Facile Preparation of High Strength Silica Aerogel Composites via a Water Solvent System and Ambient Pressure Drying without Surface Modification or Solvent Replacement

Abstract

To further reduce the manufacturing cost and improve safety, silica aerogel composites (SAC) with low density and low thermal conductivity synthesized via ambient pressure drying (APD) technology have gradually become one of the most focused research areas. As a solvent, ethanol is flammable and needs to be replaced by other low surface tension solvents, which is dangerous and time-consuming. Therefore, the key steps of solvent replacement and surface modification in the APD process need to be simplified. Here, we demonstrate a facile strategy for preparing high strength mullite fiber reinforced SAC, which is synthesized by APD using water as a solvent, rather than using surface modification or solvent replacement. The effects of the fiber density on the physical properties, mechanical properties, and thermal conductivities of SAC are discussed in detail. The results show that when the fiber density of SAC is 0.24 g/cm3, the thermal conductivity at 1100 °C is 0.127 W/m·K, and the compressive strength at 10% strain is 1.348 MPa. Because of the simple synthesis process and excellent thermal-mechanical performance, the SAC is expected to be used as an efficient and economical insulation material.

Mechanically Strengthened Aerogels through Multiscale, Multicompositional, and Multidimensional Approaches: A Review

“…[134] These types of composites can be prepared by dispersing fibers in the sol prior to gelation, followed by Figure 6. a) Schematic presentation of the synthesis of fiber-reinforced silica aerogels, [138] b) stress-strain profile for mullite fiber-reinforced silica aerogels, [140] c) effect of fiber density on the mechanical properties of silica aerogels, [138] d) process for the synthesis of polymer reinforced silica aerogels and representative set of monomers used, [141] and e) effect of PVP wt% on the Young's modulus of bending of silica aerogels. [142] a-c) Adapted with permission.…”

“…b) Adapted under the terms of the CC‐BY Creative Commons Attribution 4.0 International license ( https://creativecommons.org/licenses/by/4.0). [ 140 ] Copyright 2021, The Authors, published by MDPI. d) Adapted with permission.…”

Raman Spectroscopy and Structural Characteristics of Copper-Ion-Doped Silica Sol, Gel, and Aerogel

“…al, Fiber density's influence on SAC's thermal conductivity, mechanical qualities, and other physical characteristics is explored in depth. The findings reveal that at 10% strain, the compressive strength of SAC is 1.348 MPa and the thermal conductivity at 1100 °C is 0.127 W/m K. SAC is anticipated to be employed as a useful and costeffective insulating material because of its easy synthesis method and high thermal-mechanical performance [19]. J. Ben Naceur et al, analysis, structural and optical characteristics of sol-gelthey found processed TiO2 thin films doped with iron ions (Fe3+).…”

Hybrid RF-Si Xerogels: A Cost-Effective Proposal for Insulator Materials

“…These materials reach thermal conductivities around 10–20 mW/mK and have a wide variety of applications [ 9 , 13 ]. Nevertheless, their long and multi-step synthesis process, high production costs, poor mechanical properties and health issues (i.e., irritant to the eyes, skin, respiratory tract, and digestive system) limit their practical applications and mass production [ 1 , 6 , 16 , 17 , 18 ]. Another type of aerogels that have also attracted attention are those based on resorcinol–formaldehyde (RF).…”

“…Thermal conductivities of 26 and 38 mW/mK were achieved for silica and hybrid xerogels, respectively. The use of MTMS improve the mechanical resistance of the xerogels avoided shrinkage during drying, but did not favor the insulating performance [ 18 , 23 ]. Thus, new strategies focusing on the role of chemical and porous properties should be adopted to optimize the insulating performance of hybrid xerogels.…”