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Phase transformations in mullite-based nanocomposites
Ist Teil von
International journal of refractory metals & hard materials, 2009-03, Vol.27 (2), p.465-471
Ort / Verlag
Elsevier Ltd
Erscheinungsjahr
2009
Quelle
Alma/SFX Local Collection
Beschreibungen/Notizen
Chemical vapor deposition (CVD) has been used to deposit mullite (3Al
2O
3
·
2SiO
2) based nanocomposite coatings and powders. The nanocomposite coatings typically comprised of Si-rich nanolayer close to the coating-substrate interface which serves as a template for the growth of columnar mullite grains. Finally a third zone composed of Al-rich nanocrystallites is obtained towards the top surface of the coating. The phase stability/transformation of these three zones in the coatings, which is critical for high temperature applications, was investigated in the range 1000–1600
°C. Si-rich nanolayer converts to mullite after a two-step anneal, columnar mullite grains undergo a tetragonal–orthorhombic transformation and the Al-rich nanocrystallite powders completely transform into mullite and α Al
2O
3 above 1500
°C. Various aspects of these phase transformations which eventually lead to the formation of mullite-α Al
2O
3 nanocomposite coating are discussed.