Preparation of monodisperse silica spheres and determination of their densification behaviour

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TOPUZ B., Simsek D., Ciftcioglu M.

CERAMICS INTERNATIONAL, cilt.41, sa.1, ss.43-52, 2015 (SCI-Expanded) identifier identifier

  • Yayın Türü: Makale / Tam Makale
  • Cilt numarası: 41 Sayı: 1
  • Basım Tarihi: 2015
  • Doi Numarası: 10.1016/j.ceramint.2014.07.112
  • Dergi Adı: CERAMICS INTERNATIONAL
  • Derginin Tarandığı İndeksler: Science Citation Index Expanded (SCI-EXPANDED), Scopus
  • Sayfa Sayıları: ss.43-52
  • Anahtar Kelimeler: Stober process, Silica spheres, Growth mechanism, Densification, MODEL POWDER COMPACTS, SIO2 GLASS, GROWTH, SIZE, GEL, NUCLEATION, PARTICLES, TRANSITION, DYNAMICS, FILMS
  • Ankara Üniversitesi Adresli: Evet

Özet

Monodisperse silica spheres in the 50-520 nm size range were prepared by using the Stober process. Diffusive growth has been determined from Nielsen chronomal analysis for the 520 and 310 nm monodisperse silica spheres. The densification behaviour and evolution of the microstructure of the sphere compacts indicated an inverse dependence of shrinkage rate on the sphere size due to viscous sintering. The increase in sphere size from 50 to 500 nm shifted the densification temperature from similar to 1120 degrees C to 1240 degrees C. The amorphous nature of the spheres was conserved up to 1200 degrees C where cristobalite crystal nucleation started and complete transformation to cristobalite phase has been observed upon heat treatment at 1300 degrees C. The activation energies for viscous sintering according to the Frenkel and Mackenzie/Shuttleworth models were calculated as 125 and 335 kJ/mol, respectively. These substantially low activation energies can be attributed to the presence of a significant level of silanol groups. (C) 2014 Elsevier Ltd and Techna Group S.r.l. All rights reserved.