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Synthesis of metal oxide aerogels from their salts Helmut Schäfer, Kathleen Heinrich , Barbara Milow, Lorenz Ratke

Synthesis of metal oxide aerogels from their salts Helmut Schäfer, Kathleen Heinrich , Barbara Milow, Lorenz Ratke Institut für Materialphysik im Weltraum, Linder Höhe, D-51147 Köln. Background. Synthesis of aerogels from their metal salts for application as additives in foundry industry

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Synthesis of metal oxide aerogels from their salts Helmut Schäfer, Kathleen Heinrich , Barbara Milow, Lorenz Ratke

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  1. Synthesis of metal oxide aerogels from their salts Helmut Schäfer, Kathleen Heinrich, Barbara Milow, Lorenz Ratke Institut für Materialphysik im Weltraum, Linder Höhe, D-51147 Köln

  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

  3. Introduction • Preparation of aerogels • 1. Hydrolysis of metal alkoxides • 2. Condensation reaction to hydro- or alcogel • 3. Ageing • 4. Drying

  4. Introduction • Preparation of aerogels • 1. Hydrolysis of metal salts • 2. Condensation reaction to hydro- or alcogel • 3. Ageing strong exothermic reaction!! TiCl4, SiCl4, ZrCl4, ZnCl2, SnCl4

  5. Introduction • 4. Supercritical Drying with carbon dioxide • Before!! • Removal of residual salts • solvent exchange: water → alcohol or acetone >Sodium silicate + KCr(SO4)2 >Al(Cl)3 >FeCl3 >Sodium silicate + FeCl3 >Zr-alkoxide

  6. Characterization • Adsorption/Desorption measurement with nitrogen • TGA-FTIR • Scanning electron microscopy

  7. Zirconium aerogel: BET 498 m2/g Results – BET Surface Adsorption/Desorption BJH-Plot Desorption Adsorption

  8. Results – BET Surface Wide range of different aerogels with high surface areas!!

  9. The right choice • Toxicity • Price per kg • Availability

  10. Results – BET Surface Zr-, Ti- and Silica-Aerogels showed best results in preliminary tests for foundry applications!

  11. Results – TGA: Silica-Aerogel

  12. Results – IR (122 °C): (Silica-Aerogel) Extracted from 3D-IR-Spectra IR-Library

  13. Results – SEM Silica-Aerogel (572 m2/g)

  14. Results – Large Scale synthesis • Zirconium-Aerogels 20 cm3 (typical lab scale) Successful preparation of Zirconium aerogel up to 500 cm3 50 cm3 (works fine) 500 cm3 (monolith) 500 L Pilot plant scale with industrial partners

  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 cm3 were synthesized • Focus on Zr-, Ti- and Silica-aerogels for foundry applications

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