Bimodal hybrid lightweight sound-absorbing material with high stiffness

Abstract

An iron foam/silica aerogel composite (IFSA) with bimodal structure was designed and fabricated to solve the contradictions between acoustic damping and mechanical strength of a material. IFSA exhibits excellent broadband sound absorption performance with average absorption of ∼57% (500–6400 Hz) and maximum absorption coefficient of 0.995 at 4336 Hz, and high specific stiffness (1.6 × 105 m2 s−2). The dissipation mechanism of sound energy in IFSA is well predicted by a designed bimodal model. Such fascinating artificial composite not only provides new insights for developing structural materials with high noise reduction and strength, but also has great potential applications for various fields.

Going Beyond the Causal Limit in Acoustic Absorption

“…1(a), we show a photograph of our metallic mesh absorber used in this work, together with an enlarged view of the pores. Given their excellent thermal conductivity, our metallic mesh sample can effect an additional absorption mechanism of breaking the adiabaticity in sound propagation [4,5,35]. The use of metallic mesh at the end of an open impedance tube to reduce reflection is apparently not new and has been previously observed and analyzed [36,37].…”

Ultralight Single‐Walled Carbon Nanotube Aerogels for Low‐Frequency Sound Absorption

“…Therefore, parameters related to the porous structure, such as flow resistivity (σ) and tortuosity (α ∞ ), which affect the sound propagation path in the material, are essential for evaluating the sound-absorption properties. [7,10,11] In addition, for materials with a very large σ or nonbreathable membranes, the materials' elastic moduli are important because sound absorption is facilitated by the vibration of the framework and loss of the solid-borne sound through the framework. [12] Glass wool and polyurethane, as typical sound-absorbing materials, lack sufficient structural and elastic modulus and consequently have poor soundabsorption properties for low-frequency sounds below 1000 Hz.…”

Superhydrophobic Waste Cardboard Aerogels as Effective and Reusable Oil Absorbents

“…Three-dimensional (3D) aerogels are one of the lightest solids in the world, with low density and high surface area and porosity, making them very suitable for applications such as absorption, − impacting energy damping, and impacting heat and acoustic insulation. , In particular, superhydrophobic aerogels, − whose hydrophobic surface can selectively adsorb the oil phase from oily wastewater, are regarded as an ideal material for cleaning oily pollution and separating oil/water mixtures. In the past few decades, various aerogels have been successfully applied to effectively remove oil pollutants. − More recently, by assembling MOFs on the surface of biomass fiber and then directly carbonizing them, carbon aerogels with the three-dimensional porous structure have been prepared to adsorb 35–119 times their own weight in organic pollutants .…”