Ceramics-Silikáty 57 (3) 219-224 (2013)

STUDY OF DENSIFICATION OF SOL-GEL DERIVED MULLITE DUE TO EXCESS IRON, NICKEL AND COPPER IONS

Mullite (3Al₂O₃·2SiO₂) samples doped with 0.4 M, 0.6 M, 0.8 M, 1.0 M and 1.2 M of iron, nickel and Copper, were prepared by a sol-gel process. Prepared gels were then dried, grinded, pressed into pellets and sintered at temperatures 1100°C and 1400°C for 4 h. Phase formation, densification behavior has been investigated as a function of the metal content and sintering temperature. The density of the sintered ceramics was measured using Archimedes method. The main intention is to study the role of metal ions in influencing mullitization behavior in the case of the sol-gel reaction process, in order to provide useful information of mullite. This paper deals with the effect of metal ions on mullite formation, microstructure and densification behavior in single-phase sol-gel derived mullite. The results showed with increase in concentration of metals (Fe²⁺, Ni²⁺, Cu²⁺), crystallization of mullite was enhanced which is evident from X-ray diffraction upto G₃ and FESEM of the composites. The density of the doped samples increases with the increase of metal ion concentration as well as with the sintering temperature. Copper-doped mullite exhibits the highest density 2.46 g cm^-3 at 1400°C.

Keywords: Densification, Sol-gel processes, Nanocomposite, Scanning electron microscopy (SEM), X-ray diffraction (XRD)