A Novel Production Method for Porous Sound-Absorbing Ceramic Material for High-Temperature Applications

A new processing technique combining the freeze gelation process with sacrificial templating is used to create self-supporting ceramic sound absorption structures for high-temperature applications. The process leads to near-net shape components with an open-pored structure. Expanded perlite, acting as melting filler, increases the porosity up to 74%. The resulting properties of the microstructure such as porosity and airflow resistance are presented. Acoustical measurements in an impedance tube show high sound absorption coefficients up to 0.7. The measured sound absorption is compared with a mathematical simulation. In summary, this process allows the fabrication of temperature-resistant ceramic sound absorbers.