The effect of mechanical activation on the properties of β-sialon precursors

✍ Scribed by Małgorzata Sopicka-Lizer; Marta Tańcula; Tomasz Włodek; Kinga Rodak; Marco Hüller; Vladimir Kochnev; Elena Fokina; Kenneth MacKenzie

• Publisher: Elsevier Science
• Year: 2008
• Tongue: English
• Weight: 934 KB
• Volume: 28
• Category: Article
• ISSN: 0955-2219
• DOI: 10.1016/j.jeurceramsoc.2007.05.003

✦ Synopsis

Nanostructured ␤-sialon precursors were produced from the relevant mixtures of Si 3 N 4 , AlN and Al 2 O 3 by mechanical milling in a new planetary mill with a centrifugal factor of 28 g, at milling times <60 min. Zirconia balls were used in order to avoid the effect of the susceptibility of the separate components to deform under mechanical activation. Several milling regimes were studied and only planetary milling with a high acceleration affected the particles structure. Under these conditions, AlN and Al 2 O 3 crystallites were formed with new boundaries and dislocations, but the ␣-Si 3 N 4 particles were more resistant to deformation. Milling at the higher acceleration conditions produces only a small increase in the crystal lattice parameters of the precursor components, but FTIR and 27 Al and 29 Si solid-state MAS NMR spectroscopy indicates the formation of new tetrahedral AlO 4 units and Si-O-Al bonds, possibly in solid solution or partially reacted hybrid particles of Al 2 O 3 and ␤-Si 3 N 4 . The total oxygen content in the activated sialon precursor mixture can be limited by replacement of alumina by AlN.