Folie 1 Synthesis of metal oxide aerogels from their salts Helmut Schfer, Kathleen Heinrich, Barbara Milow, Lorenz Ratke Institut fr Materialphysik im Weltraum, Linder Hhe, D Kln Folie 2 Background Synthesis of aerogels from their metal salts for application as additives in foundry industry Desired properties:- high surface area - high temperature stability Simple process route Synthesis on a large scale Folie 3 Introduction Preparation of aerogels 1. Hydrolysis of metal alkoxides 2. Condensation reaction to hydro- or alcogel 3. Ageing 4. Drying Folie 4 Introduction Preparation of aerogels 1. Hydrolysis of metal salts 2. Condensation reaction to hydro- or alcogel 3. Ageing strong exothermic reaction!! TiCl 4, SiCl 4, ZrCl 4, ZnCl 2, SnCl 4 Folie 5 Introduction 4. Supercritical Drying with carbon dioxide Before!! Removal of residual salts solvent exchange: water alcohol or acetone >Sodium silicate + KCr(SO 4 ) 2 >Al(Cl) 3 >Sodium silicate + FeCl 3 >FeCl 3 >Zr-alkoxide Folie 6 Characterization Adsorption/Desorption measurement with nitrogen TGA-FTIR Scanning electron microscopy Folie 7 Results BET Surface BJH-PlotAdsorption/Desorption Desorption Adsorption Zirconium aerogel: BET 498 m 2 /g Folie 8 Results BET Surface PrecursorCatalystBET in m 2 /g ZrCl 4 /TiCl 4 propylene oxide577 ZrCl 4 propylene oxide498 SiCl FeCl 3 H 2 Opropylene oxide363 AlCl 3 propylene oxide389 Sodium silicate + SnCl SbCl 3 propylene oxide8 Wide range of different aerogels with high surface areas!! Folie 9 The right choice Metal oxideFp in CSintering temperature (calc.) in C ZrO Al 2 O TiO SiO Fe 2 O Toxicity -Price per kg -Availability Folie 10 Results BET Surface MetaloxideCatalystBET in m 2 /g ZrCl 4 /TiCl 4 propylene oxide577 ZrCl 4 propylene oxide498 SiCl FeCl 3 H 2 Opropylene oxide363 AlCl 3 propylene oxide389 Sodium silicate + SnCl SbCl 3 propylene oxide8 Sodium silicate + KCr(SO 4 ) 2 *H 2 O -400 Zr-, Ti- and Silica-Aerogels showed best results in preliminary tests for foundry applications! Folie 11 Results TGA: Silica-Aerogel Folie 12 Results IR (122 C): (Silica-Aerogel) IR-Library Extracted from 3D-IR-Spectra Folie 13 Results SEM Silica-Aerogel (572 m 2 /g) Folie 14 Results Large Scale synthesis Zirconium-Aerogels20 cm 3 (typical lab scale) 50 cm 3 (works fine) 500 cm 3 (monolith) Successful preparation of Zirconium aerogel up to 500 cm L Pilot plant scale with industrial partners Folie 15 Conclusion Aerogels can be easily synthesized from their metal salts A wide range of different aerogels with high surface areas were synthesized Zirconia aerogel up to 500 cm 3 were synthesized Focus on Zr-, Ti- and Silica-aerogels for foundry applications