The invention provides a secondary
drying method for preparing hydrophobic aluminum-
silicon aerogel heat-insulation materials. The secondary
drying method includes steps of S1, preparing aluminum solby means of
hydrolysis by the aid of
acid catalysis processes, and impregnating the aluminum
sol in
fiber reinforced material gel to obtain
fiber reinforced aluminum gel; S2, sealing and aging the gel, carrying out
ethanol supercritical drying and then carrying out heat treatment; S3, immersing
fiber / aluminum
aerogel composite materials in alkaline solution, carrying out surface alkaline treatment, carrying out centrifuging and then carrying out
drying; S4, preparing
silicon sol by means of
hydrolysis by the aid of
acid catalysis processes, uniformly impregnating the
silicon sol in fiber / aluminum
aerogel composite material gel to obtain composite materials; S5, immersing the composite materials in
alcohol solvents, sealing and aging the composite materials in the
alcohol solvents, carryingout solute replacement on the composite materials in the
alcohol solvents, then immersing the composite materials in surface modifier solution, carrying out surface treatment on the composite materials in the surface modifier solution and then carrying out secondary
ethanol supercritical drying to obtain the aluminum-silicon aerogel heat-insulation materials with the hydrophobic performance.
Silicon gel is available on pores of the composite materials obtained at the step S4. The secondary drying method has the advantages that the mechanical properties of the hydrophobic aluminum-silicon aerogel heat-insulation materials can be obviously improved by the aid of the secondary drying method, the hydrophobic aluminum-silicon aerogel heat-insulation materials have the hydrophobic properties, and the excellent high-temperature heat-insulation performance can be kept.