Alumina aerogels with unidirectional channels under different freezing temperatures during freeze casting——Part II: Anisotropic mechanical and thermal conductive properties

Abstract

The anisotropic mechanical and thermal conduction properties of unidirectional aligned alumina aerogels (AAs) were investigated in our part II. The anisotropic structure characteristics are the main factors to decide the physical properties of AAs. The results show that the brittle failure behavior reflects the fracture of the long pore walls along ice-crystal growth direction, but the excellent strain and low compressive strength are ascribed to the weak second structures. The structural difference in the direction of heat transfer results anisotropic thermal conduction. The heat transfers layer-by-layer at intervals of solid walls and air pores is more effective for the heat insulation.