Strength enhancement of ultralight alumina‐dried foams from particle‐stabilized foams with assistance of agar and PVA

Abstract

AbstractThe weak compressive strength of dried ceramic foams is a disadvantage of fabricating ultralight ceramic foams, especially for the ceramic foams with porosity exceeding 95%. In this study, dried alumina foams were enhanced by agar and PVA‐freezing‐thawing using sodium dodecyl sulfate as surfactant. It is found that the two additives have no negative influence on adsorption of sodium dodecyl sulfate on alumina particles as well as the hydrophobic character of alumina particles. Stable alumina particle‐stabilized foams were prepared with less than 0.5 wt% agar and 1.0 wt% PVA. High additive concentration above the critical values weakens stability of wet foams, which is probably due to the aggregate of alumina particles caused by long‐chain molecules connecting. The compressive strength of dried alumina foams has a significant improvement with the employment of agar and PVA‐freezing‐thawing. The dried foams prepared with 1wt% PVA assisted by freezing‐thawing has porosity of 97.1% and compressive strength of 0.16 MPa, which could maintain integrity of dried foams without destruction in the fabricating process.