influence on a Sound Absorption Model

Recently discussed sound absorption models for porous ceramic materials use porosity and flow resistance as variables. The prediction of the porosity and especially flow resistance of a porous ceramic is not trivial even though it was examined intensively. A particular issue is the use of porosity and flow resistance as variables without judging their likelihood, so that physically impossible combinations of porosity and flow resistance are calculated. To prevent this, a model is presented to predict the porosity and airflow resistance of a freeze cast ceramic with spherical pores provided by sacrificial templating. The model is validated by measurements of the flow resistance of ceramic samples with different porosity and pore–size distributions. An optimal sacrificial template diameter for the desired application is presented.