Additive manufacturing of ceramic porous structures for acoustical applications

Abstract

Ceramics offer the unique ability to withstand extreme temperatures and pressures without mechanical degradation-characteristics that make them ideal for acoustic applications in extreme environments. While ceramic forming is now a mature technology, traditional forming methods only allow two-dimensional design freedom, cannot create internal features, and often require expensive dies. Here, we propose the use of additive manufacturing (AM) to fabricate porous structures with complex pore geometries suitable for noise reduction applications. We fabricate cylindrical impedance tube test coupons of various pore geometries using a robocasting method that relies on clay extrusion. The printed green bodies are fired and sintered in an automated kiln to obtain the final ceramic sample. In this paper, we present the preliminary results from our wok on characterizing the relationships between the ceramic AM process parameters and the final ceramic part quality and dimensional accuracy. Finally, we investigate the acoustic absorption characteristics of the printed coupons using the normal incidence two microphone impedance tube method. Our results show that ceramics AM provides an attractive route to fabricate complex acoustic structures suitable for high temperature environments.