Preparation of pure cordierite through heat treatment of combustion synthesized magnesium aluminate spinel and silica nanoparticles

In the present work, cordierite single-phase powders with high purity were synthesized during a two-step process. First, magnesium aluminate spinel powders were prepared via the KCl-assisted solution combustion route. Then, synthesized spinel particles and nanosilica were planetary milled for ۲۴ h, followed by post-heating at different temperatures for ۳ h. Results showed that post-heating at ۷۰۰ and ۹۰۰ °C did not change the sample phases. However, a magnesium aluminate spinel phase appeared for particles post-heated at ۱۱۰۰ °C. Further heating up to ۱۲۰۰ °C led to the phase transformation of amorphous silica to cristobalite, which reacted with magnesium aluminate spinel to form a cordierite phase. Finally, at ۱۳۰۰ °C, the remaining spinel and cristobalite reaction was completed, and single-phase cordierite powders without additional phases were obtained. Moreover, there was considerable radial shrinkage, and scanning electron microscope micrographs showed the liquid phase sintering of cordierite occurred.

Keywords:

Cordierite , MgAl۲O۴ Spinel , Solution combustion synthesis , Mechanical activation