Aerogel-based ultralight noise absorbers fabricated using 3D freeze printing

Abstract

Aerogels are a group of synthetic materials with a structure comprising up to 99.8% air. This ultra-sparse skeletal structure results in extremely low-density and thermal conductivity. Because of these extreme properties, aerogels are highly attractive for thermal insulation and energy absorption applications. In acoustics, their application is typically limited to their use as granular material—either as granular layers or as additives to conventional fibrous and matrix materials. Here, we explore the possibility of controlling not only their mesostructure but also their macrostructure by fabricating aerogel-based ultralight noise absorbers using a 3-D Freeze Printing (3DFP) technique. First, we introduce the novel 3DFP method, which combines the advantages of additive manufacturing and freeze casting processes. Next, we focus on the acoustic characterization of 3-D freeze printed aerogels using a normal incidence impedance tube setup. Our results show that compared with current passive noise reduction materials, the unique structures generated by the 3DFP method can provide significantly improved absorption and transmission loss properties.