Microstructure development and properties of novel Ba-doped phase Sialon ceramics

Understanding the mechanical properties of hot pressed Ba-doped S-phase SiAlON ceramics

“…As reported in Ref. 17, the average S-phase composition, based on multiple TEM-EDS analysis, can be confirmed as Ba 2 Si 12−x Al x O 2+x N 16−x (x = 2.0 ± 0.2) . TEM-EDS analysis reveals the presence of Ba-rich aluminosilicate as residue glass phase at the grain boundary triple pockets (Fig.…”

“…XRD results indicated the predominant presence of S-phase with the detectable amount of ␤-Si 3 N 4 and in some samples unreacted ␣-Si 3 N 4 (not shown here and reported in Ref. 17). The representative SEM images (BSE mode) of S1600 and S1750 are provided in Fig.…”

“…It can be noted that the hardness and toughness values for 50 N indent load have been taken from Ref. 17. Such a selection of indent loads (50-300 N) has been made in order to study indentation size effect.…”

“…[15][16][17] In an earlier work, we have reported the microstructural development and phase assemblage 0955-2219/$ -see front matter © 2008 Elsevier Ltd. All rights reserved. doi:10.1016/j.jeurceramsoc.2008.07.005 study of the Ba-doped S-SiAlON ceramic 17 and in this follow-up work, the same hot pressed samples are investigated for detailed mechanical property evaluation. The transmission electron microscopy (TEM) analysis of the hot pressed microstructure, revealed the complex microstructure, consisting of major amount of coarser, tabular-shaped 'S-phase' grains as well as noticeable amount of ␤-Si 3 N 4 needles and residual glassy phase.…”

“…The transmission electron microscopy (TEM) analysis of the hot pressed microstructure, revealed the complex microstructure, consisting of major amount of coarser, tabular-shaped 'S-phase' grains as well as noticeable amount of ␤-Si 3 N 4 needles and residual glassy phase. 17 In order to obtain an understanding of the basic mechanical behavior of such a new SiAlON composition, we have performed systematic indentation measurements at various loads. While the mechanical properties of various compositionally tailored/modified SiAlON ceramics (␣-and ␤-SiAlON) are widely reported, it is of our interest to investigate whether the characteristic coarser elongated 'S' phase morphology in Ba-doped S-SiAlON ceramic can provide better toughness.…”