Blocky transparent silica aerogel, and rapid preparation method and application thereof

Abstract

The invention discloses a blocky transparent silica aerogel, and a rapid preparation method and an application thereof. The method comprises the following steps: a silica gel is prepared through a sol-gel two-step process with an organic silicon source as a silica precursor, water as a raw material, alcohol as a solvent and an acid and an alkali as a catalyst, an aprotic polar solvent is added inthe sol-gel stage, and then a liquid carbon dioxide replacement drying process is used to obtain the blocky transparent silica aerogel with a light mass, a large specific surface area and a low thermal conductivity. The method eliminates the tedious solvent exchange process in the conventional preparation process of aerogel, does not need a supercritical process, has a short flow and a simple andeasy process, can be wholly carried out at normal temperature, and has the advantages of energy saving, saving of raw materials and auxiliary materials, and high efficiency, and the obtained blocky transparent silica aerogel has excellent comprehensive performances, and can be widely used as a thermal insulation material, a sound absorbing material, an adsorption material or an explosion-proof material.

Description

technical field [0001] The present invention relates to a silica airgel material and its rapid preparation method and application, in particular to a method for rapid preparation of bulk transparent silica airgel aerogel, and the silica airgel in heat preservation Applications such as heat insulation materials, sound-absorbing materials, adsorption materials or explosion-proof materials belong to the technical field of preparation of nano-mesoporous materials. Background technique [0002] Airgel is a light inorganic solid material with a three-dimensional network skeleton structure and nano-scale pores. It has extremely high porosity, specific surface area, extremely low density and solid content, chemical inertness and non-combustibility, and exhibits excellent It has the characteristics of heat insulation, fire prevention, sound insulation, shock absorption and energy absorption, and transparency. The thermal conductivity can be as low as 0.011W / m·K, which is the best hea...

AI Technical Summary

Problems solved by technology

The main reasons for the low production efficiency and poor agglomeration caused by the drying process are: (1) the solubility of alcohol and carbon dioxide is not good, resulting in low exchange efficiency and a large amount of carbon dioxide; (2) due to the high surface tension of water, And the solubility with carbon dioxide is very poor, therefore, the water must be pre-removed by solvent replacement before drying

But in fact, the water in the pores is difficult to remove, and more or less remains, resulting in a certain capillary force, resulting in gel cracking, which seriously affects the agglomeration of airgel; (3) using supercritical drying to prepare agglomerates When the transparent silica airgel is formed, due to the temperature difference from room temperature heating to the supercritical temperature (external heat and internal cooling), thermal stress exists, which is easy to cause skeleton cracking, and the supercritical drying process requires high equipment, which restricts the air (4) Although in the state of supercritical carbon dioxide, the capillary force in the pores of the gel is very low, but due to the high viscosity of the mixed solvent in the pores, the overflow rate of supercritical carbon dioxide from the nanopores is slow. High, not only the exchange efficiency is low, but also increases the capillary force and increases the cracking tendency of the gel skeleton