Synthesis of Mullite-Containing Ceramics in a Low-Temperature Plasma

This work shows the possibility of synthesizing mullite-containing ceramics from an aluminosilicate melt obtained on the basis of boehmite (Al 2 O 3 ·H 2 O) and kaolin (Al 2 O 3 ·2SiO 2 ·2H 2 O) under conditions of thermal plasma energy. The morphology, phase, and chemical composition of the resulting mullite-containing ceramics have been studied by X-ray phase analysis and optical and scanning electron microscopy. It is established that the melting products are characterized by filamentous-acicular form of mullite crystals (3Al 2 O 3 ·2SiO 2 ), while, on the surface during cooling of the melt, centers of recrystallization of secondary mullite are formed that penetrate sections of the glassy phase region, in which the Si–O bonds in the silicon-oxygen tetrahedra of the amorphous phase are similar to the α-SiO 2 bonds.