Processing of polymer‐derived, aerogel‐filled, SiC foams for high‐temperature insulation

Abstract

Porous polymer‐derived ceramics (PDCs) are outperforming materials when low‐density and thermal inertia are required. In this frame, thermal insulating foams such as silicon carbide (SiC) ones possess intriguing requisites for aerospace applications, but their thermal conductivity is affected by gas phase heat transfer and, in the high temperature region, by radiative mechanisms. Owing to the versatility of the PDC route, we present a synthesis pathway to embed PDC SiC aerogels within the open cells of a SiC foam, thus sensibly decreasing the thermal conductivity at 1000°C from 0.371 W·m−1K−1 to 0.243 W·m−1K−1. In this way, it was possible to couple the mechanical properties of the foam with the insulating ability of the aerogels. The presented synthesis was optimized by selecting, among acetone, n‐hexane, and cyclohexane, the proper solvent for the gelation step of the aerogel formation to obtain a proper mesoporous colloidal structure that, after ceramization at 1000°C, presents a specific surface area of 193 m2·g−1. The so‐obtained ceramic composites present a lowest density of 0.18 g·cm−3, a porosity of 90% and a compressive strength of 0.76 MPa.

The Efficacy of Using Thermal Insulator Powder in the Production of Cellulose Acetate Aerogel Foam

“…Despite the low levels of skeletal density, C-aerogels impose a bulkier density both in preceramic and ceramic foam. On the other hand, N-aerogels and Aaerogels have lower bulk density (Zambotti, et al 2022). The most popular kind of aerogel is silica aerogel.…”

Shrinkage Reduction in Nanopore-Rich Cement Paste Based on Facile Organic Modification of Montmorillonite

“…To resolve this critical problem, the replacement of macroscopic pores (air voids) with microscopic pores was proposed to mitigate damage to the mechanical properties of pores and improve their thermal insulation performance [14]. This is because the decrease in pore size could cause a significant reduction in the thermal conductivity of the gas phase in pores and largely extend the heat transfer path of the solid phase [14,15]. Therefore, this approach is regarded as a promising method for balancing insulation performance and other properties, such as mechanical strength.…”

SiOC foam‐aerogel composites: Optimal balance of lightness and excellent thermal insulation

“…[14][15][16][17][18] Others proposed the formation of strength-improved composite structures achieved by using porous substrates (e.g., PU, carbon, SiC, and glass). 19,20,[21][22][23][24][25][26][27][28][29][30][31][32] In this context, for the first time here, the SiOC foam/aerogel composites were designed to demonstrate the manufacturing feasibility of highly porous aerogel monoliths, which can be machinable into a variety of forms while preserving their insulating abilities and mechanical properties.…”