EFFECT OF MgAl₂O₄ ON THE GROWTH OF β -Si₃Al₃O₃N₅ PREPARED BY CARBOTHERMAL REDUCTION BY NITRIDING

Abstract

The β-Si 3 Al 3 O 3 N 5 compound was experimentally prepared by carbothermal reduction by nitriding using pure SiO 2 , Al 2 O 3 , C, and N2. The effect of MgAl 2 O 4 on the growth of β-Si 3 Al 3 O 3 N 5 was investigated as a function of temperature and molar concentration of MgAl 2 O 4 . In this way, it was found that the formation of β-Si 3 Al 3 O 3 N 5 when MgAl 2 O 4 is present in concentrations lower than 13 wt. % occurs. However, when the MgAl 2 O 4 concentration was as high as 25.6 wt. %, the formation of β-Si 3 Al 3 O 3 N 5 compound was not attained and the formation of quaternary magnesium-rich SiAlON phases such as Mg-Si 4 Al 2 O 6 N 4 was found. Moreover, the mechanistic steps during the consolidation of SiAlON type structures are presented and discussed.