(163k) Metal Oxide Aerogels Development from Metal Scraps for High-Value Engineering Applications

Metal oxide aerogels have been developed successfully from metal wastes through a cost-effective sol-gel method in this work. Two aluminum and magnesium scrape wastes are recycled into the aerogels by gelation of the hydroxide of aluminum and magnesium into polyvinyl alcohol solvent at ambient conditions and then by the freeze-drying (-50°C, 30 Pa) and calcination (450°C) processes. The developed metal oxide-based aerogels have the ultra-low densities of 0.08 - 0.15 g/cm³ and the very high porosity of 89 - 96 %. The lightweight metal oxide aerogels can easily float on water and stand a 5-kg loading without damaging their structure. The aerogels exhibit the low electrical conductivity (1.8 - 5.2 ×10^-8 S/m) and low thermal conductivity (K = 0.029 - 0.042 W/m.K) at room temperature. They can stand up to 800°C. These experimental results indicate that the metal oxide aerogels could be the promising candidates for several applications such as leisure and automotive industry, acoustic insulation, defence, and aerospace.