The effect of precursor composition and sintering additives on the formation of ß-sialon from Al, Si and Al2O3 powders

Helen Ewing, S. Yang

Research output: Contribution to journalArticle

10 Citations (Scopus)

Abstract

A study was performed to investigate the effect of increasing the Al or Al2O3 precursor content, above the stoichiometric amount, on the formation of β-sialon by pressureless sintering of Al, Si and Al2O3 powders in flowing nitrogen gas. The effect of adding Y2O3 or Fe to the precursor mixture, on the β-sialon formation, was also studied. The phase morphology and yield produced by the various compositions were examined using X-ray diffraction (XRD). Additional Al2O3 decreases the β-sialon phase yield and results in a greater amount of Al2O3 in the final sintered material. Additional Al improved the conversion to β-sialon up to a maximum of 4 wt% Al beyond which the β-sialon:15R sialon ratio in the sintered material decreases. 1 wt% Y2O3 was determined to be the optimum sintering additive content, as yttrium aluminium garnet (YAG) was found to be present in materials formed from higher Y2O3 containing precursors. The presence of Fe in the precursor powder retards the formation of β-sialon by preferentially forming Fe silicides at low temperatures, thus depleting the reaction system of elemental Si, favouring the formation of 15R sialon.
LanguageEnglish
Pages1667-1673
Number of pages7
JournalCeramics International
Volume37
Issue number5
DOIs
Publication statusPublished - Jul 2011

Fingerprint

Powders
Sintering
Chemical analysis
Silicides
Garnets
Yttrium
Nitrogen
Gases
Aluminum
X ray diffraction
Temperature
yttrium-aluminum-garnet

Keywords

  • sintering
  • refractories
  • Sialon
  • ceramics

Cite this

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abstract = "A study was performed to investigate the effect of increasing the Al or Al2O3 precursor content, above the stoichiometric amount, on the formation of β-sialon by pressureless sintering of Al, Si and Al2O3 powders in flowing nitrogen gas. The effect of adding Y2O3 or Fe to the precursor mixture, on the β-sialon formation, was also studied. The phase morphology and yield produced by the various compositions were examined using X-ray diffraction (XRD). Additional Al2O3 decreases the β-sialon phase yield and results in a greater amount of Al2O3 in the final sintered material. Additional Al improved the conversion to β-sialon up to a maximum of 4 wt{\%} Al beyond which the β-sialon:15R sialon ratio in the sintered material decreases. 1 wt{\%} Y2O3 was determined to be the optimum sintering additive content, as yttrium aluminium garnet (YAG) was found to be present in materials formed from higher Y2O3 containing precursors. The presence of Fe in the precursor powder retards the formation of β-sialon by preferentially forming Fe silicides at low temperatures, thus depleting the reaction system of elemental Si, favouring the formation of 15R sialon.",
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The effect of precursor composition and sintering additives on the formation of ß-sialon from Al, Si and Al2O3 powders. / Ewing, Helen; Yang, S.

In: Ceramics International, Vol. 37, No. 5, 07.2011, p. 1667-1673.

Research output: Contribution to journalArticle

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