Mullitization and densification of Y_2O_3-doped reaction-bonded mullite ceramics with different compositions

摘要

Mullite ceramics were fabricated by a reaction-bonding technique from the powder mixtures of Al_2O_3 and Si with an Y_2O_3 addition, The effects of the initial powder composition on the mullitization and densification behaviors were investigated. It has been shown that mullitization and densification can be simultaneously enhanced by a low-viscosity yttrious silicate glass. After a 2h heating at 1400℃, all the specimens exhibited a dense microstructure. Moreover, mullite grains were observed to have an elongated morphology, while the yttrious silicate glass was found to crystallize into Y_2Si_2O_7 at the later stages of mullite growth.